ALTER SEQUENCE(7)                                         SQL Commands                                         ALTER SEQUENCE(7)



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 ]
           [ START [ WITH ] start ]
           [ RESTART [ [ WITH ] restart ] ]
           [ CACHE cache ] [ [ NO ] CYCLE ]
           [ OWNED BY { table.column | NONE } ]
       ALTER SEQUENCE name OWNER TO new_owner
       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 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  any-
       thing  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.

       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 maintained.

       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 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  equivalent  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.

       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  gener-
              ated 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  main-
              tained.

       OWNED BY table.column

       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  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_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
       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.  How-
       ever, the OWNED BY, OWNER TO, RENAME TO, 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 preallo-
       cated (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.)

       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 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)]



SQL - Language Statements                                  2011-09-22                                          ALTER SEQUENCE(7)