diff --git a/sql-statements/sql-statement-alter-table.md b/sql-statements/sql-statement-alter-table.md
index 4c88f0bc749f2..a3260bc22a883 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 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).
 
 ## See also