alter_sequence(7)

1ALTER SEQUENCE()                 SQL Commands                 ALTER SEQUENCE()
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NAME

6       ALTER SEQUENCE - change the definition of a sequence generator
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SYNOPSIS

10       ALTER SEQUENCE name [ INCREMENT [ BY ] increment ]
11           [ MINVALUE minvalue | NO MINVALUE ] [ MAXVALUE maxvalue | NO MAXVALUE ]
12           [ RESTART [ WITH ] start ] [ CACHE cache ] [ [ NO ] CYCLE ]
13           [ OWNED BY { table.column | NONE } ]
14       ALTER SEQUENCE name SET SCHEMA new_schema
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DESCRIPTION

19       ALTER  SEQUENCE  changes the parameters of an existing sequence genera‐
20       tor. Any parameters not specifically set in the ALTER SEQUENCE  command
21       retain their prior settings.
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23       You  must  own  the  sequence  to  use  ALTER  SEQUENCE.   To  change a
24       sequence's schema, you must also  have  CREATE  privilege  on  the  new
25       schema.
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PARAMETERS

28       name   The  name  (optionally  schema-qualified)  of  a  sequence to be
29              altered.
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31       increment
32              The clause INCREMENT BY increment is optional. A positive  value
33              will  make  an  ascending  sequence, a negative one a descending
34              sequence. If unspecified, the old increment value will be  main‐
35              tained.
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37       minvalue
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39       NO MINVALUE
40              The  optional  clause  MINVALUE  minvalue determines the minimum
41              value a sequence can generate. If NO MINVALUE is specified,  the
42              defaults of 1 and -263-1 for ascending and descending sequences,
43              respectively, will be used. If neither option is specified,  the
44              current minimum value will be maintained.
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46       maxvalue
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48       NO MAXVALUE
49              The  optional  clause  MAXVALUE  maxvalue determines the maximum
50              value for  the  sequence.  If  NO  MAXVALUE  is  specified,  the
51              defaults   are   263-1  and  -1  for  ascending  and  descending
52              sequences, respectively, will be  used.  If  neither  option  is
53              specified, the current maximum value will be maintained.
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55       start  The optional clause RESTART WITH start changes the current value
56              of the sequence.
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58       cache  The clause CACHE cache enables sequence numbers to  be  preallo‐
59              cated  and stored in memory for faster access. The minimum value
60              is 1 (only one value can  be  generated  at  a  time,  i.e.,  no
61              cache). If unspecified, the old cache value will be maintained.
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63       CYCLE  The  optional  CYCLE key word may be used to enable the sequence
64              to wrap around when the maxvalue or minvalue has been reached by
65              an  ascending  or descending sequence respectively. If the limit
66              is reached, the next number generated will be  the  minvalue  or
67              maxvalue, respectively.
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69       NO CYCLE
70              If  the  optional  NO  CYCLE key word is specified, any calls to
71              nextval after the sequence has reached its  maximum  value  will
72              return  an  error.   If neither CYCLE or NO CYCLE are specified,
73              the old cycle behavior will be maintained.
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75       OWNED BY table.column
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77       OWNED BY NONE
78              The OWNED BY option causes the sequence to be associated with  a
79              specific  table  column,  such that if that column (or its whole
80              table) is dropped, the sequence will be automatically dropped as
81              well.  If  specified,  this  association replaces any previously
82              specified association for the sequence. The specified table must
83              have  the  same owner and be in the same schema as the sequence.
84              Specifying OWNED BY NONE removes any existing association,  mak‐
85              ing the sequence ``free-standing''.
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87       new_schema
88              The new schema for the sequence.
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EXAMPLES

91       Restart a sequence called serial, at 105:
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93       ALTER SEQUENCE serial RESTART WITH 105;
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NOTES

97       To  avoid  blocking of concurrent transactions that obtain numbers from
98       the same sequence, ALTER SEQUENCE's effects on the sequence  generation
99       parameters are never rolled back; those changes take effect immediately
100       and are not reversible. However, the OWNED BY and  SET  SCHEMA  clauses
101       are ordinary catalog updates and can be rolled back.
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103       ALTER SEQUENCE will not immediately affect nextval results in backends,
104       other than the current one, that have  preallocated  (cached)  sequence
105       values.  They  will  use  up  all  cached  values prior to noticing the
106       changed sequence generation parameters. The  current  backend  will  be
107       affected immediately.
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109       Some  variants  of  ALTER TABLE can be used with sequences as well; for
110       example, to rename a sequence use ALTER TABLE RENAME.
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COMPATIBILITY

113       ALTER SEQUENCE conforms to the SQL standard, except for  the  OWNED  BY
114       and SET SCHEMA clauses, which are PostgreSQL extensions.
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