PolarDB:2024 data node release notes

Version

Category

Description

8.4.20 (MySQL 8.0-compatible)

Optimization

Optimized the exception handling logic for proactive O&M. A fast exit approach is used instead of the previous core dump mechanism.

Version

Category

Description

8.4.20 (MySQL 8.0-compatible)

Fixes

Fixed a calculation error in the lock wait duration field of audit logs.

Fixed an issue where the key retrieval wait time for transparent data encryption (TDE) was inaccurate. For more information, see Set transparent data encryption.

Fixed an issue where PURGE operations held an index-exclusive lock in specific scenarios.

Version

Category

Description

5.4.20 (MySQL 5.7-compatible)

Fix

Fixed an issue where .cfp files remained after the deletion of an imported tablespace.

Version

Category

Description

8.4.20 (MySQL 8.0-compatible)

Add

Added support for the DBMS_RETURNING_ALL command to view data before and after DML operations.

Added support for automatic cleanup of binlog files.

Added support for the SM4 encryption algorithm for encrypted tables.

Added support for automatic packaging of CentOS 7 RPM packages in the Aone environment.

Fixes

Fixed a deadlock on LOCK_index that occurred when a primary/secondary switchover and a binlog rotation were performed simultaneously.

Fixed an issue where .cfp files remained after the removal of an imported tablespace.

Fixed a cyclic redundancy check (CRC) failure on the secondary database that occurred when resuming a large transaction after a primary/secondary switchover.

Fixed a system startup failure during recovery that occurred when the backup offset was within a large transaction.

Fixed an issue where modifications to rds_version did not fully take effect.

Fixed an upgrade failure on the secondary database from 8018 to 8032 that was caused by a missing binlog.001 file.

Fixed an issue where online DDL operations occasionally failed due to unique constraint check errors.

Version

Category

Description

5.4.20 (MySQL 5.7-compatible)

Optimizations

Optimized the performance of audit logging over the extended remote procedure call (XRPC) protocol.

Optimized the performance of connection ID acquisition during session initialization over the XRPC protocol.

Optimized the format of the version number displayed in the results of the SELECT POLARDB_VERSION() statement.

Fixes

Fixed an issue in XRPC-enabled environments where setting the XA_DETACH_ON_PREPARE parameter to OFF caused the MDL lock to be released after a disconnection following a successful XA PREPARE operation, which interrupted replication on the secondary database.

Fixed inaccuracies in the Seconds_Behind_Master field of the SHOW_SLAVE_STATUS table on the secondary database after disabling parallel application.

Fixed a potential deadlock on the secondary database that was caused by a rotate operation triggered during a primary/secondary switchover.

Version

Category

Description

8.4.20 (MySQL 8.0-compatible)

Optimizations

Optimized the format of the version number displayed in the results of the SELECT POLARDB_VERSION() statement.

Optimized the performance of audit logging over the XRPC protocol.

Optimized the performance of connection ID acquisition during session initialization over the XRPC protocol.

Fixes

Fixed inaccuracies in the Seconds_Behind_Master field of the SHOW SLAVE STATUS output on the secondary database after parallel application was disabled.

Fixed a rare issue where the last node failed to join the cluster during a full cluster recovery in a scenario without binlog.

Fixed a potential deadlock on the secondary database that was caused by a rotate operation triggered during a primary/secondary switchover.

Fixed a primary database crash caused by modifying the BINLOG_TRANSACTION_DEPENDENCY_TRACKING property to WRITESET under active service traffic.

Fixed an issue where, under the XRPC protocol and with the XA_DETACH_ON_PREPARE parameter set to OFF, a disconnection after a successful XA PREPARE operation caused an MDL lock to be released, interrupting replication on the secondary database.

Version

Category

Description

5.4.19 (MySQL 5.7-compatible)

New feature and optimization

Added support for Faster DDL.

Fixes

Fixed an issue where data nodes failed to run on the AliOS 6 operating system.

Fixed an interruption that occurred during the recovery of the old primary node after an abnormal switchover to a new primary node.

Version

Category

Description

8.4.19 (MySQL 8.0-compatible)

New features and optimizations

Added support for transparent primary node switchover.

Added support for implicit primary keys in writesets.

Added writeset-related metrics for Service Monitoring.

Optimized the default value of the BINLOG_TRANSACTION_DEPENDENCY_HISTORY_SIZE parameter to 200,000.

Optimized the access page weight for historical data in specific scenarios to reduce the impact on the buffer pool.

Fixes

Fixed an issue where writeset calculations were incorrect in scenarios that involve composite indexes.

Fixed a system crash issue that was caused by modifying the BINLOG_TRANSACTION_DEPENDENCY_TRACKING parameter on a data node during periods of active traffic.

Fixed an issue where the rollback path could trigger a purge operation, which compromised the security of flashback queries.

Fixed an issue where shared sessions were sometimes not released promptly after a primary node switchover in a three-node cluster.

Version

Category

Description

5.4.19 (MySQL 5.7-compatible)

New feature

Data nodes (DNs) now support the MySQL primary/secondary replication mode.

Version

Category

Description

8.4.19 (MySQL 8.0-compatible)

Add

Added support for the GUESS PRIMARY PAGE Cleanout feature for indexes to improve the hit rate of table queries.

Data nodes (DNs) now support the MySQL primary/secondary replication mode.

Fixes

Fixed an issue where index visibility did not function as expected in a flashback query if DDL operations were performed after the point in time specified in the flashback query.

Fixed an issue where delete operations were not strictly performed in the order of their system change numbers (SCNs).

Fixed an inconsistency in the FLASHBACK AREA table property between the data dictionary and the engine.

Fixed an issue where the size of redo space was incorrectly calculated.

Version

Category

Description

8.4.19 (MySQL 8.0-compatible)

Fixes

Fixed a rare deadlock issue caused by the GUESS PRIMARY PAGE mechanism in high-concurrency scenarios.

Fixed a data inconsistency issue in backup sets that could occur when you imported tablespaces during an XtraBackup data backup.

Fixed an issue where the system crashed when the XPLAN command was used to view the execution plan of a MySQL native partitioned table (a table created in DRDS or AUTO mode and partitioned by specifying LOCAL PARTITION).

Fixed an issue where audit logs could not be generated when the XRPC protocol was used.

Version

Category

Description

8.4.19 (MySQL 8.0-compatible)

New features and optimizations

Added the dbms_consensus.force_learner_node O&M command.

Improved the integrity of O&M parameters in manual backup and recovery scenarios.

Added the Guess Primary Key Page No (GPP) feature to optimize the performance of queries that use secondary indexes to obtain data from tables.

Fixes

Fixed the database crash caused by sampling when optimizer trace is enabled.

Fixed the database crash caused by executing XA or RENAME TABLE on the secondary database.

Fixed an issue where excessive debug logs were printed in some scenarios.

Version

Category

Description

5.4.19 (MySQL 5.7-compatible)

Fix

Fixed an issue where releasing a gap lock on the supremum record during an XA PREPARE operation caused latency on the secondary database.

Version

Category

Description

8.4.19 (MySQL 8.0-compatible)

New features and optimizations

Added support for retaining historical versions of data in specified tables for a custom retention period. This allows users to query past records.

Added the innodb_pfs_data_locks_max_locks_per_batch parameter to control the number of returned pfs.data_locks records.

Optimized the performance of Flashback Area space reclamation operations.

Optimized the performance of update operations for the system table scn_history.

Fixes

Fixed an issue where the apply thread failed to start when some backup sets were used to restore an instance.

Fixed the issue of prolonged instance creation time.

Fixed a memory calculation error for changeset.

Fixed an issue where the SQL statement-based concurrency control (CCL) mechanism caused thundering herd problems in high-concurrency environments, which led to database performance degradation.

Fixed an issue where querying a SEQUENCE table after applying a write lock caused the instance to crash.

Fixed an issue where shutting down the instance (SHUTDOWN) during parallel DDL operations prevented dirty pages from being flushed.

Fixed an instance crash that occurred when Instant DDL was executed during an upgrade from an earlier version of MySQL to MySQL 5.7.

Fixed an issue where simultaneous ALTER STORED COLUMN ORDER and Instant DDL operations on a table resulted in incorrect redo log entries.

Version

Category

Description

5.4.19 (MySQL 5.7-compatible)

New feature

Added the XRPC.CMD() stored procedure, which clears database caches generated by running SQL or execution plans to eliminate cache pollution introduced by earlier compute node versions.

Fixes

Fixed an issue where a PURGE operation on a temporary table could cause the database instance to become unavailable.

Fixed a data inconsistency issue in backup sets that could occur when you imported tablespaces during an XtraBackup data backup.

Fixed an issue where using a non-primary key index to query a partitioned table caused high CPU usage.

Fixed a path conflict issue during the installation of an RPM package.

Version

Category

Description

5.4.19 (MySQL 5.7-compatible)

New feature

Added support for statement rule-based concurrency control (CCL).

Fixes

Fixed an issue where out-of-memory (OOM) kills might occur during scaling operations when write traffic was high.

Fixed an issue where community partitioned tables incorrectly performed a full table scan when the partition key was used for sorting in reverse order.

Fixed an issue where sorting results were incorrect when the partition key was used as a composite prefix index in community partitioned tables.

Fixed an issue where the check_stack_overrun function failed and caused a core dump when the user thread stack was exhausted.

Version

Category

Description

8.4.19 (MySQL 8.0-compatible)

New features

Added support for Transparent Data Encryption (TDE) based on Key Management Service (KMS).

Added support for the inventory hint feature.

Added support for the IMPORT TABLESPACE IF NOT EXISTS clause.

Optimized the cleanup of unused files during redo file creation.

Optimized global transaction identifier (GTID) recording for modifications to non-transactional tables.

Improved error log notifications.

Fixes

Fixed an issue where the running status of the slave coordinator was displayed incorrectly.

Fixed an issue where apply threads started too early, which caused interruptions in log application on the secondary database.

Fixed an issue where purging large files resulted in excessively long timeout periods.

Fixed an issue where member changes occasionally caused dumps in debug mode.

Fixed an issue where occasional deadlocks occurred when flush and rotate operations were performed simultaneously.

Fixed an issue where querying pfs.metadata_locks occasionally caused crashes.

Fixed an issue where binlog files were empty during full backups on the secondary database.

Version

Category

Description

5.4.19 (MySQL 5.7-compatible)

New features and optimizations

Introduced a new packaging format. The package name is in the t-polardbx-engine-57-yyyymmdd- format.

Added the polardbx_release_date and polardbx_engine_version system variables to record the current version information.

Added the backfill returning feature for data backfill operations.

Fixes

Fixed an issue where return value checks for file system calls were missing.

Fixed a core dump issue that occurred during strong consistency checks on a secondary database after an abnormal restart.

Fixed an issue where data nodes occasionally crashed during the data migration process.

Fixed a bug where an insert statement applied a next-key lock on the subsequent record, which caused primary/secondary replication to break.

8.4.19 (MySQL 8.0-compatible)

New features

Ensured compatibility with MySQL 8.0.32.

Integrated statically compiled jemalloc 5.3.0 as a built-in component.

Integrated statically compiled OpenSSL 1.1.1 as a built-in component.

Added a feature to independently control the retention period of lizard transaction slots.

Added a strong uniqueness check for server_id.

Added an SQL statement to display the undo purge status.

Fixes

Fixed several bugs in large transaction scenarios.

Fixed several bugs in Sampling Scan scenarios.

Category

Description

New feature

Added the import tablespace if not exists syntax.

Fixes

Fixed a core dump issue that occurred during consistency reads when the secondary database started abnormally.

Fixed an issue where the changeset was closed during the DROP TABLE operation.

Fixed a state management issue in multi-phase DDL operations that occurred when database or table names were long or contained non-ASCII special characters.

Fixed an incorrect encoding issue for empty sets in enum and set data types in XRPC.

Fixed a rare process crash in XRPC TCP when a connection was disconnected.

Category

Description

New features

Added timestamps to single-node transactions and XA transactions.

Added support for two-phase DDL.

Added defensive code for potential machine protection exceptions (MPEs) in the XRPC cache during an abnormal exit.

Fixes

Fixed issues with binary logging and synchronization protocols in large transactions.

Fixed an issue where the TCP listener was not gracefully released when an XRPC process exited.

Fixed encoder compatibility issues in XRPC with later versions of Protocol Buffers (protobuf).

Fixed binary logging compatibility issues with auto-savepoints.