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| Original file line number | Diff line number | Diff line change |
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| --- | ||
| title: TiDB Accelerated Table Creation | ||
| summary: Learn the concept, principles, and implementation details of performance optimization for creating tables in TiDB. | ||
| aliases: ['/tidb/dev/ddl-v2/'] | ||
| --- | ||
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| # TiDB Accelerated Table Creation | ||
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| TiDB v7.6.0 introduces the system variable [`tidb_ddl_version`](https://docs.pingcap.com/tidb/v7.6/system-variables#tidb_enable_fast_create_table-new-in-v800) to support accelerating table creation, which improves the efficiency of bulk table creation. Starting from v8.0.0, this system variable is renamed to [`tidb_enable_fast_create_table`](/system-variables.md#tidb_enable_fast_create_table-new-in-v800). | ||
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| TiDB uses the online asynchronous schema change algorithm to change the metadata. All DDL jobs are submitted to the `mysql.tidb_ddl_job` table, and the owner node pulls the DDL job to execute. After executing each phase of the online DDL algorithm, the DDL job is marked as completed and moved to the `mysql.tidb_ddl_history` table. Therefore, DDL statements can only be executed on the owner node and cannot be linearly extended. | ||
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| However, for some DDL statements, it is not necessary to strictly follow the online DDL algorithm. For example, the `CREATE TABLE` statement only has two states for the job: `none` and `public`. Therefore, TiDB can simplify the execution process of DDL, and executes the `CREATE TABLE` statement on a non-owner node to accelerate table creation. | ||
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| > **Warning:** | ||
| > | ||
| > This feature is currently an experimental feature and it is not recommended to use in a production environment. This feature might change or be removed without prior notice. If you find a bug, please give feedback by raising an [issue](https://github.com/pingcap/tidb/issues) on GitHub. | ||
| ## Compatibility with TiDB tools | ||
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| - [TiCDC](https://docs.pingcap.com/tidb/stable/ticdc-overview) does not support replicating the tables that are created by `tidb_enable_fast_create_table`. | ||
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| ## Limitation | ||
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| You can now use performance optimization for table creation only in the [`CREATE TABLE`](/sql-statements/sql-statement-create-table.md) statement, and this statement must not include any foreign key constraints. | ||
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| ## Use `tidb_enable_fast_create_table` to accelerate table creation | ||
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| You can enable or disable performance optimization for creating tables by specifying the value of the system variable [`tidb_enable_fast_create_table`](/system-variables.md#tidb_enable_fast_create_table-new-in-v800). | ||
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| To enable performance optimization for creating tables, set the value of this variable to `ON`: | ||
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| ```sql | ||
| SET GLOBAL tidb_enable_fast_create_table = ON; | ||
| ``` | ||
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| To disable performance optimization for creating tables, set the value of this variable to `OFF`: | ||
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| ```sql | ||
| SET GLOBAL tidb_enable_fast_create_table = OFF; | ||
| ``` | ||
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| ## Implementation principle | ||
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| The detailed implementation principle of performance optimization for table creation is as follows: | ||
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| 1. Create a `CREATE TABLE` Job. | ||
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| The corresponding DDL Job is generated by parsing the `CREATE TABLE` statement. | ||
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| 2. Execute the `CREATE TABLE` job. | ||
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| The TiDB node that receives the `CREATE TABLE` statement executes it directly, and then persists the table structure to TiKV. At the same time, the `CREATE TABLE` job is marked as completed and inserted into the `mysql.tidb_ddl_history` table. | ||
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| 3. Synchronize the table information. | ||
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| TiDB notifies other nodes to synchronize the newly created table structure. |
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