Kernel Version Release Notes

Last updated: 2020-09-10 15:29:48

    This document describes the MySQL kernel version updates. For information on how to upgrade the kernel, please see Upgrading Kernel Minor Version.

    MySQL 8.0

    20200630

    New features

    • Supports async deletion of big tables. You can clear files asynchronously and slowly to avoid business performance fluctuation caused by deleting big tables. To apply for this feature, please submit a ticket.
    • Supports automatic killing of idle tasks to reduce resource conflicts. To apply for this feature, please submit a ticket.
    • Supports Transparent Data Encryption (TDE).

    Bug fixes

    • Fixed the error where switch failed due to inconsistent checkpoints between relay_log_pos and master_log_pos.
    • Fixed the data file error caused by asynchronously storing data in the disk.
    • Fixed the hard error when fsync returned EIO and retries were made repeatedly.
    • Fixed the crash caused by phrase search under multi-byte character sets in full-text index.

    MySQL 5.7

    20200331

    New features

    • Added the official MySQL 5.7.22 JSON series functions.
    • Supports the Hotspot Update feature for ecommerce flash sale scenarios.
    • Supports the [SQL throttling] (https://intl.cloud.tencent.com/document/product/1035/36037) feature.
    • Supports encryption with custom KMS keys.

    Bug fixes

    • Fixed the crash caused by phrase search under multi-byte character sets in full-text index.
    • Fixed the crash of the CATS lock scheduling module in high-concurrence scenarios.

    20190830

    New features

    • Supports skipping the corrupted data and continuing to parse when a binlog is corrupted. If the source instance and binlog are both damaged, this feature helps restore data from the replica database for use as much as possible.
    • Supports syncing data from non-GTID to GTID mode.
    • Supports querying the "user thread memory usage" by executing the show full processlist statement.
    • Supports quick column adding for tables. This feature does not replicate the data or use disk space/IO and can implement changes during peak hours.
    • Supports persistent auto-increment values.

    Bug fixes

    • Fixed the error where replication would be interrupted if the column name in a GRANT statement contained reserved words.
    • Fixed the error where SQL execution efficiency dropped when reverse scan was performed on a partitioned table.
    • Fixed the error where the query result had an exception due to data inconsistency when using virtual column index and primary key.
    • Fixed the error where data was missing due to InnoDB primary key range queries.
    • Fixed the error where the system crashed when a DDL statement was executed for a table with spatial indexes.
    • Fixed the error where source/replica disconnection occurred when the binlog size was too large and the file length in the heartbeat information exceeded the limit.
    • Fixed the error where other events could not be executed as scheduled when an event was deleted.
    • Fixed the error where the aggregate query result was incorrect.

    20190615

    New features

    • Supports transparent data encryption (TDE).

    20190430

    Bug fixes

    • Fixed the error where null pointer reference occurred when the LONGTEXT feature was used in subqueries.
    • Fixed the error where source/replica disconnection occurred due to hash scan.
    • Fixed the error where the replica I/O thread was interrupted due to source binlog switch.
    • Fixed the crash caused by the use of NAME_CONST.
    • Fixed the illegal mix of collation error caused by character set.

    20190203

    New features

    • Supports async deletion of big tables. You can clear files asynchronously and slowly to avoid business performance fluctuation caused by deleting big tables. To apply for this feature, please submit a ticket.
    • Supports CATS lock scheduling.
    • Supports creating and deleting temp tables and CTS syntax in transactions when GTID is enabled. To apply for this feature, please submit a ticket.
    • Supports implicit primary keys. To apply for this feature, please submit a ticket.
    • Supports users without super privileges to kill sessions of other users by configuring the cdb_kill_user_extra parameter (default value: root@%).
    • Supports enterprise-grade encryption functions. To apply for this feature, please submit a ticket.

    Bug fixes

    • Fixed the error where replication was interrupted when binlog cache file ran out of space.
    • Fixed the hard error when fsync returned EIO and retries were made repeatedly.
    • Fixed the error where replication was interrupted and could not be recovered due to GTID holes.

    20180918

    New features

    • Supports automatic killing of idle transactions to reduce resource conflicts. To apply for this feature, please submit a ticket.
    • Supports automatically changing the storage engine from MEMORY to InnoDB: if the global variable cdb_convert_memory_to_innodb is ON, the engine will be changed from MEMORY to InnoDB when a table is created or modified.
    • Supports invisible indexes.
    • Supports memory management with jemalloc, which can replace the jlibc memory management module to reduce memory usage and improve allocation efficiency.

    Performance optimizations

    • Optimizes binlog switch to reduce the rotate holdlock duration and improve system performance.
    • Increases the crash recovery speed.

    Bug fixes

    • Fixed the error where an event became invalid due to source/replica switch.
    • Fixed the crash caused by REPLAY LOG RECORD.
    • Fixed the error where the query result was incorrect due to loose index scans.

    20180530

    New features

    • Supports SQL auditing.
    • Supports table-level concurrent replication. To apply for this feature, please submit a ticket.

    Performance optimizations

    • Optimizes replica instance locks to improve the performance synchronization of replica instances.
    • Optimizes the pushdown of the select ... limit statement.

    Bug fixes

    • Fixed the error where switch failed due to inconsistent checkpoints between relay_log_pos and master_log_pos.
    • Fixed the crash caused by Crash on UPDATE ON DUPLICATE KEY.
    • Fixed the “Invalid escape character in string.” error when a JSON column was imported.

    20171130

    New features

    • Supports the information_schema.metadata_locks view to query the MDL grant and wait status in the current instance.
    • Supports the ALTER TABLE NO_WAIT | TIMEOUT syntax to grant DDL operations wait timeout. To apply for this feature, please submit a ticket.
    • Supports the thread pool. To apply for this feature, please submit a ticket.

    Bug fixes

    • Fixed the error of innodb_buffer_pool_pages_data overflow by calculating it based on bytes_data.
    • Fixed the error where speed limit plugin became unavailable in async mode.

    MySQL 5.6

    20190930

    New features

    • Supports querying the "user thread memory usage" by executing the show full processlist statement. To apply for this feature, please submit a ticket.

    Bug fixes

    • Fixed GTID holes caused by the replication filter of the replica.
    • Fixed the error where source/replica disconnection occurred when the binlog size was too large and the file length in the heartbeat information exceeded the limit.
    • Fixed the illegal mix of collation error caused by character set.
    • Fixed the error where the source/replica disconnection occurred due to hash scan.
    • Fixed the crash caused by the use of NAME_CONST.
    • Fixed the error where the replica I/O thread was interrupted due to source binlog switch.
    • Fixed the error of incompatible backups due to innodb_log_checusum.

    20190530

    Bug fixes

    • Fixed the error where dirty data might be read in RC mode.
    • Fixed the error where replica instance replay might fail due to the deletion of temp table.
    • Fixed the error of deadlock under high concurrency.

    20190203

    New features

    • Supports async deletion of big tables. You can clear files asynchronously and slowly to avoid business performance fluctuation caused by deleting big tables. To apply for this feature, please submit a ticket.
    • Supports users without super privileges to kill sessions of other users by configuring the cdb_kill_user_extra parameter (default value: root@%).
    • Supports creating and deleting temp tables and CTS syntax in transactions when GTID is enabled. To apply for this feature, please submit a ticket.

    Performance optimizations

    • Optimizes the replication and replay of partitioned tables to improve efficiency.

    Bug fixes

    • Fixed the error of data inconsistency between source and replica due to insufficient temporary space.
    • Fixed the error of suspended hot record updates.
    • Fixed the error where the Seconds_Behind_Master value had an exception during concurrent replication.

    20180915

    New features

    • Supports automatically changing the storage engine from MEMORY to InnoDB: if the global variable cdb_convert_memory_to_innodb is ON, the engine will be changed from MEMORY to InnoDB when a table is created or modified.
    • Supports automatic killing of idle transactions to reduce resource conflicts. To apply for this feature, please submit a ticket.

    Bug fixes

    • Fixed the crash caused by REPLAY LOG RECORD.
    • Fixed the error of time data inconsistency between source and replica due to decimal precision issues.

    20180130

    New features

    • Supports the thread pool. To apply for this feature, please submit a ticket.
    • Supports dynamically modifying replication filtering rules for replica nodes.

    Performance optimizations

    • Reduces performance fluctuation caused by drop table.

    Bug fixes

    • Fixed the error where the database crashed due to authentication password strings.

    20180122

    New features

    • Supports SQL auditing.

    Bug fixes

    • Fixed the error of integer overflow.
    • Fixed the error caused by queries using full-text index.
    • Fixed the error where the replica crashed during replication.

    20170830

    Bug fixes

    • Fixed the error where binlog speed limit became invalid in async mode.
    • Fixed the error where the buffer_pool status had an exception.
    • Fixed the error where SEQUENCE and implicit primary key conflicted.

    20170228

    Bug fixes

    • Fixed the character encoding bug in drop table.
    • Fixed the error where special symbols such as decimal point in a database or table could not be properly filtered by the replicate-wild-do-table statement.
    • Fixed the error where SQL threads exited too early after the replica had a rotate event.

    20161130

    Performance optimizations

    • Splits the lock_log lock to reduce the time used by lock log and improve the concurrency performance.
    • Separates the ACK thread of the source to improve the response time.
    • Prohibits the user thread from being killed while waiting for ACK in order to prevent phantom reads.
    • Fixes the unnecessary lock_sync lock when sync_binlog != 1.

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