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MySQL 5.6 Reference Manual  /  The InnoDB Storage Engine  /  InnoDB Restrictions and Limitations

14.23 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 lettercase.

    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 12.19.1, “Aggregate Function Descriptions”.

  • There is no guarantee that InnoDB functions normally with a page size greater than 16KB. Problems compiling or running InnoDB may occur. In particular, ROW_FORMAT=COMPRESSED in the Barracuda file format assumes that the page size is at most 16KB and uses 14-bit pointers.

  • 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.

  • InnoDB does not support indexes on spatial data type columns.

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

  • For limitations associated with online DDL, see Section 14.13.6, “Online DDL Limitations”.