vitessio/vitess Release Notes

Vitess v21.0.0 (2024-10-29)

# Release of Vitess v21.0.0
## Summary

### Table of Contents

- **[Known Issue](#known-issues)**
    - **[Backup reports itself as successful despite failures](#backup-reports-as-successful)**
- **[Major Changes](#major-changes)**
    - **[Deprecations and Deletions](#deprecations-and-deletions)**
        - [Deprecated VTTablet Flags](#vttablet-flags)
        - [Deletion of deprecated metrics](#metric-deletion)
        - [Deprecated Metrics](#deprecations-metrics)
    - **[Traffic Mirroring](#traffic-mirroring)**
    - **[Atomic Distributed Transaction Support](#atomic-transaction)**
    - **[New VTGate Shutdown Behavior](#new-vtgate-shutdown-behavior)**
    - **[Tablet Throttler: Multi-Metric support](#tablet-throttler)**
    - **[Allow Cross Cell Promotion in PRS](#allow-cross-cell)**
    - **[Support for recursive CTEs](#recursive-cte)**
    - **[VTGate Tablet Balancer](#tablet-balancer)**
    - **[Query Timeout Override](#query-timeout)**
    - **[New Backup Engine](#new-backup-engine)**
    - **[Dynamic VReplication Configuration](#dynamic-vreplication-configuration)**
    - **[Reference Table Materialization](#reference-table-materialization)**
    - **[New VEXPLAIN Modes: TRACE and KEYS](#new-vexplain-modes)**
    - **[Automatically Replace MySQL auto_increment Clauses with Vitess Sequences](#auto-replace-mysql-autoinc-with-seq)**
    - **[Experimental MySQL 8.4 support](#experimental-mysql-84)**
    - **[Current Errant GTIDs Count Metric](#errant-gtid-metric)**
    - **[vtctldclient ChangeTabletTags](#vtctldclient-changetablettags)**
    - **[Support for specifying expected primary in reparents](#reparents-expectedprimary)**

## Known Issue

### Backup reports itself as successful despite failures

In this release, we identified an issue where a backup may succeed even if a file fails to be backed up.
Leading to a successful backup, even if some errors occurred.
This only happen with the Builtin Backup Engine, and when all files have already been initiated in the backup process.
For more details, please refer to the related GitHub Issue https://github.com/vitessio/vitess/issues/17063.

## Major Changes

### Deprecations and Deletions

#### Deprecated VTTablet Flags

- `queryserver-enable-settings-pool` flag, added in `v15`, has been on by default since `v17`.
  It is now deprecated and will be removed in a future release.

#### Deletion of deprecated metrics

The following VTOrc metrics were deprecated in `v20`. They have now been deleted.

|                 Metric Name                  |
|:--------------------------------------------:|
|           `analysis.change.write`            |        
|                `audit.write`                 |     
|            `discoveries.attempt`             |          
|              `discoveries.fail`              |        
| `discoveries.instance_poll_seconds_exceeded` | 
|          `discoveries.queue_length`          |       
|          `discoveries.recent_count`          |        
|               `instance.read`                |            
|           `instance.read_topology`           |       
|         `emergency_reparent_counts`          |       
|          `planned_reparent_counts`           |      
|      `reparent_shard_operation_timings`      |  

#### Deprecated Metrics

The following metrics are now deprecated and will be deleted in a future release, please use their replacements.

| Component  |      Metric Name      |           Replaced By           |
|------------|:---------------------:|:-------------------------------:|
| `vttablet` |  `QueryCacheLength`   |  `QueryEnginePlanCacheLength`   |
| `vttablet` |   `QueryCacheSize`    |   `QueryEnginePlanCacheSize`    |
| `vttablet` | `QueryCacheCapacity`  | `QueryEnginePlanCacheCapacity`  |
| `vttablet` | `QueryCacheEvictions` | `QueryEnginePlanCacheEvictions` |
| `vttablet` |   `QueryCacheHits`    |   `QueryEnginePlanCacheHits`    |
| `vttablet` |  `QueryCacheMisses`   |  `QueryEnginePlanCacheMisses`   |

### Traffic Mirroring

Traffic mirroring is intended to help reduce some of the uncertainty inherent to `MoveTables SwitchTraffic`. When
traffic mirroring is enabled, VTGate will mirror a percentage of traffic from one keyspace to another.

Mirror rules may be enabled through `vtctldclient` with `MoveTables MirrorTraffic`. For example:

```bash
$ vtctldclient --server :15999 MoveTables --target-keyspace customer --workflow commerce2customer MirrorTraffic --percent 5.0
```

Mirror rules can be inspected with `GetMirrorRules`.

### Atomic Distributed Transaction Support

We have introduced atomic distributed transactions as an experimental feature.
Users can now run multi-shard transactions with stronger guarantees. 
Vitess now provides two modes of transactional guarantees for multi-shard transactions: Best Effort and Atomic. 
These can be selected based on the user’s requirements and the trade-offs they are willing to make.

Follow the documentation to enable [Atomic Distributed Transaction](https://vitess.io/docs/21.0/reference/features/distributed-transaction/)

For more details on the implementation and trade-offs, please refer to the [RFC](https://github.com/vitessio/vitess/issues/16245)

### New VTGate Shutdown Behavior

We added a new option to VTGate to disallow new connections while VTGate is shutting down,
while allowing existing connections to finish their work until they manually disconnect or until
the `--onterm_timeout` is reached, without getting a `Server shutdown in progress` error.

This new behavior can be enabled by specifying the new `--mysql-server-drain-onterm` flag to VTGate.

You can find more information about this option in the [RFC](https://github.com/vitessio/vitess/issues/15971).

### Tablet Throttler: Multi-Metric support

Up until `v20`, the tablet throttler would only monitor and use a single metric. That would be replication lag, by
default, or could be the result of a custom query. In this release, we introduce a major redesign so that the throttler 
monitors and uses multiple metrics at the same time, including the above two.

The default behavior now is to monitor all metrics, but only use `lag` (if the custom query is undefined) or the `custom` 
metric (if the custom query is defined). This is backwards-compatible with `v20`. A `v20` `PRIMARY` is compatible with
a `v21` `REPLICA`, and a `v21` `PRIMARY` is compatible with a `v20` `REPLICA`.

However, it is now possible to assign any combination of one or more metrics for a given app. The throttler
would then accept or reject the app's requests based on the health of _all_ assigned metrics. We have provided a pre-defined
list of metrics:

- `lag`: replication lag based on heartbeat injection.
- `threads_running`: concurrent active threads on the MySQL server.
- `loadavg`: per core load average measured on the tablet instance/pod.
- `custom`: the result of a custom query executed on the MySQL server.

Each metric has a default threshold which can be overridden by the `UpdateThrottlerConfig` command.

The throttler also supports the catch-all `"all"` app name, and it is thus possible to assign metrics to **all** apps.
Explicit app to metric assignments will override the catch-all configuration.

Metrics are assigned a default _scope_, which could be `self` (isolated to the tablet) or `shard` (max, aka **worst**
value among shard tablets). It is further possible to require a different scope for each metric.

### Allow Cross Cell Promotion in PRS

Up until now if the users wanted to promote a replica in a different cell from the current primary
using `PlannedReparentShard`, they had to specify the new primary with the `--new-primary` flag.

We have now added a new flag `--allow-cross-cell-promotion` that lets `PlannedReparentShard` choose a primary in a
different cell even if no new primary is provided explicitly.

### Experimental support for recursive CTEs

We have added experimental support for recursive CTEs in Vitess. We are marking it as experimental because it is not yet
fully tested and may have some limitations. We are looking for feedback from the community to improve this feature.

### VTGate Tablet Balancer

When a VTGate routes a query and has multiple available tablets for a given shard / tablet type (e.g. REPLICA), the
current default behavior routes the query with local cell affinity and round robin policy. The VTGate Tablet Balancer
provides an alternate mechanism that routes queries to maintain an even distribution of query load to each tablet, while
preferentially routing to tablets in the same cell as the VTGate.

The tablet balancer is enabled by a new flag `--enable-balancer` and configured by `--balancer-vtgate-cells`
and `--balancer-keyspaces`.

See the [RFC ](https://github.com/vitessio/vitess/issues/12241) for more details on the design and configuration of this feature.

### Query Timeout Override

VTGate sends an authoritative query timeout to VTTablet when the `QUERY_TIMEOUT_MS` comment directive,
`query_timeout` session system variable, or `query-timeout` flag is set.
The order of precedence is: comment directive > session variable > VTGate flag.
VTTablet overrides its default query timeout with the value received from VTGate.
All timeouts are specified in milliseconds.

When a query is executed inside a transaction, there is an additional nuance. The actual timeout used will be the smaller 
of the transaction timeout and the query timeout.

A query can also be set to have no timeout by using the `QUERY_TIMEOUT_MS` comment directive with a value of `0`.

Example usage:
`select /*vt+ QUERY_TIMEOUT_MS=30 */ col from tbl`

### New Backup Engine (EXPERIMENTAL)

We are introducing a new backup engine for logical backups in order to support use cases that require something other 
than physical backups. This feature is experimental and is based on [MySQL Shell](https://dev.mysql.com/doc/mysql-shell/8.0/en/).

The new engine is enabled by using `--backup_engine_implementation=mysqlshell`. There are other options that are required, 
so please read the [documentation](https://vitess.io/docs/21.0/user-guides/operating-vitess/backup-and-restore/creating-a-backup/) to learn which options are required and how to configure them.

### Dynamic VReplication Configuration

Previously, many of the configuration options for VReplication Workflows had to be provided using VTTablet flags. This 
meant that any change to VReplication configuration required restarting VTTablets. We now allow these to be overridden 
while creating a workflow or dynamically after the workflow is already in progress.

### Reference Table Materialization

There is a new option in [`Materialize` workflows](https://vitess.io/docs/reference/vreplication/materialize/) to keep a synced copy of [reference or lookup tables](https://vitess.io/docs/reference/vreplication/reference_tables/) 
(countries, states, zip codes, etc) from an unsharded keyspace, which holds the source of truth for the reference 
table, to all shards in a sharded keyspace.

### New VEXPLAIN Modes: TRACE and KEYS

#### VEXPLAIN TRACE

The new `TRACE` mode for `VEXPLAIN` provides a detailed execution trace of queries, showing how they're processed through various 
operators and interactions with tablets. This mode is particularly useful for:

- Identifying performance bottlenecks
- Understanding query execution patterns
- Optimizing complex queries
- Debugging unexpected query behavior

`TRACE` mode runs the query and logs all interactions, returning a JSON representation of the query execution plan with additional 
statistics like number of calls, average rows processed, and number of shards queried.

#### VEXPLAIN KEYS

The `KEYS` mode for `VEXPLAIN` offers a concise summary of query structure, highlighting columns used in joins, filters, and 
grouping operations. This information is crucial for:

- Identifying potential sharding key candidates
- Optimizing query performance
- Analyzing query patterns to inform database design decisions

`KEYS` mode analyzes the query structure without executing it, providing JSON output that includes grouping columns, join columns, 
filter columns (potential candidates for indexes, primary keys, or sharding keys), and the statement type.

These new `VEXPLAIN` modes enhance Vitess's query analysis capabilities, allowing for more informed decisions about sharding 
strategies and query optimization.

### Automatically Replace MySQL auto_increment Clauses with Vitess Sequences

In https://github.com/vitessio/vitess/pull/16860 we added support for replacing MySQL `auto_increment` clauses with [Vitess Sequences](https://vitess.io/docs/reference/features/vitess-sequences/), performing all of the setup and initialization
work automatically during the [`MoveTables`](https://vitess.io/docs/reference/vreplication/movetables/) workflow. As part of that work we have deprecated the
[`--remove-sharded-auto-increment` boolean flag](https://vitess.io/docs/20.0/reference/programs/vtctldclient/vtctldclient_movetables/vtctldclient_movetables_create/) and you should begin using the new
[`--sharded-auto-increment-handling` flag](https://vitess.io/docs/21.0/reference/programs/vtctldclient/vtctldclient_movetables/vtctldclient_movetables_create/) instead. Please see the new
[`MoveTables` Auto Increment Handling](https://vitess.io/docs/21.0/reference/vreplication/movetables/#auto-increment-handling) documentation for additional details.

### Experimental MySQL 8.4 support

We have added experimental support for MySQL 8.4. It passes the Vitess test suite, but it is otherwise not yet tested. We are looking for feedback from the community to improve this to move support out of the experimental phase in a future release.

### Current Errant GTIDs Count Metric
A new metric called `CurrentErrantGTIDCount` has been added to the `VTOrc` component. 
This metric shows the current count of the errant GTIDs in the tablets.

### `vtctldclient ChangeTabletTags` command

The `vtctldclient` command `ChangeTabletTags` was added to allow the tags of a tablet to be changed dynamically.

### Support specifying expected primary in reparents

The `EmergencyReparentShard` and `PlannedReparentShard` commands and RPCs now support specifying a primary we expect to still be the current primary in order for a reparent operation to be processed. This allows reparents to be conditional on a specific state being true.

------------
The entire changelog for this release can be found [here](https://github.com/vitessio/vitess/blob/main/changelog/21.0/21.0.0/changelog.md).

The release includes 364 merged Pull Requests.

Thanks to all our contributors: @GrahamCampbell, @GuptaManan100, @Utkar5hM, @anshikavashistha, @app/dependabot, @app/vitess-bot, @arthurschreiber, @beingnoble03, @brendar, @cameronmccord2, @chrism1001, @cuishuang, @dbussink, @deepthi, @demmer, @frouioui, @harshit-gangal, @harshitasao, @icyflame, @kirtanchandak, @mattlord, @mattrobenolt, @maxenglander, @mcrauwel, @notfelineit, @perminov, @rafer, @rohit-nayak-ps, @runewake2, @rvrangel, @shanth96, @shlomi-noach, @systay, @timvaillancourt, @vitess-bot

Vitess v21.0.0-rc2 (2024-10-23)

# Release of Vitess v21.0.0
## Summary

### Table of Contents

- **[Major Changes](#major-changes)**
    - **[Deprecations and Deletions](#deprecations-and-deletions)**
        - [Deprecated VTTablet Flags](#vttablet-flags)
        - [Deletion of deprecated metrics](#metric-deletion)
        - [Deprecated Metrics](#deprecations-metrics)
    - **[Traffic Mirroring](#traffic-mirroring)**
    - **[New VTGate Shutdown Behavior](#new-vtgate-shutdown-behavior)**
    - **[Tablet Throttler: Multi-Metric support](#tablet-throttler)**
    - **[Allow Cross Cell Promotion in PRS](#allow-cross-cell)**
    - **[Support for recursive CTEs](#recursive-cte)**
    - **[VTGate Tablet Balancer](#tablet-balancer)**
    - **[Query Timeout Override](#query-timeout)**
    - **[New Backup Engine](#new-backup-engine)**
    - **[Dynamic VReplication Configuration](#dynamic-vreplication-configuration)**
    - **[Reference Table Materialization](#reference-table-materialization)**
    - **[New VEXPLAIN Modes: TRACE and KEYS](#new-vexplain-modes)**
    - **[Errant GTID Detection on VTTablets](#errant-gtid-vttablet)**
    - **[Automatically Replace MySQL auto_increment Clauses with Vitess Sequences](#auto-replace-mysql-autoinc-with-seq)**
    - **[Experimental MySQL 8.4 support](#experimental-mysql-84)**
    - **[Current Errant GTIDs Count Metric](#errant-gtid-metric)**
    - **[vtctldclient ChangeTabletTags](#vtctldclient-changetablettags)**
    - **[Support for specifying expected primary in reparents](#reparents-expectedprimary)**


## Major Changes

### Deprecations and Deletions

#### Deprecated VTTablet Flags

- `queryserver-enable-settings-pool` flag, added in `v15`, has been on by default since `v17`.
  It is now deprecated and will be removed in a future release.

#### Deletion of deprecated metrics

The following VTOrc metrics were deprecated in `v20`. They have now been deleted.

|                 Metric Name                  |
|:--------------------------------------------:|
|           `analysis.change.write`            |        
|                `audit.write`                 |     
|            `discoveries.attempt`             |          
|              `discoveries.fail`              |        
| `discoveries.instance_poll_seconds_exceeded` | 
|          `discoveries.queue_length`          |       
|          `discoveries.recent_count`          |        
|               `instance.read`                |            
|           `instance.read_topology`           |       
|         `emergency_reparent_counts`          |       
|          `planned_reparent_counts`           |      
|      `reparent_shard_operation_timings`      |  

#### Deprecated Metrics

The following metrics are now deprecated and will be deleted in a future release, please use their replacements.

| Component  |      Metric Name      |           Replaced By           |
|------------|:---------------------:|:-------------------------------:|
| `vttablet` |  `QueryCacheLength`   |  `QueryEnginePlanCacheLength`   |
| `vttablet` |   `QueryCacheSize`    |   `QueryEnginePlanCacheSize`    |
| `vttablet` | `QueryCacheCapacity`  | `QueryEnginePlanCacheCapacity`  |
| `vttablet` | `QueryCacheEvictions` | `QueryEnginePlanCacheEvictions` |
| `vttablet` |   `QueryCacheHits`    |   `QueryEnginePlanCacheHits`    |
| `vttablet` |  `QueryCacheMisses`   |  `QueryEnginePlanCacheMisses`   |

### Traffic Mirroring

Traffic mirroring is intended to help reduce some of the uncertainty inherent to `MoveTables SwitchTraffic`. When
traffic mirroring is enabled, VTGate will mirror a percentage of traffic from one keyspace to another.

Mirror rules may be enabled through `vtctldclient` with `MoveTables MirrorTraffic`. For example:

```bash
$ vtctldclient --server :15999 MoveTables --target-keyspace customer --workflow commerce2customer MirrorTraffic --percent 5.0
```

Mirror rules can be inspected with `GetMirrorRules`.

### New VTGate Shutdown Behavior

We added a new option to VTGate to disallow new connections while VTGate is shutting down,
while allowing existing connections to finish their work until they manually disconnect or until
the `--onterm_timeout` is reached, without getting a `Server shutdown in progress` error.

This new behavior can be enabled by specifying the new `--mysql-server-drain-onterm` flag to VTGate.

You can find more information about this option in the [RFC](https://github.com/vitessio/vitess/issues/15971).

### Tablet Throttler: Multi-Metric support

Up until `v20`, the tablet throttler would only monitor and use a single metric. That would be replication lag, by
default, or could be the result of a custom query. In this release, we introduce a major redesign so that the throttler 
monitors and uses multiple metrics at the same time, including the above two.

The default behavior now is to monitor all metrics, but only use `lag` (if the custom query is undefined) or the `custom` 
metric (if the custom query is defined). This is backwards-compatible with `v20`. A `v20` `PRIMARY` is compatible with
a `v21` `REPLICA`, and a `v21` `PRIMARY` is compatible with a `v20` `REPLICA`.

However, it is now possible to assign any combination of one or more metrics for a given app. The throttler
would then accept or reject the app's requests based on the health of _all_ assigned metrics. We have provided a pre-defined
list of metrics:

- `lag`: replication lag based on heartbeat injection.
- `threads_running`: concurrent active threads on the MySQL server.
- `loadavg`: per core load average measured on the tablet instance/pod.
- `custom`: the result of a custom query executed on the MySQL server.

Each metric has a default threshold which can be overridden by the `UpdateThrottlerConfig` command.

The throttler also supports the catch-all `"all"` app name, and it is thus possible to assign metrics to **all** apps.
Explicit app to metric assignments will override the catch-all configuration.

Metrics are assigned a default _scope_, which could be `self` (isolated to the tablet) or `shard` (max, aka **worst**
value among shard tablets). It is further possible to require a different scope for each metric.

### Allow Cross Cell Promotion in PRS

Up until now if the users wanted to promote a replica in a different cell from the current primary
using `PlannedReparentShard`, they had to specify the new primary with the `--new-primary` flag.

We have now added a new flag `--allow-cross-cell-promotion` that lets `PlannedReparentShard` choose a primary in a
different cell even if no new primary is provided explicitly.

### Experimental support for recursive CTEs

We have added experimental support for recursive CTEs in Vitess. We are marking it as experimental because it is not yet
fully tested and may have some limitations. We are looking for feedback from the community to improve this feature.

### VTGate Tablet Balancer

When a VTGate routes a query and has multiple available tablets for a given shard / tablet type (e.g. REPLICA), the
current default behavior routes the query with local cell affinity and round robin policy. The VTGate Tablet Balancer
provides an alternate mechanism that routes queries to maintain an even distribution of query load to each tablet, while
preferentially routing to tablets in the same cell as the VTGate.

The tablet balancer is enabled by a new flag `--enable-balancer` and configured by `--balancer-vtgate-cells`
and `--balancer-keyspaces`.

See the [RFC ](https://github.com/vitessio/vitess/issues/12241) for more details on the design and configuration of this feature.

### Query Timeout Override

VTGate sends an authoritative query timeout to VTTablet when the `QUERY_TIMEOUT_MS` comment directive,
`query_timeout` session system variable, or `query-timeout` flag is set.
The order of precedence is: comment directive > session variable > VTGate flag.
VTTablet overrides its default query timeout with the value received from VTGate.
All timeouts are specified in milliseconds.

When a query is executed inside a transaction, there is an additional nuance. The actual timeout used will be the smaller 
of the transaction timeout and the query timeout.

A query can also be set to have no timeout by using the `QUERY_TIMEOUT_MS` comment directive with a value of `0`.

Example usage:
`select /*vt+ QUERY_TIMEOUT_MS=30 */ col from tbl`

### New Backup Engine (EXPERIMENTAL)

We are introducing a new backup engine for logical backups in order to support use cases that require something other 
than physical backups. This feature is experimental and is based on [MySQL Shell](https://dev.mysql.com/doc/mysql-shell/8.0/en/).

The new engine is enabled by using `--backup_engine_implementation=mysqlshell`. There are other options that are required, 
so please read the [documentation](https://vitess.io/docs/21.0/user-guides/operating-vitess/backup-and-restore/creating-a-backup/) to learn which options are required and how to configure them.

### Dynamic VReplication Configuration

Previously, many of the configuration options for VReplication Workflows had to be provided using VTTablet flags. This 
meant that any change to VReplication configuration required restarting VTTablets. We now allow these to be overridden 
while creating a workflow or dynamically after the workflow is already in progress.

### Reference Table Materialization

There is a new option in [`Materialize` workflows](https://vitess.io/docs/reference/vreplication/materialize/) to keep a synced copy of [reference or lookup tables](https://vitess.io/docs/reference/vreplication/reference_tables/) 
(countries, states, zip codes, etc) from an unsharded keyspace, which holds the source of truth for the reference 
table, to all shards in a sharded keyspace.

### New VEXPLAIN Modes: TRACE and KEYS

#### VEXPLAIN TRACE

The new `TRACE` mode for `VEXPLAIN` provides a detailed execution trace of queries, showing how they're processed through various 
operators and interactions with tablets. This mode is particularly useful for:

- Identifying performance bottlenecks
- Understanding query execution patterns
- Optimizing complex queries
- Debugging unexpected query behavior

`TRACE` mode runs the query and logs all interactions, returning a JSON representation of the query execution plan with additional 
statistics like number of calls, average rows processed, and number of shards queried.

#### VEXPLAIN KEYS

The `KEYS` mode for `VEXPLAIN` offers a concise summary of query structure, highlighting columns used in joins, filters, and 
grouping operations. This information is crucial for:

- Identifying potential sharding key candidates
- Optimizing query performance
- Analyzing query patterns to inform database design decisions

`KEYS` mode analyzes the query structure without executing it, providing JSON output that includes grouping columns, join columns, 
filter columns (potential candidates for indexes, primary keys, or sharding keys), and the statement type.

These new `VEXPLAIN` modes enhance Vitess's query analysis capabilities, allowing for more informed decisions about sharding 
strategies and query optimization.

### Errant GTID Detection on VTTablets

VTTablets now run an errant GTID detection logic before they join the replication stream. So, if a replica has an errant GTID, it will
not start replicating from the primary. This protects us from running into situations which are very difficult to recover from.

For users running with the vitess-operator on Kubernetes, this change means that replica tablets with errant GTIDs will have broken 
replication and will report as unready. Users will need to manually replace and clean up these errant replica tablets.

### Automatically Replace MySQL auto_increment Clauses with Vitess Sequences

In https://github.com/vitessio/vitess/pull/16860 we added support for replacing MySQL `auto_increment` clauses with [Vitess Sequences](https://vitess.io/docs/reference/features/vitess-sequences/), performing all of the setup and initialization
work automatically during the [`MoveTables`](https://vitess.io/docs/reference/vreplication/movetables/) workflow. As part of that work we have deprecated the
[`--remove-sharded-auto-increment` boolean flag](https://vitess.io/docs/20.0/reference/programs/vtctldclient/vtctldclient_movetables/vtctldclient_movetables_create/) and you should begin using the new
[`--sharded-auto-increment-handling` flag](https://vitess.io/docs/21.0/reference/programs/vtctldclient/vtctldclient_movetables/vtctldclient_movetables_create/) instead. Please see the new
[`MoveTables` Auto Increment Handling](https://vitess.io/docs/21.0/reference/vreplication/movetables/#auto-increment-handling) documentation for additional details.

### Experimental MySQL 8.4 support

We have added experimental support for MySQL 8.4. It passes the Vitess test suite, but it is otherwise not yet tested. We are looking for feedback from the community to improve this to move support out of the experimental phase in a future release.

### Current Errant GTIDs Count Metric
A new metric called `CurrentErrantGTIDCount` has been added to the `VTOrc` component. 
This metric shows the current count of the errant GTIDs in the tablets.

### `vtctldclient ChangeTabletTags` command

The `vtctldclient` command `ChangeTabletTags` was added to allow the tags of a tablet to be changed dynamically.

### Support specifying expected primary in reparents

The `EmergencyReparentShard` and `PlannedReparentShard` commands and RPCs now support specifying a primary we expect to still be the current primary in order for a reparent operation to be processed. This allows reparents to be conditional on a specific state being true.

------------
The entire changelog for this release can be found [here](https://github.com/vitessio/vitess/blob/main/changelog/21.0/21.0.0/changelog.md).

The release includes 354 merged Pull Requests.

Thanks to all our contributors: @GrahamCampbell, @GuptaManan100, @Utkar5hM, @anshikavashistha, @app/dependabot, @app/vitess-bot, @arthurschreiber, @beingnoble03, @brendar, @cameronmccord2, @chrism1001, @cuishuang, @dbussink, @deepthi, @demmer, @frouioui, @harshit-gangal, @harshitasao, @icyflame, @kirtanchandak, @mattlord, @mattrobenolt, @maxenglander, @mcrauwel, @notfelineit, @perminov, @rafer, @rohit-nayak-ps, @runewake2, @rvrangel, @shanth96, @shlomi-noach, @systay, @timvaillancourt, @vitess-bot

Vitess v21.0.0-rc1 (2024-10-15)

# Release of Vitess v21.0.0
## Summary

### Table of Contents

- **[Major Changes](#major-changes)**
    - **[Deprecations and Deletions](#deprecations-and-deletions)**
        - [Deprecated VTTablet Flags](#vttablet-flags)
        - [Deletion of deprecated metrics](#metric-deletion)
        - [Deprecated Metrics](#deprecations-metrics)
    - **[Traffic Mirroring](#traffic-mirroring)**
    - **[New VTGate Shutdown Behavior](#new-vtgate-shutdown-behavior)**
    - **[Tablet Throttler: Multi-Metric support](#tablet-throttler)**
    - **[Allow Cross Cell Promotion in PRS](#allow-cross-cell)**
    - **[Support for recursive CTEs](#recursive-cte)**
    - **[VTGate Tablet Balancer](#tablet-balancer)**
    - **[Query Timeout Override](#query-timeout)**
    - **[New Backup Engine](#new-backup-engine)**
    - **[Dynamic VReplication Configuration](#dynamic-vreplication-configuration)**
    - **[Reference Table Materialization](#reference-table-materialization)**
    - **[New VEXPLAIN Modes: TRACE and KEYS](#new-vexplain-modes)**
    - **[Errant GTID Detection on VTTablets](#errant-gtid-vttablet)**
    - **[Automatically Replace MySQL auto_increment Clauses with Vitess Sequences](#auto-replace-mysql-autoinc-with-seq)**
    - **[Experimental MySQL 8.4 support](#experimental-mysql-84)**
    - **[Current Errant GTIDs Count Metric](#errant-gtid-metric)**
    - **[vtctldclient ChangeTabletTags](#vtctldclient-changetablettags)**


## Major Changes

### Deprecations and Deletions

#### Deprecated VTTablet Flags

- `queryserver-enable-settings-pool` flag, added in `v15`, has been on by default since `v17`.
  It is now deprecated and will be removed in a future release.

#### Deletion of deprecated metrics

The following VTOrc metrics were deprecated in `v20`. They have now been deleted.

|                 Metric Name                  |
|:--------------------------------------------:|
|           `analysis.change.write`            |        
|                `audit.write`                 |     
|            `discoveries.attempt`             |          
|              `discoveries.fail`              |        
| `discoveries.instance_poll_seconds_exceeded` | 
|          `discoveries.queue_length`          |       
|          `discoveries.recent_count`          |        
|               `instance.read`                |            
|           `instance.read_topology`           |       
|         `emergency_reparent_counts`          |       
|          `planned_reparent_counts`           |      
|      `reparent_shard_operation_timings`      |  

#### Deprecated Metrics

The following metrics are now deprecated and will be deleted in a future release, please use their replacements.

| Component  |      Metric Name      |           Replaced By           |
|------------|:---------------------:|:-------------------------------:|
| `vttablet` |  `QueryCacheLength`   |  `QueryEnginePlanCacheLength`   |
| `vttablet` |   `QueryCacheSize`    |   `QueryEnginePlanCacheSize`    |
| `vttablet` | `QueryCacheCapacity`  | `QueryEnginePlanCacheCapacity`  |
| `vttablet` | `QueryCacheEvictions` | `QueryEnginePlanCacheEvictions` |
| `vttablet` |   `QueryCacheHits`    |   `QueryEnginePlanCacheHits`    |
| `vttablet` |  `QueryCacheMisses`   |  `QueryEnginePlanCacheMisses`   |

### Traffic Mirroring

Traffic mirroring is intended to help reduce some of the uncertainty inherent to `MoveTables SwitchTraffic`. When
traffic mirroring is enabled, VTGate will mirror a percentage of traffic from one keyspace to another.

Mirror rules may be enabled through `vtctldclient` with `MoveTables MirrorTraffic`. For example:

```bash
$ vtctldclient --server :15999 MoveTables --target-keyspace customer --workflow commerce2customer MirrorTraffic --percent 5.0
```

Mirror rules can be inspected with `GetMirrorRules`.

### New VTGate Shutdown Behavior

We added a new option to VTGate to disallow new connections while VTGate is shutting down,
while allowing existing connections to finish their work until they manually disconnect or until
the `--onterm_timeout` is reached, without getting a `Server shutdown in progress` error.

This new behavior can be enabled by specifying the new `--mysql-server-drain-onterm` flag to VTGate.

You can find more information about this option in the [RFC](https://github.com/vitessio/vitess/issues/15971).

### Tablet Throttler: Multi-Metric support

Up until `v20`, the tablet throttler would only monitor and use a single metric. That would be replication lag, by
default, or could be the result of a custom query. In this release, we introduce a major redesign so that the throttler 
monitors and uses multiple metrics at the same time, including the above two.

The default behavior now is to monitor all metrics, but only use `lag` (if the custom query is undefined) or the `custom` 
metric (if the custom query is defined). This is backwards-compatible with `v20`. A `v20` `PRIMARY` is compatible with
a `v21` `REPLICA`, and a `v21` `PRIMARY` is compatible with a `v20` `REPLICA`.

However, it is now possible to assign any combination of one or more metrics for a given app. The throttler
would then accept or reject the app's requests based on the health of _all_ assigned metrics. We have provided a pre-defined
list of metrics:

- `lag`: replication lag based on heartbeat injection.
- `threads_running`: concurrent active threads on the MySQL server.
- `loadavg`: per core load average measured on the tablet instance/pod.
- `custom`: the result of a custom query executed on the MySQL server.

Each metric has a default threshold which can be overridden by the `UpdateThrottlerConfig` command.

The throttler also supports the catch-all `"all"` app name, and it is thus possible to assign metrics to **all** apps.
Explicit app to metric assignments will override the catch-all configuration.

Metrics are assigned a default _scope_, which could be `self` (isolated to the tablet) or `shard` (max, aka **worst**
value among shard tablets). It is further possible to require a different scope for each metric.

### Allow Cross Cell Promotion in PRS

Up until now if the users wanted to promote a replica in a different cell from the current primary
using `PlannedReparentShard`, they had to specify the new primary with the `--new-primary` flag.

We have now added a new flag `--allow-cross-cell-promotion` that lets `PlannedReparentShard` choose a primary in a
different cell even if no new primary is provided explicitly.

### Experimental support for recursive CTEs

We have added experimental support for recursive CTEs in Vitess. We are marking it as experimental because it is not yet
fully tested and may have some limitations. We are looking for feedback from the community to improve this feature.

### VTGate Tablet Balancer

When a VTGate routes a query and has multiple available tablets for a given shard / tablet type (e.g. REPLICA), the
current default behavior routes the query with local cell affinity and round robin policy. The VTGate Tablet Balancer
provides an alternate mechanism that routes queries to maintain an even distribution of query load to each tablet, while
preferentially routing to tablets in the same cell as the VTGate.

The tablet balancer is enabled by a new flag `--enable-balancer` and configured by `--balancer-vtgate-cells`
and `--balancer-keyspaces`.

See the [RFC ](https://github.com/vitessio/vitess/issues/12241) for more details on the design and configuration of this feature.

### Query Timeout Override

VTGate sends an authoritative query timeout to VTTablet when the `QUERY_TIMEOUT_MS` comment directive,
`query_timeout` session system variable, or `query-timeout` flag is set.
The order of precedence is: comment directive > session variable > VTGate flag.
VTTablet overrides its default query timeout with the value received from VTGate.
All timeouts are specified in milliseconds.

When a query is executed inside a transaction, there is an additional nuance. The actual timeout used will be the smaller 
of the transaction timeout and the query timeout.

A query can also be set to have no timeout by using the `QUERY_TIMEOUT_MS` comment directive with a value of `0`.

Example usage:
`select /*vt+ QUERY_TIMEOUT_MS=30 */ col from tbl`

### New Backup Engine (EXPERIMENTAL)

We are introducing a new backup engine for logical backups in order to support use cases that require something other 
than physical backups. This feature is experimental and is based on [MySQL Shell](https://dev.mysql.com/doc/mysql-shell/8.0/en/).

The new engine is enabled by using `--backup_engine_implementation=mysqlshell`. There are other options that are required, 
so please read the [documentation](https://vitess.io/docs/21.0/user-guides/operating-vitess/backup-and-restore/creating-a-backup/) to learn which options are required and how to configure them.

### Dynamic VReplication Configuration

Previously, many of the configuration options for VReplication Workflows had to be provided using VTTablet flags. This 
meant that any change to VReplication configuration required restarting VTTablets. We now allow these to be overridden 
while creating a workflow or dynamically after the workflow is already in progress.

### Reference Table Materialization

There is a new option in [`Materialize` workflows](https://vitess.io/docs/reference/vreplication/materialize/) to keep a synced copy of [reference or lookup tables](https://vitess.io/docs/reference/vreplication/reference_tables/) 
(countries, states, zip codes, etc) from an unsharded keyspace, which holds the source of truth for the reference 
table, to all shards in a sharded keyspace.

### New VEXPLAIN Modes: TRACE and KEYS

#### VEXPLAIN TRACE

The new `TRACE` mode for `VEXPLAIN` provides a detailed execution trace of queries, showing how they're processed through various 
operators and interactions with tablets. This mode is particularly useful for:

- Identifying performance bottlenecks
- Understanding query execution patterns
- Optimizing complex queries
- Debugging unexpected query behavior

`TRACE` mode runs the query and logs all interactions, returning a JSON representation of the query execution plan with additional 
statistics like number of calls, average rows processed, and number of shards queried.

#### VEXPLAIN KEYS

The `KEYS` mode for `VEXPLAIN` offers a concise summary of query structure, highlighting columns used in joins, filters, and 
grouping operations. This information is crucial for:

- Identifying potential sharding key candidates
- Optimizing query performance
- Analyzing query patterns to inform database design decisions

`KEYS` mode analyzes the query structure without executing it, providing JSON output that includes grouping columns, join columns, 
filter columns (potential candidates for indexes, primary keys, or sharding keys), and the statement type.

These new `VEXPLAIN` modes enhance Vitess's query analysis capabilities, allowing for more informed decisions about sharding 
strategies and query optimization.

### Errant GTID Detection on VTTablets

VTTablets now run an errant GTID detection logic before they join the replication stream. So, if a replica has an errant GTID, it will
not start replicating from the primary. This protects us from running into situations which are very difficult to recover from.

For users running with the vitess-operator on Kubernetes, this change means that replica tablets with errant GTIDs will have broken 
replication and will report as unready. Users will need to manually replace and clean up these errant replica tablets.

### Automatically Replace MySQL auto_increment Clauses with Vitess Sequences

In https://github.com/vitessio/vitess/pull/16860 we added support for replacing MySQL `auto_increment` clauses with [Vitess Sequences](https://vitess.io/docs/reference/features/vitess-sequences/), performing all of the setup and initialization
work automatically during the [`MoveTables`](https://vitess.io/docs/reference/vreplication/movetables/) workflow. As part of that work we have deprecated the
[`--remove-sharded-auto-increment` boolean flag](https://vitess.io/docs/20.0/reference/programs/vtctldclient/vtctldclient_movetables/vtctldclient_movetables_create/) and you should begin using the new
[`--sharded-auto-increment-handling` flag](https://vitess.io/docs/21.0/reference/programs/vtctldclient/vtctldclient_movetables/vtctldclient_movetables_create/) instead. Please see the new
[`MoveTables` Auto Increment Handling](https://vitess.io/docs/21.0/reference/vreplication/movetables/#auto-increment-handling) documentation for additional details.

### Experimental MySQL 8.4 support

We have added experimental support for MySQL 8.4. It passes the Vitess test suite, but it is otherwise not yet tested. We are looking for feedback from the community to improve this to move support out of the experimental phase in a future release.

### Current Errant GTIDs Count Metric
A new metric called `CurrentErrantGTIDCount` has been added to the `VTOrc` component. 
This metric shows the current count of the errant GTIDs in the tablets.

### `vtctldclient ChangeTabletTags` command

The `vtctldclient` command `ChangeTabletTags` was added to allow the tags of a tablet to be changed dynamically.

------------
The entire changelog for this release can be found [here](https://github.com/vitessio/vitess/blob/main/changelog/21.0/21.0.0/changelog.md).

The release includes 338 merged Pull Requests.

Thanks to all our contributors: @GrahamCampbell, @GuptaManan100, @Utkar5hM, @anshikavashistha, @app/dependabot, @app/vitess-bot, @arthurschreiber, @beingnoble03, @brendar, @cameronmccord2, @chrism1001, @cuishuang, @dbussink, @deepthi, @demmer, @frouioui, @harshit-gangal, @harshitasao, @icyflame, @kirtanchandak, @mattlord, @mattrobenolt, @maxenglander, @mcrauwel, @notfelineit, @perminov, @rafer, @rohit-nayak-ps, @runewake2, @rvrangel, @shanth96, @shlomi-noach, @systay, @timvaillancourt, @vitess-bot

Vitess v20.0.0 (2024-06-27)

# Release of Vitess v20.0.0

## Summary

### Table of Contents

- **[Major Changes](#major-changes)**
  - **[Deletions](#deletions)** 
    - [`--vreplication_tablet_type` flag](#vreplication-tablet-type-deletion)
    - [Pool Capacity Flags](#pool-flags-deletion)
    - [vitess/base and vitess/k8s Docker images](#base-k8s-images)
    - [`gh-ost` binary and endtoend tests](#gh-ost-binary-tests-removal)
    - [Legacy `EmergencyReparentShard` stats](#legacy-emergencyshardreparent-stats)
  - **[Breaking changes](#breaking-changes)**
    - [Metric Name Changes in VTOrc](#metric-change-vtorc)
    - [ENUM and SET column handling in VTGate VStream API](#enum-set-vstream)
    - [`shutdown_grace_period` Default Change](#shutdown-grace-period-default)
    - [New `unmanaged` Flag and `disable_active_reparents` deprecation](#unmanaged-flag)
    - [`recovery-period-block-duration` Flag deprecation](#recovery-block-deprecation)
    - [`mysqlctld` `onterm-timeout` Default Change](#mysqlctld-onterm-timeout)
    - [`MoveTables` now removes `auto_increment` clauses by default when moving tables from an unsharded keyspace to a sharded one](#move-tables-auto-increment)
    - [`Durabler` interface method renaming](#durabler-interface-method-renaming)
  - **[Query Compatibility](#query-compatibility)**
    - [Vindex Hints](#vindex-hints)
    - [Update with Limit Support](#update-limit)
    - [Update with Multi Table Support](#multi-table-update)
    - [Update with Multi Target Support](#update-multi-target)
    - [Delete with Subquery Support](#delete-subquery)
    - [Delete with Multi Target Support](#delete-multi-target)
    - [User Defined Functions Support](#udf-support)
    - [Insert Row Alias Support](#insert-row-alias-support)
  - **[VReplication](#vreplication)**
    - [Multi-tenant Imports](#multi-tenant)
    - [VDiff Support For OnlineDDL Migrations](#vdiff-online-ddl)
  - **[Query Timeout](#query-timeout)**
  - **[Flag changes](#flag-changes)**
    - [`pprof-http` default change](#pprof-http-default)
    - [New `healthcheck-dial-concurrency` flag](#healthcheck-dial-concurrency-flag)
    - [New minimum for `--buffer_min_time_between_failovers`](#buffer_min_time_between_failovers-flag)
    - [New `track-udfs` vtgate flag](#vtgate-track-udfs-flag)
    - [Help text fix for `--lock-timeout`](#documentation-lock-timeout)
    - [New `--querylog-sample-rate` flag](#querylog-sample-rate-flag)
    - [New `--tablet-filter-tags` flag](#tablet-filter-tags-flag)

- **[Minor Changes](#minor-changes)**
  - **[New Stats](#new-stats)**
    - [VTTablet Query Cache Hits and Misses](#vttablet-query-cache-hits-and-misses)
    - [VTGate and VTTablet Query Text Characters Processed](#vttablet-query-text-characters-processed)
  - **[`SIGHUP` reload of gRPC client static auth creds](#sighup-reload-of-grpc-client-auth-creds)**
  - **[VTAdmin](#vtadmin)**
    - [Updated to node v20.12.2](#updated-node)
    - [Replaced highcharts with d3](#replaced-highcharts)

## Major Changes

### Deletion

#### `--vreplication_tablet_type` flag

The previously deprecated flag `--vreplication_tablet_type` has been deleted.

#### Pool Capacity Flags

The previously deprecated flags `--queryserver-config-query-pool-waiter-cap`, `--queryserver-config-stream-pool-waiter-cap` and `--queryserver-config-txpool-waiter-cap` have been deleted.

#### `vitess/base` and `vitess/k8s` Docker images

Since we have deleted MySQL from our `vitess/lite` image, we are removing the `vitess/base` and `vitess/k8s` images.

These images are no longer useful since we can use `vitess/lite` as the base of many other Docker images (`vitess/vtgate`, `vitess/vtgate`, ...).

#### `gh-ost` binary and endtoend tests

Vitess 20.0 drops support for `gh-ost` DDL strategy.

`vttablet` binary no longer embeds a `gh-ost` binary. Users of `gh-ost` DDL strategy will need to supply a `gh-ost` binary on the `vttablet` host or pod. Vitess will look for the `gh-ost` binary in the system `PATH`; otherwise the user should supply `vttablet --gh-ost-path`.

Vitess' endtoend tests no longer use nor test `gh-ost` migrations.

#### Legacy `EmergencyReparentShard` stats

The following `EmergencyReparentShard` stats were deprecated in Vitess 18.0 and are removed in Vitess 20.0:
- `ers_counter`
- `ers_success_counter`
- `ers_failure_counter`

These counters are replaced by the following stats _(introduced in Vitess 18.0)_:
- `emergency_reparent_counts` - Number of times `EmergencyReparentShard` has been run. It is further subdivided by the keyspace, shard and the result of the operation.
- `planned_reparent_counts` - Number of times `PlannedReparentShard` has been run. It is further subdivided by the keyspace, shard and the result of the operation.

Also, the `reparent_shard_operation_timings` stat was added to provide per-operation timings of reparent operations.

### Breaking Changes

#### Metric Name Changes in VTOrc

The following metric names have been changed in VTOrc. The old metrics are still available in `/debug/vars` for this release, but will be removed in later releases. The new metric names and the deprecated metric names resolve to the same metric name on prometheus, so there is no change there.

|               Old Metric Name                |             New Metric Name              |                 Name in Prometheus                 |
|:--------------------------------------------:|:----------------------------------------:|:--------------------------------------------------:|
|           `analysis.change.write`            |          `AnalysisChangeWrite`           |           `vtorc_analysis_change_write`            |  
|                `audit.write`                 |               `AuditWrite`               |                `vtorc_audit_write`                 |  
|            `discoveries.attempt`             |           `DiscoveriesAttempt`           |            `vtorc_discoveries_attempt`             |  
|              `discoveries.fail`              |            `DiscoveriesFail`             |              `vtorc_discoveries_fail`              |  
| `discoveries.instance_poll_seconds_exceeded` | `DiscoveriesInstancePollSecondsExceeded` | `vtorc_discoveries_instance_poll_seconds_exceeded` |  
|          `discoveries.queue_length`          |         `DiscoveriesQueueLength`         |          `vtorc_discoveries_queue_length`          |  
|          `discoveries.recent_count`          |         `DiscoveriesRecentCount`         |          `vtorc_discoveries_recent_count`          |  
|               `instance.read`                |              `InstanceRead`              |               `vtorc_instance_read`                |  
|           `instance.read_topology`           |          `InstanceReadTopology`          |           `vtorc_instance_read_topology`           |
|         `emergency_reparent_counts`          |        `EmergencyReparentCounts`         |         `vtorc_emergency_reparent_counts`          |
|          `planned_reparent_counts`           |         `PlannedReparentCounts`          |          `vtorc_planned_reparent_counts`           |
|      `reparent_shard_operation_timings`      |     `ReparentShardOperationTimings`      |  `vtorc_reparent_shard_operation_timings_bucket`   |
		
		

#### ENUM and SET column handling in VTGate VStream API

The [VTGate VStream API](https://vitess.io/docs/reference/vreplication/vstream/) now returns [`ENUM`](https://dev.mysql.com/doc/refman/en/enum.html) and [`SET`](https://dev.mysql.com/doc/refman/en/set.html) column type values in [`VEvent`](https://pkg.go.dev/vitess.io/vitess/go/vt/proto/binlogdata#VEvent) messages (in the embedded [`RowChange`](https://pkg.go.dev/vitess.io/vitess/go/vt/proto/binlogdata#RowChange) messages) as their string values instead of the integer based ones — in both the copy/snapshot phase and the streaming phase. This change was done to make the `VStream` API more user-friendly, intuitive, and to align the behavior across both phases. Before [this change](https://github.com/vitessio/vitess/pull/15723) the values for [`ENUM`](https://dev.mysql.com/doc/refman/en/enum.html) and [`SET`](https://dev.mysql.com/doc/refman/en/set.html) columns were string values in the copy phase but integer values (which only have an internal meaning to MySQL) in the streaming phase. This inconsistency led to various [challenges and issues](https://github.com/vitessio/vitess/issues/15750) for each `VStream` client/consumer (e.g. the [`Debezium` Vitess connector](https://debezium.io/documentation/reference/stable/connectors/vitess.html) failed to properly perform a snapshot for tables containing these column types). Now the behavior is intuitive — clients need the string values as the eventual sink is often not MySQL so each consumer needed to perform the mappings themselves — and consistent. While this is a (potentially) breaking change, a new boolean field has been added to the [`FieldEvent`](https://pkg.go.dev/vitess.io/vitess/go/vt/proto/binlogdata#FieldEvent) message called `EnumSetStringValues`. When that field is `false` (in Vitess v19 and older) then the consumer will need to perform the mappings during streaming phase, but not during copy phase. When this field is `true`, then no mapping is required. This will help to ensure a smooth transition for all consumers over time. To demonstrate, let's look at the textual output (printing the received `VEvents` as strings) when streaming a single `enum_set_test` table from the unsharded `commerce` keyspace so that we can see what the VStream looks like before and after when we start a new VStream in copy/snapshot mode and then transition to streaming mode for the following table:

```sql
CREATE TABLE `enum_set_test` (
  `id` int NOT NULL AUTO_INCREMENT,
  `name` varchar(120) DEFAULT NULL,
  `shirt_size` enum('small','medium','large','xlarge','xxlarge') DEFAULT NULL,
  `hobbies` set('knitting','cooking','pickleball','biking','hiking','motorcycle','video games','reading') DEFAULT NULL,
  PRIMARY KEY (`id`)
)
```

And with the table having this data when we start our `VStream` and begin the copy/snapshot phase:

```sql
mysql> select * from enum_set_test;
+----+-----------+------------+-------------------------+
| id | name      | shirt_size | hobbies                 |
+----+-----------+------------+-------------------------+
|  1 | Billy Bob | xlarge     | cooking,reading         |
|  2 | Sally Mae | medium     | knitting,cooking,hiking |
+----+-----------+------------+-------------------------+
2 rows in set (0.00 sec)
```

And finally we will perform the following inserts and updates to the table during the streaming phase:

```sql
insert into enum_set_test values (3, "Matt Lord", 'medium', 'pickleball,biking,hiking,motorcycle,video games,reading');
insert into enum_set_test values (4, "Jerry Badyellow", 'large', '');
update enum_set_test set shirt_size = 'small', hobbies = 'knitting,cooking,hiking,reading' where id = 2;
```

Vitess v19 and older:

```text
[type:BEGIN keyspace:"commerce" shard:"0" type:FIELD field_event:{table_name:"commerce.enum_set_test" fields:{name:"id" type:INT32 table:"enum_set_test" org_table:"enum_set_test" database:"vt_commerce" org_name:"id" column_length:11 charset:63 flags:49667 column_type:"int"} fields:{name:"name" type:VARCHAR table:"enum_set_test" org_table:"enum_set_test" database:"vt_commerce" org_name:"name" column_length:480 charset:255 column_type:"varchar(120)"} fields:{name:"shirt_size" type:ENUM table:"enum_set_test" org_table:"enum_set_test" database:"vt_commerce" org_name:"shirt_size" column_length:28 charset:255 flags:256 column_type:"enum('small','medium','large','xlarge','xxlarge')"} fields:{name:"hobbies" type:SET table:"enum_set_test" org_table:"enum_set_test" database:"vt_commerce" org_name:"hobbies" column_length:288 charset:255 flags:2048 column_type:"set('knitting','cooking','pickleball','biking','hiking','motorcycle','video games','reading')"} keyspace:"commerce" shard:"0"} keyspace:"commerce" shard:"0"]
[type:VGTID vgtid:{shard_gtids:{keyspace:"commerce" shard:"0" gtid:"MySQL56/ce357206-0d49-11ef-8fd1-a74564279579:1-35"}} keyspace:"commerce" shard:"0"]
[type:ROW row_event:{table_name:"commerce.enum_set_test" row_changes:{after:{lengths:1 lengths:9 lengths:6 lengths:15 values:"1Billy Bobxlargecooking,reading"}} keyspace:"commerce" shard:"0"} keyspace:"commerce" shard:"0" type:ROW row_event:{table_name:"commerce.enum_set_test" row_changes:{after:{lengths:1 lengths:9 lengths:6 lengths:23 values:"2Sally Maemediumknitting,cooking,hiking"}} keyspace:"commerce" shard:"0"} keyspace:"commerce" shard:"0" type:VGTID vgtid:{shard_gtids:{keyspace:"commerce" shard:"0" gtid:"MySQL56/ce357206-0d49-11ef-8fd1-a74564279579:1-35" table_p_ks:{table_name:"enum_set_test" lastpk:{fields:{name:"id" type:INT32 charset:63 flags:49667} rows:{lengths:1 values:"2"}}}}} keyspace:"commerce" shard:"0" type:COMMIT keyspace:"commerce" shard:"0"]
[type:BEGIN keyspace:"commerce" shard:"0" type:VGTID vgtid:{shard_gtids:{keyspace:"commerce" shard:"0" gtid:"MySQL56/ce357206-0d49-11ef-8fd1-a74564279579:1-35"}} keyspace:"commerce" shard:"0" type:COMMIT keyspace:"commerce" shard:"0"]
[type:COPY_COMPLETED keyspace:"commerce" shard:"0" type:COPY_COMPLETED]
[type:BEGIN timestamp:1715179728 current_time:1715179728532658000 keyspace:"commerce" shard:"0" type:FIELD timestamp:1715179728 field_event:{table_name:"commerce.enum_set_test" fields:{name:"id" type:INT32 table:"enum_set_test" org_table:"enum_set_test" database:"vt_commerce" org_name:"id" column_length:11 charset:63 flags:49667 column_type:"int"} fields:{name:"name" type:VARCHAR table:"enum_set_test" org_table:"enum_set_test" database:"vt_commerce" org_name:"name" column_length:480 charset:255 column_type:"varchar(120)"} fields:{name:"shirt_size" type:ENUM table:"enum_set_test" org_table:"enum_set_test" database:"vt_commerce" org_name:"shirt_size" column_length:28 charset:255 flags:256 column_type:"enum('small','medium','large','xlarge','xxlarge')"} fields:{name:"hobbies" type:SET table:"enum_set_test" org_table:"enum_set_test" database:"vt_commerce" org_name:"hobbies" column_length:288 charset:255 flags:2048 column_type:"set('knitting','cooking','pickleball','biking','hiking','motorcycle','video games','reading')"} keyspace:"commerce" shard:"0"} current_time:1715179728535652000 keyspace:"commerce" shard:"0" type:ROW timestamp:1715179728 row_event:{table_name:"commerce.enum_set_test" row_changes:{after:{lengths:1 lengths:9 lengths:1 lengths:3 values:"3Matt Lord2252"}} keyspace:"commerce" shard:"0" flags:1} current_time:1715179728535739000 keyspace:"commerce" shard:"0" type:VGTID vgtid:{shard_gtids:{keyspace:"commerce" shard:"0" gtid:"MySQL56/ce357206-0d49-11ef-8fd1-a74564279579:1-36"}} keyspace:"commerce" shard:"0" type:COMMIT timestamp:1715179728 current_time:1715179728535754000 keyspace:"commerce" shard:"0"]
[type:BEGIN timestamp:1715179735 current_time:1715179735538607000 keyspace:"commerce" shard:"0" type:ROW timestamp:1715179735 row_event:{table_name:"commerce.enum_set_test" row_changes:{after:{lengths:1 lengths:15 lengths:1 lengths:1 values:"4Jerry Badyellow30"}} keyspace:"commerce" shard:"0" flags:1} current_time:1715179735538659000 keyspace:"commerce" shard:"0" type:VGTID vgtid:{shard_gtids:{keyspace:"commerce" shard:"0" gtid:"MySQL56/ce357206-0d49-11ef-8fd1-a74564279579:1-37"}} keyspace:"commerce" shard:"0" type:COMMIT timestamp:1715179735 current_time:1715179735538672000 keyspace:"commerce" shard:"0"]
[type:BEGIN timestamp:1715179741 current_time:1715179741728690000 keyspace:"commerce" shard:"0" type:ROW timestamp:1715179741 row_event:{table_name:"commerce.enum_set_test" row_changes:{before:{lengths:1 lengths:9 lengths:1 lengths:2 values:"2Sally Mae219"} after:{lengths:1 lengths:9 lengths:1 lengths:3 values:"2Sally Mae1147"}} keyspace:"commerce" shard:"0" flags:1} current_time:1715179741728730000 keyspace:"commerce" shard:"0" type:VGTID vgtid:{shard_gtids:{keyspace:"commerce" shard:"0" gtid:"MySQL56/ce357206-0d49-11ef-8fd1-a74564279579:1-38"}} keyspace:"commerce" shard:"0" type:COMMIT timestamp:1715179741 current_time:1715179741728744000 keyspace:"commerce" shard:"0"]
```

Vitess v20 and newer:

```text
[type:BEGIN keyspace:"commerce" shard:"0" type:FIELD field_event:{table_name:"commerce.enum_set_test" fields:{name:"id" type:INT32 table:"enum_set_test" org_table:"enum_set_test" database:"vt_commerce" org_name:"id" column_length:11 charset:63 flags:49667 column_type:"int"} fields:{name:"name" type:VARCHAR table:"enum_set_test" org_table:"enum_set_test" database:"vt_commerce" org_name:"name" column_length:480 charset:255 column_type:"varchar(120)"} fields:{name:"shirt_size" type:ENUM table:"enum_set_test" org_table:"enum_set_test" database:"vt_commerce" org_name:"shirt_size" column_length:28 charset:255 flags:256 column_type:"enum('small','medium','large','xlarge','xxlarge')"} fields:{name:"hobbies" type:SET table:"enum_set_test" org_table:"enum_set_test" database:"vt_commerce" org_name:"hobbies" column_length:288 charset:255 flags:2048 column_type:"set('knitting','cooking','pickleball','biking','hiking','motorcycle','video games','reading')"} keyspace:"commerce" shard:"0" enum_set_string_values:true} keyspace:"commerce" shard:"0"]
[type:VGTID vgtid:{shard_gtids:{keyspace:"commerce" shard:"0" gtid:"MySQL56/156f702a-0d47-11ef-8723-653d045ab990:1-50"}} keyspace:"commerce" shard:"0"]
[type:ROW row_event:{table_name:"commerce.enum_set_test" row_changes:{after:{lengths:1 lengths:9 lengths:6 lengths:15 values:"1Billy Bobxlargecooking,reading"}} keyspace:"commerce" shard:"0"} keyspace:"commerce" shard:"0" type:ROW row_event:{table_name:"commerce.enum_set_test" row_changes:{after:{lengths:1 lengths:9 lengths:6 lengths:23 values:"2Sally Maemediumknitting,cooking,hiking"}} keyspace:"commerce" shard:"0"} keyspace:"commerce" shard:"0" type:VGTID vgtid:{shard_gtids:{keyspace:"commerce" shard:"0" gtid:"MySQL56/156f702a-0d47-11ef-8723-653d045ab990:1-50" table_p_ks:{table_name:"enum_set_test" lastpk:{fields:{name:"id" type:INT32 charset:63 flags:49667} rows:{lengths:1 values:"2"}}}}} keyspace:"commerce" shard:"0" type:COMMIT keyspace:"commerce" shard:"0"]
[type:BEGIN keyspace:"commerce" shard:"0" type:VGTID vgtid:{shard_gtids:{keyspace:"commerce" shard:"0" gtid:"MySQL56/156f702a-0d47-11ef-8723-653d045ab990:1-50"}} keyspace:"commerce" shard:"0" type:COMMIT keyspace:"commerce" shard:"0"]
[type:COPY_COMPLETED keyspace:"commerce" shard:"0" type:COPY_COMPLETED]
[type:BEGIN timestamp:1715179399 current_time:1715179399817221000 keyspace:"commerce" shard:"0" type:FIELD timestamp:1715179399 field_event:{table_name:"commerce.enum_set_test" fields:{name:"id" type:INT32 table:"enum_set_test" org_table:"enum_set_test" database:"vt_commerce" org_name:"id" column_length:11 charset:63 flags:49667 column_type:"int"} fields:{name:"name" type:VARCHAR table:"enum_set_test" org_table:"enum_set_test" database:"vt_commerce" org_name:"name" column_length:480 charset:255 column_type:"varchar(120)"} fields:{name:"shirt_size" type:ENUM table:"enum_set_test" org_table:"enum_set_test" database:"vt_commerce" org_name:"shirt_size" column_length:28 charset:255 flags:256 column_type:"enum('small','medium','large','xlarge','xxlarge')"} fields:{name:"hobbies" type:SET table:"enum_set_test" org_table:"enum_set_test" database:"vt_commerce" org_name:"hobbies" column_length:288 charset:255 flags:2048 column_type:"set('knitting','cooking','pickleball','biking','hiking','motorcycle','video games','reading')"} keyspace:"commerce" shard:"0" enum_set_string_values:true} current_time:1715179399821735000 keyspace:"commerce" shard:"0" type:ROW timestamp:1715179399 row_event:{table_name:"commerce.enum_set_test" row_changes:{after:{lengths:1 lengths:9 lengths:6 lengths:55 values:"3Matt Lordmediumpickleball,biking,hiking,motorcycle,video games,reading"}} keyspace:"commerce" shard:"0" flags:1} current_time:1715179399821762000 keyspace:"commerce" shard:"0" type:VGTID vgtid:{shard_gtids:{keyspace:"commerce" shard:"0" gtid:"MySQL56/156f702a-0d47-11ef-8723-653d045ab990:1-51"}} keyspace:"commerce" shard:"0" type:COMMIT timestamp:1715179399 current_time:1715179399821801000 keyspace:"commerce" shard:"0"]
[type:BEGIN timestamp:1715179399 current_time:1715179399822310000 keyspace:"commerce" shard:"0" type:ROW timestamp:1715179399 row_event:{table_name:"commerce.enum_set_test" row_changes:{after:{lengths:1 lengths:15 lengths:5 lengths:0 values:"4Jerry Badyellowlarge"}} keyspace:"commerce" shard:"0" flags:1} current_time:1715179399822355000 keyspace:"commerce" shard:"0" type:VGTID vgtid:{shard_gtids:{keyspace:"commerce" shard:"0" gtid:"MySQL56/156f702a-0d47-11ef-8723-653d045ab990:1-52"}} keyspace:"commerce" shard:"0" type:COMMIT timestamp:1715179399 current_time:1715179399822360000 keyspace:"commerce" shard:"0"]
[type:BEGIN timestamp:1715179400 current_time:1715179400512056000 keyspace:"commerce" shard:"0" type:ROW timestamp:1715179400 row_event:{table_name:"commerce.enum_set_test" row_changes:{before:{lengths:1 lengths:9 lengths:6 lengths:23 values:"2Sally Maemediumknitting,cooking,hiking"} after:{lengths:1 lengths:9 lengths:5 lengths:31 values:"2Sally Maesmallknitting,cooking,hiking,reading"}} keyspace:"commerce" shard:"0" flags:1} current_time:1715179400512094000 keyspace:"commerce" shard:"0" type:VGTID vgtid:{shard_gtids:{keyspace:"commerce" shard:"0" gtid:"MySQL56/156f702a-0d47-11ef-8723-653d045ab990:1-53"}} keyspace:"commerce" shard:"0" type:COMMIT timestamp:1715179400 current_time:1715179400512108000 keyspace:"commerce" shard:"0"]
```

An example key difference there being that `after:{lengths:1 lengths:9 lengths:1 lengths:3 values:"2Sally Mae1147"}` from Vitess v19 and older becomes `after:{lengths:1 lengths:9 lengths:5 lengths:31 values:"2Sally Maesmallknitting,cooking,hiking,reading"}` from Vitess v20 and newer. So `1` -> `small` and `147` -> `knitting,cooking,hiking,reading` for the `ENUM` and `SET` column values respectively. This also demonstrates why this mapping is necessary in consumers/clients, as `147` has no logical meaning/value for this column outside of MySQL internals.

If you're using the [`Debezium` Vitess connector](https://debezium.io/documentation/reference/stable/connectors/vitess.html), you should upgrade your connector to 2.7 (the next release) — which should contain [the relevant necessary changes](https://issues.redhat.com/browse/DBZ-7792) — *prior to upgrading Vitess* to v20.0.1 or later. If you're using any of the PlanetScale connectors ([`AirByte`](https://github.com/planetscale/airbyte-source/), [`FiveTran`](https://github.com/planetscale/fivetran-source), or [`singer-tap`](https://github.com/planetscale/singer-tap)) then no actions are required.

If you're using a custom `VStream` client/consumer, then you will need to build a new client with the updated v20 [binlogdata protos](https://pkg.go.dev/vitess.io/vitess/go/vt/proto/binlogdata) ([source](https://github.com/vitessio/vitess/blob/main/proto/binlogdata.proto) for which would be in `main` or the `release-20.0` branch) before needing to support Vitess v20.0.1 or later. Your client will then be able to handle old and new messages, with older messages always having this new field set to `false`.

#### `shutdown_grace_period` Default Change

The `--shutdown_grace_period` flag, which was introduced in v2 with a default of `0 seconds`, has now been changed to default to `3 seconds`.
This makes reparenting in Vitess resilient to client errors, and prevents PlannedReparentShard from timing out.

In order to preserve the old behaviour, the users can set the flag back to `0 seconds` causing open transactions to never be shutdown, but in that case, they run the risk of PlannedReparentShard calls timing out.

####  New `unmanaged` Flag and `disable_active_reparents` deprecation

New flag `--unmanaged` has been introduced in this release to make it easier to flag unmanaged tablets. It also runs validations to make sure the unmanaged tablets are configured properly. `--disable_active_reparents` flag has been deprecated for `vttablet`, `vtcombo` and `vttestserver` binaries and will be removed in future releases. Specifying the `--unmanaged` flag will also block replication commands and replication repairs.

Starting this release, all unmanaged tablets should specify this flag.


####  `recovery-period-block-duration` Flag deprecation

The flag `--recovery-period-block-duration` has been deprecated in VTOrc from this release. Its value is now ignored and the flag will be removed in later releases.
VTOrc no longer blocks recoveries for a certain duration after a previous recovery has completed. Since VTOrc refreshes the required information after
acquiring a shard lock, blocking of recoveries is not required.

#### `mysqlctld` `onterm_timeout` Default Change

The `--onterm_timeout` flag default value has changed for `mysqlctld`. It now is by default long enough to be able to wait for the default `--shutdown-wait-time` when shutting down on a `TERM` signal. 

This is necessary since otherwise MySQL would never shut down cleanly with the old defaults, since `mysqlctld` would shut down already after 10 seconds by default.

#### `MoveTables` now removes `auto_increment` clauses by default when moving tables from an unsharded keyspace to a sharded one

A new `--remove-sharded-auto-increment` flag has been added to the [`MoveTables` create sub-command](https://vitess.io/docs/20.0/reference/programs/vtctldclient/vtctldclient_movetables/vtctldclient_movetables_create/) and it is set to `true` by default. This flag controls whether any [MySQL `auto_increment`](https://dev.mysql.com/doc/refman/en/example-auto-increment.html) clauses should be removed from the table definitions when moving tables from an unsharded keyspace to a sharded one. This is now done by default as `auto_increment` clauses should not typically be used with sharded tables and you should instead rely on externally generated values such as a form of universally/globally unique identifiers or use [Vitess sequences](https://vitess.io/docs/reference/features/vitess-sequences/) in order to ensure that each row has a unique identifier (Primary Key value) across all shards. If for some reason you want to retain them you can set this new flag to `false` when creating the workflow.

#### `Durabler` interface method renaming

The methods of [the `Durabler` interface](https://github.com/vitessio/vitess/blob/main/go/vt/vtctl/reparentutil/durability.go#L70-L79) in `go/vt/vtctl/reparentutil` were renamed to be public _(capitalized)_ methods to make it easier to integrate custom Durability Policies from external packages. See [RFC for details](https://github.com/vitessio/vitess/issues/15544).

Users of custom Durability Policies must rename private `Durabler` methods.

Changes:
- The `promotionRule` method was renamed to `PromotionRule`
- The `semiSyncAckers` method was renamed to `SemiSyncAckers`
- The `isReplicaSemiSync` method was renamed to `IsReplicaSemiSync`

### Query Compatibility

####  Vindex Hints

Vitess now supports Vindex hints that provide a way for users to influence the shard routing of queries in Vitess by specifying, which vindexes should be considered or ignored by the query planner. This feature enhances the control over query execution, allowing for potentially more efficient data access patterns in sharded databases.

Example:
 ```sql
    SELECT * FROM user USE VINDEX (hash_user_id, secondary_vindex) WHERE user_id = 123;
    SELECT * FROM order IGNORE VINDEX (range_order_id) WHERE order_date = '2021-01-01';
 ```

For more information about Vindex hints and its usage, please consult the documentation.

####  Update with Limit Support

Support is added for sharded update with limit.

Example: `update t1 set t1.foo = 'abc', t1.bar = 23 where t1.baz > 5 limit 1`

The support is built on performing a selection of primary keys and then performing an update with those primary keys. 
For query syntax, refer to the [MySQL Docs](https://dev.mysql.com/doc/refman/8.0/en/update.html)

####  Update with Multi Table Support

Support is added for sharded multi-table update with column update on single target table using multiple table join.

Example: `update t1 join t2 on t1.id = t2.id join t3 on t1.col = t3.col set t1.baz = 'abc', t1.apa = 23 where t3.foo = 5 and t2.bar = 7`

The support is built on performing a selection of primary keys and then performing an update with those primary keys.
For query syntax, refer to the [MySQL Docs](https://dev.mysql.com/doc/refman/8.0/en/update.html)

####  Update with Multi Target Support

Support is added for sharded multi table target update.

Example: `update t1 join t2 on t1.id = t2.id set t1.foo = 'abc', t2.bar = 23`

The support is built on performing a selection of primary keys from all target tables and 
then performing an update for each table with their selected primary keys. 
For query syntax, refer to the [MySQL Docs](https://dev.mysql.com/doc/refman/8.0/en/update.html)

####  Delete with Subquery Support

Support is added for sharded table delete with subquery

Example: `delete from t1 where id in (select col from t2 where foo = 32 and bar = 43)`

The support is built by performing the uncorrelated subquery first and then providing the value for deletion.

####  Delete with Multi Target Support

Support is added for sharded multi table target delete.

Example: `delete t1, t3 from t1 join t2 on t1.id = t2.id join t3 on t1.col = t3.col`

The support is built on performing a selection of primary keys from all target tables and 
then performing a delete operation for each table with their selected primary keys. 
For query syntax, refer to the [MySQL Docs](https://dev.mysql.com/doc/refman/8.0/en/delete.html)

####  User Defined Functions Support

VTGate can track any user defined functions for better planning.
User Defined Functions (UDFs) should be directly loaded in the underlying MySQL.

It should be enabled in VTGate with the `--track-udfs` flag.
This will enable the tracking of UDFs in VTGate and will be used for planning.
Without this flag, VTGate will not be aware that there might be aggregating user-defined functions in the query that need to be pushed down to MySQL.

More details about how to load UDFs is available in [MySQL Docs](https://dev.mysql.com/doc/extending-mysql/8.0/en/adding-loadable-function.html)

####  Insert Row Alias Support

Support is added to have row alias in Insert statement to be used with `on duplicate key update`.

Example:
- `insert into user(id, name, email) valies (100, 'Alice', 'alice@mail.com') as new on duplicate key update name = new.name, email = new.email`
- `insert into user(id, name, email) valies (100, 'Alice', 'alice@mail.com') as new(m, n, p) on duplicate key update name = n, email = p`

For query syntax, refer to the [MySQL Docs](https://dev.mysql.com/doc/refman/8.0/en/insert-on-duplicate.html)

### Query Timeout
On a query timeout, Vitess closed the connection using the `kill connection` statement. This leads to connection churn 
which is not desirable in some cases. To avoid this, Vitess now uses the `kill query` statement to cancel the query. 
This will only cancel the query and does not terminate the connection.

### Flag Changes

####  `pprof-http` Default Change

The `--pprof-http` flag, which was introduced in v19 with a default of `true`, has now been changed to default to `false`.
This makes HTTP `pprof` endpoints now an *opt-in* feature, rather than opt-out.
To continue enabling these endpoints, explicitly set `--pprof-http` when starting up Vitess components.

#### New `--healthcheck-dial-concurrency` flag

The new `--healthcheck-dial-concurrency` flag defines the maximum number of healthcheck connections that can open concurrently. This limit is to avoid hitting Go runtime panics on deployments watching enough tablets [to hit the runtime's maximum thread limit of `10000`](https://pkg.go.dev/runtime/debug#SetMaxThreads) due to blocking network syscalls. This flag applies to `vtcombo`, `vtctld` and `vtgate` only and a value less than the runtime max thread limit _(`10000`)_ is recommended.

#### New minimum for `--buffer_min_time_between_failovers`

The `--buffer_min_time_between_failovers` `vttablet` flag now has a minimum value of `1s`. This is because a value of 0 can cause issues with the buffering mechanics resulting in unexpected and unnecessary query errors — in particular during `MoveTables SwitchTraffic` operations. If you are currently specifying a value of 0 for this flag then you will need to update the config value to 1s *prior to upgrading to v20 or later* as `vttablet` will report an error and terminate if you attempt to start it with a value of 0.

#### New `--track-udfs` vtgate flag

The new `--track-udfs` flag enables VTGate to track user defined functions for better planning.

#### Help text fix for `--lock-timeout`

The help text for the flag `--lock-timeout` was incorrect. We were documenting it as a flag that controlled the duration for which the shard lock was acquired. It is actually the maximum duration for which we wait while attempting to acquire a lock from the topology server.

#### New `--querylog-sample-rate` flag

The new flag `--querylog-sample-rate float` adds support for sampling queries based on a float value between 0.0 _(no logging)_ and 1.0 _(all queries logged)_. If configured, this filtering is applied after the existing `--querylog-filter-tag` filter.

#### New `--tablet-filter-tags` flag

The new flag `--tablet-filter-tags StringMap` adds support to VTGate for filtering tablets by tablet tag key/values, specified as comma-separated list of key:values. The tags of a tablet are defined by the VTTablet flag `--init_tags`, which is also defined as a comma-separated list of key:values.

### VReplication

####  Multi-tenant Imports

Support for multi-tenant imports has been added to `MoveTables`. If you have a multi-tenant architecture where each
tenant has their own database, you can import the tenants using multiple `MoveTables` workfows, one per tenant.
Each import is initiated with the new `--tenant-id` flag. The column name (and data type) need to be specified in
the VSchema of the target keyspace.

####  VDiff support for OnlineDDL migrations

You can now run `VDiff`s on OnlineDDL schema change migrations, which are not yet cut over.

## Minor Changes

### New Stats

#### VTTablet Query Cache Hits and Misses

VTTablet exposes two new counter stats:

 * `QueryCacheHits`: Query engine query plan cache hits
 * `QueryCacheMisses`: Query engine query plan cache misses

> [!NOTE]
> `QueryCache` does not refer to a query cache, but to a query plan cache.
> In v21, these metrics will be deprecated and renamed.

### VTTablet Query Text Characters Processed

VTGate and VTTablet expose a new counter stat `QueryTextCharactersProcessed` to reflect the number of query text characters processed.

VTGate groups this metric by Operation, Keyspace and TabletType. On VTTablet it is grouped by Table, Plan and optionally Workload.

### `SIGHUP` reload of gRPC client static auth creds

The internal gRPC client now caches the static auth credentials and supports reloading via the `SIGHUP` signal. Previous to v20 the credentials were not cached. They were re-loaded from disk on every use.

### VTAdmin

#### vtadmin-web updated to node v20.12.2 (LTS)

Building `vtadmin-web` now requires node >= v20.12.0 (LTS). Breaking changes from v18 to v20 can be found at https://nodejs.org/en/blog/release/v20.12.0 -- with no known issues that apply to VTAdmin.
Full details on the node v20.12.2 release can be found at https://nodejs.org/en/blog/release/v20.12.2.

#### Replaced highcharts with d3

The vtadmin-web UI no longer has a dependency on highcharts for licensing reasons. The tablet QPS, tablet VReplication QPS, and workflow streams lag charts have all been replaced by d3. We'll be iteratively improving the d3 charts until they reach feature parity with the original highcharts charts. 

------------
The entire changelog for this release can be found [here](https://github.com/vitessio/vitess/blob/main/changelog/20.0/20.0.0/changelog.md).

The release includes 419 merged Pull Requests.

Thanks to all our contributors: @Aoang, @Ari1009, @GuptaManan100, @Its-Maniaco, @Maniktherana, @VaibhavMalik4187, @ajm188, @aparajon, @app/dependabot, @app/github-actions, @app/vitess-bot, @arthurschreiber, @bddicken, @beingnoble03, @brendar, @crazeteam, @dbussink, @deepthi, @demmer, @derekperkins, @ejortegau, @frouioui, @harshit-gangal, @mattlord, @maxenglander, @mdlayher, @notfelineit, @pavedroad, @rafer, @rohit-nayak-ps, @rvrangel, @shlomi-noach, @systay, @timvaillancourt, @tycol7, @vitess-bot, @vmg, @wangweicugw, @whuang8, @yoheimuta

Vitess v20.0.0-rc2 (2024-06-20)

# Release of Vitess v20.0.0

## Summary

### Table of Contents

- **[Major Changes](#major-changes)**
  - **[Deletions](#deletions)** 
    - [`--vreplication_tablet_type` flag](#vreplication-tablet-type-deletion)
    - [Pool Capacity Flags](#pool-flags-deletion)
    - [vitess/base and vitess/k8s Docker images](#base-k8s-images)
    - [`gh-ost` binary and endtoend tests](#gh-ost-binary-tests-removal)
    - [Legacy `EmergencyReparentShard` stats](#legacy-emergencyshardreparent-stats)
  - **[Breaking changes](#breaking-changes)**
    - [Metric Name Changes in VTOrc](#metric-change-vtorc)
    - [ENUM and SET column handling in VTGate VStream API](#enum-set-vstream)
    - [`shutdown_grace_period` Default Change](#shutdown-grace-period-default)
    - [New `unmanaged` Flag and `disable_active_reparents` deprecation](#unmanaged-flag)
    - [`recovery-period-block-duration` Flag deprecation](#recovery-block-deprecation)
    - [`mysqlctld` `onterm-timeout` Default Change](#mysqlctld-onterm-timeout)
    - [`MoveTables` now removes `auto_increment` clauses by default when moving tables from an unsharded keyspace to a sharded one](#move-tables-auto-increment)
    - [`Durabler` interface method renaming](#durabler-interface-method-renaming)
  - **[Query Compatibility](#query-compatibility)**
    - [Vindex Hints](#vindex-hints)
    - [Update with Limit Support](#update-limit)
    - [Update with Multi Table Support](#multi-table-update)
    - [Update with Multi Target Support](#update-multi-target)
    - [Delete with Subquery Support](#delete-subquery)
    - [Delete with Multi Target Support](#delete-multi-target)
    - [User Defined Functions Support](#udf-support)
    - [Insert Row Alias Support](#insert-row-alias-support)
  - **[Query Timeout](#query-timeout)**
  - **[Flag changes](#flag-changes)**
    - [`pprof-http` default change](#pprof-http-default)
    - [New `healthcheck-dial-concurrency` flag](#healthcheck-dial-concurrency-flag)
    - [New minimum for `--buffer_min_time_between_failovers`](#buffer_min_time_between_failovers-flag)
    - [New `track-udfs` vtgate flag](#vtgate-track-udfs-flag)
    - [Help text fix for `--lock-timeout`](#documentation-lock-timeout)
    - [New `--querylog-sample-rate` flag](#querylog-sample-rate-flag)
    - [New `--tablet-filter-tags` flag](#tablet-filter-tags-flag)

- **[Minor Changes](#minor-changes)**
  - **[New Stats](#new-stats)**
    - [VTTablet Query Cache Hits and Misses](#vttablet-query-cache-hits-and-misses)
    - [VTGate and VTTablet Query Text Characters Processed](#vttablet-query-text-characters-processed)
  - **[`SIGHUP` reload of gRPC client static auth creds](#sighup-reload-of-grpc-client-auth-creds)**
  - **[VTAdmin](#vtadmin)**
    - [Updated to node v20.12.2](#updated-node)
    - [Replaced highcharts with d3](#replaced-highcharts)

## Major Changes

### Deletion

#### `--vreplication_tablet_type` flag

The previously deprecated flag `--vreplication_tablet_type` has been deleted.

#### Pool Capacity Flags

The previously deprecated flags `--queryserver-config-query-pool-waiter-cap`, `--queryserver-config-stream-pool-waiter-cap` and `--queryserver-config-txpool-waiter-cap` have been deleted.

#### `vitess/base` and `vitess/k8s` Docker images

Since we have deleted MySQL from our `vitess/lite` image, we are removing the `vitess/base` and `vitess/k8s` images.

These images are no longer useful since we can use `vitess/lite` as the base of many other Docker images (`vitess/vtgate`, `vitess/vtgate`, ...).

#### `gh-ost` binary and endtoend tests

Vitess 20.0 drops support for `gh-ost` DDL strategy.

`vttablet` binary no longer embeds a `gh-ost` binary. Users of `gh-ost` DDL strategy will need to supply a `gh-ost` binary on the `vttablet` host or pod. Vitess will look for the `gh-ost` binary in the system `PATH`; otherwise the user should supply `vttablet --gh-ost-path`.

Vitess' endtoend tests no longer use nor test `gh-ost` migrations.

#### Legacy `EmergencyReparentShard` stats

The following `EmergencyReparentShard` stats were deprecated in Vitess 18.0 and are removed in Vitess 20.0:
- `ers_counter`
- `ers_success_counter`
- `ers_failure_counter`

These counters are replaced by the following stats _(introduced in Vitess 18.0)_:
- `emergency_reparent_counts` - Number of times `EmergencyReparentShard` has been run. It is further subdivided by the keyspace, shard and the result of the operation.
- `planned_reparent_counts` - Number of times `PlannedReparentShard` has been run. It is further subdivided by the keyspace, shard and the result of the operation.

Also, the `reparent_shard_operation_timings` stat was added to provide per-operation timings of reparent operations.

### Breaking Changes

#### Metric Name Changes in VTOrc

The following metric names have been changed in VTOrc. The old metrics are still available in `/debug/vars` for this release, but will be removed in later releases. The new metric names and the deprecated metric names resolve to the same metric name on prometheus, so there is no change there.

|               Old Metric Name                |             New Metric Name              |                 Name in Prometheus                 |
|:--------------------------------------------:|:----------------------------------------:|:--------------------------------------------------:|
|           `analysis.change.write`            |          `AnalysisChangeWrite`           |           `vtorc_analysis_change_write`            |  
|                `audit.write`                 |               `AuditWrite`               |                `vtorc_audit_write`                 |  
|            `discoveries.attempt`             |           `DiscoveriesAttempt`           |            `vtorc_discoveries_attempt`             |  
|              `discoveries.fail`              |            `DiscoveriesFail`             |              `vtorc_discoveries_fail`              |  
| `discoveries.instance_poll_seconds_exceeded` | `DiscoveriesInstancePollSecondsExceeded` | `vtorc_discoveries_instance_poll_seconds_exceeded` |  
|          `discoveries.queue_length`          |         `DiscoveriesQueueLength`         |          `vtorc_discoveries_queue_length`          |  
|          `discoveries.recent_count`          |         `DiscoveriesRecentCount`         |          `vtorc_discoveries_recent_count`          |  
|               `instance.read`                |              `InstanceRead`              |               `vtorc_instance_read`                |  
|           `instance.read_topology`           |          `InstanceReadTopology`          |           `vtorc_instance_read_topology`           |
|         `emergency_reparent_counts`          |        `EmergencyReparentCounts`         |         `vtorc_emergency_reparent_counts`          |
|          `planned_reparent_counts`           |         `PlannedReparentCounts`          |          `vtorc_planned_reparent_counts`           |
|      `reparent_shard_operation_timings`      |     `ReparentShardOperationTimings`      |  `vtorc_reparent_shard_operation_timings_bucket`   |
		
		

#### ENUM and SET column handling in VTGate VStream API

The [VTGate VStream API](https://vitess.io/docs/reference/vreplication/vstream/) now returns [`ENUM`](https://dev.mysql.com/doc/refman/en/enum.html) and [`SET`](https://dev.mysql.com/doc/refman/en/set.html) column type values in [`VEvent`](https://pkg.go.dev/vitess.io/vitess/go/vt/proto/binlogdata#VEvent) messages (in the embedded [`RowChange`](https://pkg.go.dev/vitess.io/vitess/go/vt/proto/binlogdata#RowChange) messages) as their string values instead of the integer based ones — in both the copy/snapshot phase and the streaming phase. This change was done to make the `VStream` API more user-friendly, intuitive, and to align the behavior across both phases. Before [this change](https://github.com/vitessio/vitess/pull/15723) the values for [`ENUM`](https://dev.mysql.com/doc/refman/en/enum.html) and [`SET`](https://dev.mysql.com/doc/refman/en/set.html) columns were string values in the copy phase but integer values (which only have an internal meaning to MySQL) in the streaming phase. This inconsistency led to various [challenges and issues](https://github.com/vitessio/vitess/issues/15750) for each `VStream` client/consumer (e.g. the [`Debezium` Vitess connector](https://debezium.io/documentation/reference/stable/connectors/vitess.html) failed to properly perform a snapshot for tables containing these column types). Now the behavior is intuitive — clients need the string values as the eventual sink is often not MySQL so each consumer needed to perform the mappings themselves — and consistent. While this is a (potentially) breaking change, a new boolean field has been added to the [`FieldEvent`](https://pkg.go.dev/vitess.io/vitess/go/vt/proto/binlogdata#FieldEvent) message called `EnumSetStringValues`. When that field is `false` (in Vitess v19 and older) then the consumer will need to perform the mappings during streaming phase, but not during copy phase. When this field is `true`, then no mapping is required. This will help to ensure a smooth transition for all consumers over time. To demonstrate, let's look at the textual output (printing the received `VEvents` as strings) when streaming a single `enum_set_test` table from the unsharded `commerce` keyspace so that we can see what the VStream looks like before and after when we start a new VStream in copy/snapshot mode and then transition to streaming mode for the following table:

```sql
CREATE TABLE `enum_set_test` (
  `id` int NOT NULL AUTO_INCREMENT,
  `name` varchar(120) DEFAULT NULL,
  `shirt_size` enum('small','medium','large','xlarge','xxlarge') DEFAULT NULL,
  `hobbies` set('knitting','cooking','pickleball','biking','hiking','motorcycle','video games','reading') DEFAULT NULL,
  PRIMARY KEY (`id`)
)
```

And with the table having this data when we start our `VStream` and begin the copy/snapshot phase:

```sql
mysql> select * from enum_set_test;
+----+-----------+------------+-------------------------+
| id | name      | shirt_size | hobbies                 |
+----+-----------+------------+-------------------------+
|  1 | Billy Bob | xlarge     | cooking,reading         |
|  2 | Sally Mae | medium     | knitting,cooking,hiking |
+----+-----------+------------+-------------------------+
2 rows in set (0.00 sec)
```

And finally we will perform the following inserts and updates to the table during the streaming phase:

```sql
insert into enum_set_test values (3, "Matt Lord", 'medium', 'pickleball,biking,hiking,motorcycle,video games,reading');
insert into enum_set_test values (4, "Jerry Badyellow", 'large', '');
update enum_set_test set shirt_size = 'small', hobbies = 'knitting,cooking,hiking,reading' where id = 2;
```

Vitess v19 and older:

```text
[type:BEGIN keyspace:"commerce" shard:"0" type:FIELD field_event:{table_name:"commerce.enum_set_test" fields:{name:"id" type:INT32 table:"enum_set_test" org_table:"enum_set_test" database:"vt_commerce" org_name:"id" column_length:11 charset:63 flags:49667 column_type:"int"} fields:{name:"name" type:VARCHAR table:"enum_set_test" org_table:"enum_set_test" database:"vt_commerce" org_name:"name" column_length:480 charset:255 column_type:"varchar(120)"} fields:{name:"shirt_size" type:ENUM table:"enum_set_test" org_table:"enum_set_test" database:"vt_commerce" org_name:"shirt_size" column_length:28 charset:255 flags:256 column_type:"enum('small','medium','large','xlarge','xxlarge')"} fields:{name:"hobbies" type:SET table:"enum_set_test" org_table:"enum_set_test" database:"vt_commerce" org_name:"hobbies" column_length:288 charset:255 flags:2048 column_type:"set('knitting','cooking','pickleball','biking','hiking','motorcycle','video games','reading')"} keyspace:"commerce" shard:"0"} keyspace:"commerce" shard:"0"]
[type:VGTID vgtid:{shard_gtids:{keyspace:"commerce" shard:"0" gtid:"MySQL56/ce357206-0d49-11ef-8fd1-a74564279579:1-35"}} keyspace:"commerce" shard:"0"]
[type:ROW row_event:{table_name:"commerce.enum_set_test" row_changes:{after:{lengths:1 lengths:9 lengths:6 lengths:15 values:"1Billy Bobxlargecooking,reading"}} keyspace:"commerce" shard:"0"} keyspace:"commerce" shard:"0" type:ROW row_event:{table_name:"commerce.enum_set_test" row_changes:{after:{lengths:1 lengths:9 lengths:6 lengths:23 values:"2Sally Maemediumknitting,cooking,hiking"}} keyspace:"commerce" shard:"0"} keyspace:"commerce" shard:"0" type:VGTID vgtid:{shard_gtids:{keyspace:"commerce" shard:"0" gtid:"MySQL56/ce357206-0d49-11ef-8fd1-a74564279579:1-35" table_p_ks:{table_name:"enum_set_test" lastpk:{fields:{name:"id" type:INT32 charset:63 flags:49667} rows:{lengths:1 values:"2"}}}}} keyspace:"commerce" shard:"0" type:COMMIT keyspace:"commerce" shard:"0"]
[type:BEGIN keyspace:"commerce" shard:"0" type:VGTID vgtid:{shard_gtids:{keyspace:"commerce" shard:"0" gtid:"MySQL56/ce357206-0d49-11ef-8fd1-a74564279579:1-35"}} keyspace:"commerce" shard:"0" type:COMMIT keyspace:"commerce" shard:"0"]
[type:COPY_COMPLETED keyspace:"commerce" shard:"0" type:COPY_COMPLETED]
[type:BEGIN timestamp:1715179728 current_time:1715179728532658000 keyspace:"commerce" shard:"0" type:FIELD timestamp:1715179728 field_event:{table_name:"commerce.enum_set_test" fields:{name:"id" type:INT32 table:"enum_set_test" org_table:"enum_set_test" database:"vt_commerce" org_name:"id" column_length:11 charset:63 flags:49667 column_type:"int"} fields:{name:"name" type:VARCHAR table:"enum_set_test" org_table:"enum_set_test" database:"vt_commerce" org_name:"name" column_length:480 charset:255 column_type:"varchar(120)"} fields:{name:"shirt_size" type:ENUM table:"enum_set_test" org_table:"enum_set_test" database:"vt_commerce" org_name:"shirt_size" column_length:28 charset:255 flags:256 column_type:"enum('small','medium','large','xlarge','xxlarge')"} fields:{name:"hobbies" type:SET table:"enum_set_test" org_table:"enum_set_test" database:"vt_commerce" org_name:"hobbies" column_length:288 charset:255 flags:2048 column_type:"set('knitting','cooking','pickleball','biking','hiking','motorcycle','video games','reading')"} keyspace:"commerce" shard:"0"} current_time:1715179728535652000 keyspace:"commerce" shard:"0" type:ROW timestamp:1715179728 row_event:{table_name:"commerce.enum_set_test" row_changes:{after:{lengths:1 lengths:9 lengths:1 lengths:3 values:"3Matt Lord2252"}} keyspace:"commerce" shard:"0" flags:1} current_time:1715179728535739000 keyspace:"commerce" shard:"0" type:VGTID vgtid:{shard_gtids:{keyspace:"commerce" shard:"0" gtid:"MySQL56/ce357206-0d49-11ef-8fd1-a74564279579:1-36"}} keyspace:"commerce" shard:"0" type:COMMIT timestamp:1715179728 current_time:1715179728535754000 keyspace:"commerce" shard:"0"]
[type:BEGIN timestamp:1715179735 current_time:1715179735538607000 keyspace:"commerce" shard:"0" type:ROW timestamp:1715179735 row_event:{table_name:"commerce.enum_set_test" row_changes:{after:{lengths:1 lengths:15 lengths:1 lengths:1 values:"4Jerry Badyellow30"}} keyspace:"commerce" shard:"0" flags:1} current_time:1715179735538659000 keyspace:"commerce" shard:"0" type:VGTID vgtid:{shard_gtids:{keyspace:"commerce" shard:"0" gtid:"MySQL56/ce357206-0d49-11ef-8fd1-a74564279579:1-37"}} keyspace:"commerce" shard:"0" type:COMMIT timestamp:1715179735 current_time:1715179735538672000 keyspace:"commerce" shard:"0"]
[type:BEGIN timestamp:1715179741 current_time:1715179741728690000 keyspace:"commerce" shard:"0" type:ROW timestamp:1715179741 row_event:{table_name:"commerce.enum_set_test" row_changes:{before:{lengths:1 lengths:9 lengths:1 lengths:2 values:"2Sally Mae219"} after:{lengths:1 lengths:9 lengths:1 lengths:3 values:"2Sally Mae1147"}} keyspace:"commerce" shard:"0" flags:1} current_time:1715179741728730000 keyspace:"commerce" shard:"0" type:VGTID vgtid:{shard_gtids:{keyspace:"commerce" shard:"0" gtid:"MySQL56/ce357206-0d49-11ef-8fd1-a74564279579:1-38"}} keyspace:"commerce" shard:"0" type:COMMIT timestamp:1715179741 current_time:1715179741728744000 keyspace:"commerce" shard:"0"]
```

Vitess v20 and newer:

```text
[type:BEGIN keyspace:"commerce" shard:"0" type:FIELD field_event:{table_name:"commerce.enum_set_test" fields:{name:"id" type:INT32 table:"enum_set_test" org_table:"enum_set_test" database:"vt_commerce" org_name:"id" column_length:11 charset:63 flags:49667 column_type:"int"} fields:{name:"name" type:VARCHAR table:"enum_set_test" org_table:"enum_set_test" database:"vt_commerce" org_name:"name" column_length:480 charset:255 column_type:"varchar(120)"} fields:{name:"shirt_size" type:ENUM table:"enum_set_test" org_table:"enum_set_test" database:"vt_commerce" org_name:"shirt_size" column_length:28 charset:255 flags:256 column_type:"enum('small','medium','large','xlarge','xxlarge')"} fields:{name:"hobbies" type:SET table:"enum_set_test" org_table:"enum_set_test" database:"vt_commerce" org_name:"hobbies" column_length:288 charset:255 flags:2048 column_type:"set('knitting','cooking','pickleball','biking','hiking','motorcycle','video games','reading')"} keyspace:"commerce" shard:"0" enum_set_string_values:true} keyspace:"commerce" shard:"0"]
[type:VGTID vgtid:{shard_gtids:{keyspace:"commerce" shard:"0" gtid:"MySQL56/156f702a-0d47-11ef-8723-653d045ab990:1-50"}} keyspace:"commerce" shard:"0"]
[type:ROW row_event:{table_name:"commerce.enum_set_test" row_changes:{after:{lengths:1 lengths:9 lengths:6 lengths:15 values:"1Billy Bobxlargecooking,reading"}} keyspace:"commerce" shard:"0"} keyspace:"commerce" shard:"0" type:ROW row_event:{table_name:"commerce.enum_set_test" row_changes:{after:{lengths:1 lengths:9 lengths:6 lengths:23 values:"2Sally Maemediumknitting,cooking,hiking"}} keyspace:"commerce" shard:"0"} keyspace:"commerce" shard:"0" type:VGTID vgtid:{shard_gtids:{keyspace:"commerce" shard:"0" gtid:"MySQL56/156f702a-0d47-11ef-8723-653d045ab990:1-50" table_p_ks:{table_name:"enum_set_test" lastpk:{fields:{name:"id" type:INT32 charset:63 flags:49667} rows:{lengths:1 values:"2"}}}}} keyspace:"commerce" shard:"0" type:COMMIT keyspace:"commerce" shard:"0"]
[type:BEGIN keyspace:"commerce" shard:"0" type:VGTID vgtid:{shard_gtids:{keyspace:"commerce" shard:"0" gtid:"MySQL56/156f702a-0d47-11ef-8723-653d045ab990:1-50"}} keyspace:"commerce" shard:"0" type:COMMIT keyspace:"commerce" shard:"0"]
[type:COPY_COMPLETED keyspace:"commerce" shard:"0" type:COPY_COMPLETED]
[type:BEGIN timestamp:1715179399 current_time:1715179399817221000 keyspace:"commerce" shard:"0" type:FIELD timestamp:1715179399 field_event:{table_name:"commerce.enum_set_test" fields:{name:"id" type:INT32 table:"enum_set_test" org_table:"enum_set_test" database:"vt_commerce" org_name:"id" column_length:11 charset:63 flags:49667 column_type:"int"} fields:{name:"name" type:VARCHAR table:"enum_set_test" org_table:"enum_set_test" database:"vt_commerce" org_name:"name" column_length:480 charset:255 column_type:"varchar(120)"} fields:{name:"shirt_size" type:ENUM table:"enum_set_test" org_table:"enum_set_test" database:"vt_commerce" org_name:"shirt_size" column_length:28 charset:255 flags:256 column_type:"enum('small','medium','large','xlarge','xxlarge')"} fields:{name:"hobbies" type:SET table:"enum_set_test" org_table:"enum_set_test" database:"vt_commerce" org_name:"hobbies" column_length:288 charset:255 flags:2048 column_type:"set('knitting','cooking','pickleball','biking','hiking','motorcycle','video games','reading')"} keyspace:"commerce" shard:"0" enum_set_string_values:true} current_time:1715179399821735000 keyspace:"commerce" shard:"0" type:ROW timestamp:1715179399 row_event:{table_name:"commerce.enum_set_test" row_changes:{after:{lengths:1 lengths:9 lengths:6 lengths:55 values:"3Matt Lordmediumpickleball,biking,hiking,motorcycle,video games,reading"}} keyspace:"commerce" shard:"0" flags:1} current_time:1715179399821762000 keyspace:"commerce" shard:"0" type:VGTID vgtid:{shard_gtids:{keyspace:"commerce" shard:"0" gtid:"MySQL56/156f702a-0d47-11ef-8723-653d045ab990:1-51"}} keyspace:"commerce" shard:"0" type:COMMIT timestamp:1715179399 current_time:1715179399821801000 keyspace:"commerce" shard:"0"]
[type:BEGIN timestamp:1715179399 current_time:1715179399822310000 keyspace:"commerce" shard:"0" type:ROW timestamp:1715179399 row_event:{table_name:"commerce.enum_set_test" row_changes:{after:{lengths:1 lengths:15 lengths:5 lengths:0 values:"4Jerry Badyellowlarge"}} keyspace:"commerce" shard:"0" flags:1} current_time:1715179399822355000 keyspace:"commerce" shard:"0" type:VGTID vgtid:{shard_gtids:{keyspace:"commerce" shard:"0" gtid:"MySQL56/156f702a-0d47-11ef-8723-653d045ab990:1-52"}} keyspace:"commerce" shard:"0" type:COMMIT timestamp:1715179399 current_time:1715179399822360000 keyspace:"commerce" shard:"0"]
[type:BEGIN timestamp:1715179400 current_time:1715179400512056000 keyspace:"commerce" shard:"0" type:ROW timestamp:1715179400 row_event:{table_name:"commerce.enum_set_test" row_changes:{before:{lengths:1 lengths:9 lengths:6 lengths:23 values:"2Sally Maemediumknitting,cooking,hiking"} after:{lengths:1 lengths:9 lengths:5 lengths:31 values:"2Sally Maesmallknitting,cooking,hiking,reading"}} keyspace:"commerce" shard:"0" flags:1} current_time:1715179400512094000 keyspace:"commerce" shard:"0" type:VGTID vgtid:{shard_gtids:{keyspace:"commerce" shard:"0" gtid:"MySQL56/156f702a-0d47-11ef-8723-653d045ab990:1-53"}} keyspace:"commerce" shard:"0" type:COMMIT timestamp:1715179400 current_time:1715179400512108000 keyspace:"commerce" shard:"0"]
```

An example key difference there being that `after:{lengths:1 lengths:9 lengths:1 lengths:3 values:"2Sally Mae1147"}` from Vitess v19 and older becomes `after:{lengths:1 lengths:9 lengths:5 lengths:31 values:"2Sally Maesmallknitting,cooking,hiking,reading"}` from Vitess v20 and newer. So `1` -> `small` and `147` -> `knitting,cooking,hiking,reading` for the `ENUM` and `SET` column values respectively. This also demonstrates why this mapping is necessary in consumers/clients, as `147` has no logical meaning/value for this column outside of MySQL internals.

If you're using the [`Debezium` Vitess connector](https://debezium.io/documentation/reference/stable/connectors/vitess.html), you should upgrade your connector to 2.7 (the next release) — which should contain [the relevant necessary changes](https://issues.redhat.com/browse/DBZ-7792) — *prior to upgrading Vitess* to v20.0.1 or later. If you're using any of the PlanetScale connectors ([`AirByte`](https://github.com/planetscale/airbyte-source/), [`FiveTran`](https://github.com/planetscale/fivetran-source), or [`singer-tap`](https://github.com/planetscale/singer-tap)) then no actions are required.

If you're using a custom `VStream` client/consumer, then you will need to build a new client with the updated v20 [binlogdata protos](https://pkg.go.dev/vitess.io/vitess/go/vt/proto/binlogdata) ([source](https://github.com/vitessio/vitess/blob/main/proto/binlogdata.proto) for which would be in `main` or the `release-20.0` branch) before needing to support Vitess v20.0.1 or later. Your client will then be able to handle old and new messages, with older messages always having this new field set to `false`.

#### `shutdown_grace_period` Default Change

The `--shutdown_grace_period` flag, which was introduced in v2 with a default of `0 seconds`, has now been changed to default to `3 seconds`.
This makes reparenting in Vitess resilient to client errors, and prevents PlannedReparentShard from timing out.

In order to preserve the old behaviour, the users can set the flag back to `0 seconds` causing open transactions to never be shutdown, but in that case, they run the risk of PlannedReparentShard calls timing out.

####  New `unmanaged` Flag and `disable_active_reparents` deprecation

New flag `--unmanaged` has been introduced in this release to make it easier to flag unmanaged tablets. It also runs validations to make sure the unmanaged tablets are configured properly. `--disable_active_reparents` flag has been deprecated for `vttablet`, `vtcombo` and `vttestserver` binaries and will be removed in future releases. Specifying the `--unmanaged` flag will also block replication commands and replication repairs.

Starting this release, all unmanaged tablets should specify this flag.


####  `recovery-period-block-duration` Flag deprecation

The flag `--recovery-period-block-duration` has been deprecated in VTOrc from this release. Its value is now ignored and the flag will be removed in later releases.
VTOrc no longer blocks recoveries for a certain duration after a previous recovery has completed. Since VTOrc refreshes the required information after
acquiring a shard lock, blocking of recoveries is not required.

#### `mysqlctld` `onterm_timeout` Default Change

The `--onterm_timeout` flag default value has changed for `mysqlctld`. It now is by default long enough to be able to wait for the default `--shutdown-wait-time` when shutting down on a `TERM` signal. 

This is necessary since otherwise MySQL would never shut down cleanly with the old defaults, since `mysqlctld` would shut down already after 10 seconds by default.

#### `MoveTables` now removes `auto_increment` clauses by default when moving tables from an unsharded keyspace to a sharded one

A new `--remove-sharded-auto-increment` flag has been added to the [`MoveTables` create sub-command](https://vitess.io/docs/20.0/reference/programs/vtctldclient/vtctldclient_movetables/vtctldclient_movetables_create/) and it is set to `true` by default. This flag controls whether any [MySQL `auto_increment`](https://dev.mysql.com/doc/refman/en/example-auto-increment.html) clauses should be removed from the table definitions when moving tables from an unsharded keyspace to a sharded one. This is now done by default as `auto_increment` clauses should not typically be used with sharded tables and you should instead rely on externally generated values such as a form of universally/globally unique identifiers or use [Vitess sequences](https://vitess.io/docs/reference/features/vitess-sequences/) in order to ensure that each row has a unique identifier (Primary Key value) across all shards. If for some reason you want to retain them you can set this new flag to `false` when creating the workflow.

#### `Durabler` interface method renaming

The methods of [the `Durabler` interface](https://github.com/vitessio/vitess/blob/main/go/vt/vtctl/reparentutil/durability.go#L70-L79) in `go/vt/vtctl/reparentutil` were renamed to be public _(capitalized)_ methods to make it easier to integrate custom Durability Policies from external packages. See [RFC for details](https://github.com/vitessio/vitess/issues/15544).

Users of custom Durability Policies must rename private `Durabler` methods.

Changes:
- The `promotionRule` method was renamed to `PromotionRule`
- The `semiSyncAckers` method was renamed to `SemiSyncAckers`
- The `isReplicaSemiSync` method was renamed to `IsReplicaSemiSync`

### Query Compatibility

####  Vindex Hints

Vitess now supports Vindex hints that provide a way for users to influence the shard routing of queries in Vitess by specifying, which vindexes should be considered or ignored by the query planner. This feature enhances the control over query execution, allowing for potentially more efficient data access patterns in sharded databases.

Example:
 ```sql
    SELECT * FROM user USE VINDEX (hash_user_id, secondary_vindex) WHERE user_id = 123;
    SELECT * FROM order IGNORE VINDEX (range_order_id) WHERE order_date = '2021-01-01';
 ```

For more information about Vindex hints and its usage, please consult the documentation.

####  Update with Limit Support

Support is added for sharded update with limit.

Example: `update t1 set t1.foo = 'abc', t1.bar = 23 where t1.baz > 5 limit 1`

More details about how it works is available in [MySQL Docs](https://dev.mysql.com/doc/refman/8.0/en/update.html)

####  Update with Multi Table Support

Support is added for sharded multi-table update with column update on single target table using multiple table join.

Example: `update t1 join t2 on t1.id = t2.id join t3 on t1.col = t3.col set t1.baz = 'abc', t1.apa = 23 where t3.foo = 5 and t2.bar = 7`

More details about how it works is available in [MySQL Docs](https://dev.mysql.com/doc/refman/8.0/en/update.html)

####  Update with Multi Target Support

Support is added for sharded multi table target update.

Example: `update t1 join t2 on t1.id = t2.id set t1.foo = 'abc', t2.bar = 23`

More details about how it works is available in [MySQL Docs](https://dev.mysql.com/doc/refman/8.0/en/update.html)

####  Delete with Subquery Support

Support is added for sharded table delete with subquery

Example: `delete from t1 where id in (select col from t2 where foo = 32 and bar = 43)`

####  Delete with Multi Target Support

Support is added for sharded multi table target delete.

Example: `delete t1, t3 from t1 join t2 on t1.id = t2.id join t3 on t1.col = t3.col`

More details about how it works is available in [MySQL Docs](https://dev.mysql.com/doc/refman/8.0/en/delete.html)

####  User Defined Functions Support

VTGate can track any user defined functions for better planning.
User Defined Functions (UDFs) should be directly loaded in the underlying MySQL.

It should be enabled in VTGate with the `--track-udfs` flag.
This will enable the tracking of UDFs in VTGate and will be used for planning.
Without this flag, VTGate will not be aware that there might be aggregating user-defined functions in the query that need to be pushed down to MySQL.

More details about how to load UDFs is available in [MySQL Docs](https://dev.mysql.com/doc/extending-mysql/8.0/en/adding-loadable-function.html)

####  Insert Row Alias Support

Support is added to have row alias in Insert statement to be used with `on duplicate key update`.

Example:
- `insert into user(id, name, email) valies (100, 'Alice', 'alice@mail.com') as new on duplicate key update name = new.name, email = new.email`
- `insert into user(id, name, email) valies (100, 'Alice', 'alice@mail.com') as new(m, n, p) on duplicate key update name = n, email = p`

More details about how it works is available in [MySQL Docs](https://dev.mysql.com/doc/refman/8.0/en/insert-on-duplicate.html)

### Query Timeout
On a query timeout, Vitess closed the connection using the `kill connection` statement. This leads to connection churn 
which is not desirable in some cases. To avoid this, Vitess now uses the `kill query` statement to cancel the query. 
This will only cancel the query and does not terminate the connection.

### Flag Changes

####  `pprof-http` Default Change

The `--pprof-http` flag, which was introduced in v19 with a default of `true`, has now been changed to default to `false`.
This makes HTTP `pprof` endpoints now an *opt-in* feature, rather than opt-out.
To continue enabling these endpoints, explicitly set `--pprof-http` when starting up Vitess components.

#### New `--healthcheck-dial-concurrency` flag

The new `--healthcheck-dial-concurrency` flag defines the maximum number of healthcheck connections that can open concurrently. This limit is to avoid hitting Go runtime panics on deployments watching enough tablets [to hit the runtime's maximum thread limit of `10000`](https://pkg.go.dev/runtime/debug#SetMaxThreads) due to blocking network syscalls. This flag applies to `vtcombo`, `vtctld` and `vtgate` only and a value less than the runtime max thread limit _(`10000`)_ is recommended.

#### New minimum for `--buffer_min_time_between_failovers`

The `--buffer_min_time_between_failovers` `vttablet` flag now has a minimum value of `1s`. This is because a value of 0 can cause issues with the buffering mechanics resulting in unexpected and unnecessary query errors — in particular during `MoveTables SwitchTraffic` operations. If you are currently specifying a value of 0 for this flag then you will need to update the config value to 1s *prior to upgrading to v20 or later* as `vttablet` will report an error and terminate if you attempt to start it with a value of 0.

#### New `--track-udfs` vtgate flag

The new `--track-udfs` flag enables VTGate to track user defined functions for better planning.

#### Help text fix for `--lock-timeout`

The help text for the flag `--lock-timeout` was incorrect. We were documenting it as a flag that controlled the duration for which the shard lock was acquired. It is actually the maximum duration for which we wait while attempting to acquire a lock from the topology server.

#### New `--querylog-sample-rate` flag

The new flag `--querylog-sample-rate float` adds support for sampling queries based on a float value between 0.0 _(no logging)_ and 1.0 _(all queries logged)_. If configured, this filtering is applied after the existing `--querylog-filter-tag` filter.

#### New `--tablet-filter-tags` flag

The new flag `--tablet-filter-tags StringMap` adds support to VTGate for filtering tablets by tablet tag key/values, specified as comma-separated list of key:values. The tags of a tablet are defined by the VTTablet flag `--init_tags`, which is also defined as a comma-separated list of key:values.

## Minor Changes

### New Stats

#### VTTablet Query Cache Hits and Misses

VTTablet exposes two new counter stats:

 * `QueryCacheHits`: Query engine query cache hits
 * `QueryCacheMisses`: Query engine query cache misses

### VTTablet Query Text Characters Processed

VTGate and VTTablet expose a new counter stat `QueryTextCharactersProcessed` to reflect the number of query text characters processed.

VTGate groups this metric by Operation, Keyspace and TabletType. On VTTablet it is grouped by Table, Plan and optionally Workload.

### `SIGHUP` reload of gRPC client static auth creds

The internal gRPC client now caches the static auth credentials and supports reloading via the `SIGHUP` signal. Previous to v20 the credentials were not cached. They were re-loaded from disk on every use.

### VTAdmin

#### vtadmin-web updated to node v20.12.2 (LTS)

Building `vtadmin-web` now requires node >= v20.12.0 (LTS). Breaking changes from v18 to v20 can be found at https://nodejs.org/en/blog/release/v20.12.0 -- with no known issues that apply to VTAdmin.
Full details on the node v20.12.2 release can be found at https://nodejs.org/en/blog/release/v20.12.2.

#### Replaced highcharts with d3

The vtadmin-web UI no longer has a dependency on highcharts for licensing reasons. The tablet QPS, tablet VReplication QPS, and workflow streams lag charts have all been replaced by d3. We'll be iteratively improving the d3 charts until they reach feature parity with the original highcharts charts. 

------------
The entire changelog for this release can be found [here](https://github.com/vitessio/vitess/blob/main/changelog/20.0/20.0.0/changelog.md).

The release includes 441 merged Pull Requests.

Thanks to all our contributors: @Aoang, @Ari1009, @GuptaManan100, @Its-Maniaco, @Maniktherana, @VaibhavMalik4187, @ajm188, @aparajon, @app/dependabot, @app/github-actions, @app/vitess-bot, @arthurschreiber, @bddicken, @beingnoble03, @brendar, @crazeteam, @dbussink, @deepthi, @demmer, @derekperkins, @ejortegau, @frouioui, @harshit-gangal, @mattlord, @maxenglander, @mdlayher, @notfelineit, @pavedroad, @rafer, @rohit-nayak-ps, @rvrangel, @shlomi-noach, @systay, @timvaillancourt, @tycol7, @vitess-bot, @vmg, @wangweicugw, @whuang8, @yoheimuta

Vitess v20.0.0-rc1 (2024-06-13)

# Release of Vitess v20.0.0

## Summary

### Table of Contents

- **[Major Changes](#major-changes)**
  - **[Deletions](#deletions)** 
    - [`--vreplication_tablet_type` flag](#vreplication-tablet-type-deletion)
    - [Pool Capacity Flags](#pool-flags-deletion)
    - [vitess/base and vitess/k8s Docker images](#base-k8s-images)
    - [`gh-ost` binary and endtoend tests](#gh-ost-binary-tests-removal)
    - [Legacy `EmergencyReparentShard` stats](#legacy-emergencyshardreparent-stats)
  - **[Breaking changes](#breaking-changes)**
    - [Metric Name Changes in VTOrc](#metric-change-vtorc)
    - [ENUM and SET column handling in VTGate VStream API](#enum-set-vstream)
    - [`shutdown_grace_period` Default Change](#shutdown-grace-period-default)
    - [New `unmanaged` Flag and `disable_active_reparents` deprecation](#unmanaged-flag)
    - [`recovery-period-block-duration` Flag deprecation](#recovery-block-deprecation)
    - [`mysqlctld` `onterm-timeout` Default Change](#mysqlctld-onterm-timeout)
    - [`MoveTables` now removes `auto_increment` clauses by default when moving tables from an unsharded keyspace to a sharded one](#move-tables-auto-increment)
    - [`Durabler` interface method renaming](#durabler-interface-method-renaming)
  - **[Query Compatibility](#query-compatibility)**
    - [Vindex Hints](#vindex-hints)
    - [Update with Limit Support](#update-limit)
    - [Update with Multi Table Support](#multi-table-update)
    - [Update with Multi Target Support](#update-multi-target)
    - [Delete with Subquery Support](#delete-subquery)
    - [Delete with Multi Target Support](#delete-multi-target)
    - [User Defined Functions Support](#udf-support)
    - [Insert Row Alias Support](#insert-row-alias-support)
  - **[Query Timeout](#query-timeout)**
  - **[Flag changes](#flag-changes)**
    - [`pprof-http` default change](#pprof-http-default)
    - [New `healthcheck-dial-concurrency` flag](#healthcheck-dial-concurrency-flag)
    - [New minimum for `--buffer_min_time_between_failovers`](#buffer_min_time_between_failovers-flag)
    - [New `track-udfs` vtgate flag](#vtgate-track-udfs-flag)
    - [Help text fix for `--lock-timeout`](#documentation-lock-timeout)
    - [New `--querylog-sample-rate` flag](#querylog-sample-rate-flag)
    - [New `--tablet-filter-tags` flag](#tablet-filter-tags-flag)

- **[Minor Changes](#minor-changes)**
  - **[New Stats](#new-stats)**
    - [VTTablet Query Cache Hits and Misses](#vttablet-query-cache-hits-and-misses)
    - [VTGate and VTTablet Query Text Characters Processed](#vttablet-query-text-characters-processed)
  - **[`SIGHUP` reload of gRPC client static auth creds](#sighup-reload-of-grpc-client-auth-creds)**
  - **[VTAdmin](#vtadmin)**
    - [Updated to node v20.12.2](#updated-node)
    - [Replaced highcharts with d3](#replaced-highcharts)

## Major Changes

### Deletion

#### `--vreplication_tablet_type` flag

The previously deprecated flag `--vreplication_tablet_type` has been deleted.

#### Pool Capacity Flags

The previously deprecated flags `--queryserver-config-query-pool-waiter-cap`, `--queryserver-config-stream-pool-waiter-cap` and `--queryserver-config-txpool-waiter-cap` have been deleted.

#### `vitess/base` and `vitess/k8s` Docker images

Since we have deleted MySQL from our `vitess/lite` image, we are removing the `vitess/base` and `vitess/k8s` images.

These images are no longer useful since we can use `vitess/lite` as the base of many other Docker images (`vitess/vtgate`, `vitess/vtgate`, ...).

#### `gh-ost` binary and endtoend tests

Vitess 20.0 drops support for `gh-ost` DDL strategy.

`vttablet` binary no longer embeds a `gh-ost` binary. Users of `gh-ost` DDL strategy will need to supply a `gh-ost` binary on the `vttablet` host or pod. Vitess will look for the `gh-ost` binary in the system `PATH`; otherwise the user should supply `vttablet --gh-ost-path`.

Vitess' endtoend tests no longer use nor test `gh-ost` migrations.

#### Legacy `EmergencyReparentShard` stats

The following `EmergencyReparentShard` stats were deprecated in Vitess 18.0 and are removed in Vitess 20.0:
- `ers_counter`
- `ers_success_counter`
- `ers_failure_counter`

These counters are replaced by the following stats _(introduced in Vitess 18.0)_:
- `emergency_reparent_counts` - Number of times `EmergencyReparentShard` has been run. It is further subdivided by the keyspace, shard and the result of the operation.
- `planned_reparent_counts` - Number of times `PlannedReparentShard` has been run. It is further subdivided by the keyspace, shard and the result of the operation.

Also, the `reparent_shard_operation_timings` stat was added to provide per-operation timings of reparent operations.

### Breaking Changes

#### Metric Name Changes in VTOrc

The following metric names have been changed in VTOrc. The old metrics are still available in `/debug/vars` for this release, but will be removed in later releases. The new metric names and the deprecated metric names resolve to the same metric name on prometheus, so there is no change there.

|               Old Metric Name                |             New Metric Name              |                 Name in Prometheus                 |
|:--------------------------------------------:|:----------------------------------------:|:--------------------------------------------------:|
|           `analysis.change.write`            |          `AnalysisChangeWrite`           |           `vtorc_analysis_change_write`            |  
|                `audit.write`                 |               `AuditWrite`               |                `vtorc_audit_write`                 |  
|            `discoveries.attempt`             |           `DiscoveriesAttempt`           |            `vtorc_discoveries_attempt`             |  
|              `discoveries.fail`              |            `DiscoveriesFail`             |              `vtorc_discoveries_fail`              |  
| `discoveries.instance_poll_seconds_exceeded` | `DiscoveriesInstancePollSecondsExceeded` | `vtorc_discoveries_instance_poll_seconds_exceeded` |  
|          `discoveries.queue_length`          |         `DiscoveriesQueueLength`         |          `vtorc_discoveries_queue_length`          |  
|          `discoveries.recent_count`          |         `DiscoveriesRecentCount`         |          `vtorc_discoveries_recent_count`          |  
|               `instance.read`                |              `InstanceRead`              |               `vtorc_instance_read`                |  
|           `instance.read_topology`           |          `InstanceReadTopology`          |           `vtorc_instance_read_topology`           |
|         `emergency_reparent_counts`          |        `EmergencyReparentCounts`         |         `vtorc_emergency_reparent_counts`          |
|          `planned_reparent_counts`           |         `PlannedReparentCounts`          |          `vtorc_planned_reparent_counts`           |
|      `reparent_shard_operation_timings`      |     `ReparentShardOperationTimings`      |  `vtorc_reparent_shard_operation_timings_bucket`   |
		
		

#### ENUM and SET column handling in VTGate VStream API

The [VTGate VStream API](https://vitess.io/docs/reference/vreplication/vstream/) now returns [`ENUM`](https://dev.mysql.com/doc/refman/en/enum.html) and [`SET`](https://dev.mysql.com/doc/refman/en/set.html) column type values in [`VEvent`](https://pkg.go.dev/vitess.io/vitess/go/vt/proto/binlogdata#VEvent) messages (in the embedded [`RowChange`](https://pkg.go.dev/vitess.io/vitess/go/vt/proto/binlogdata#RowChange) messages) as their string values instead of the integer based ones — in both the copy/snapshot phase and the streaming phase. This change was done to make the `VStream` API more user-friendly, intuitive, and to align the behavior across both phases. Before [this change](https://github.com/vitessio/vitess/pull/15723) the values for [`ENUM`](https://dev.mysql.com/doc/refman/en/enum.html) and [`SET`](https://dev.mysql.com/doc/refman/en/set.html) columns were string values in the copy phase but integer values (which only have an internal meaning to MySQL) in the streaming phase. This inconsistency led to various [challenges and issues](https://github.com/vitessio/vitess/issues/15750) for each `VStream` client/consumer (e.g. the [`Debezium` Vitess connector](https://debezium.io/documentation/reference/stable/connectors/vitess.html) failed to properly perform a snapshot for tables containing these column types). Now the behavior is intuitive — clients need the string values as the eventual sink is often not MySQL so each consumer needed to perform the mappings themselves — and consistent. While this is a (potentially) breaking change, a new boolean field has been added to the [`FieldEvent`](https://pkg.go.dev/vitess.io/vitess/go/vt/proto/binlogdata#FieldEvent) message called `EnumSetStringValues`. When that field is `false` (in Vitess v19 and older) then the consumer will need to perform the mappings during streaming phase, but not during copy phase. When this field is `true`, then no mapping is required. This will help to ensure a smooth transition for all consumers over time. To demonstrate, let's look at the textual output (printing the received `VEvents` as strings) when streaming a single `enum_set_test` table from the unsharded `commerce` keyspace so that we can see what the VStream looks like before and after when we start a new VStream in copy/snapshot mode and then transition to streaming mode for the following table:

```sql
CREATE TABLE `enum_set_test` (
  `id` int NOT NULL AUTO_INCREMENT,
  `name` varchar(120) DEFAULT NULL,
  `shirt_size` enum('small','medium','large','xlarge','xxlarge') DEFAULT NULL,
  `hobbies` set('knitting','cooking','pickleball','biking','hiking','motorcycle','video games','reading') DEFAULT NULL,
  PRIMARY KEY (`id`)
)
```

And with the table having this data when we start our `VStream` and begin the copy/snapshot phase:

```sql
mysql> select * from enum_set_test;
+----+-----------+------------+-------------------------+
| id | name      | shirt_size | hobbies                 |
+----+-----------+------------+-------------------------+
|  1 | Billy Bob | xlarge     | cooking,reading         |
|  2 | Sally Mae | medium     | knitting,cooking,hiking |
+----+-----------+------------+-------------------------+
2 rows in set (0.00 sec)
```

And finally we will perform the following inserts and updates to the table during the streaming phase:

```sql
insert into enum_set_test values (3, "Matt Lord", 'medium', 'pickleball,biking,hiking,motorcycle,video games,reading');
insert into enum_set_test values (4, "Jerry Badyellow", 'large', '');
update enum_set_test set shirt_size = 'small', hobbies = 'knitting,cooking,hiking,reading' where id = 2;
```

Vitess v19 and older:

```text
[type:BEGIN keyspace:"commerce" shard:"0" type:FIELD field_event:{table_name:"commerce.enum_set_test" fields:{name:"id" type:INT32 table:"enum_set_test" org_table:"enum_set_test" database:"vt_commerce" org_name:"id" column_length:11 charset:63 flags:49667 column_type:"int"} fields:{name:"name" type:VARCHAR table:"enum_set_test" org_table:"enum_set_test" database:"vt_commerce" org_name:"name" column_length:480 charset:255 column_type:"varchar(120)"} fields:{name:"shirt_size" type:ENUM table:"enum_set_test" org_table:"enum_set_test" database:"vt_commerce" org_name:"shirt_size" column_length:28 charset:255 flags:256 column_type:"enum('small','medium','large','xlarge','xxlarge')"} fields:{name:"hobbies" type:SET table:"enum_set_test" org_table:"enum_set_test" database:"vt_commerce" org_name:"hobbies" column_length:288 charset:255 flags:2048 column_type:"set('knitting','cooking','pickleball','biking','hiking','motorcycle','video games','reading')"} keyspace:"commerce" shard:"0"} keyspace:"commerce" shard:"0"]
[type:VGTID vgtid:{shard_gtids:{keyspace:"commerce" shard:"0" gtid:"MySQL56/ce357206-0d49-11ef-8fd1-a74564279579:1-35"}} keyspace:"commerce" shard:"0"]
[type:ROW row_event:{table_name:"commerce.enum_set_test" row_changes:{after:{lengths:1 lengths:9 lengths:6 lengths:15 values:"1Billy Bobxlargecooking,reading"}} keyspace:"commerce" shard:"0"} keyspace:"commerce" shard:"0" type:ROW row_event:{table_name:"commerce.enum_set_test" row_changes:{after:{lengths:1 lengths:9 lengths:6 lengths:23 values:"2Sally Maemediumknitting,cooking,hiking"}} keyspace:"commerce" shard:"0"} keyspace:"commerce" shard:"0" type:VGTID vgtid:{shard_gtids:{keyspace:"commerce" shard:"0" gtid:"MySQL56/ce357206-0d49-11ef-8fd1-a74564279579:1-35" table_p_ks:{table_name:"enum_set_test" lastpk:{fields:{name:"id" type:INT32 charset:63 flags:49667} rows:{lengths:1 values:"2"}}}}} keyspace:"commerce" shard:"0" type:COMMIT keyspace:"commerce" shard:"0"]
[type:BEGIN keyspace:"commerce" shard:"0" type:VGTID vgtid:{shard_gtids:{keyspace:"commerce" shard:"0" gtid:"MySQL56/ce357206-0d49-11ef-8fd1-a74564279579:1-35"}} keyspace:"commerce" shard:"0" type:COMMIT keyspace:"commerce" shard:"0"]
[type:COPY_COMPLETED keyspace:"commerce" shard:"0" type:COPY_COMPLETED]
[type:BEGIN timestamp:1715179728 current_time:1715179728532658000 keyspace:"commerce" shard:"0" type:FIELD timestamp:1715179728 field_event:{table_name:"commerce.enum_set_test" fields:{name:"id" type:INT32 table:"enum_set_test" org_table:"enum_set_test" database:"vt_commerce" org_name:"id" column_length:11 charset:63 flags:49667 column_type:"int"} fields:{name:"name" type:VARCHAR table:"enum_set_test" org_table:"enum_set_test" database:"vt_commerce" org_name:"name" column_length:480 charset:255 column_type:"varchar(120)"} fields:{name:"shirt_size" type:ENUM table:"enum_set_test" org_table:"enum_set_test" database:"vt_commerce" org_name:"shirt_size" column_length:28 charset:255 flags:256 column_type:"enum('small','medium','large','xlarge','xxlarge')"} fields:{name:"hobbies" type:SET table:"enum_set_test" org_table:"enum_set_test" database:"vt_commerce" org_name:"hobbies" column_length:288 charset:255 flags:2048 column_type:"set('knitting','cooking','pickleball','biking','hiking','motorcycle','video games','reading')"} keyspace:"commerce" shard:"0"} current_time:1715179728535652000 keyspace:"commerce" shard:"0" type:ROW timestamp:1715179728 row_event:{table_name:"commerce.enum_set_test" row_changes:{after:{lengths:1 lengths:9 lengths:1 lengths:3 values:"3Matt Lord2252"}} keyspace:"commerce" shard:"0" flags:1} current_time:1715179728535739000 keyspace:"commerce" shard:"0" type:VGTID vgtid:{shard_gtids:{keyspace:"commerce" shard:"0" gtid:"MySQL56/ce357206-0d49-11ef-8fd1-a74564279579:1-36"}} keyspace:"commerce" shard:"0" type:COMMIT timestamp:1715179728 current_time:1715179728535754000 keyspace:"commerce" shard:"0"]
[type:BEGIN timestamp:1715179735 current_time:1715179735538607000 keyspace:"commerce" shard:"0" type:ROW timestamp:1715179735 row_event:{table_name:"commerce.enum_set_test" row_changes:{after:{lengths:1 lengths:15 lengths:1 lengths:1 values:"4Jerry Badyellow30"}} keyspace:"commerce" shard:"0" flags:1} current_time:1715179735538659000 keyspace:"commerce" shard:"0" type:VGTID vgtid:{shard_gtids:{keyspace:"commerce" shard:"0" gtid:"MySQL56/ce357206-0d49-11ef-8fd1-a74564279579:1-37"}} keyspace:"commerce" shard:"0" type:COMMIT timestamp:1715179735 current_time:1715179735538672000 keyspace:"commerce" shard:"0"]
[type:BEGIN timestamp:1715179741 current_time:1715179741728690000 keyspace:"commerce" shard:"0" type:ROW timestamp:1715179741 row_event:{table_name:"commerce.enum_set_test" row_changes:{before:{lengths:1 lengths:9 lengths:1 lengths:2 values:"2Sally Mae219"} after:{lengths:1 lengths:9 lengths:1 lengths:3 values:"2Sally Mae1147"}} keyspace:"commerce" shard:"0" flags:1} current_time:1715179741728730000 keyspace:"commerce" shard:"0" type:VGTID vgtid:{shard_gtids:{keyspace:"commerce" shard:"0" gtid:"MySQL56/ce357206-0d49-11ef-8fd1-a74564279579:1-38"}} keyspace:"commerce" shard:"0" type:COMMIT timestamp:1715179741 current_time:1715179741728744000 keyspace:"commerce" shard:"0"]
```

Vitess v20 and newer:

```text
[type:BEGIN keyspace:"commerce" shard:"0" type:FIELD field_event:{table_name:"commerce.enum_set_test" fields:{name:"id" type:INT32 table:"enum_set_test" org_table:"enum_set_test" database:"vt_commerce" org_name:"id" column_length:11 charset:63 flags:49667 column_type:"int"} fields:{name:"name" type:VARCHAR table:"enum_set_test" org_table:"enum_set_test" database:"vt_commerce" org_name:"name" column_length:480 charset:255 column_type:"varchar(120)"} fields:{name:"shirt_size" type:ENUM table:"enum_set_test" org_table:"enum_set_test" database:"vt_commerce" org_name:"shirt_size" column_length:28 charset:255 flags:256 column_type:"enum('small','medium','large','xlarge','xxlarge')"} fields:{name:"hobbies" type:SET table:"enum_set_test" org_table:"enum_set_test" database:"vt_commerce" org_name:"hobbies" column_length:288 charset:255 flags:2048 column_type:"set('knitting','cooking','pickleball','biking','hiking','motorcycle','video games','reading')"} keyspace:"commerce" shard:"0" enum_set_string_values:true} keyspace:"commerce" shard:"0"]
[type:VGTID vgtid:{shard_gtids:{keyspace:"commerce" shard:"0" gtid:"MySQL56/156f702a-0d47-11ef-8723-653d045ab990:1-50"}} keyspace:"commerce" shard:"0"]
[type:ROW row_event:{table_name:"commerce.enum_set_test" row_changes:{after:{lengths:1 lengths:9 lengths:6 lengths:15 values:"1Billy Bobxlargecooking,reading"}} keyspace:"commerce" shard:"0"} keyspace:"commerce" shard:"0" type:ROW row_event:{table_name:"commerce.enum_set_test" row_changes:{after:{lengths:1 lengths:9 lengths:6 lengths:23 values:"2Sally Maemediumknitting,cooking,hiking"}} keyspace:"commerce" shard:"0"} keyspace:"commerce" shard:"0" type:VGTID vgtid:{shard_gtids:{keyspace:"commerce" shard:"0" gtid:"MySQL56/156f702a-0d47-11ef-8723-653d045ab990:1-50" table_p_ks:{table_name:"enum_set_test" lastpk:{fields:{name:"id" type:INT32 charset:63 flags:49667} rows:{lengths:1 values:"2"}}}}} keyspace:"commerce" shard:"0" type:COMMIT keyspace:"commerce" shard:"0"]
[type:BEGIN keyspace:"commerce" shard:"0" type:VGTID vgtid:{shard_gtids:{keyspace:"commerce" shard:"0" gtid:"MySQL56/156f702a-0d47-11ef-8723-653d045ab990:1-50"}} keyspace:"commerce" shard:"0" type:COMMIT keyspace:"commerce" shard:"0"]
[type:COPY_COMPLETED keyspace:"commerce" shard:"0" type:COPY_COMPLETED]
[type:BEGIN timestamp:1715179399 current_time:1715179399817221000 keyspace:"commerce" shard:"0" type:FIELD timestamp:1715179399 field_event:{table_name:"commerce.enum_set_test" fields:{name:"id" type:INT32 table:"enum_set_test" org_table:"enum_set_test" database:"vt_commerce" org_name:"id" column_length:11 charset:63 flags:49667 column_type:"int"} fields:{name:"name" type:VARCHAR table:"enum_set_test" org_table:"enum_set_test" database:"vt_commerce" org_name:"name" column_length:480 charset:255 column_type:"varchar(120)"} fields:{name:"shirt_size" type:ENUM table:"enum_set_test" org_table:"enum_set_test" database:"vt_commerce" org_name:"shirt_size" column_length:28 charset:255 flags:256 column_type:"enum('small','medium','large','xlarge','xxlarge')"} fields:{name:"hobbies" type:SET table:"enum_set_test" org_table:"enum_set_test" database:"vt_commerce" org_name:"hobbies" column_length:288 charset:255 flags:2048 column_type:"set('knitting','cooking','pickleball','biking','hiking','motorcycle','video games','reading')"} keyspace:"commerce" shard:"0" enum_set_string_values:true} current_time:1715179399821735000 keyspace:"commerce" shard:"0" type:ROW timestamp:1715179399 row_event:{table_name:"commerce.enum_set_test" row_changes:{after:{lengths:1 lengths:9 lengths:6 lengths:55 values:"3Matt Lordmediumpickleball,biking,hiking,motorcycle,video games,reading"}} keyspace:"commerce" shard:"0" flags:1} current_time:1715179399821762000 keyspace:"commerce" shard:"0" type:VGTID vgtid:{shard_gtids:{keyspace:"commerce" shard:"0" gtid:"MySQL56/156f702a-0d47-11ef-8723-653d045ab990:1-51"}} keyspace:"commerce" shard:"0" type:COMMIT timestamp:1715179399 current_time:1715179399821801000 keyspace:"commerce" shard:"0"]
[type:BEGIN timestamp:1715179399 current_time:1715179399822310000 keyspace:"commerce" shard:"0" type:ROW timestamp:1715179399 row_event:{table_name:"commerce.enum_set_test" row_changes:{after:{lengths:1 lengths:15 lengths:5 lengths:0 values:"4Jerry Badyellowlarge"}} keyspace:"commerce" shard:"0" flags:1} current_time:1715179399822355000 keyspace:"commerce" shard:"0" type:VGTID vgtid:{shard_gtids:{keyspace:"commerce" shard:"0" gtid:"MySQL56/156f702a-0d47-11ef-8723-653d045ab990:1-52"}} keyspace:"commerce" shard:"0" type:COMMIT timestamp:1715179399 current_time:1715179399822360000 keyspace:"commerce" shard:"0"]
[type:BEGIN timestamp:1715179400 current_time:1715179400512056000 keyspace:"commerce" shard:"0" type:ROW timestamp:1715179400 row_event:{table_name:"commerce.enum_set_test" row_changes:{before:{lengths:1 lengths:9 lengths:6 lengths:23 values:"2Sally Maemediumknitting,cooking,hiking"} after:{lengths:1 lengths:9 lengths:5 lengths:31 values:"2Sally Maesmallknitting,cooking,hiking,reading"}} keyspace:"commerce" shard:"0" flags:1} current_time:1715179400512094000 keyspace:"commerce" shard:"0" type:VGTID vgtid:{shard_gtids:{keyspace:"commerce" shard:"0" gtid:"MySQL56/156f702a-0d47-11ef-8723-653d045ab990:1-53"}} keyspace:"commerce" shard:"0" type:COMMIT timestamp:1715179400 current_time:1715179400512108000 keyspace:"commerce" shard:"0"]
```

An example key difference there being that `after:{lengths:1 lengths:9 lengths:1 lengths:3 values:"2Sally Mae1147"}` from Vitess v19 and older becomes `after:{lengths:1 lengths:9 lengths:5 lengths:31 values:"2Sally Maesmallknitting,cooking,hiking,reading"}` from Vitess v20 and newer. So `1` -> `small` and `147` -> `knitting,cooking,hiking,reading` for the `ENUM` and `SET` column values respectively. This also demonstrates why this mapping is necessary in consumers/clients, as `147` has no logical meaning/value for this column outside of MySQL internals.

If you're using the [`Debezium` Vitess connector](https://debezium.io/documentation/reference/stable/connectors/vitess.html), you should upgrade your connector to 2.7 (the next release) — which should contain [the relevant necessary changes](https://issues.redhat.com/browse/DBZ-7792) — *prior to upgrading Vitess* to v20.0.1 or later. If you're using any of the PlanetScale connectors ([`AirByte`](https://github.com/planetscale/airbyte-source/), [`FiveTran`](https://github.com/planetscale/fivetran-source), or [`singer-tap`](https://github.com/planetscale/singer-tap)) then no actions are required.

If you're using a custom `VStream` client/consumer, then you will need to build a new client with the updated v20 [binlogdata protos](https://pkg.go.dev/vitess.io/vitess/go/vt/proto/binlogdata) ([source](https://github.com/vitessio/vitess/blob/main/proto/binlogdata.proto) for which would be in `main` or the `release-20.0` branch) before needing to support Vitess v20.0.1 or later. Your client will then be able to handle old and new messages, with older messages always having this new field set to `false`.

#### `shutdown_grace_period` Default Change

The `--shutdown_grace_period` flag, which was introduced in v2 with a default of `0 seconds`, has now been changed to default to `3 seconds`.
This makes reparenting in Vitess resilient to client errors, and prevents PlannedReparentShard from timing out.

In order to preserve the old behaviour, the users can set the flag back to `0 seconds` causing open transactions to never be shutdown, but in that case, they run the risk of PlannedReparentShard calls timing out.

####  New `unmanaged` Flag and `disable_active_reparents` deprecation

New flag `--unmanaged` has been introduced in this release to make it easier to flag unmanaged tablets. It also runs validations to make sure the unmanaged tablets are configured properly. `--disable_active_reparents` flag has been deprecated for `vttablet`, `vtcombo` and `vttestserver` binaries and will be removed in future releases. Specifying the `--unmanaged` flag will also block replication commands and replication repairs.

Starting this release, all unmanaged tablets should specify this flag.


####  `recovery-period-block-duration` Flag deprecation

The flag `--recovery-period-block-duration` has been deprecated in VTOrc from this release. Its value is now ignored and the flag will be removed in later releases.
VTOrc no longer blocks recoveries for a certain duration after a previous recovery has completed. Since VTOrc refreshes the required information after
acquiring a shard lock, blocking of recoveries is not required.

#### `mysqlctld` `onterm_timeout` Default Change

The `--onterm_timeout` flag default value has changed for `mysqlctld`. It now is by default long enough to be able to wait for the default `--shutdown-wait-time` when shutting down on a `TERM` signal. 

This is necessary since otherwise MySQL would never shut down cleanly with the old defaults, since `mysqlctld` would shut down already after 10 seconds by default.

#### `MoveTables` now removes `auto_increment` clauses by default when moving tables from an unsharded keyspace to a sharded one

A new `--remove-sharded-auto-increment` flag has been added to the [`MoveTables` create sub-command](https://vitess.io/docs/20.0/reference/programs/vtctldclient/vtctldclient_movetables/vtctldclient_movetables_create/) and it is set to `true` by default. This flag controls whether any [MySQL `auto_increment`](https://dev.mysql.com/doc/refman/en/example-auto-increment.html) clauses should be removed from the table definitions when moving tables from an unsharded keyspace to a sharded one. This is now done by default as `auto_increment` clauses should not typically be used with sharded tables and you should instead rely on externally generated values such as a form of universally/globally unique identifiers or use [Vitess sequences](https://vitess.io/docs/reference/features/vitess-sequences/) in order to ensure that each row has a unique identifier (Primary Key value) across all shards. If for some reason you want to retain them you can set this new flag to `false` when creating the workflow.

#### `Durabler` interface method renaming

The methods of [the `Durabler` interface](https://github.com/vitessio/vitess/blob/main/go/vt/vtctl/reparentutil/durability.go#L70-L79) in `go/vt/vtctl/reparentutil` were renamed to be public _(capitalized)_ methods to make it easier to integrate custom Durability Policies from external packages. See [RFC for details](https://github.com/vitessio/vitess/issues/15544).

Users of custom Durability Policies must rename private `Durabler` methods.

Changes:
- The `promotionRule` method was renamed to `PromotionRule`
- The `semiSyncAckers` method was renamed to `SemiSyncAckers`
- The `isReplicaSemiSync` method was renamed to `IsReplicaSemiSync`

### Query Compatibility

####  Vindex Hints

Vitess now supports Vindex hints that provide a way for users to influence the shard routing of queries in Vitess by specifying, which vindexes should be considered or ignored by the query planner. This feature enhances the control over query execution, allowing for potentially more efficient data access patterns in sharded databases.

Example:
 ```sql
    SELECT * FROM user USE VINDEX (hash_user_id, secondary_vindex) WHERE user_id = 123;
    SELECT * FROM order IGNORE VINDEX (range_order_id) WHERE order_date = '2021-01-01';
 ```

For more information about Vindex hints and its usage, please consult the documentation.

####  Update with Limit Support

Support is added for sharded update with limit.

Example: `update t1 set t1.foo = 'abc', t1.bar = 23 where t1.baz > 5 limit 1`

More details about how it works is available in [MySQL Docs](https://dev.mysql.com/doc/refman/8.0/en/update.html)

####  Update with Multi Table Support

Support is added for sharded multi-table update with column update on single target table using multiple table join.

Example: `update t1 join t2 on t1.id = t2.id join t3 on t1.col = t3.col set t1.baz = 'abc', t1.apa = 23 where t3.foo = 5 and t2.bar = 7`

More details about how it works is available in [MySQL Docs](https://dev.mysql.com/doc/refman/8.0/en/update.html)

####  Update with Multi Target Support

Support is added for sharded multi table target update.

Example: `update t1 join t2 on t1.id = t2.id set t1.foo = 'abc', t2.bar = 23`

More details about how it works is available in [MySQL Docs](https://dev.mysql.com/doc/refman/8.0/en/update.html)

####  Delete with Subquery Support

Support is added for sharded table delete with subquery

Example: `delete from t1 where id in (select col from t2 where foo = 32 and bar = 43)`

####  Delete with Multi Target Support

Support is added for sharded multi table target delete.

Example: `delete t1, t3 from t1 join t2 on t1.id = t2.id join t3 on t1.col = t3.col`

More details about how it works is available in [MySQL Docs](https://dev.mysql.com/doc/refman/8.0/en/delete.html)

####  User Defined Functions Support

VTGate can track any user defined functions for better planning.
User Defined Functions (UDFs) should be directly loaded in the underlying MySQL.

It should be enabled in VTGate with the `--track-udfs` flag.
This will enable the tracking of UDFs in VTGate and will be used for planning.
Without this flag, VTGate will not be aware that there might be aggregating user-defined functions in the query that need to be pushed down to MySQL.

More details about how to load UDFs is available in [MySQL Docs](https://dev.mysql.com/doc/extending-mysql/8.0/en/adding-loadable-function.html)

####  Insert Row Alias Support

Support is added to have row alias in Insert statement to be used with `on duplicate key update`.

Example:
- `insert into user(id, name, email) valies (100, 'Alice', 'alice@mail.com') as new on duplicate key update name = new.name, email = new.email`
- `insert into user(id, name, email) valies (100, 'Alice', 'alice@mail.com') as new(m, n, p) on duplicate key update name = n, email = p`

More details about how it works is available in [MySQL Docs](https://dev.mysql.com/doc/refman/8.0/en/insert-on-duplicate.html)

### Query Timeout
On a query timeout, Vitess closed the connection using the `kill connection` statement. This leads to connection churn 
which is not desirable in some cases. To avoid this, Vitess now uses the `kill query` statement to cancel the query. 
This will only cancel the query and does not terminate the connection.

### Flag Changes

####  `pprof-http` Default Change

The `--pprof-http` flag, which was introduced in v19 with a default of `true`, has now been changed to default to `false`.
This makes HTTP `pprof` endpoints now an *opt-in* feature, rather than opt-out.
To continue enabling these endpoints, explicitly set `--pprof-http` when starting up Vitess components.

#### New `--healthcheck-dial-concurrency` flag

The new `--healthcheck-dial-concurrency` flag defines the maximum number of healthcheck connections that can open concurrently. This limit is to avoid hitting Go runtime panics on deployments watching enough tablets [to hit the runtime's maximum thread limit of `10000`](https://pkg.go.dev/runtime/debug#SetMaxThreads) due to blocking network syscalls. This flag applies to `vtcombo`, `vtctld` and `vtgate` only and a value less than the runtime max thread limit _(`10000`)_ is recommended.

#### New minimum for `--buffer_min_time_between_failovers`

The `--buffer_min_time_between_failovers` `vttablet` flag now has a minimum value of `1s`. This is because a value of 0 can cause issues with the buffering mechanics resulting in unexpected and unnecessary query errors — in particular during `MoveTables SwitchTraffic` operations. If you are currently specifying a value of 0 for this flag then you will need to update the config value to 1s *prior to upgrading to v20 or later* as `vttablet` will report an error and terminate if you attempt to start it with a value of 0.

#### New `--track-udfs` vtgate flag

The new `--track-udfs` flag enables VTGate to track user defined functions for better planning.

#### Help text fix for `--lock-timeout`

The help text for the flag `--lock-timeout` was incorrect. We were documenting it as a flag that controlled the duration for which the shard lock was acquired. It is actually the maximum duration for which we wait while attempting to acquire a lock from the topology server.

#### New `--querylog-sample-rate` flag

The new flag `--querylog-sample-rate float` adds support for sampling queries based on a float value between 0.0 _(no logging)_ and 1.0 _(all queries logged)_. If configured, this filtering is applied after the existing `--querylog-filter-tag` filter.

#### New `--tablet-filter-tags` flag

The new flag `--tablet-filter-tags StringMap` adds support to VTGate for filtering tablets by tablet tag key/values, specified as comma-separated list of key:values. The tags of a tablet are defined by the VTTablet flag `--init_tags`, which is also defined as a comma-separated list of key:values.

## Minor Changes

### New Stats

#### VTTablet Query Cache Hits and Misses

VTTablet exposes two new counter stats:

 * `QueryCacheHits`: Query engine query cache hits
 * `QueryCacheMisses`: Query engine query cache misses

### VTTablet Query Text Characters Processed

VTGate and VTTablet expose a new counter stat `QueryTextCharactersProcessed` to reflect the number of query text characters processed.

VTGate groups this metric by Operation, Keyspace and TabletType. On VTTablet it is grouped by Table, Plan and optionally Workload.

### `SIGHUP` reload of gRPC client static auth creds

The internal gRPC client now caches the static auth credentials and supports reloading via the `SIGHUP` signal. Previous to v20 the credentials were not cached. They were re-loaded from disk on every use.

### VTAdmin

#### vtadmin-web updated to node v20.12.2 (LTS)

Building `vtadmin-web` now requires node >= v20.12.0 (LTS). Breaking changes from v18 to v20 can be found at https://nodejs.org/en/blog/release/v20.12.0 -- with no known issues that apply to VTAdmin.
Full details on the node v20.12.2 release can be found at https://nodejs.org/en/blog/release/v20.12.2.

#### Replaced highcharts with d3

The vtadmin-web UI no longer has a dependency on highcharts for licensing reasons. The tablet QPS, tablet VReplication QPS, and workflow streams lag charts have all been replaced by d3. We'll be iteratively improving the d3 charts until they reach feature parity with the original highcharts charts. 

------------
The entire changelog for this release can be found [here](https://github.com/vitessio/vitess/blob/main/changelog/20.0/20.0.0/changelog.md).

The release includes 410 merged Pull Requests.

Thanks to all our contributors: @Aoang, @GuptaManan100, @Its-Maniaco, @Maniktherana, @VaibhavMalik4187, @ajm188, @aparajon, @app/dependabot, @app/github-actions, @app/vitess-bot, @arthurschreiber, @bddicken, @beingnoble03, @brendar, @crazeteam, @dbussink, @deepthi, @demmer, @derekperkins, @ejortegau, @frouioui, @harshit-gangal, @mattlord, @maxenglander, @mdlayher, @notfelineit, @pavedroad, @rafer, @rohit-nayak-ps, @rvrangel, @shlomi-noach, @systay, @timvaillancourt, @tycol7, @vitess-bot, @vmg, @wangweicugw, @whuang8, @yoheimuta

🚀 vitessio/vitess - Release Notes

Vitess v21.0.3 (2025-02-12)

Vitess v20.0.6 (2025-02-12)

Vitess v19.0.10 (2025-02-12)

Vitess v21.0.2 (2025-01-21)

Vitess v20.0.5 (2025-01-21)

Vitess v19.0.9 (2025-01-21)

Vitess v21.0.1 (2024-12-03)

Vitess v20.0.4 (2024-12-03)

Vitess v19.0.8 (2024-12-03)

Vitess v20.0.3 (2024-11-06)

Vitess v19.0.7 (2024-11-06)

Vitess v18.0.8 (2024-11-06)

Vitess v21.0.0 (2024-10-29)

Vitess v21.0.0-rc2 (2024-10-23)

Vitess v21.0.0-rc1 (2024-10-15)

Vitess v20.0.2 (2024-09-11)

Vitess v19.0.6 (2024-09-11)

Vitess v18.0.7 (2024-09-11)

Vitess v20.0.1 (2024-07-23)

Vitess v19.0.5 (2024-07-23)

Vitess v18.0.6 (2024-07-23)

Vitess v20.0.0 (2024-06-27)

Vitess v20.0.0-rc2 (2024-06-20)

Vitess v20.0.0-rc1 (2024-06-13)

Vitess v19.0.4 (2024-05-08)

Vitess v18.0.5 (2024-05-08)

Vitess v17.0.7 (2024-05-08)

Vitess v19.0.3 (2024-04-04)

Vitess v18.0.4 (2024-04-04)

Vitess v19.0.1 (2024-03-14)