Provided by: postgresql-client-9.1_9.1.3-2_i386 bug

NAME

       CREATE_SEQUENCE - define a new sequence generator

SYNOPSIS

       CREATE [ TEMPORARY | TEMP ] SEQUENCE name [ INCREMENT [ BY ] increment ]
           [ MINVALUE minvalue | NO MINVALUE ] [ MAXVALUE maxvalue | NO MAXVALUE ]
           [ START [ WITH ] start ] [ CACHE cache ] [ [ NO ] CYCLE ]
           [ OWNED BY { table.column | NONE } ]

DESCRIPTION

       CREATE SEQUENCE creates a new sequence number generator. This involves
       creating and initializing a new special single-row table with the name
       name. The generator will be owned by the user issuing the command.

       If a schema name is given then the sequence is created in the specified
       schema. Otherwise it is created in the current schema. Temporary
       sequences exist in a special schema, so a schema name cannot be given
       when creating a temporary sequence. The sequence name must be distinct
       from the name of any other sequence, table, index, view, or foreign
       table in the same schema.

       After a sequence is created, you use the functions nextval, currval,
       and setval to operate on the sequence. These functions are documented
       in Section 9.15, "Sequence Manipulation Functions", in the
       documentation.

       Although you cannot update a sequence directly, you can use a query
       like:

           SELECT * FROM name;

       to examine the parameters and current state of a sequence. In
       particular, the last_value field of the sequence shows the last value
       allocated by any session. (Of course, this value might be obsolete by
       the time it's printed, if other sessions are actively doing nextval
       calls.)

PARAMETERS

       TEMPORARY or TEMP
           If specified, the sequence object is created only for this session,
           and is automatically dropped on session exit. Existing permanent
           sequences with the same name are not visible (in this session)
           while the temporary sequence exists, unless they are referenced
           with schema-qualified names.

       name
           The name (optionally schema-qualified) of the sequence to be
           created.

       increment
           The optional clause INCREMENT BY increment specifies which value is
           added to the current sequence value to create a new value. A
           positive value will make an ascending sequence, a negative one a
           descending sequence. The default value is 1.

       minvalue, NO MINVALUE
           The optional clause MINVALUE minvalue determines the minimum value
           a sequence can generate. If this clause is not supplied or NO
           MINVALUE is specified, then defaults will be used. The defaults are
           1 and -263-1 for ascending and descending sequences, respectively.

       maxvalue, NO MAXVALUE
           The optional clause MAXVALUE maxvalue determines the maximum value
           for the sequence. If this clause is not supplied or NO MAXVALUE is
           specified, then default values will be used. The defaults are 263-1
           and -1 for ascending and descending sequences, respectively.

       start
           The optional clause START WITH start allows the sequence to begin
           anywhere. The default starting value is minvalue for ascending
           sequences and maxvalue for descending ones.

       cache
           The optional clause CACHE cache specifies how many sequence numbers
           are 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), and this is also the default.

       CYCLE, NO CYCLE
           The CYCLE option allows 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.

           If NO CYCLE 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, NO CYCLE is the default.

       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. The specified table must have the same owner and be in the
           same schema as the sequence.  OWNED BY NONE, the default, specifies
           that there is no such association.

NOTES

       Use DROP SEQUENCE to remove a sequence.

       Sequences are based on bigint arithmetic, so the range cannot exceed
       the range of an eight-byte integer (-9223372036854775808 to
       9223372036854775807). On some older platforms, there might be no
       compiler support for eight-byte integers, in which case sequences use
       regular integer arithmetic (range -2147483648 to +2147483647).

       Unexpected results might be obtained if a cache setting greater than
       one is used for a sequence object that will be used concurrently by
       multiple sessions. Each session will allocate and cache successive
       sequence values during one access to the sequence object and increase
       the sequence object's last_value accordingly. Then, the next cache-1
       uses of nextval within that session simply return the preallocated
       values without touching the sequence object. So, any numbers allocated
       but not used within a session will be lost when that session ends,
       resulting in "holes" in the sequence.

       Furthermore, although multiple sessions are guaranteed to allocate
       distinct sequence values, the values might be generated out of sequence
       when all the sessions are considered. For example, with a cache setting
       of 10, session A might reserve values 1..10 and return nextval=1, then
       session B might reserve values 11..20 and return nextval=11 before
       session A has generated nextval=2. Thus, with a cache setting of one it
       is safe to assume that nextval values are generated sequentially; with
       a cache setting greater than one you should only assume that the
       nextval values are all distinct, not that they are generated purely
       sequentially. Also, last_value will reflect the latest value reserved
       by any session, whether or not it has yet been returned by nextval.

       Another consideration is that a setval executed on such a sequence will
       not be noticed by other sessions until they have used up any
       preallocated values they have cached.

EXAMPLES

       Create an ascending sequence called serial, starting at 101:

           CREATE SEQUENCE serial START 101;

       Select the next number from this sequence:

           SELECT nextval('serial');

            nextval
           ---------
                101

       Select the next number from this sequence:

           SELECT nextval('serial');

            nextval
           ---------
                102

       Use this sequence in an INSERT command:

           INSERT INTO distributors VALUES (nextval('serial'), 'nothing');

       Update the sequence value after a COPY FROM:

           BEGIN;
           COPY distributors FROM 'input_file';
           SELECT setval('serial', max(id)) FROM distributors;
           END;

COMPATIBILITY

       CREATE SEQUENCE conforms to the SQL standard, with the following
       exceptions:

       o   The standard's AS <data type> expression is not supported.

       o   Obtaining the next value is done using the nextval() function
           instead of the standard's NEXT VALUE FOR expression.

       o   The OWNED BY clause is a PostgreSQL extension.

SEE ALSO

       ALTER SEQUENCE (ALTER_SEQUENCE(7)), DROP SEQUENCE (DROP_SEQUENCE(7))