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Under GNU General Public License
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ALTER SEQUENCE() SQL Commands ALTER SEQUENCE()
NAME
ALTER SEQUENCE - change the definition of a sequence generator
SYNOPSIS
ALTER SEQUENCE name [ INCREMENT [ BY ] increment ]
[ MINVALUE minvalue | NO MINVALUE ] [ MAXVALUE maxvalue | NO MAXVALUE ]
[ RESTART [ WITH ] start ] [ CACHE cache ] [ [ NO ] CYCLE ]
[ OWNED BY { table.column | NONE } ]
ALTER SEQUENCE name RENAME TO new_name
ALTER SEQUENCE name SET SCHEMA new_schema
DESCRIPTION
ALTER SEQUENCE changes the parameters of an existing sequence generator. Any param-
eters not specifically set in the ALTER SEQUENCE command retain their prior set-
tings.
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.
PARAMETERS
name The name (optionally schema-qualified) of a sequence to be altered.
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
-263-1 for ascending and descending sequences, respectively, will be used.
If neither option is specified, the current minimum value will be main-
tained.
maxvalue
NO MAXVALUE
The optional clause MAXVALUE maxvalue determines the maximum value for the
sequence. If NO 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 start changes the current value of the
sequence. This is equivalent to calling the setval function with is_called =
false: the specified value will be returned by the next call of nextval.
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.
OWNED BY table.column
OWNED BY NONE
The OWNED BY option causes the sequence to be associated with a specific ta-
ble column, such that if that column (or its whole table) is dropped, the
sequence will be automatically dropped as well. If specified, this associa-
tion 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_name
The new name for the sequence.
new_schema
The new schema for the sequence.
NOTES
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, RENAME, and SET SCHEMA clauses cause ordinary catalog updates that
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.
ALTER SEQUENCE does not affect the currval status for the sequence. (Before Post-
greSQL 8.3, it sometimes did.)
Some variants of ALTER TABLE can be used with sequences as well; for example, to
rename a sequence it is also possible to use ALTER TABLE RENAME.
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 OWNED BY, RENAME, and
SET SCHEMA clauses, which are PostgreSQL extensions.
SEE ALSO
CREATE SEQUENCE [create_sequence(7)], DROP SEQUENCE [drop_sequence(l)]
SQL - Language Statements 2009-03-12 ALTER SEQUENCE()
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On Apache/2.2.3 (Red Hat)
Under GNU General Public License
2009-12-23 21:03 @127.0.0.1 CrawledBy CCBot/1.0 (+http://www.commoncrawl.org/bot.html)