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sql-statements: document ALTER TABLE COMPRESSION='NONE' behavior #23299

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sql-statements: document ALTER TABLE COMPRESSION='NONE' behavior
takaidohigasi Jul 16, 2026
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sql-statement-alter-table.md を更新
takaidohigasi Jul 16, 2026
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sql-statements: apply review suggestion on COMPRESSION wording
takaidohigasi Jul 21, 2026
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2 changes: 2 additions & 0 deletions sql-statements/sql-statement-alter-table.md
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Expand Up @@ -189,6 +189,8 @@ The following major restrictions apply to `ALTER TABLE` in TiDB:

- `ALTER TABLE t CACHE | NOCACHE` is a TiDB extension to MySQL syntax. For details, see [Cached Tables](/cached-tables.md).

- `ALTER TABLE ... COMPRESSION` accepts only the string literal `'NONE'` (case-insensitive) and is a no-op. TiDB accepts this statement only for compatibility, for example, for tables migrated from MySQL that carry a `COMPRESSION` attribute. It does not compress or uncompress table data. Other values, such as `'ZLIB'` or `'LZ4'`, return error code 8200 (`This type of ALTER TABLE is currently unsupported`). If you specify an unsupported `COMPRESSION` value together with other options in a single statement, none of the options take effect.

For further restrictions, see [MySQL Compatibility](/mysql-compatibility.md#ddl-operations).

## See also
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