Data types overview

Last updated on

25 September 2018

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The following table shows all the legal combinations of the 'type' and 'size' fields of a column specification along with the underlying database data types used by each combination. As of Drupal 7, MySQL, PostgreSQL, and SQLite data types are supported in Drupal core. Drupal 6 core supports MySQL and PostgreSQL.

The maximum size or range of each underlying type is also shown. For integer types, the number of storage bytes is given; the maximum range depends on whether the field is signed or unsigned. For varchar, text, and blob types, the maximum size is given.

type	size	MySQL type & size/range	PostgreSQL type & size/range	SQLite type
serial	tiny	tinyint, 1 B	serial, 4 B	integer
serial	small	smallint, 2 B	serial, 4 B	integer
serial	medium	mediumint, 3 B	serial, 4 B	integer
serial	big	bigint, 8 B	bigserial, 8 B	integer
serial	normal	int, 4 B	serial, 4 B	integer
int	tiny	tinyint, 1 B	smallint, 2 B	integer
int	small	smallint, 2 B	smallint, 2 B	integer
int	medium	mediumint, 3 B	int, 4 B	integer
int	big	bigint, 8 B	bigint, 8 B	integer
int	normal	int, 4 B	int, 4 B	integer
float	tiny	float, 4 B	real, 6 digits	float
float	small	float, 4 B	real, 6 digits	float
float	medium	float, 4 B	real, 6 digits	float
float	big	double, 8 B	double precision, 15 digits	float
float	normal	float, 4 B	real, 6 digits	float
numeric	normal	numeric, 65 digits	numeric, 1000 digits	numeric
varchar	normal	varchar, 255 B (D6) or 64 KB (D7 and later) [1]	varchar, 1 GB	varchar
char	normal	char, 255 B	character, 1 GB	(UNSUPPORTED)
text	tiny	tinytext, 256 B	text, unlimited	text
text	small	tinytext, 256 B	text, unlimited	text
text	medium	mediumtext, 16 MB	text, unlimited	text
text	big	longtext, 4 GB	text, unlimited	text
text	normal	text, 16 KB	text, unlimited	text
blob [2]	big	longblob, 4 GB	bytea, 4 GB	blob
blob [2]	normal	blob, 16 KB	bytea, 4 GB	blob
datetime [3]	normal [3]	datetime, years 1001 CE to 9999 CE [3]	timestamp, years 4713 BCE to 5874897 CE [3]	(UNSUPPORTED) [3]

[1] MySQL 5.0.3 or later (see http://dev.mysql.com/doc/refman/5.0/en/char.html).
PostgreSQL 9.0 or later (see http://www.postgresql.org/docs/9.0/static/datatype.html).
SQLite 3.0 or later (see http://www.sqlite.org/datatype3.html).

[2] For database portability blob fields must be used to store serialized data since PHP adds null bytes if objects are serialized. Null bytes cannot be stored in Postgres text or varchar fields.

[3] Note that DateTime support was removed from D7 DB API - use mysql_type or pgsql_type if you want this functionality