14.23 InnoDB Limits
This section describes limits for
InnoDB tables, indexes, tablespaces, and other aspects of the
InnoDB storage engine.
A table can contain a maximum of 1017 columns (raised in MySQL 5.6.9 from the earlier limit of 1000). Virtual generated columns are included in this limit.
A table can contain a maximum of 64 secondary indexes.
innodb_large_prefixis enabled (the default), the index key prefix limit is 3072 bytes for
InnoDBtables that use the
COMPRESSEDrow format. If
innodb_large_prefixis disabled, the index key prefix limit is 767 bytes for tables of any row format.
innodb_large_prefixis deprecated and will be removed in a future release.
innodb_large_prefixwas introduced in MySQL 5.5 to disable large index key prefixes for compatibility with earlier versions of
InnoDBthat do not support large index key prefixes.
The index key prefix length limit is 767 bytes for
InnoDBtables that use the
COMPACTrow format. For example, you might hit this limit with a column prefix index of more than 255 characters on a
VARCHARcolumn, assuming a
utf8mb3character set and the maximum of 3 bytes for each character.
Attempting to use an index key prefix length that exceeds the limit returns an error. To avoid such errors in replication configurations, avoid enabling
innodb_large_prefixon the source if it cannot also be enabled on replicas.
If you reduce the
InnoDBpage size to 8KB or 4KB by specifying the
innodb_page_sizeoption when creating the MySQL instance, the maximum length of the index key is lowered proportionally, based on the limit of 3072 bytes for a 16KB page size. That is, the maximum index key length is 1536 bytes when the page size is 8KB, and 768 bytes when the page size is 4KB.
The limits that apply to index key prefixes also apply to full-column index keys.
A maximum of 16 columns is permitted for multicolumn indexes. Exceeding the limit returns an error.
ERROR 1070 (42000): Too many key parts specified; max 16 parts allowed
The maximum row size, excluding any variable-length columns that are stored off-page, is slightly less than half of a page for 4KB, 8KB, 16KB, and 32KB page sizes. For example, the maximum row size for the default
innodb_page_sizeof 16KB is about 8000 bytes. However, for an
InnoDBpage size of 64KB, the maximum row size is approximately 16000 bytes.
LONGTEXTcolumns must be less than 4GB, and the total row size, including
TEXTcolumns, must be less than 4GB.
If a row is less than half a page long, all of it is stored locally within the page. If it exceeds half a page, variable-length columns are chosen for external off-page storage until the row fits within half a page, as described in Section 14.12.2, “File Space Management”.
InnoDBsupports row sizes larger than 65,535 bytes internally, MySQL itself imposes a row-size limit of 65,535 for the combined size of all columns. See Section 8.4.7, “Limits on Table Column Count and Row Size”.
On some older operating systems, files must be less than 2GB. This is not an
InnoDBlimitation. If you require a large system tablespace, configure it using several smaller data files rather than one large data file, or distribute table data across file-per-table and general tablespace data files.
The combined maximum size for
InnoDBlog files is 512GB.
The minimum tablespace size is slightly larger than 10MB. The maximum tablespace size depends on the
Table 14.25 InnoDB Maximum Tablespace Size
InnoDB Page Size Maximum Tablespace Size 4KB 16TB 8KB 32TB 16KB 64TB 32KB 128TB 64KB 256TB
The maximum tablespace size is also the maximum size for a table.
Tablespace files cannot exceed 4GB on Windows 32-bit systems (Bug #80149).
The path of a tablespace file, including the file name, cannot exceed the
MAX_PATHlimit on Windows. Prior to Windows 10, the
MAX_PATHlimit is 260 characters. As of Windows 10, version 1607,
MAX_PATHlimitations are removed from common Win32 file and directory functions, but you must enable the new behavior.
ROW_FORMAT=COMPRESSEDin the Barracuda file format assumes that the page size is at most 16KB and uses 14-bit pointers.
For limits associated with concurrent read-write transactions, see Section 14.6.7, “Undo Logs”.