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Postgres FD Implementation
Commit 3600fd32 authored by Bruce Momjian's avatar Bruce Momjian
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Major man page update from Tom Lane. c

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src/backend/nodes/outfuncs.c
View file @ 3600fd32
......@@ -7,7 +7,7 @@
*
*
* IDENTIFICATION
* $Header: /cvsroot/pgsql/src/backend/nodes/outfuncs.c,v 1.38 1998/07/13 21:27:58 momjian Exp $
* $Header: /cvsroot/pgsql/src/backend/nodes/outfuncs.c,v 1.39 1998/07/14 01:45:24 momjian Exp $
*
* NOTES
* Every (plan) node in POSTGRES has an associated "out" routine which
......@@ -660,10 +660,7 @@ _outResdom(StringInfo str, Resdom *node)
sprintf(buf, " :restypmod %d ", node->restypmod);
appendStringInfo(str, buf);
appendStringInfo(str, " :resname ");
if (*node->resname)
sprintf(buf,"\"%s\"", node->resname); /* fix for SELECT col AS "my name" */
else
buf[0] = '\0';
sprintf(buf,"\"%s\"", node->resname); /* fix for SELECT col AS "my name" */
appendStringInfo(str, buf);
sprintf(buf, " :reskey %d ", node->reskey);
appendStringInfo(str, buf);
......@@ -1506,7 +1503,6 @@ _outDatum(StringInfo str, Datum value, Oid type)
appendStringInfo(str, buf);
}
}
}
static void
......
src/backend/nodes/readfuncs.c
View file @ 3600fd32
......@@ -7,7 +7,7 @@
*
*
* IDENTIFICATION
* $Header: /cvsroot/pgsql/src/backend/nodes/readfuncs.c,v 1.30 1998/06/15 19:28:33 momjian Exp $
* $Header: /cvsroot/pgsql/src/backend/nodes/readfuncs.c,v 1.31 1998/07/14 01:45:24 momjian Exp $
*
* NOTES
* Most of the read functions for plan nodes are tested. (In fact, they
......@@ -716,7 +716,7 @@ _readResdom()
else
{
local_node->resname = (char *) palloc(length + 1);
StrNCpy(local_node->resname, token, length + 1);
StrNCpy(local_node->resname, token+1, length + 1 - 2);/* strip quotes */
}
token = lsptok(NULL, &length); /* eat :reskey */
......
src/man/create_sequence.l
View file @ 3600fd32
.\" This is -*-nroff-*-
.\" XXX standard disclaimer belongs here....
.\" $Header: /cvsroot/pgsql/src/man/Attic/create_sequence.l,v 1.4 1998/06/23 17:52:32 momjian Exp $
.TH "CREATE SEQUENCE" SQL 04/01/97 PostgreSQL PostgreSQL
.\" $Header: /cvsroot/pgsql/src/man/Attic/create_sequence.l,v 1.5 1998/07/14 01:45:25 momjian Exp $
.TH "CREATE SEQUENCE" SQL 07/13/98 PostgreSQL PostgreSQL
.SH NAME
create sequence - create a new sequence number generator
.SH SYNOPSIS
......@@ -17,7 +17,7 @@ create sequence - create a new sequence number generator
.SH DESCRIPTION
.BR "Create sequence"
will enter a new sequence number generator into the current data base.
Actually, new single block
Actually, a new single-record
.BR table
with name
.IR seqname
......@@ -26,23 +26,23 @@ 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,
.BR increment
clause is optional. A positive value will make an ascending sequence,
negative - descending. Default value is 1.
.PP
The optional integer
.BR minvalue
determines the minimum value a sequence can be. Defaults are
determines the minimum value the sequence can generate. Defaults are
1/-2147483647 for ascending/descending sequences.
.PP
Use optional integer
The optional integer
.BR maxvalue
to determine the maximum value for sequence. Defaults are
determines the maximum value the sequence can generate. Defaults are
2147483647/-1 for ascending/descending sequences.
.PP
The optinal
.BR "start"
value enables sequence to begin anywhere. Default is
The optional
.BR start
value sets the first value to be generated. Default is
.BR minvalue
for ascending sequences and
.BR maxvalue
......@@ -52,14 +52,12 @@ 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.
(one value will be allocated at a time, i.e., no cache)
and that is the default. See below for details.
.PP
The optional
.BR cycle
keyword may be used to enable sequence to continue when the
keyword may be used to enable the sequence to continue after the
.BR maxvalue/minvalue
has been reached by ascending/descending sequence.
If the limit is reached, the next number generated will be
......@@ -67,27 +65,56 @@ whatever the
.BR minvalue/maxvalue
is.
.PP
After sequence created, You may use function
After a sequence object has been created, you may use the function
.BR nextval
with sequence name as argument to get new number from sequence
specified.
Function
with the sequence name as argument to generate a new number from the
specified sequence.
.PP
The function
.BR currval
('sequence_name')
may be used to determine number returned by last call to
may be used to re-fetch the number returned by the last call to
.BR nextval
for specified sequence in current session.
for the specified sequence in the current session.
.BR NOTE:
currval will return an error if nextval has never been called for the
given sequence in the current backend session. Also beware that it
does not give the last number ever allocated, only the last one allocated
by this backend.
.PP
Use a query like
.nf
Use query like
select * from <sequence_name>;
to get parameters of a sequence.
SELECT * FROM <sequence_name>;
.fi
to get the parameters of a sequence. Aside from fetching the original
parameters, you can use
.nf
SELECT last_value FROM <sequence_name>;
.fi
to obtain the last value allocated by any backend.
.PP
Low-level locking is used to enable multiple simultaneous calls
to a generator.
Low-level locking is used to ensure that multiple backends can safely use
a sequence object concurrently.
.PP
.BR NOTE:
Unexpected results may be obtained if a cache setting greater than one
is used for a sequence object that will be used concurrently by multiple
backends. Each backend will allocate "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 backend simply return the preallocated values without touching
the shared object. So, numbers allocated but not used in the current session
will be lost. Furthermore, although multiple backends are guaranteed to
allocate distinct sequence values, the values may be generated out of
sequence when all the backends are considered. (For example, with a cache
setting of 10, backend A might reserve values 1..10 and return nextval=1, then
backend B might reserve values 11..20 and return nextval=11 before backend
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 backend,
whether or not it has yet been returned by nextval.
.PP
.SH EXAMPLES
.nf
......
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