diff --git a/sql-statements/sql-statement-alter-table.md b/sql-statements/sql-statement-alter-table.md
index 4c88f0bc749f2..23c9460ae0da7 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` accepts only the string literal `'NONE'` (case-insensitive), but has no effect. TiDB accepts this statement only for MySQL 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