Practical PostgreSQL

Create Sequence

Creates a new sequence number generator.

Synopsis

CREATE SEQUENCE seqname [ INCREMENT increment ]
       [ MINVALUE minvalue ] [ MAXVALUE maxvalue ]
       [ START start ] [ CACHE cache ] [ CYCLE ]

Parameters

seqname

The name of the new sequence.

increment

The value to be applied on each sequence increment. Specify a positive number to make an ascending sequence; specify a negative number to make a descending sequence.

minvalue

The minimum value the new sequence will generate. The default minimum is 1 for an ascending sequence and –2147483647 for a descending sequence.

maxvalue

The maximum value the new sequence will generate. The default is 2147483647 for an ascending sequence, and –1 for a descending sequence.

start

The starting value of the sequence. By default, an ascending sequence will start at minvalue, and a descending sequence will start at maxvalue.

cache

The quantity of sequence numbers that can be stored in cache memory. Using a cache value greater than 1 will speed up performance, because some calls for new sequence values will be satisfied from the cache. By default, the cache value is set at 1, which forces generation of one sequence number at a time (by default, cache is not used). Set it to a number higher than 1 to enable the use of caching.

CYCLE

Use this keyword to enable wrapping. When wrapping is enabled, a sequence can wrap around past its minimum or maximum value and begin again at its minimum or maximum value. The direction of the wrap depends on whether a sequence ...