alter_sequence

ALTER SEQUENCE()		 SQL Commands		     ALTER SEQUENCE()



NAME
       ALTER SEQUENCE - alter 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 ]



DESCRIPTION
       ALTER  SEQUENCE changes the parameters of an existing sequence genera-
       tor. Any parameter not specifically set in the ALTER SEQUENCE  command
       retains its prior setting.

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 main-
	      tained.

       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  RESTART  WITH  start changes the current
	      value of the sequence.

       cache  The clause CACHE cache enables sequence numbers to be  preallo-
	      cated 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 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 min-
	      value 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 behaviour will be maintained.


EXAMPLES
       Restart a sequence called serial, at 105:

       ALTER SEQUENCE serial RESTART WITH 105;


NOTES
       To  avoid blocking of concurrent transactions that obtain numbers from
       the same sequence, ALTER SEQUENCE is never rolled  back;	 the  changes
       take effect immediately and are not reversible.

       ALTER  SEQUENCE	will  not immediately affect nextval results in back-
       ends, other than the current  one,  that	 have  preallocated  (cached)
       sequence	 values. They will use up all cached values prior to noticing
       the changed sequence parameters. The current backend will be  affected
       immediately.

COMPATIBILITY
   SQL99
       ALTER  SEQUENCE is a PostgreSQL language extension.  There is no ALTER
       SEQUENCE statement in SQL99.



SQL - Language Statements	  2008-01-03		     ALTER SEQUENCE()