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SHOW ALTER TABLE

Description​

Shows the execution of the ongoing ALTER TABLE operations, including:

  • Modify columns.
  • Optimize table schema (from v3.2), including modifying the bucketing method and the number of buckets.
  • Create and delete the rollup index.

Syntax​

  • Show the execution of operations of modifying columns or optimizing table schema.

    SHOW ALTER TABLE { COLUMN | OPTIMIZE } [FROM db_name] [WHERE TableName|CreateTime|FinishTime|State] [ORDER BY] [LIMIT]

  • Show the execution of operations of adding or deleting the rollup index.

    SHOW ALTER TABLE ROLLUP [FROM db_name]

Parameters​

  • {COLUMN ｜ OPTIMIZE | ROLLUP}:

    • If COLUMN is specified, this statement shows operations of modifying columns.
    • If OPTIMIZE is specified, this statement shows operations of optimizing table structure.
    • If ROLLUP is specified, this statement shows operations of adding or deleting the rollup index.

  • db_name: optional. If db_name is not specified, the current database is used by default.

Examples​

  1. Show the execution of operations of modifying columns, optimizing table schema, and creating or deleting the rollup index in the current database.

    SHOW ALTER TABLE COLUMN;
    SHOW ALTER TABLE OPTIMIZE;
    SHOW ALTER TABLE ROLLUP;

  2. Show the execution of operations related to modifying columns, optimizing table schema, and creating or deleting the rollup index in a specified database.

    SHOW ALTER TABLE COLUMN FROM example_db;
    SHOW ALTER TABLE OPTIMIZE FROM example_db;
    SHOW ALTER TABLE ROLLUP FROM example_db;

  3. Show the execution of the most recent operation of modifying columns or optimizing table schema in a specified table.

    SHOW ALTER TABLE COLUMN WHERE TableName = "table1" ORDER BY CreateTime DESC LIMIT 1;
    SHOW ALTER TABLE OPTIMIZE WHERE TableName = "table1" ORDER BY CreateTime DESC LIMIT 1;

References​