Manuals for SEQUENCEs.
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.\" This is -*-nroff-*-
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.\" XXX standard disclaimer belongs here....
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.\" $Header: /cvsroot/pgsql/src/man/Attic/create_sequence.l,v 1.1 1997/04/02 04:19:58 vadim Exp $
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.TH "CREATE SEQUENCE" SQL 04/01/97 PostgreSQL PostgreSQL
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.SH NAME
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create sequence \(em create a new sequence number generator
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.SH SYNOPSIS
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.nf
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\fBcreate sequence\fR seqname
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[\fBincrement\fP incby_value]
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[\fBminvalue\fP min_value]
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[\fBmaxvalue\fP max_value]
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[\fBstart\fP start_value]
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[\fBcache\fP cache_value]
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[\fBcycle\fP]
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.fi
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.SH DESCRIPTION
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.BR "Create sequence"
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will enter a new sequence number generator into the current data base.
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Actually, new single block
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.BR table
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with name
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.IR seqname
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will be created and initialized.
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The generator will be
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\*(lqowned\*(rq by the user issuing the command.
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.PP
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The
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.BR "increment"
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is optional clause. Positive value will make ascending sequence,
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negative - descending. Default value is 1.
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.PP
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The optional integer
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.BR minvalue
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determines the minimum value a sequence can be. Defaults are
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1/-2147483647 for ascending/descending sequences.
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.PP
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Use optional integer
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.BR maxvalue
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to determine the maximum value for sequence. Defaults are
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2147483647/-1 for ascending/descending sequences.
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.PP
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The optinal
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.BR "start"
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value enables sequence to begin anywhere. Default is
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.BR minvalue
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for ascending sequences and
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.BR maxvalue
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for descending ones.
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.PP
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The
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.BR cache
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option enables sequence numbers to be preallocated and
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stored in memory for faster access. The minimum value is 1
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(i.e. - no cache) and it is default.
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.BR NOTE:
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each backend uses own cache to store allocated numbers.
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Cached but not used in current session numbers will be lost.
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.PP
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The optional
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.BR cycle
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keyword may be used to enable sequence to continue when the
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.BR maxvalue/minvalue
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has been reached by ascending/descending sequence.
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If the limit is reached, the next number generated will be
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whatever the
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.BR minvalue/maxvalue
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is.
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.PP
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After sequence created, You may use function
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.BR nextval
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with sequence name as argument to get new number from sequence
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specified.
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To determine the current sequence number use function
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.BR currval
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('sequence_name').
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.BR NOTE:
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after sequence creation You are to call
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.BR nextval
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before first call to
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.BR currval.
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.PP
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.nf
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Use query like
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select * from <sequence_name>;
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to get parameters of a sequence.
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.fi
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.PP
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Low-level locking is used to enable multiple simultaneous calls
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to a generator.
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.PP
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.SH EXAMPLES
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.nf
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--
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-- Create sequence seq caching 2 numbers, starting with 10
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--
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create sequence seq cache 2 start 10;
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.fi
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.nf
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--
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-- Select next number from sequence
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--
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select nextval ('seq');
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.fi
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.nf
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--
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-- Use sequence in insert
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--
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insert into table _table_ values (nextval ('seq'),...);
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.fi
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.SH "SEE ALSO"
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drop sequence(l).
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.\" This is -*-nroff-*-
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.\" XXX standard disclaimer belongs here....
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.\" $Header: /cvsroot/pgsql/src/man/Attic/drop_sequence.l,v 1.1 1997/04/02 04:20:00 vadim Exp $
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.TH "DROP TABLE" SQL 04/01/97 PostgreSQL PostgreSQL
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.SH NAME
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drop sequence \(em destroy existing sequence
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.SH SYNOPSIS
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.nf
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\fBdrop sequence\fR sequence_name_1 { \fB,\fR sequence_name_N }
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.fi
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.SH DESCRIPTION
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.BR "Drop Sequence"
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removes sequence number generators from the data base.
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With current implementation of sequences as special tables it
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works just like \fBdrop table\fR(l).
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