Limitations of MySQL

General limitations of MySQL

32-bit binaries cannot addess more than 4 GB of memory. This is not a MySQL limitation, this is a technical limitation.

Limits of MySQL 4.1

Limits of Joins

In MySQL 4.1, the maximum number of tables that can be referenced in a single join is 61. This also applies to the number of tables that can be referenced in the definition of a view.

Limits of the MyISAM storage engine

There is a limit of 2³² (~4.2 Mia) rows in a MyISAM table. You can increase this limitation if you build MySQL with the --with-big-tables option then the row limitation is increased to 2⁶⁴ (1.8 * 10¹⁹) rows.

Limits of MySQL 5.0

Limits of Joins

The maximum number of tables that can be referenced in a single join is 61. This also applies to the number of tables that can be referenced in the definition of a view. This also applies to LEFT and RIGHT OUTER
JOINS.

Limits of the MyISAM storage engine

Large files up to 63-bit file length are supported.

There is a limit of 2⁶⁴ (1.8 * 10¹⁹) rows in a MyISAM table.

The maximum number of indexes per MyISAM table is 64. You can configure the build by invoking configure with the --with-max-indexes=N option, where N is the maximum number of indexes to permit per MyISAM
table. N must be less thann or equal to 128.

The maximum number of columns per index is 16.

The maximum key length is 1000 bytes. This can be changed by changing the source and recompiling.

Limits of the InnoDB storage engine

A table cannot contain more than 1000 columns.

The internal maximum key length is 3500 bytes, but MySQL itself restricts this to 1024 bytes.

The maximum row length, except for VARCHAR, BLOB and TEXT columns, is slightly less than half of a database page. That is, the maximum row length is about 8000 bytes. LONGBLOB and LONGTEXT columns must be less
than 4GB, and the total row length, including also BLOB and TEXT
columns, must be less than 4GB.

Although InnoDB supports row sizes larger than 65535 internally, you cannot define a row containing VARCHAR columns with a combined size larger than 65535.

The maximum tablespace size is 4 Mia database pages (64TB). This is also the maximum size for a table.

Limits of MySQL 5.1

Limits of Joins

The maximum number of tables that can be referenced in a single join is 61. This also applies to the number of tables that can be referenced in the definition of a view.