ALTER SEQUENCE — change the definition of a sequence generator
ALTER SEQUENCEname[ INCREMENT [ BY ]increment] [ MINVALUEminvalue| NO MINVALUE ] [ MAXVALUEmaxvalue| NO MAXVALUE ] [ RESTART [ WITH ]start] [ CACHEcache] [ [ NO ] CYCLE ] [ OWNED BY {table.column| NONE } ] ALTER SEQUENCEnameSET SCHEMAnew_schema
ALTER SEQUENCE changes the parameters of an existing
sequence generator. Any parameters not specifically set in the
ALTER SEQUENCE command retain their prior settings.
You must own the sequence to use ALTER SEQUENCE.
To change a sequence's schema, you must also have CREATE
privilege on the new schema.
nameThe name (optionally schema-qualified) of a sequence to be altered.
increment The clause INCREMENT BY is
optional. A positive value will make an ascending sequence, a
negative one a descending sequence. If unspecified, the old
increment value will be maintained.
increment
minvalueNO MINVALUE
The optional clause MINVALUE determines
the minimum value a sequence can generate. If minvalueNO
MINVALUE is specified, the defaults of 1 and
-263-1 for ascending and descending sequences,
respectively, will be used. If neither option is specified,
the current minimum value will be maintained.
maxvalueNO MAXVALUE
The optional clause MAXVALUE determines
the maximum value for the sequence. If maxvalueNO
MAXVALUE is specified, the defaults are
263-1 and -1 for ascending and descending
sequences, respectively, will be used. If neither option is
specified, the current maximum value will be maintained.
start The optional clause RESTART WITH changes the
current value of the sequence.
start
cache The clause CACHE enables
sequence numbers to be preallocated and stored in memory for
faster access. The minimum value is 1 (only one value can be
generated at a time, i.e., no cache). If unspecified, the old
cache value will be maintained.
cache
CYCLE The optional CYCLE key word may be used to enable
the sequence to wrap around when the
maxvalue or
minvalue has been
reached by
an ascending or descending sequence respectively. If the limit is
reached, the next number generated will be the
minvalue or
maxvalue,
respectively.
NO CYCLE If the optional NO CYCLE key word is
specified, any calls to nextval after the
sequence has reached its maximum value will return an error.
If neither CYCLE or NO
CYCLE are specified, the old cycle behavior will be
maintained.
OWNED BY table.columnOWNED BY NONE
The OWNED BY option causes the sequence to be
associated with a specific table column, such that if that column
(or its whole table) is dropped, the sequence will be automatically
dropped as well. If specified, this association replaces any
previously specified association for the sequence. The specified
table must have the same owner and be in the same schema as the
sequence.
Specifying OWNED BY NONE removes any existing
association, making the sequence “free-standing”.
new_schemaThe new schema for the sequence.
To avoid blocking of concurrent transactions that obtain numbers from the
same sequence, ALTER SEQUENCE's effects on the sequence
generation parameters are never rolled back;
those changes take effect immediately and are not reversible. However,
the OWNED BY and SET SCHEMA clauses are ordinary
catalog updates and can be rolled back.
ALTER SEQUENCE will not immediately affect
nextval results in backends,
other than the current one, that have preallocated (cached) sequence
values. They will use up all cached values prior to noticing the changed
sequence generation parameters. The current backend will be affected
immediately.
Some variants of ALTER TABLE can be used with
sequences as well; for example, to rename a sequence use ALTER
TABLE RENAME.