CREATE 
SEQUENCE(7)					  PostgreSQL 9.2.7 Documentation					CREATE SEQUENCE(7)

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_name.column_name | 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 9.16, "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_name.column_name, 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))

PostgreSQL 9.2.7						    2014-02-17							CREATE SEQUENCE(7)