tencent cloud

All product documents
TDSQL-C for MySQL
DocumentationTDSQL-C for MySQLKernel FeaturesFunctionality FeaturesParallel Copy DDL
Parallel Copy DDL
Download PDF
Last updated: 2024-12-11 10:23:54
Parallel Copy DDL
Last updated: 2024-12-11 10:23:54
Download PDF

Overview

During database Ops, Data Definition Language (DDL) operations often become sensitive operations that impact database performance due to their modifications to data structures, especially when executed on a large number of tables. Traditional Copy DDL operations may cause prolonged lock waits, affecting normal business operations. To address this issue, TXSQL introduces the Parallel Copy DDL mechanism. Compared to traditional Copy DDL, Parallel Copy DDL uses the InnoDB layer's Parallel Reader framework to read data from the original table in parallel and insert it into a created temporary table, thereby improving data migration efficiency.

Supported Versions

Kernel version: TXSQL 5.7 2.1.13.001 and later.
Kernel version: TXSQL 8.0 3.1.15.001 and later.

Applicable Scenario

Copy DDL resides in the upper layer of the storage engine, that is, the execution layer. It calls engine layer interfaces only for querying and inserting, without directly operating on files. Any DDL operation can be abstracted to this execution method, so all DDL operations can be executed using the Copy algorithm.
Parallel Copy DDL is applicable to the following scenarios:
Table structure modifications with large data volumes, such as adding new columns or modifying column types.
Scenarios requiring quick completion of DDL operations to minimize business impact.
Scenarios with strict requirements on database performance, needing to reduce lock wait time caused by DDL operations.

Notes

The following types of tables do not currently support Parallel Copy DDL:
Non-InnoDB tables.
Temporary tables.
Tables using alter table order by, which have requirements on row orders and need to be processed with a single thread.
Tables with newly added auto-increment columns.
Partitioned tables.
Tables with foreign key constraints.
Tables with multi-value function indexes.

Use Instructions

Add two session-level parameters.
Parameter Name
Level
Type
Default Value
Value
Description
txsql_parallel_copy_ddl
session
bool
0
0/1
Whether to enable the Parallel Copy DDL feature.
1 means enabling the Parallel Copy DDL feature.
0 means disabling the Parallel Copy DDL feature.
innodb_parallel_read_threads
session
int
4
1 - 256
Number of threads used by Parallel Read.
Was this page helpful?
You can also Contact Sales or Submit a Ticket for help.
Yes
No

Feedback

Contact Us

Contact our sales team or business advisors to help your business.

Contact Us
Technical Support

Open a ticket if you're looking for further assistance. Our Ticket is 7x24 avaliable.

Submit a Ticket
7x24 Phone Support
Hong Kong, China
+852 800 906 020 (Toll Free)
United States
+1 844 606 0804 (Toll Free)
United Kingdom
+44 808 196 4551 (Toll Free)
Canada
+1 888 605 7930 (Toll Free)
Australia
+61 1300 986 386 (Toll Free)
EdgeOne hotline
+852 300 80699
More local hotlines coming soon