General limitations of MySQL

General limitations of MySQL

32-bit binaries cannot address more than 4 Gbyte of memory. This is not a MySQL limitation, this is a technical limitation.
BLOB's are limited to 1 Gbyte in size even thought you use LONGBLOB because of a limitation in the MySQL protocol: The protocol limit for max_allowed_packet is 1GB.

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Limitations of MySQL 4.1

Limitations 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.

Limitations of the MyISAM storage engine

There is a limitation 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.

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Limitations of MySQL 5.0

Limitations 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.

Limitations of the MyISAM storage engine

Large files up to 63-bit file length are supported.
There is a limitation 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 than 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.

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Limitations 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 4 Gbyte, and the total row length, including also BLOB and TEXT columns, must be less than 4 Gbyte.
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 (64 Tbyte). This is also the maximum size for a table.

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Limitations of MySQL 5.1

Limitations 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.

Limitations of Partitions

The limitation of partitions with MySQL is 1024 (internal mail). But one have to increase open_files_limit. See also:

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Limitations of MySQL Cluster

Max attributes/columns in an index: 32
Max number of attributes (columns and indexes) in a table: 128
Max number of table: 1792 (v5.0)
Max size in bytes of a row is 8052 byte, excluding blobs which are stored separately.
Max number of nodes in a cluster: 63, max. number of data nodes: 48 (in v5.0/5.1)
Max number of nodes in a cluster: 255 in CGE.
Max number of metadata objects: 20320.
Max attribute name length: 31 characters.
Max database + table name length: 122 characters.