Documentation Home
MySQL 8.0 Reference Manual
Related Documentation Download this Manual
PDF (US Ltr) - 47.0Mb
PDF (A4) - 47.0Mb
PDF (RPM) - 42.4Mb
HTML Download (TGZ) - 10.8Mb
HTML Download (Zip) - 10.9Mb
HTML Download (RPM) - 9.4Mb
Man Pages (TGZ) - 227.1Kb
Man Pages (Zip) - 333.8Kb
Info (Gzip) - 4.2Mb
Info (Zip) - 4.2Mb
Excerpts from this Manual

MySQL 8.0 Reference Manual  /  The InnoDB Storage Engine  /  InnoDB Restrictions and Limitations

15.23 InnoDB Restrictions and Limitations

This section describes restrictions and limitations of the InnoDB storage engine.

  • You cannot create a table with a column name that matches the name of an internal InnoDB column (including DB_ROW_ID, DB_TRX_ID, and DB_ROLL_PTR. This restriction applies to use of the names in any letter case.

    mysql> CREATE TABLE t1 (c1 INT, db_row_id INT) ENGINE=INNODB;
    ERROR 1166 (42000): Incorrect column name 'db_row_id'
  • SHOW TABLE STATUS does not provide accurate statistics for InnoDB tables except for the physical size reserved by the table. The row count is only a rough estimate used in SQL optimization.

  • InnoDB does not keep an internal count of rows in a table because concurrent transactions might see different numbers of rows at the same time. Consequently, SELECT COUNT(*) statements only count rows visible to the current transaction.

    For information about how InnoDB processes SELECT COUNT(*) statements, refer to the COUNT() description in Section 12.20.1, “Aggregate (GROUP BY) Function Descriptions”.

  • ROW_FORMAT=COMPRESSED is unsupported for page sizes greater than 16KB.

  • A MySQL instance using a particular InnoDB page size (innodb_page_size) cannot use data files or log files from an instance that uses a different page size.

  • For limitations associated with importing tables using the Transportable Tablespaces feature, see Table Import Limitations.

  • For limitations associated with online DDL, see Section 15.12.6, “Online DDL Limitations”.

  • For limitations associated with general tablespaces, see General Tablespace Limitations.

  • For limitations associated with data-at-rest encryption, see Encryption Limitations.