Manuals for SEQUENCEs.

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

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.\" This is -*-nroff-*-
.\" XXX standard disclaimer belongs here....
.\" $Header: /cvsroot/pgsql/src/man/Attic/drop_sequence.l,v 1.1 1997/04/02 04:20:00 vadim Exp $
.TH "DROP TABLE" SQL 04/01/97 PostgreSQL PostgreSQL
.SH NAME
drop sequence \(em destroy existing sequence
.SH SYNOPSIS
.nf
\fBdrop sequence\fR sequence_name_1 { \fB,\fR sequence_name_N }
.fi
.SH DESCRIPTION
.BR "Drop Sequence"
removes sequence number generators from the data base.
With current implementation of sequences as special tables it
works just like \fBdrop table\fR(l).