tencent cloud

TencentDB for MySQL

DocumentationTencentDB for MySQLKernel FeaturesFunctionality FeaturesParallel replication

Parallel replication

PDF
Focus Mode
Font Size
Last updated: 2026-02-24 11:36:56

Feature Introduction

Official MySQL versions below 5.6 perform replay on the standby node and synchronize binlog on the primary node in single-thread mode. Versions 5.6 and later are changed to parallel mode. However, the official parallel mode is based on database and logical clock, and the granularity of parallelism is too coarse, resulting in suboptimal parallel performance in many cases.
The Tencent Cloud TXSQL kernel team optimized the parallel replication feature to support parallel processing by table, effectively splitting the granularity to the table level, which improves parallelism and thereby reduces primary/standby delay.

Supported Versions

Kernel version MySQL 8.0 20201230 and above
Kernel version MySQL 5.7 20180530 and above
Kernel version MySQL 5.6 20170830 and above

Applicable Scenarios

This feature mainly targets certain workloads to improve the speed of binlog replay on the standby node, reducing primary/standby delay.

Usage Instructions

Note:
Parallel replication capability is enabled by setting the parameter slave_parallel_workers to a non-zero value. In the high-stability parameter templates for MySQL versions 5.6, 5.7, and 8.0, this parameter defaults to 0, while in the high-performance parameter templates, it defaults to 8.
MySQL 5.6 and 5.7 versions can enable this feature by setting the parameter slave_parallel_type to the newly added value TABLE. MySQL 8.0 version does not support the TABLE mode. Additionally, a new status table cdb_slave_thread_status has been added under information_schema to display status information.
MySQL 5.6 Version Parameters Description
MySQL 5.7 Version Related Parameters Reference
MySQL 8.0 Version Parameter Descriptions
Parameter Name
Dynamic
Type
Default Value
Value Range
Description
slave_parallel_type
YES
char*
SCHEMA
SCHEMA/TABLE
Slave parallel replication level:
SCHEMA is object-level replication, where replication events for different objects can be executed in parallel.
TABLE is table-level replication, where replication events for different tables can be executed in parallel.
Parameter Name
Dynamic
Type
Default Value
Value Range
Description
slave_parallel_type
YES
char*
LOGICAL_CLOCK
DATABASE/TABLE/LOGICAL_CLOCK
Slave parallel replication level:
DATABASE is database-level replication, where replication events for different databases can be executed in parallel.
TABLE is table-level replication, where replication events for different tables can be executed in parallel.
LOGICAL_CLOCK is logical clock-level replication, where events belonging to the same logical clock on the primary can be executed concurrently.
Parameter Name
Dynamic
Type
Default Value
Value Range
Description
slave_parallel_type
YES
char*
LOGICAL_CLOCK
DATABASE/LOGICAL_CLOCK
Slave parallel replication level:
DATABASE is database-level replication, where replication events for different databases can be executed in parallel.
LOGICAL_CLOCK is logical clock-level replication, where events belonging to the same logical clock on the primary can be executed concurrently.
Previous Topic: Killing Idle Transactions AutomaticallyNext Topic: Dynamic Thread Pool

Help and Support

Was this page helpful?

Help us improve! Rate your documentation experience in 5 mins.

Feedback