ALTER SEQUENCE(7) PostgreSQL 15.7 Documentation ALTER SEQUENCE(7)
NAME
ALTER_SEQUENCE - change the definition of a sequence generator
SYNOPSIS
ALTER SEQUENCE [ IF EXISTS ] name
[ AS data_type ]
[ INCREMENT [ BY ] increment ]
[ MINVALUE minvalue | NO MINVALUE ] [ MAXVALUE maxvalue | NO MAXVALUE ]
[ START [ WITH ] start ]
[ RESTART [ [ WITH ] restart ] ]
[ CACHE cache ] [ [ NO ] CYCLE ]
[ OWNED BY { table_name.column_name | NONE } ]
ALTER SEQUENCE [ IF EXISTS ] name SET { LOGGED | UNLOGGED }
ALTER SEQUENCE [ IF EXISTS ] name OWNER TO { new_owner | CURRENT_ROLE | CURRENT_USER | SESSION_USER }
ALTER SEQUENCE [ IF EXISTS ] name RENAME TO new_name
ALTER SEQUENCE [ IF EXISTS ] name SET SCHEMA new_schema
DESCRIPTION
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. To alter
the owner, you must also be a direct or indirect member of the new
owning role, and that role must have CREATE privilege on the sequence's
schema. (These restrictions enforce that altering the owner doesn't do
anything you couldn't do by dropping and recreating the sequence.
However, a superuser can alter ownership of any sequence anyway.)
PARAMETERS
name
The name (optionally schema-qualified) of a sequence to be altered.
IF EXISTS
Do not throw an error if the sequence does not exist. A notice is
issued in this case.
data_type
The optional clause AS data_type changes the data type of the
sequence. Valid types are smallint, integer, and bigint.
Changing the data type automatically changes the minimum and
maximum values of the sequence if and only if the previous minimum
and maximum values were the minimum or maximum value of the old
data type (in other words, if the sequence had been created using
NO MINVALUE or NO MAXVALUE, implicitly or explicitly). Otherwise,
the minimum and maximum values are preserved, unless new values are
given as part of the same command. If the minimum and maximum
values do not fit into the new data type, an error will be
generated.
increment
The clause INCREMENT BY increment 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.
minvalue
NO MINVALUE
The optional clause MINVALUE minvalue determines the minimum value
a sequence can generate. If NO MINVALUE is specified, the defaults
of 1 and the minimum value of the data type for ascending and
descending sequences, respectively, will be used. If neither option
is specified, the current minimum value will be maintained.
maxvalue
NO MAXVALUE
The optional clause MAXVALUE maxvalue determines the maximum value
for the sequence. If NO MAXVALUE is specified, the defaults of the
maximum value of the data type 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 START WITH start changes the recorded start
value of the sequence. This has no effect on the current sequence
value; it simply sets the value that future ALTER SEQUENCE RESTART
commands will use.
restart
The optional clause RESTART [ WITH restart ] changes the current
value of the sequence. This is similar to calling the setval
function with is_called = false: the specified value will be
returned by the next call of nextval. Writing RESTART with no
restart value is equivalent to supplying the start value that was
recorded by CREATE SEQUENCE or last set by ALTER SEQUENCE START
WITH.
In contrast to a setval call, a RESTART operation on a sequence is
transactional and blocks concurrent transactions from obtaining
numbers from the same sequence. If that's not the desired mode of
operation, setval should be used.
cache
The clause CACHE 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.
CYCLE
The optional CYCLE key word can 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.
SET { LOGGED | UNLOGGED }
This form changes the sequence from unlogged to logged or
vice-versa (see CREATE SEQUENCE (CREATE_SEQUENCE(7))). It cannot be
applied to a temporary sequence.
OWNED BY table_name.column_name
OWNED 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_owner
The user name of the new owner of the sequence.
new_name
The new name for the sequence.
new_schema
The new schema for the sequence.
NOTES
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.
ALTER SEQUENCE does not affect the currval status for the sequence.
(Before PostgreSQL 8.3, it sometimes did.)
ALTER SEQUENCE blocks concurrent nextval, currval, lastval, and setval
calls.
For historical reasons, ALTER TABLE can be used with sequences too; but
the only variants of ALTER TABLE that are allowed with sequences are
equivalent to the forms shown above.
EXAMPLES
Restart a sequence called serial, at 105:
ALTER SEQUENCE serial RESTART WITH 105;
COMPATIBILITY
ALTER SEQUENCE conforms to the SQL standard, except for the AS, START
WITH, OWNED BY, OWNER TO, RENAME TO, and SET SCHEMA clauses, which are
PostgreSQL extensions.
SEE ALSO
CREATE SEQUENCE (CREATE_SEQUENCE(7)), DROP SEQUENCE (DROP_SEQUENCE(7))
PostgreSQL 15.7 2024 ALTER SEQUENCE(7)
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