From e238a6238562cd44bacebc0c16de94243aef4213 Mon Sep 17 00:00:00 2001 From: takaidohigasi Date: Thu, 16 Jul 2026 19:43:47 +0900 Subject: [PATCH 1/2] sql-statements: document ALTER TABLE COMPRESSION='NONE' behavior Co-Authored-By: Claude Fable 5 --- sql-statements/sql-statement-alter-table.md | 2 ++ 1 file changed, 2 insertions(+) diff --git a/sql-statements/sql-statement-alter-table.md b/sql-statements/sql-statement-alter-table.md index 4c88f0bc749f2..625080766a878 100644 --- a/sql-statements/sql-statement-alter-table.md +++ b/sql-statements/sql-statement-alter-table.md @@ -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` only accepts `'NONE'` (case-insensitive) and it is a no-op: the statement is accepted only for compatibility (for example, for tables migrated from MySQL that carry a `COMPRESSION` attribute), and TiDB does not compress or uncompress any table data. Other values such as `'ZLIB'` and `'LZ4'` return the error `This type of ALTER TABLE is currently unsupported` (error code 8200). If an unsupported `COMPRESSION` value is specified together with other options in one statement, none of the options take effect. + For further restrictions, see [MySQL Compatibility](/mysql-compatibility.md#ddl-operations). ## See also From e2bf73818ea1e567484181675b583087cdfb2625 Mon Sep 17 00:00:00 2001 From: takaidohigasi Date: Thu, 16 Jul 2026 19:52:21 +0900 Subject: [PATCH 2/2] =?UTF-8?q?sql-statement-alter-table.md=20=E3=82=92?= =?UTF-8?q?=E6=9B=B4=E6=96=B0?= MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit Co-authored-by: gemini-code-assist[bot] <176961590+gemini-code-assist[bot]@users.noreply.github.com> --- sql-statements/sql-statement-alter-table.md | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/sql-statements/sql-statement-alter-table.md b/sql-statements/sql-statement-alter-table.md index 625080766a878..a3260bc22a883 100644 --- a/sql-statements/sql-statement-alter-table.md +++ b/sql-statements/sql-statement-alter-table.md @@ -189,7 +189,7 @@ 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` only accepts `'NONE'` (case-insensitive) and it is a no-op: the statement is accepted only for compatibility (for example, for tables migrated from MySQL that carry a `COMPRESSION` attribute), and TiDB does not compress or uncompress any table data. Other values such as `'ZLIB'` and `'LZ4'` return the error `This type of ALTER TABLE is currently unsupported` (error code 8200). If an unsupported `COMPRESSION` value is specified together with other options in one statement, none of the options take effect. +- `ALTER TABLE ... COMPRESSION` only accepts `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) and does not compress or uncompress any table data. Specifying other values, such as `ZLIB` or `LZ4`, returns the error `This type of ALTER TABLE is currently unsupported` (error code 8200). 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).