17.22 InnoDB Restrictions and Limitations

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MySQL 8.4 Reference Manual Including MySQL NDB Cluster 8.4

17.22 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 14.19.1, “Aggregate 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 17.12.8, “Online DDL Limitations”. - For limitations associated with general tablespaces, see General Tablespace Limitations. - For limitations associated with data-at-rest encryption, see Encryption Limitations.