Major man page update from Tom Lane. c
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Bruce Momjian
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f99dcd6d15
commit
3600fd320f
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@ -7,7 +7,7 @@
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*
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*
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* IDENTIFICATION
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* $Header: /cvsroot/pgsql/src/backend/nodes/outfuncs.c,v 1.38 1998/07/13 21:27:58 momjian Exp $
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* $Header: /cvsroot/pgsql/src/backend/nodes/outfuncs.c,v 1.39 1998/07/14 01:45:24 momjian Exp $
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*
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* NOTES
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* Every (plan) node in POSTGRES has an associated "out" routine which
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@ -660,10 +660,7 @@ _outResdom(StringInfo str, Resdom *node)
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sprintf(buf, " :restypmod %d ", node->restypmod);
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appendStringInfo(str, buf);
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appendStringInfo(str, " :resname ");
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if (*node->resname)
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sprintf(buf,"\"%s\"", node->resname); /* fix for SELECT col AS "my name" */
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else
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buf[0] = '\0';
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sprintf(buf,"\"%s\"", node->resname); /* fix for SELECT col AS "my name" */
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appendStringInfo(str, buf);
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sprintf(buf, " :reskey %d ", node->reskey);
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appendStringInfo(str, buf);
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@ -1506,7 +1503,6 @@ _outDatum(StringInfo str, Datum value, Oid type)
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appendStringInfo(str, buf);
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}
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}
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}
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static void
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@ -7,7 +7,7 @@
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*
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*
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* IDENTIFICATION
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* $Header: /cvsroot/pgsql/src/backend/nodes/readfuncs.c,v 1.30 1998/06/15 19:28:33 momjian Exp $
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* $Header: /cvsroot/pgsql/src/backend/nodes/readfuncs.c,v 1.31 1998/07/14 01:45:24 momjian Exp $
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*
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* NOTES
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* Most of the read functions for plan nodes are tested. (In fact, they
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@ -716,7 +716,7 @@ _readResdom()
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else
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{
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local_node->resname = (char *) palloc(length + 1);
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StrNCpy(local_node->resname, token, length + 1);
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StrNCpy(local_node->resname, token+1, length + 1 - 2);/* strip quotes */
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}
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token = lsptok(NULL, &length); /* eat :reskey */
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@ -1,7 +1,7 @@
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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 1.4 1998/06/23 17:52:32 momjian Exp $
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.TH "CREATE SEQUENCE" SQL 04/01/97 PostgreSQL PostgreSQL
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.\" $Header: /cvsroot/pgsql/src/man/Attic/create_sequence.l,v 1.5 1998/07/14 01:45:25 momjian Exp $
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.TH "CREATE SEQUENCE" SQL 07/13/98 PostgreSQL PostgreSQL
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.SH NAME
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create sequence - create a new sequence number generator
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.SH SYNOPSIS
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@ -17,7 +17,7 @@ create sequence - create a new sequence number generator
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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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Actually, a new single-record
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.BR table
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with name
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.IR seqname
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@ -26,23 +26,23 @@ 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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.BR increment
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clause is optional. A positive value will make an 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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determines the minimum value the sequence can generate. 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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The 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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determines the maximum value the sequence can generate. 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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The optional
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.BR start
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value sets the first value to be generated. 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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@ -52,14 +52,12 @@ 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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(one value will be allocated at a time, i.e., no cache)
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and that is the default. See below for details.
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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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keyword may be used to enable the sequence to continue after 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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@ -67,27 +65,56 @@ 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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After a sequence object has been created, you may use the 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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Function
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with the sequence name as argument to generate a new number from the
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specified sequence.
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.PP
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The function
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.BR currval
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('sequence_name')
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may be used to determine number returned by last call to
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may be used to re-fetch the number returned by the last call to
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.BR nextval
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for specified sequence in current session.
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for the specified sequence in the current session.
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.BR NOTE:
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currval will return an error if nextval has never been called for the
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given sequence in the current backend session. Also beware that it
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does not give the last number ever allocated, only the last one allocated
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by this backend.
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.PP
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Use a query like
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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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SELECT * FROM <sequence_name>;
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.fi
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to get the parameters of a sequence. Aside from fetching the original
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parameters, you can use
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.nf
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SELECT last_value FROM <sequence_name>;
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.fi
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to obtain the last value allocated by any backend.
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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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Low-level locking is used to ensure that multiple backends can safely use
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a sequence object concurrently.
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.PP
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.BR NOTE:
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Unexpected results may be obtained if a cache setting greater than one
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is used for a sequence object that will be used concurrently by multiple
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backends. Each backend will allocate "cache" successive sequence values
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during one access to the sequence object and increase the sequence
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object's last_value accordingly. Then, the next cache-1 uses of nextval
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within that backend simply return the preallocated values without touching
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the shared object. So, numbers allocated but not used in the current session
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will be lost. Furthermore, although multiple backends are guaranteed to
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allocate distinct sequence values, the values may be generated out of
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sequence when all the backends are considered. (For example, with a cache
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setting of 10, backend A might reserve values 1..10 and return nextval=1, then
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backend B might reserve values 11..20 and return nextval=11 before backend
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A has generated nextval=2.) Thus, with a cache setting of one it is safe
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to assume that nextval values are generated sequentially; with a cache
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setting greater than one you should only assume that the nextval values
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are all distinct, not that they are generated purely sequentially.
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Also, last_value will reflect the latest value reserved by any backend,
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whether or not it has yet been returned by nextval.
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.PP
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.SH EXAMPLES
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.nf
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