# Percona XtraDB Cluster 8.0.29-21 (2022-09-12)

Percona XtraDB Cluster (PXC) supports critical business applications in your public, private, or hybrid cloud environment. Our free, open source, enterprise-grade solution includes the high availability and security features your business requires to meet your customer expectations and business goals.

## Release Highlights

Percona XtraDB Cluster is based on Percona Server for MySQL. Find a complete list of improvements and bug fixes in the [Percona Server for MySQL 8.0.29-21 (2022-08-08) release notes](https://docs.percona.com/percona-server/latest/release-notes/8.0.29-21.html).

The improvements and bug fixes for MySQL 8.0.29, provided by Oracle, and included in Percona Server for MySQL are the following:

The Performance Schema tracks if a query was processed on the PRIMARY engine, InnoDB, or a SECONDARY engine, HeatWave. An EXECUTION_ENGINE column, which indicates the engine used, was added to the Performance Schema statement event tables and the sys.processlist and the sys.x$processlist views.

Added support for the IF NOT EXISTS option for the CREATE FUNCTION, CREATE PROCEDURE, and CREATE TRIGGER statements.

Added support for ALTER TABLE … DROP COLUMN ALGORITHM=INSTANT.

An anonymous user with the PROCESS privilege was unable to select processlist table rows.

Find the full list of bug fixes and changes in the [MySQL 8.0.29 Release Notes](https://dev.mysql.com/doc/relnotes/mysql/8.0/en/news-8-0-29.html).

!!! note

    Percona Server for MySQL has changed the default for the [supported DDL column operations](https://dev.mysql.com/doc/refman/8.0/en/innodb-online-ddl-operations.html) to ALGORITHM=INPLACE. This change fixes the corruption issue with the INSTANT ADD/DROP COLUMNS (find more details in [PS-8292](https://jira.percona.com/browse/PS-8292).

    In MySQL 8.0.29, the default setting for supported DDL operations is ALGORITHM=INSTANT. You can explicitly specify ALGORITHM=INSTANT in DDL column operations.

## Bugs Fixed

* [PXC-3982](https://jira.percona.com/browse/PXC-3982): When the replica node is also an asynchronous slave and, while joining the cluster, this node was not ready to accept connections, a SQL thread failed at the start.

* [PXC-3118](https://jira.percona.com/browse/PXC-3118): A fix for when, using a thread pool, a brute force abort for a metadata locking (MDL) subsystem conflict stalled.

* [PXC-3999](https://jira.percona.com/browse/PXC-3999): The cluster was stalled on `Waiting for acl cache lock` with concurrent user DDL commands.

## Packaging Notes

Debian 9 is no longer supported.

## Useful Links

* The [Percona XtraDB Cluster installation instructions](https://docs.percona.com/percona-xtradb-cluster/8.0/install-index.html)

* The [Percona XtraDB Cluster downloads](https://www.percona.com/downloads/Percona-XtraDB-Cluster-LATEST/#)

* The [Percona XtraDB Cluster GitHub location](https://github.com/percona/percona-xtradb-cluster)

* To contribute to the documentation, review the [Documentation Contribution Guide](https://github.com/percona/pxc-docs/blob/8.0/contributing.md)