MySQL 8.0 Reference Manual Including MySQL NDB Cluster 8.0 SQL Compression Syntax Warnings and Errors

This section describes syntax warnings and errors that you may encounter when using the table compression feature with file-per-table tablespaces and general tablespaces.

SQL Compression Syntax Warnings and Errors for File-Per-Table Tablespaces

When innodb_strict_mode is enabled (the default), specifying ROW_FORMAT=COMPRESSED or KEY_BLOCK_SIZE in CREATE TABLE or ALTER TABLE statements produces the following error if innodb_file_per_table is disabled.

ERROR 1031 (HY000): Table storage engine for 't1' doesn't have this option

The table is not created if the current configuration does not permit using compressed tables.

When innodb_strict_mode is disabled, specifying ROW_FORMAT=COMPRESSED or KEY_BLOCK_SIZE in CREATE TABLE or ALTER TABLE statements produces the following warnings if innodb_file_per_table is disabled.

| Level   | Code | Message                                                       |
| Warning | 1478 | InnoDB: KEY_BLOCK_SIZE requires innodb_file_per_table.        |
| Warning | 1478 | InnoDB: ignoring KEY_BLOCK_SIZE=4.                            |
| Warning | 1478 | InnoDB: ROW_FORMAT=COMPRESSED requires innodb_file_per_table. |
| Warning | 1478 | InnoDB: assuming ROW_FORMAT=DYNAMIC.                          |

These messages are only warnings, not errors, and the table is created without compression, as if the options were not specified.

The non-strict behavior lets you import a mysqldump file into a database that does not support compressed tables, even if the source database contained compressed tables. In that case, MySQL creates the table in ROW_FORMAT=DYNAMIC instead of preventing the operation.

To import the dump file into a new database, and have the tables re-created as they exist in the original database, ensure the server has the proper setting for the innodb_file_per_table configuration parameter.

The attribute KEY_BLOCK_SIZE is permitted only when ROW_FORMAT is specified as COMPRESSED or is omitted. Specifying a KEY_BLOCK_SIZE with any other ROW_FORMAT generates a warning that you can view with SHOW WARNINGS. However, the table is non-compressed; the specified KEY_BLOCK_SIZE is ignored).

Level Code Message
Warning 1478 InnoDB: ignoring KEY_BLOCK_SIZE=n unless ROW_FORMAT=COMPRESSED.

If you are running with innodb_strict_mode enabled, the combination of a KEY_BLOCK_SIZE with any ROW_FORMAT other than COMPRESSED generates an error, not a warning, and the table is not created.

Table 15.12, “ROW_FORMAT and KEY_BLOCK_SIZE Options” provides an overview the ROW_FORMAT and KEY_BLOCK_SIZE options that are used with CREATE TABLE or ALTER TABLE.

Table 15.12 ROW_FORMAT and KEY_BLOCK_SIZE Options

Option Usage Notes Description
ROW_FORMAT=​REDUNDANT Storage format used prior to MySQL 5.0.3 Less efficient than ROW_FORMAT=COMPACT; for backward compatibility
ROW_FORMAT=​COMPACT Default storage format since MySQL 5.0.3 Stores a prefix of 768 bytes of long column values in the clustered index page, with the remaining bytes stored in an overflow page
ROW_FORMAT=​DYNAMIC Store values within the clustered index page if they fit; if not, stores only a 20-byte pointer to an overflow page (no prefix)
ROW_FORMAT=​COMPRESSED Compresses the table and indexes using zlib
KEY_BLOCK_​SIZE=n Specifies compressed page size of 1, 2, 4, 8 or 16 kilobytes; implies ROW_FORMAT=COMPRESSED. For general tablespaces, a KEY_BLOCK_SIZE value equal to the InnoDB page size is not permitted.

Table 15.13, “CREATE/ALTER TABLE Warnings and Errors when InnoDB Strict Mode is OFF” summarizes error conditions that occur with certain combinations of configuration parameters and options on the CREATE TABLE or ALTER TABLE statements, and how the options appear in the output of SHOW TABLE STATUS.

When innodb_strict_mode is OFF, MySQL creates or alters the table, but ignores certain settings as shown below. You can see the warning messages in the MySQL error log. When innodb_strict_mode is ON, these specified combinations of options generate errors, and the table is not created or altered. To see the full description of the error condition, issue the SHOW ERRORS statement: example:



ERROR 1005 (HY000): Can't create table 'test.x' (errno: 1478)

| Level | Code | Message                                   |
| Error | 1478 | InnoDB: invalid KEY_BLOCK_SIZE=33333.     |
| Error | 1005 | Can't create table 'test.x' (errno: 1478) |

Table 15.13 CREATE/ALTER TABLE Warnings and Errors when InnoDB Strict Mode is OFF

Syntax Warning or Error Condition Resulting ROW_FORMAT, as shown in SHOW TABLE STATUS
ROW_FORMAT=COMPRESSED or ROW_FORMAT=DYNAMIC or KEY_BLOCK_SIZE is specified Ignored for file-per-table tablespaces unless innodb_file_per_table is enabled. General tablespaces support all row formats. See Section, “General Tablespaces”. the default row format for file-per-table tablespaces; the specified row format for general tablespaces
Invalid KEY_BLOCK_SIZE is specified (not 1, 2, 4, 8 or 16) KEY_BLOCK_SIZE is ignored the specified row format, or the default row format
ROW_FORMAT=COMPRESSED and valid KEY_BLOCK_SIZE are specified None; KEY_BLOCK_SIZE specified is used COMPRESSED
ROW_FORMAT is not one of REDUNDANT, COMPACT, DYNAMIC or COMPRESSED Ignored if recognized by the MySQL parser. Otherwise, an error is issued. the default row format or N/A

When innodb_strict_mode is ON, MySQL rejects invalid ROW_FORMAT or KEY_BLOCK_SIZE parameters and issues errors. Strict mode is ON by default. When innodb_strict_mode is OFF, MySQL issues warnings instead of errors for ignored invalid parameters.

It is not possible to see the chosen KEY_BLOCK_SIZE using SHOW TABLE STATUS. The statement SHOW CREATE TABLE displays the KEY_BLOCK_SIZE (even if it was ignored when creating the table). The real compressed page size of the table cannot be displayed by MySQL.

SQL Compression Syntax Warnings and Errors for General Tablespaces

innodb_strict_mode is not applicable to general tablespaces. Tablespace management rules for general tablespaces are strictly enforced independently of innodb_strict_mode. For more information, see Section 13.1.21, “CREATE TABLESPACE Statement”.

For more information about using compressed tables with general tablespaces, see Section, “General Tablespaces”.