Vitess v20.0.0-rc1

Release of Vitess v20.0.0

Summary

Table of Contents

• Major Changes

  • Deletions
    • --vreplication_tablet_type flag
    • Pool Capacity Flags
    • vitess/base and vitess/k8s Docker images
    • gh-ost binary and endtoend tests
    • Legacy EmergencyReparentShard stats
  • Breaking changes
    • Metric Name Changes in VTOrc
    • ENUM and SET column handling in VTGate VStream API
    • shutdown_grace_period Default Change
    • New unmanaged Flag and disable_active_reparents deprecation
    • recovery-period-block-duration Flag deprecation
    • mysqlctld onterm-timeout Default Change
    • MoveTables now removes auto_increment clauses by default when moving tables from an unsharded keyspace to a sharded one
    • Durabler interface method renaming
  • Query Compatibility
    • Vindex Hints
    • Update with Limit Support
    • Update with Multi Table Support
    • Update with Multi Target Support
    • Delete with Subquery Support
    • Delete with Multi Target Support
    • User Defined Functions Support
    • Insert Row Alias Support
  • Query Timeout
  • Flag changes
    • pprof-http default change
    • New healthcheck-dial-concurrency flag
    • New minimum for --buffer_min_time_between_failovers
    • New track-udfs vtgate flag
    • Help text fix for --lock-timeout
    • New --querylog-sample-rate flag
    • New --tablet-filter-tags flag

• Minor Changes

  • New Stats
    • VTTablet Query Cache Hits and Misses
    • VTGate and VTTablet Query Text Characters Processed
  • SIGHUP reload of gRPC client static auth creds
  • VTAdmin
    • Updated to node v20.12.2
    • Replaced highcharts with d3

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 now returns ENUM and SET column type values in VEvent messages (in the embedded 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 the values for ENUM and SET 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 for each VStream client/consumer (e.g. the Debezium Vitess connector 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 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:

CREATE TABLE `enum_set_test` (
  `id` int NOT NULL AUTO_INCREMENT,
  `name` varchar(120) DEFAULT NULL,
  `shirt_size` enum('small','medium','large','xlarge'...

Vitess v19.0.4

Release of Vitess v19.0.4

The entire changelog for this release can be found here.

The release includes 19 merged Pull Requests.

Thanks to all our contributors: @GuptaManan100, @app/vitess-bot, @systay, @vitess-bot

Vitess v18.0.5

Release of Vitess v18.0.5

The entire changelog for this release can be found here.

The release includes 14 merged Pull Requests.

Thanks to all our contributors: @app/vitess-bot, @notfelineit, @rohit-nayak-ps, @shlomi-noach, @vitess-bot

Vitess v17.0.7

Release of Vitess v17.0.7

The entire changelog for this release can be found here.

The release includes 14 merged Pull Requests.

Thanks to all our contributors: @app/vitess-bot, @frouioui, @systay, @vitess-bot

Vitess v19.0.3

Release of Vitess v19.0.3

Removal of v19.0.2

The maintainers team decided to remove the v19.0.2 release as it contained a CVE fixed in v19.0.3.

---

The entire changelog for this release can be found here.

The release includes 16 merged Pull Requests.

Thanks to all our contributors: @GrahamCampbell, @app/vitess-bot, @frouioui, @rohit-nayak-ps, @shlomi-noach, @systay

Vitess v18.0.4

Release of Vitess v18.0.4

The entire changelog for this release can be found here.

The release includes 8 merged Pull Requests.

Thanks to all our contributors: @app/vitess-bot, @frouioui, @shlomi-noach, @systay

Vitess v19.0.1

Release of Vitess v19.0.1

The entire changelog for this release can be found here.

The release includes 11 merged Pull Requests.

Thanks to all our contributors: @app/vitess-bot, @systay

Vitess v18.0.3

Release of Vitess v18.0.3

Summary

Table of Contents

• Major Changes
  • Breaking Changes
    • ExecuteFetchAsDBA rejects multi-statement SQL

Major Changes

Breaking Changes

ExecuteFetchAsDBA rejects multi-statement SQL

vtctldclient ExecuteFetchAsDBA (and similarly the vtctl and vtctlclient commands) now reject multi-statement SQL with error.

For example, vtctldclient ExecuteFetchAsDBA my-tablet "stop replica; change replication source to auto_position=1; start replica will return an error, without attempting to execute any of these queries.

Previously, ExecuteFetchAsDBA silently accepted multi statement SQL. It would (attempt to) execute all of them, but:

• It would only indicate error for the first statement. Errors on 2nd, 3rd, ... statements were silently ignored.
• It would not consume the result sets of the 2nd, 3rd, ... statements. It would then return the used connection to the pool in a dirty state. Any further query that happens to take that connection out of the pool could get unexpected results.
• As another side effect, multi-statement schema changes would cause schema to be reloaded with only the first change, leaving the cached schema inconsistent with the underlying database.

ExecuteFetchAsDBA does allow a specific use case of multi-statement SQL, which is where all statements are in the form of CREATE TABLE or CREATE VIEW. This is to support a common pattern of schema initialization, formalized in ApplySchema --batch-size which uses ExecuteFetchAsDBA under the hood.

---

The entire changelog for this release can be found here.

The release includes 47 merged Pull Requests.

Thanks to all our contributors: @app/github-actions, @app/vitess-bot, @frouioui, @harshit-gangal, @rohit-nayak-ps, @shlomi-noach, @systay, @wangweicugw

Vitess v17.0.6

Release of Vitess v17.0.6

Summary

Table of Contents

• Major Changes
  • Breaking Changes
    • ExecuteFetchAsDBA rejects multi-statement SQL

Major Changes

Breaking Changes

ExecuteFetchAsDBA rejects multi-statement SQL

vtctldclient ExecuteFetchAsDBA (and similarly the vtctl and vtctlclient commands) now reject multi-statement SQL with error.

For example, vtctldclient ExecuteFetchAsDBA my-tablet "stop replica; change replication source to auto_position=1; start replica will return an error, without attempting to execute any of these queries.

Previously, ExecuteFetchAsDBA silently accepted multi statement SQL. It would (attempt to) execute all of them, but:

• It would only indicate error for the first statement. Errors on 2nd, 3rd, ... statements were silently ignored.
• It would not consume the result sets of the 2nd, 3rd, ... statements. It would then return the used connection to the pool in a dirty state. Any further query that happens to take that connection out of the pool could get unexpected results.
• As another side effect, multi-statement schema changes would cause schema to be reloaded with only the first change, leaving the cached schema inconsistent with the underlying database.

ExecuteFetchAsDBA does allow a specific use case of multi-statement SQL, which is where all statements are in the form of CREATE TABLE or CREATE VIEW. This is to support a common pattern of schema initialization.

---

The entire changelog for this release can be found here.

The release includes 24 merged Pull Requests.

Thanks to all our contributors: @app/vitess-bot, @frouioui, @harshit-gangal, @shlomi-noach, @systay

Vitess v19.0.0

Release of Vitess v19.0.0

Summary

Table of Contents

• Major Changes
  • Dropping Support for MySQL 5.7
  • Deprecations and Deletions
    • VTTablet Flags
    • Docker Image vitess/lite
    • Explain Statement Format
  • Breaking Changes
    • ExecuteFetchAsDBA rejects multi-statement SQL
  • New Stats
    • Stream Consolidations
    • Build Version in /debug/vars
  • Planned Reparent Shard
    • --tolerable-replication-lag Sub-flag
  • Query Compatibility
    • Multi Table Delete Support
    • SHOW VSCHEMA KEYSPACES Query
    • FOREIGN_KEY_CHECKS is now a Vitess Aware Variable
    • Explain Statement
    • Partial Multi-shard Commit Warnings
    • New Lock Syntax
    • Support for AVG()
    • Support for non-recursive CTEs
  • Vttestserver
    • --vtcombo-bind-host flag
• Minor Changes
  • Apply VSchema
    • --strict sub-flag and strict gRPC field

Major Changes

Dropping Support for MySQL 5.7

Oracle has marked MySQL 5.7 end of life as of October 2023. Vitess is also dropping support for MySQL 5.7 from v19 onwards. Users are advised to upgrade to MySQL 8.0 while on v18 version of Vitess before
upgrading to v19.

Vitess will however, continue to support importing from MySQL 5.7 into Vitess even in v19.

Deprecations and Deletions

• The MYSQL_FLAVOR environment variable is now removed from all Docker Images.

VTTablet Flags

• The following flags — which were deprecated in Vitess 7.0 — have been removed:
  --vreplication_healthcheck_topology_refresh, --vreplication_healthcheck_retry_delay, and --vreplication_healthcheck_timeout.
• The --vreplication_tablet_type flag is now deprecated and ignored.

Docker Image vitess/lite

The mysqld binary is now deprecated in the vitess/lite Docker image and will be removed in a future release.
This means that the MySQL/Percona version specific image tags for the vitess/lite image are deprecated.

Below is a full list of available tags for v19.0.0 and their deprecation status:

Image	Deprecated
vitess/lite:v19.0.0	NO
vitess/lite:v19.0.0-mysql57	YES
vitess/lite:v19.0.0-mysql80	YES
vitess/lite:v19.0.0-percona57	YES
vitess/lite:v19.0.0-percona80	YES

If you are currently using vitess/lite as your mysqld image in your vitess-operator deployment we invite you to use an official MySQL image, such as mysql:8.0.30.

Below is an example of a kubernetes yaml file before and after upgrading to an official MySQL image:

# before:

# the image used here includes MySQL 8.0.30 and its binaries

    mysqld:
      mysql80Compatible: vitess/lite:v19.0.0-mysql80

# after:

# if we still want to use MySQL 8.0.30, we now have to use the
# official MySQL image with the 8.0.30 tag as shown below 

    mysqld:
      mysql80Compatible: mysql:8.0.30 # or even mysql:8.0.34 for instance

Explain Statement Format

Explain statement format vitess and vexplain were deprecated in v16 and removed in v19 version.
Use VExplain Statement for understanding Vitess plans.

Breaking Changes

ExecuteFetchAsDBA rejects multi-statement SQL

vtctldclient ExecuteFetchAsDBA (and similarly the vtctl and vtctlclient commands) now reject multi-statement SQL with error.

For example, vtctldclient ExecuteFetchAsDBA my-tablet "stop replica; change replication source to auto_position=1; start replica will return an error, without attempting to execute any of these queries.

Previously, ExecuteFetchAsDBA silently accepted multi statement SQL. It would (attempt to) execute all of them, but:

• It would only indicate error for the first statement. Errors on 2nd, 3rd, ... statements were silently ignored.
• It would not consume the result sets of the 2nd, 3rd, ... statements. It would then return the used connection to the pool in a dirty state. Any further query that happens to take that connection out of the pool could get unexpected results.
• As another side effect, multi-statement schema changes would cause schema to be reloaded with only the first change, leaving the cached schema inconsistent with the underlying database.

ExecuteFetchAsDBA does allow a specific use case of multi-statement SQL, which is where all statements are in the form of CREATE TABLE or CREATE VIEW. This is to support a common pattern of schema initialization, formalized in ApplySchema --batch-size which uses ExecuteFetchAsDBA under the hood.

New Stats

Stream Consolidations

Prior to 19.0 VTTablet reported how much time non-streaming executions spend waiting for consolidations to occur. In 19.0, VTTablet reports a similar stat for streaming executions in /debug/vars stat Waits.Histograms.StreamConsolidations.

Build Version in /debug/vars

The build version (e.g., 19.0.0-SNAPSHOT) has been added to /debug/vars, allowing users to programmatically inspect Vitess components' build version at runtime.

Planned Reparent Shard

--tolerable-replication-lag Sub-flag

A new sub-flag --tolerable-replication-lag has been added to the command PlannedReparentShard that allows users to specify the amount of replication lag that is considered acceptable for a tablet to be eligible for promotion when Vitess makes the choice of a new primary.
This feature is opt-in and not specifying this sub-flag makes Vitess ignore the replication lag entirely.

A new flag in VTOrc with the same name has been added to control the behaviour of the PlannedReparentShard calls that VTOrc issues.

Query Compatibility

Multi Table Delete Support

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

Example: Delete t1 from t1 join t2 on t1.id = t2.id join t3 on t1.col = t3.col where t3.foo = 5 and t2.bar = 7

More details about how it works is available in MySQL Docs

SHOW VSCHEMA KEYSPACES Query

A SQL query, SHOW VSCHEMA KEYSPACES is now supported in Vitess. This query prints the vschema information
for all the keyspaces. It is useful for seeing the foreign key mode, whether the keyspace is sharded, and if there is an
error in the VSchema for the keyspace.

An example output of the query looks like -

mysql> show vschema keyspaces;
+----------+---------+-------------+---------+
| Keyspace | Sharded | Foreign Key | Comment |
+----------+---------+-------------+---------+
| ks       | true    | managed     |         |
| uks      | false   | managed     |         |
+----------+---------+-------------+---------+
2 rows in set (0.01 sec)

FOREIGN_KEY_CHECKS is now a Vitess Aware Variable

When VTGate receives a query to change the FOREIGN_KEY_CHECKS value for a session, instead of sending the value down to MySQL, VTGate now keeps track of the value and changes the queries by adding SET_VAR(FOREIGN_KEY_CHECKS=On/Off) style query optimizer hints wherever required.

Explain Statement

Explain statement can handle routed table queries now. Explain is unsupported when the tables involved in the query refers more than one keyspace. Users should use VExplain Statement in those cases.

Partial Multi-shard Commit Warnings

When using multi transaction mode (the default), it is possible for Vitess to successfully commit to one shard, but fail to commit to a subsequent shard, thus breaking the atomicity of a multi-shard transaction.

In v19.0, VTGate reports partial-success commits in warnings, e.g.:

mysql> commit;
ERROR 1317 (70100): target: customer.-80.primary: vttablet: rpc error: code = Aborted desc = transaction 1703182545849001001: ended at 2023-12-21 14:07:41.515 EST (exceeded timeout: 30s) (CallerID: userData1)
mysql> show warnings;
+---------+------+----------------------------------------------------------+
| Level   | Code | Message                                                  |
+---------+------+----------------------------------------------------------+
| Warning |  301 | multi-db commit failed after committing to 1 shards: 80- |
+---------+------+----------------------------------------------------------+
1 row in set, 1 warning (0.00 sec)

Vttestserver

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