Re: Implementing SELECT FOR UPDATE [NOWAIT]

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Karel Zak
Тема
Re: Implementing SELECT FOR UPDATE [NOWAIT]
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Msg-id
1119880134.3806.72.camel@petra
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Implementing SELECT FOR UPDATE [NOWAIT] Hans-Juergen Schoenig <hs@cybertec.at>
Re: Implementing SELECT FOR UPDATE [NOWAIT] Bruce Momjian <pgman@candle.pha.pa.us>
Re: Implementing SELECT FOR UPDATE [NOWAIT] Bruce Momjian <pgman@candle.pha.pa.us>
Re: Implementing SELECT FOR UPDATE [NOWAIT] Bruce Momjian <pgman@candle.pha.pa.us>
Re: Implementing SELECT FOR UPDATE [NOWAIT] Karel Zak <zakkr@zf.jcu.cz>
Re: Implementing SELECT FOR UPDATE [NOWAIT] Hans-Juergen Schoenig <hs@cybertec.at>
Re: Implementing SELECT FOR UPDATE [NOWAIT] Karel Zak <zakkr@zf.jcu.cz>
Re: Implementing SELECT FOR UPDATE [NOWAIT] Tom Lane <tgl@sss.pgh.pa.us>
Re: Implementing SELECT FOR UPDATE [NOWAIT] Bruce Momjian <pgman@candle.pha.pa.us>
Re: Implementing SELECT FOR UPDATE [NOWAIT] Bruce Momjian <pgman@candle.pha.pa.us>
On Fri, 2005-06-24 at 22:32 -0400, Bruce Momjian wrote:
> Are you working on a updated version of this?

I will work on new version during this week.

	Karel


> ---------------------------------------------------------------------------
> 
> Bruce Momjian wrote:
> > 
> > Uh, seems the code has drifted too much and now I can't apply this. 
> > Would you redo this against current CVS?  Thanks.
> > 
> > ---------------------------------------------------------------------------
> > 
> > Hans-Juergen Schoenig wrote:
> > > Folks,
> > > 
> > > We have implemented SELECT FOR UPDATE NOWAIT for PostgreSQL.
> > > The patch attached to this email contains all the required code 
> > > including ECPG updates and some documentation.
> > > It would be nice if this patch would be included in PostgreSQL 8.1
> > > 
> > > 	Best regards,
> > > 
> > > 		Ewald Geschwinde & Hans-Juergen Schoenig
> > > 
> > > --
> > > Cybertec Geschwinde u Schoenig GmbH.
> > > Schoengrabern 134, A-2020 Hollabrunn, Austria
> > > Tel: +43/660/816 40 77
> > > www.cybertec.at, www.postgresql.at
> > 
> > [ text/x-patch is unsupported, treating like TEXT/PLAIN ]
> > 
> > > diff -r -c postgresql-8.0.0rc2.orig/doc/src/sgml/ref/select.sgml postgresql-8.0.0rc2/doc/src/sgml/ref/select.sgml
> > > *** postgresql-8.0.0rc2.orig/doc/src/sgml/ref/select.sgml	Sat Nov 27 22:27:07 2004
> > > --- postgresql-8.0.0rc2/doc/src/sgml/ref/select.sgml	Mon Dec 27 10:57:05 2004
> > > ***************
> > > *** 30,36 ****
> > >       [ ORDER BY expression [ ASC | DESC | USING operator ] [, ...] ]
> > >       [ LIMIT { count | ALL } ]
> > >       [ OFFSET start ]
> > > !     [ FOR UPDATE [ OF table_name [, ...] ] ]
> > >   
> > >   where from_item can be one of:
> > >   
> > > --- 30,36 ----
> > >       [ ORDER BY expression [ ASC | DESC | USING operator ] [, ...] ]
> > >       [ LIMIT { count | ALL } ]
> > >       [ OFFSET start ]
> > > !     [ FOR UPDATE [ OF table_name [, ...] ] [NOWAIT] ]
> > >   
> > >   where from_item can be one of:
> > >   
> > > ***************
> > > *** 772,778 ****
> > >      
> > >       The FOR UPDATE clause has this form:
> > >   
> > > ! FOR UPDATE [ OF table_name [, ...] ]
> > >   
> > >      
> > >   
> > > --- 772,778 ----
> > >      
> > >       The FOR UPDATE clause has this form:
> > >   
> > > ! FOR UPDATE [ OF table_name [, ...] ] [NOWAIT]
> > >   
> > >      
> > >   
> > > ***************
> > > *** 789,796 ****
> > >       has already locked a selected row or rows, SELECT FOR
> > >       UPDATE will wait for the other transaction to complete,
> > >       and will then lock and return the updated row (or no row, if the
> > > !     row was deleted).  For further discussion see  > > !     linkend="mvcc">.
> > >      
> > >   
> > >      
> > > --- 789,802 ----
> > >       has already locked a selected row or rows, SELECT FOR
> > >       UPDATE will wait for the other transaction to complete,
> > >       and will then lock and return the updated row (or no row, if the
> > > !     row was deleted).  If the current transaction is not supposed to
> > > !     wait on other transactions to commit the NOWAIT option can be
> > > !     used.  If SELECT FOR UPDATE NOWAIT finds out
> > > !     that somebody else is holding a lock an error will be thrown.
> > > !     This will only happen in case of row level locks - if somebody
> > > !     holds a table lock SELECT FOR UPDATE NOWAIT
> > > !     will still wait for concurrent transactions.  For further 
> > > !     discussion see .
> > >      
> > >   
> > >      
> > > diff -r -c postgresql-8.0.0rc2.orig/doc/src/sgml/sql.sgml postgresql-8.0.0rc2/doc/src/sgml/sql.sgml
> > > *** postgresql-8.0.0rc2.orig/doc/src/sgml/sql.sgml	Mon Nov 15 07:32:14 2004
> > > --- postgresql-8.0.0rc2/doc/src/sgml/sql.sgml	Mon Dec 27 10:57:05 2004
> > > ***************
> > > *** 866,872 ****
> > >       [ ORDER BY expression [ ASC | DESC | USING operator ] [, ...] ]
> > >       [ LIMIT { count | ALL } ]
> > >       [ OFFSET start ]
> > > !     [ FOR UPDATE [ OF class_name [, ...] ] ]
> > >        
> > >       
> > >   
> > > --- 866,872 ----
> > >       [ ORDER BY expression [ ASC | DESC | USING operator ] [, ...] ]
> > >       [ LIMIT { count | ALL } ]
> > >       [ OFFSET start ]
> > > !     [ FOR UPDATE [ OF class_name [, ...] ] [NOWAIT] ]
> > >        
> > >       
> > >   
> > > diff -r -c postgresql-8.0.0rc2.orig/src/backend/access/heap/heapam.c postgresql-8.0.0rc2/src/backend/access/heap/heapam.c
> > > *** postgresql-8.0.0rc2.orig/src/backend/access/heap/heapam.c	Sun Nov 14 03:04:12 2004
> > > --- postgresql-8.0.0rc2/src/backend/access/heap/heapam.c	Mon Dec 27 10:56:52 2004
> > > ***************
> > > *** 16,21 ****
> > > --- 16,22 ----
> > >    *		relation_openrv - open any relation specified by a RangeVar
> > >    *		relation_openr	- open a system relation by name
> > >    *		relation_close	- close any relation
> > > +  *		conditional_relation_open - open with option not to wait
> > >    *		heap_open		- open a heap relation by relation OID
> > >    *		heap_openrv		- open a heap relation specified by a RangeVar
> > >    *		heap_openr		- open a system heap relation by name
> > > ***************
> > > *** 1828,1834 ****
> > >    */
> > >   int
> > >   heap_mark4update(Relation relation, HeapTuple tuple, Buffer *buffer,
> > > ! 				 CommandId cid)
> > >   {
> > >   	TransactionId xid = GetCurrentTransactionId();
> > >   	ItemPointer tid = &(tuple->t_self);
> > > --- 1829,1835 ----
> > >    */
> > >   int
> > >   heap_mark4update(Relation relation, HeapTuple tuple, Buffer *buffer,
> > > ! 				 CommandId cid, bool nowait)
> > >   {
> > >   	TransactionId xid = GetCurrentTransactionId();
> > >   	ItemPointer tid = &(tuple->t_self);
> > > ***************
> > > *** 1858,1866 ****
> > >   	{
> > >   		TransactionId xwait = HeapTupleHeaderGetXmax(tuple->t_data);
> > >   
> > > - 		/* sleep until concurrent transaction ends */
> > >   		LockBuffer(*buffer, BUFFER_LOCK_UNLOCK);
> > > ! 		XactLockTableWait(xwait);
> > >   
> > >   		LockBuffer(*buffer, BUFFER_LOCK_EXCLUSIVE);
> > >   		if (!TransactionIdDidCommit(xwait))
> > > --- 1859,1881 ----
> > >   	{
> > >   		TransactionId xwait = HeapTupleHeaderGetXmax(tuple->t_data);
> > >   
> > >   		LockBuffer(*buffer, BUFFER_LOCK_UNLOCK);
> > > ! 
> > > ! 		if (nowait)
> > > ! 		{
> > > ! 			/* rather error than sleep until concurrent transaction ends */ 
> > > ! 			if (!ConditionalXactLockTableWait(xwait))
> > > ! 			{
> > > ! 				ReleaseBuffer(*buffer);
> > > ! 				ereport(ERROR,
> > > ! 					(errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
> > > ! 					 errmsg("data in table \"%s\" was modify by concurrent trasaction.", 
> > > ! 						 RelationGetRelationName(relation))));
> > > ! 			}
> > > ! 		}
> > > ! 		else
> > > ! 			/* sleep until concurrent transaction ends */
> > > ! 			XactLockTableWait(xwait);
> > >   
> > >   		LockBuffer(*buffer, BUFFER_LOCK_EXCLUSIVE);
> > >   		if (!TransactionIdDidCommit(xwait))
> > > diff -r -c postgresql-8.0.0rc2.orig/src/backend/commands/trigger.c postgresql-8.0.0rc2/src/backend/commands/trigger.c
> > > *** postgresql-8.0.0rc2.orig/src/backend/commands/trigger.c	Tue Dec  7 00:57:17 2004
> > > --- postgresql-8.0.0rc2/src/backend/commands/trigger.c	Mon Dec 27 10:56:52 2004
> > > ***************
> > > *** 1574,1580 ****
> > >   		*newSlot = NULL;
> > >   		tuple.t_self = *tid;
> > >   ltrmark:;
> > > ! 		test = heap_mark4update(relation, &tuple, &buffer, cid);
> > >   		switch (test)
> > >   		{
> > >   			case HeapTupleSelfUpdated:
> > > --- 1574,1580 ----
> > >   		*newSlot = NULL;
> > >   		tuple.t_self = *tid;
> > >   ltrmark:;
> > > ! 		test = heap_mark4update(relation, &tuple, &buffer, cid, estate->es_nowait);
> > >   		switch (test)
> > >   		{
> > >   			case HeapTupleSelfUpdated:
> > > diff -r -c postgresql-8.0.0rc2.orig/src/backend/executor/execMain.c postgresql-8.0.0rc2/src/backend/executor/execMain.c
> > > *** postgresql-8.0.0rc2.orig/src/backend/executor/execMain.c	Thu Oct  7 20:38:49 2004
> > > --- postgresql-8.0.0rc2/src/backend/executor/execMain.c	Mon Dec 27 10:56:52 2004
> > > ***************
> > > *** 558,563 ****
> > > --- 558,564 ----
> > >   	/*
> > >   	 * Have to lock relations selected for update
> > >   	 */
> > > + 	estate->es_nowait = parseTree->nowait;
> > >   	estate->es_rowMark = NIL;
> > >   	if (parseTree->rowMarks != NIL)
> > >   	{
> > > ***************
> > > *** 1133,1139 ****
> > >   
> > >   					tuple.t_self = *((ItemPointer) DatumGetPointer(datum));
> > >   					test = heap_mark4update(erm->relation, &tuple, &buffer,
> > > ! 											estate->es_snapshot->curcid);
> > >   					ReleaseBuffer(buffer);
> > >   					switch (test)
> > >   					{
> > > --- 1134,1140 ----
> > >   
> > >   					tuple.t_self = *((ItemPointer) DatumGetPointer(datum));
> > >   					test = heap_mark4update(erm->relation, &tuple, &buffer,
> > > ! 							estate->es_snapshot->curcid, estate->es_nowait);
> > >   					ReleaseBuffer(buffer);
> > >   					switch (test)
> > >   					{
> > > ***************
> > > *** 2082,2087 ****
> > > --- 2083,2089 ----
> > >   	epqstate->es_instrument = estate->es_instrument;
> > >   	epqstate->es_select_into = estate->es_select_into;
> > >   	epqstate->es_into_oids = estate->es_into_oids;
> > > + 	epqstate->es_nowait = estate->es_nowait;
> > >   	epqstate->es_topPlan = estate->es_topPlan;
> > >   
> > >   	/*
> > > diff -r -c postgresql-8.0.0rc2.orig/src/backend/executor/execUtils.c postgresql-8.0.0rc2/src/backend/executor/execUtils.c
> > > *** postgresql-8.0.0rc2.orig/src/backend/executor/execUtils.c	Fri Oct  1 01:21:23 2004
> > > --- postgresql-8.0.0rc2/src/backend/executor/execUtils.c	Mon Dec 27 10:56:52 2004
> > > ***************
> > > *** 203,209 ****
> > >   	estate->es_instrument = false;
> > >   	estate->es_select_into = false;
> > >   	estate->es_into_oids = false;
> > > ! 
> > >   	estate->es_exprcontexts = NIL;
> > >   
> > >   	estate->es_per_tuple_exprcontext = NULL;
> > > --- 203,210 ----
> > >   	estate->es_instrument = false;
> > >   	estate->es_select_into = false;
> > >   	estate->es_into_oids = false;
> > > ! 	estate->es_nowait = false;
> > > ! 	
> > >   	estate->es_exprcontexts = NIL;
> > >   
> > >   	estate->es_per_tuple_exprcontext = NULL;
> > > diff -r -c postgresql-8.0.0rc2.orig/src/backend/nodes/copyfuncs.c postgresql-8.0.0rc2/src/backend/nodes/copyfuncs.c
> > > *** postgresql-8.0.0rc2.orig/src/backend/nodes/copyfuncs.c	Sun Dec 12 00:26:33 2004
> > > --- postgresql-8.0.0rc2/src/backend/nodes/copyfuncs.c	Mon Dec 27 10:56:52 2004
> > > ***************
> > > *** 1426,1431 ****
> > > --- 1426,1442 ----
> > >   	return newnode;
> > >   }
> > >   
> > > + static ForUpdate *
> > > + _copyForUpdate(ForUpdate *from)
> > > + {
> > > + 	ForUpdate *newnode = makeNode(ForUpdate);
> > > + 
> > > + 	COPY_NODE_FIELD(update_list);
> > > + 	COPY_SCALAR_FIELD(nowait);
> > > + 
> > > + 	return newnode;
> > > + }
> > > + 
> > >   static RangeSubselect *
> > >   _copyRangeSubselect(RangeSubselect *from)
> > >   {
> > > ***************
> > > *** 1537,1542 ****
> > > --- 1548,1554 ----
> > >   	COPY_NODE_FIELD(groupClause);
> > >   	COPY_NODE_FIELD(havingQual);
> > >   	COPY_NODE_FIELD(distinctClause);
> > > + 	COPY_SCALAR_FIELD(nowait);
> > >   	COPY_NODE_FIELD(sortClause);
> > >   	COPY_NODE_FIELD(limitOffset);
> > >   	COPY_NODE_FIELD(limitCount);
> > > ***************
> > > *** 1611,1617 ****
> > >   	COPY_NODE_FIELD(sortClause);
> > >   	COPY_NODE_FIELD(limitOffset);
> > >   	COPY_NODE_FIELD(limitCount);
> > > ! 	COPY_NODE_FIELD(forUpdate);
> > >   	COPY_SCALAR_FIELD(op);
> > >   	COPY_SCALAR_FIELD(all);
> > >   	COPY_NODE_FIELD(larg);
> > > --- 1623,1629 ----
> > >   	COPY_NODE_FIELD(sortClause);
> > >   	COPY_NODE_FIELD(limitOffset);
> > >   	COPY_NODE_FIELD(limitCount);
> > > ! 	COPY_NODE_FIELD(forupdateClause);
> > >   	COPY_SCALAR_FIELD(op);
> > >   	COPY_SCALAR_FIELD(all);
> > >   	COPY_NODE_FIELD(larg);
> > > ***************
> > > *** 3065,3070 ****
> > > --- 3077,3085 ----
> > >   		case T_SortBy:
> > >   			retval = _copySortBy(from);
> > >   			break;
> > > + 		case T_ForUpdate:
> > > + 			retval = _copyForUpdate(from);
> > > + 			break;
> > >   		case T_RangeSubselect:
> > >   			retval = _copyRangeSubselect(from);
> > >   			break;
> > > diff -r -c postgresql-8.0.0rc2.orig/src/backend/nodes/equalfuncs.c postgresql-8.0.0rc2/src/backend/nodes/equalfuncs.c
> > > *** postgresql-8.0.0rc2.orig/src/backend/nodes/equalfuncs.c	Sun Dec 12 00:26:33 2004
> > > --- postgresql-8.0.0rc2/src/backend/nodes/equalfuncs.c	Mon Dec 27 10:56:52 2004
> > > ***************
> > > *** 656,661 ****
> > > --- 656,662 ----
> > >   	COMPARE_NODE_FIELD(groupClause);
> > >   	COMPARE_NODE_FIELD(havingQual);
> > >   	COMPARE_NODE_FIELD(distinctClause);
> > > + 	COMPARE_SCALAR_FIELD(nowait);
> > >   	COMPARE_NODE_FIELD(sortClause);
> > >   	COMPARE_NODE_FIELD(limitOffset);
> > >   	COMPARE_NODE_FIELD(limitCount);
> > > ***************
> > > *** 719,725 ****
> > >   	COMPARE_NODE_FIELD(sortClause);
> > >   	COMPARE_NODE_FIELD(limitOffset);
> > >   	COMPARE_NODE_FIELD(limitCount);
> > > ! 	COMPARE_NODE_FIELD(forUpdate);
> > >   	COMPARE_SCALAR_FIELD(op);
> > >   	COMPARE_SCALAR_FIELD(all);
> > >   	COMPARE_NODE_FIELD(larg);
> > > --- 720,726 ----
> > >   	COMPARE_NODE_FIELD(sortClause);
> > >   	COMPARE_NODE_FIELD(limitOffset);
> > >   	COMPARE_NODE_FIELD(limitCount);
> > > ! 	COMPARE_NODE_FIELD(forupdateClause);
> > >   	COMPARE_SCALAR_FIELD(op);
> > >   	COMPARE_SCALAR_FIELD(all);
> > >   	COMPARE_NODE_FIELD(larg);
> > > ***************
> > > *** 1577,1582 ****
> > > --- 1578,1592 ----
> > >   }
> > >   
> > >   static bool
> > > + _equalForUpdate(ForUpdate *a, ForUpdate *b)
> > > + {
> > > + 	COMPARE_SCALAR_FIELD(nowait);
> > > + 	COMPARE_NODE_FIELD(update_list);
> > > + 
> > > + 	return true;
> > > + }
> > > + 
> > > + static bool
> > >   _equalRangeSubselect(RangeSubselect *a, RangeSubselect *b)
> > >   {
> > >   	COMPARE_NODE_FIELD(subquery);
> > > ***************
> > > *** 2202,2207 ****
> > > --- 2212,2220 ----
> > >   		case T_SortBy:
> > >   			retval = _equalSortBy(a, b);
> > >   			break;
> > > + 		case T_ForUpdate:
> > > + 			retval = _equalForUpdate(a, b);
> > > + 			break;
> > >   		case T_RangeSubselect:
> > >   			retval = _equalRangeSubselect(a, b);
> > >   			break;
> > > diff -r -c postgresql-8.0.0rc2.orig/src/backend/nodes/outfuncs.c postgresql-8.0.0rc2/src/backend/nodes/outfuncs.c
> > > *** postgresql-8.0.0rc2.orig/src/backend/nodes/outfuncs.c	Sun Dec 12 00:26:33 2004
> > > --- postgresql-8.0.0rc2/src/backend/nodes/outfuncs.c	Mon Dec 27 10:56:52 2004
> > > ***************
> > > *** 1202,1208 ****
> > >   	WRITE_NODE_FIELD(sortClause);
> > >   	WRITE_NODE_FIELD(limitOffset);
> > >   	WRITE_NODE_FIELD(limitCount);
> > > ! 	WRITE_NODE_FIELD(forUpdate);
> > >   	WRITE_ENUM_FIELD(op, SetOperation);
> > >   	WRITE_BOOL_FIELD(all);
> > >   	WRITE_NODE_FIELD(larg);
> > > --- 1202,1208 ----
> > >   	WRITE_NODE_FIELD(sortClause);
> > >   	WRITE_NODE_FIELD(limitOffset);
> > >   	WRITE_NODE_FIELD(limitCount);
> > > ! 	WRITE_NODE_FIELD(forupdateClause);
> > >   	WRITE_ENUM_FIELD(op, SetOperation);
> > >   	WRITE_BOOL_FIELD(all);
> > >   	WRITE_NODE_FIELD(larg);
> > > ***************
> > > *** 1323,1328 ****
> > > --- 1323,1329 ----
> > >   	WRITE_NODE_FIELD(groupClause);
> > >   	WRITE_NODE_FIELD(havingQual);
> > >   	WRITE_NODE_FIELD(distinctClause);
> > > + 	WRITE_BOOL_FIELD(nowait);
> > >   	WRITE_NODE_FIELD(sortClause);
> > >   	WRITE_NODE_FIELD(limitOffset);
> > >   	WRITE_NODE_FIELD(limitCount);
> > > diff -r -c postgresql-8.0.0rc2.orig/src/backend/nodes/readfuncs.c postgresql-8.0.0rc2/src/backend/nodes/readfuncs.c
> > > *** postgresql-8.0.0rc2.orig/src/backend/nodes/readfuncs.c	Sun Dec 12 00:26:34 2004
> > > --- postgresql-8.0.0rc2/src/backend/nodes/readfuncs.c	Mon Dec 27 10:56:52 2004
> > > ***************
> > > *** 149,154 ****
> > > --- 149,155 ----
> > >   	READ_NODE_FIELD(groupClause);
> > >   	READ_NODE_FIELD(havingQual);
> > >   	READ_NODE_FIELD(distinctClause);
> > > + 	READ_BOOL_FIELD(nowait);
> > >   	READ_NODE_FIELD(sortClause);
> > >   	READ_NODE_FIELD(limitOffset);
> > >   	READ_NODE_FIELD(limitCount);
> > > diff -r -c postgresql-8.0.0rc2.orig/src/backend/parser/analyze.c postgresql-8.0.0rc2/src/backend/parser/analyze.c
> > > *** postgresql-8.0.0rc2.orig/src/backend/parser/analyze.c	Wed Nov 17 00:34:26 2004
> > > --- postgresql-8.0.0rc2/src/backend/parser/analyze.c	Mon Dec 27 10:56:52 2004
> > > ***************
> > > *** 135,141 ****
> > >   					   bool isAddConstraint);
> > >   static void applyColumnNames(List *dst, List *src);
> > >   static List *getSetColTypes(ParseState *pstate, Node *node);
> > > ! static void transformForUpdate(Query *qry, List *forUpdate);
> > >   static void transformConstraintAttrs(List *constraintList);
> > >   static void transformColumnType(ParseState *pstate, ColumnDef *column);
> > >   static void release_pstate_resources(ParseState *pstate);
> > > --- 135,141 ----
> > >   					   bool isAddConstraint);
> > >   static void applyColumnNames(List *dst, List *src);
> > >   static List *getSetColTypes(ParseState *pstate, Node *node);
> > > ! static void transformForUpdate(Query *qry, Node *forupdateClause);
> > >   static void transformConstraintAttrs(List *constraintList);
> > >   static void transformColumnType(ParseState *pstate, ColumnDef *column);
> > >   static void release_pstate_resources(ParseState *pstate);
> > > ***************
> > > *** 1804,1810 ****
> > >   	qry->commandType = CMD_SELECT;
> > >   
> > >   	/* make FOR UPDATE clause available to addRangeTableEntry */
> > > ! 	pstate->p_forUpdate = stmt->forUpdate;
> > >   
> > >   	/* process the FROM clause */
> > >   	transformFromClause(pstate, stmt->fromClause);
> > > --- 1804,1810 ----
> > >   	qry->commandType = CMD_SELECT;
> > >   
> > >   	/* make FOR UPDATE clause available to addRangeTableEntry */
> > > ! 	pstate->p_forUpdate = stmt->forupdateClause ? ((ForUpdate *)stmt->forupdateClause)->update_list : NIL;
> > >   
> > >   	/* process the FROM clause */
> > >   	transformFromClause(pstate, stmt->fromClause);
> > > ***************
> > > *** 1864,1871 ****
> > >   	if (pstate->p_hasAggs || qry->groupClause)
> > >   		parseCheckAggregates(pstate, qry);
> > >   
> > > ! 	if (stmt->forUpdate != NIL)
> > > ! 		transformForUpdate(qry, stmt->forUpdate);
> > >   
> > >   	return qry;
> > >   }
> > > --- 1864,1871 ----
> > >   	if (pstate->p_hasAggs || qry->groupClause)
> > >   		parseCheckAggregates(pstate, qry);
> > >   
> > > ! 	if (stmt->forupdateClause)
> > > ! 		transformForUpdate(qry, stmt->forupdateClause);
> > >   
> > >   	return qry;
> > >   }
> > > ***************
> > > *** 1893,1899 ****
> > >   	List	   *sortClause;
> > >   	Node	   *limitOffset;
> > >   	Node	   *limitCount;
> > > ! 	List	   *forUpdate;
> > >   	Node	   *node;
> > >   	ListCell   *left_tlist,
> > >   			   *dtlist;
> > > --- 1893,1899 ----
> > >   	List	   *sortClause;
> > >   	Node	   *limitOffset;
> > >   	Node	   *limitCount;
> > > ! 	Node	   *forUpdate;
> > >   	Node	   *node;
> > >   	ListCell   *left_tlist,
> > >   			   *dtlist;
> > > ***************
> > > *** 1931,1942 ****
> > >   	sortClause = stmt->sortClause;
> > >   	limitOffset = stmt->limitOffset;
> > >   	limitCount = stmt->limitCount;
> > > ! 	forUpdate = stmt->forUpdate;
> > >   
> > >   	stmt->sortClause = NIL;
> > >   	stmt->limitOffset = NULL;
> > >   	stmt->limitCount = NULL;
> > > ! 	stmt->forUpdate = NIL;
> > >   
> > >   	/* We don't support forUpdate with set ops at the moment. */
> > >   	if (forUpdate)
> > > --- 1931,1942 ----
> > >   	sortClause = stmt->sortClause;
> > >   	limitOffset = stmt->limitOffset;
> > >   	limitCount = stmt->limitCount;
> > > ! 	forUpdate = stmt->forupdateClause;
> > >   
> > >   	stmt->sortClause = NIL;
> > >   	stmt->limitOffset = NULL;
> > >   	stmt->limitCount = NULL;
> > > ! 	stmt->forupdateClause = NULL;
> > >   
> > >   	/* We don't support forUpdate with set ops at the moment. */
> > >   	if (forUpdate)
> > > ***************
> > > *** 2080,2086 ****
> > >   	if (pstate->p_hasAggs || qry->groupClause)
> > >   		parseCheckAggregates(pstate, qry);
> > >   
> > > ! 	if (forUpdate != NIL)
> > >   		transformForUpdate(qry, forUpdate);
> > >   
> > >   	return qry;
> > > --- 2080,2086 ----
> > >   	if (pstate->p_hasAggs || qry->groupClause)
> > >   		parseCheckAggregates(pstate, qry);
> > >   
> > > ! 	if (forUpdate)
> > >   		transformForUpdate(qry, forUpdate);
> > >   
> > >   	return qry;
> > > ***************
> > > *** 2105,2111 ****
> > >   				(errcode(ERRCODE_SYNTAX_ERROR),
> > >   				 errmsg("INTO is only allowed on first SELECT of UNION/INTERSECT/EXCEPT")));
> > >   	/* We don't support forUpdate with set ops at the moment. */
> > > ! 	if (stmt->forUpdate)
> > >   		ereport(ERROR,
> > >   				(errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
> > >   				 errmsg("SELECT FOR UPDATE is not allowed with UNION/INTERSECT/EXCEPT")));
> > > --- 2105,2111 ----
> > >   				(errcode(ERRCODE_SYNTAX_ERROR),
> > >   				 errmsg("INTO is only allowed on first SELECT of UNION/INTERSECT/EXCEPT")));
> > >   	/* We don't support forUpdate with set ops at the moment. */
> > > ! 	if (stmt->forupdateClause)
> > >   		ereport(ERROR,
> > >   				(errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
> > >   				 errmsg("SELECT FOR UPDATE is not allowed with UNION/INTERSECT/EXCEPT")));
> > > ***************
> > > *** 2125,2131 ****
> > >   	{
> > >   		Assert(stmt->larg != NULL && stmt->rarg != NULL);
> > >   		if (stmt->sortClause || stmt->limitOffset || stmt->limitCount ||
> > > ! 			stmt->forUpdate)
> > >   			isLeaf = true;
> > >   		else
> > >   			isLeaf = false;
> > > --- 2125,2131 ----
> > >   	{
> > >   		Assert(stmt->larg != NULL && stmt->rarg != NULL);
> > >   		if (stmt->sortClause || stmt->limitOffset || stmt->limitCount ||
> > > ! 			stmt->forupdateClause)
> > >   			isLeaf = true;
> > >   		else
> > >   			isLeaf = false;
> > > ***************
> > > *** 2737,2752 ****
> > >    * in rewriteHandler.c.
> > >    */
> > >   static void
> > > ! transformForUpdate(Query *qry, List *forUpdate)
> > >   {
> > >   	List	   *rowMarks = qry->rowMarks;
> > >   	ListCell   *l;
> > >   	ListCell   *rt;
> > > ! 	Index		i;
> > >   
> > >   	CheckSelectForUpdate(qry);
> > >   
> > > ! 	if (linitial(forUpdate) == NULL)
> > >   	{
> > >   		/* all regular tables used in query */
> > >   		i = 0;
> > > --- 2737,2761 ----
> > >    * in rewriteHandler.c.
> > >    */
> > >   static void
> > > ! transformForUpdate(Query *qry, Node *forupdateClause)
> > >   {
> > >   	List	   *rowMarks = qry->rowMarks;
> > >   	ListCell   *l;
> > >   	ListCell   *rt;
> > > ! 	Index	   i;
> > > ! 	ForUpdate  *fu = (ForUpdate *) forupdateClause;
> > > ! 	ForUpdate  empty;
> > > ! 	List       *update_list;
> > >   
> > >   	CheckSelectForUpdate(qry);
> > >   
> > > ! 	update_list = fu->update_list;
> > > ! 	qry->nowait = fu->nowait;
> > > ! 
> > > ! 	memset(&empty, 0, sizeof(ForUpdate));
> > > ! 	empty.nowait = FALSE;
> > > ! 	
> > > ! 	if (linitial(update_list) == NULL)
> > >   	{
> > >   		/* all regular tables used in query */
> > >   		i = 0;
> > > ***************
> > > *** 2768,2774 ****
> > >   					 * FOR UPDATE of subquery is propagated to subquery's
> > >   					 * rels
> > >   					 */
> > > ! 					transformForUpdate(rte->subquery, list_make1(NULL));
> > >   					break;
> > >   				default:
> > >   					/* ignore JOIN, SPECIAL, FUNCTION RTEs */
> > > --- 2777,2785 ----
> > >   					 * FOR UPDATE of subquery is propagated to subquery's
> > >   					 * rels
> > >   					 */
> > > ! 					empty.update_list = list_make1(NULL);
> > > ! 					transformForUpdate(rte->subquery, (Node *) &empty);
> > > ! 					empty.update_list = NIL;
> > >   					break;
> > >   				default:
> > >   					/* ignore JOIN, SPECIAL, FUNCTION RTEs */
> > > ***************
> > > *** 2779,2785 ****
> > >   	else
> > >   	{
> > >   		/* just the named tables */
> > > ! 		foreach(l, forUpdate)
> > >   		{
> > >   			char	   *relname = strVal(lfirst(l));
> > >   
> > > --- 2790,2796 ----
> > >   	else
> > >   	{
> > >   		/* just the named tables */
> > > ! 		foreach(l, update_list)
> > >   		{
> > >   			char	   *relname = strVal(lfirst(l));
> > >   
> > > ***************
> > > *** 2804,2810 ****
> > >   							 * FOR UPDATE of subquery is propagated to
> > >   							 * subquery's rels
> > >   							 */
> > > ! 							transformForUpdate(rte->subquery, list_make1(NULL));
> > >   							break;
> > >   						case RTE_JOIN:
> > >   							ereport(ERROR,
> > > --- 2815,2823 ----
> > >   							 * FOR UPDATE of subquery is propagated to
> > >   							 * subquery's rels
> > >   							 */
> > > ! 							empty.update_list = list_make1(NULL);
> > > ! 							transformForUpdate(rte->subquery, (Node *) &empty);
> > > ! 							empty.update_list = NULL;
> > >   							break;
> > >   						case RTE_JOIN:
> > >   							ereport(ERROR,
> > > diff -r -c postgresql-8.0.0rc2.orig/src/backend/parser/gram.y postgresql-8.0.0rc2/src/backend/parser/gram.y
> > > *** postgresql-8.0.0rc2.orig/src/backend/parser/gram.y	Mon Nov  8 05:02:20 2004
> > > --- postgresql-8.0.0rc2/src/backend/parser/gram.y	Mon Dec 27 10:56:52 2004
> > > ***************
> > > *** 87,93 ****
> > >   static List *extractArgTypes(List *parameters);
> > >   static SelectStmt *findLeftmostSelect(SelectStmt *node);
> > >   static void insertSelectOptions(SelectStmt *stmt,
> > > ! 								List *sortClause, List *forUpdate,
> > >   								Node *limitOffset, Node *limitCount);
> > >   static Node *makeSetOp(SetOperation op, bool all, Node *larg, Node *rarg);
> > >   static Node *doNegate(Node *n);
> > > --- 87,93 ----
> > >   static List *extractArgTypes(List *parameters);
> > >   static SelectStmt *findLeftmostSelect(SelectStmt *node);
> > >   static void insertSelectOptions(SelectStmt *stmt,
> > > ! 								List *sortClause, Node *forUpdate,
> > >   								Node *limitOffset, Node *limitCount);
> > >   static Node *makeSetOp(SetOperation op, bool all, Node *larg, Node *rarg);
> > >   static Node *doNegate(Node *n);
> > > ***************
> > > *** 239,245 ****
> > >   %type  OnCommitOption
> > >   %type  OptWithOids WithOidsAs
> > >   
> > > ! %type 	for_update_clause opt_for_update_clause update_list
> > >   %type 	opt_all
> > >   
> > >   %type 	join_outer join_qual
> > > --- 239,247 ----
> > >   %type  OnCommitOption
> > >   %type  OptWithOids WithOidsAs
> > >   
> > > ! %type 	for_update_clause opt_for_update_clause
> > > ! %type 	update_list
> > > ! 
> > >   %type 	opt_all
> > >   
> > >   %type 	join_outer join_qual
> > > ***************
> > > *** 4801,4807 ****
> > >   			simple_select						{ $$ = $1; }
> > >   			| select_clause sort_clause
> > >   				{
> > > ! 					insertSelectOptions((SelectStmt *) $1, $2, NIL,
> > >   										NULL, NULL);
> > >   					$$ = $1;
> > >   				}
> > > --- 4803,4809 ----
> > >   			simple_select						{ $$ = $1; }
> > >   			| select_clause sort_clause
> > >   				{
> > > ! 					insertSelectOptions((SelectStmt *) $1, $2, NULL,
> > >   										NULL, NULL);
> > >   					$$ = $1;
> > >   				}
> > > ***************
> > > *** 4862,4867 ****
> > > --- 4864,4870 ----
> > >   					n->whereClause = $6;
> > >   					n->groupClause = $7;
> > >   					n->havingClause = $8;
> > > + 					n->forupdateClause = NULL;
> > >   					$$ = (Node *)n;
> > >   				}
> > >   			| select_clause UNION opt_all select_clause
> > > ***************
> > > *** 5053,5060 ****
> > >   		;
> > >   
> > >   for_update_clause:
> > > ! 			FOR UPDATE update_list					{ $$ = $3; }
> > > ! 			| FOR READ ONLY							{ $$ = NULL; }
> > >   		;
> > >   
> > >   opt_for_update_clause:
> > > --- 5056,5069 ----
> > >   		;
> > >   
> > >   for_update_clause:
> > > ! 			FOR UPDATE update_list opt_nowait	
> > > ! 				{ 
> > > ! 					ForUpdate *n = makeNode(ForUpdate);
> > > ! 					n->update_list = $3;
> > > ! 					n->nowait = $4;
> > > ! 					$$ = (Node *) n;
> > > ! 				}
> > > ! 			| FOR READ ONLY							{ $$ = NULL; }	
> > >   		;
> > >   
> > >   opt_for_update_clause:
> > > ***************
> > > *** 8284,8290 ****
> > >    */
> > >   static void
> > >   insertSelectOptions(SelectStmt *stmt,
> > > ! 					List *sortClause, List *forUpdate,
> > >   					Node *limitOffset, Node *limitCount)
> > >   {
> > >   	/*
> > > --- 8293,8299 ----
> > >    */
> > >   static void
> > >   insertSelectOptions(SelectStmt *stmt,
> > > ! 					List *sortClause, Node *forUpdate,
> > >   					Node *limitOffset, Node *limitCount)
> > >   {
> > >   	/*
> > > ***************
> > > *** 8301,8311 ****
> > >   	}
> > >   	if (forUpdate)
> > >   	{
> > > ! 		if (stmt->forUpdate)
> > >   			ereport(ERROR,
> > >   					(errcode(ERRCODE_SYNTAX_ERROR),
> > >   					 errmsg("multiple FOR UPDATE clauses not allowed")));
> > > ! 		stmt->forUpdate = forUpdate;
> > >   	}
> > >   	if (limitOffset)
> > >   	{
> > > --- 8310,8320 ----
> > >   	}
> > >   	if (forUpdate)
> > >   	{
> > > ! 		if (stmt->forupdateClause)
> > >   			ereport(ERROR,
> > >   					(errcode(ERRCODE_SYNTAX_ERROR),
> > >   					 errmsg("multiple FOR UPDATE clauses not allowed")));
> > > ! 		stmt->forupdateClause = forUpdate;
> > >   	}
> > >   	if (limitOffset)
> > >   	{
> > > diff -r -c postgresql-8.0.0rc2.orig/src/backend/parser/parse_type.c postgresql-8.0.0rc2/src/backend/parser/parse_type.c
> > > *** postgresql-8.0.0rc2.orig/src/backend/parser/parse_type.c	Wed Dec 15 21:15:17 2004
> > > --- postgresql-8.0.0rc2/src/backend/parser/parse_type.c	Mon Dec 27 10:56:52 2004
> > > ***************
> > > *** 432,438 ****
> > >   		stmt->sortClause != NIL ||
> > >   		stmt->limitOffset != NULL ||
> > >   		stmt->limitCount != NULL ||
> > > ! 		stmt->forUpdate != NIL ||
> > >   		stmt->op != SETOP_NONE)
> > >   		goto fail;
> > >   	if (list_length(stmt->targetList) != 1)
> > > --- 432,438 ----
> > >   		stmt->sortClause != NIL ||
> > >   		stmt->limitOffset != NULL ||
> > >   		stmt->limitCount != NULL ||
> > > ! 		stmt->forupdateClause != NULL ||
> > >   		stmt->op != SETOP_NONE)
> > >   		goto fail;
> > >   	if (list_length(stmt->targetList) != 1)
> > > diff -r -c postgresql-8.0.0rc2.orig/src/backend/storage/lmgr/lmgr.c postgresql-8.0.0rc2/src/backend/storage/lmgr/lmgr.c
> > > *** postgresql-8.0.0rc2.orig/src/backend/storage/lmgr/lmgr.c	Thu Sep 16 18:58:33 2004
> > > --- postgresql-8.0.0rc2/src/backend/storage/lmgr/lmgr.c	Mon Dec 27 10:56:52 2004
> > > ***************
> > > *** 393,395 ****
> > > --- 393,435 ----
> > >   	if (!TransactionIdDidCommit(xid) && !TransactionIdDidAbort(xid))
> > >   		TransactionIdAbort(xid);
> > >   }
> > > + 
> > > + /*
> > > +  * As above, but only lock if we can get the lock without blocking.
> > > +  * Returns TRUE if the lock was acquired. 
> > > +  */
> > > + bool
> > > + ConditionalXactLockTableWait(TransactionId xid)
> > > + {
> > > + 	LOCKTAG		tag;
> > > + 	TransactionId myxid = GetTopTransactionId();
> > > + 
> > > + 	for (;;)
> > > + 	{
> > > + 		Assert(TransactionIdIsValid(xid));
> > > + 		Assert(!TransactionIdEquals(xid, myxid));
> > > + 
> > > + 		MemSet(&tag, 0, sizeof(tag));
> > > + 		tag.relId = XactLockTableId;
> > > + 		tag.dbId = InvalidOid;
> > > + 		tag.objId.xid = xid;
> > > + 
> > > + 		if (!LockAcquire(LockTableId, &tag, myxid, ShareLock, true))
> > > + 			return FALSE;
> > > + 		LockRelease(LockTableId, &tag, myxid, ShareLock);
> > > + 
> > > + 		if (!TransactionIdIsInProgress(xid))
> > > + 			break;
> > > + 		xid = SubTransGetParent(xid);
> > > + 	}
> > > + 
> > > + 	/*
> > > + 	 * Transaction was committed/aborted/crashed - we have to update
> > > + 	 * pg_clog if transaction is still marked as running.
> > > + 	 */
> > > + 	if (!TransactionIdDidCommit(xid) && !TransactionIdDidAbort(xid))
> > > + 		TransactionIdAbort(xid);
> > > + 	
> > > + 	return TRUE;
> > > + }
> > > + 
> > > diff -r -c postgresql-8.0.0rc2.orig/src/bin/psql/sql_help.h postgresql-8.0.0rc2/src/bin/psql/sql_help.h
> > > *** postgresql-8.0.0rc2.orig/src/bin/psql/sql_help.h	Tue Dec 21 05:22:44 2004
> > > --- postgresql-8.0.0rc2/src/bin/psql/sql_help.h	Mon Dec 27 10:57:05 2004
> > > ***************
> > > *** 383,393 ****
> > >   
> > >       { "SELECT",
> > >         N_("retrieve rows from a table or view"),
> > > !       N_("SELECT [ ALL | DISTINCT [ ON ( expression [, ...] ) ] ]\n    * | expression [ AS output_name ] [, ...]\n    [ FROM from_item [, ...] ]\n    [ WHERE condition ]\n    [ GROUP BY expression [, ...] ]\n    [ HAVING condition [, ...] ]\n    [ { UNION | INTERSECT | EXCEPT } [ ALL ] select ]\n    [ ORDER BY expression [ ASC | DESC | USING operator ] [, ...] ]\n    [ LIMIT { count | ALL } ]\n    [ OFFSET start ]\n    [ FOR UPDATE [ OF table_name [, ...] ] ]\n\nwhere from_item can be one of:\n\n    [ ONLY ] table_name [ * ] [ [ AS ] alias [ ( column_alias [, ...] ) ] ]\n    ( select ) [ AS ] alias [ ( column_alias [, ...] ) ]\n    function_name ( [ argument [, ...] ] ) [ AS ] alias [ ( column_alias [, ...] | column_definition [, ...] ) ]\n    function_name ( [ argument [, ...] ] ) AS ( column_definition [, ...] )\n    from_item [ NATURAL ] join_type from_item [ ON join_condition | USING ( join_column [, ...] ) ]") },
> > >   
> > >       { "SELECT INTO",
> > >         N_("define a new table from the results of a query"),
> > > !       N_("SELECT [ ALL | DISTINCT [ ON ( expression [, ...] ) ] ]\n    * | expression [ AS output_name ] [, ...]\n    INTO [ TEMPORARY | TEMP ] [ TABLE ] new_table\n    [ FROM from_item [, ...] ]\n    [ WHERE condition ]\n    [ GROUP BY expression [, ...] ]\n    [ HAVING condition [, ...] ]\n    [ { UNION | INTERSECT | EXCEPT } [ ALL ] select ]\n    [ ORDER BY expression [ ASC | DESC | USING operator ] [, ...] ]\n    [ LIMIT { count | ALL } ]\n    [ OFFSET start ]\n    [ FOR UPDATE [ OF tablename [, ...] ] ]") },
> > >   
> > >       { "SET",
> > >         N_("change a run-time parameter"),
> > > --- 383,393 ----
> > >   
> > >       { "SELECT",
> > >         N_("retrieve rows from a table or view"),
> > > !       N_("SELECT [ ALL | DISTINCT [ ON ( expression [, ...] ) ] ]\n    * | expression [ AS output_name ] [, ...]\n    [ FROM from_item [, ...] ]\n    [ WHERE condition ]\n    [ GROUP BY expression [, ...] ]\n    [ HAVING condition [, ...] ]\n    [ { UNION | INTERSECT | EXCEPT } [ ALL ] select ]\n    [ ORDER BY expression [ ASC | DESC | USING operator ] [, ...] ]\n    [ LIMIT { count | ALL } ]\n    [ OFFSET start ]\n    [ FOR UPDATE [ OF table_name [, ...] ] [NOWAIT] ]\n\nwhere from_item can be one of:\n\n    [ ONLY ] table_name [ * ] [ [ AS ] alias [ ( column_alias [, ...] ) ] ]\n    ( select ) [ AS ] alias [ ( column_alias [, ...] ) ]\n    function_name ( [ argument [, ...] ] ) [ AS ] alias [ ( column_alias [, ...] | column_definition [, ...] ) ]\n    function_name ( [ argument [, ...] ] ) AS ( column_definition [, ...] )\n    from_item [ NATURAL ] join_type from_item [ ON join_condition | USING ( join_column [, ...] ) ]") },
> > >   
> > >       { "SELECT INTO",
> > >         N_("define a new table from the results of a query"),
> > > !       N_("SELECT [ ALL | DISTINCT [ ON ( expression [, ...] ) ] ]\n    * | expression [ AS output_name ] [, ...]\n    INTO [ TEMPORARY | TEMP ] [ TABLE ] new_table\n    [ FROM from_item [, ...] ]\n    [ WHERE condition ]\n    [ GROUP BY expression [, ...] ]\n    [ HAVING condition [, ...] ]\n    [ { UNION | INTERSECT | EXCEPT } [ ALL ] select ]\n    [ ORDER BY expression [ ASC | DESC | USING operator ] [, ...] ]\n    [ LIMIT { count | ALL } ]\n    [ OFFSET start ]\n    [ FOR UPDATE [ OF tablename [, ...] ] [NOWAIT] ]") },
> > >   
> > >       { "SET",
> > >         N_("change a run-time parameter"),
> > > diff -r -c postgresql-8.0.0rc2.orig/src/include/access/heapam.h postgresql-8.0.0rc2/src/include/access/heapam.h
> > > *** postgresql-8.0.0rc2.orig/src/include/access/heapam.h	Sun Aug 29 07:06:55 2004
> > > --- postgresql-8.0.0rc2/src/include/access/heapam.h	Mon Dec 27 10:57:05 2004
> > > ***************
> > > *** 164,170 ****
> > >   extern int heap_update(Relation relation, ItemPointer otid, HeapTuple tup,
> > >   		ItemPointer ctid, CommandId cid, Snapshot crosscheck, bool wait);
> > >   extern int heap_mark4update(Relation relation, HeapTuple tup,
> > > ! 				 Buffer *userbuf, CommandId cid);
> > >   
> > >   extern Oid	simple_heap_insert(Relation relation, HeapTuple tup);
> > >   extern void simple_heap_delete(Relation relation, ItemPointer tid);
> > > --- 164,170 ----
> > >   extern int heap_update(Relation relation, ItemPointer otid, HeapTuple tup,
> > >   		ItemPointer ctid, CommandId cid, Snapshot crosscheck, bool wait);
> > >   extern int heap_mark4update(Relation relation, HeapTuple tup,
> > > ! 				 Buffer *userbuf, CommandId cid, bool nowait);
> > >   
> > >   extern Oid	simple_heap_insert(Relation relation, HeapTuple tup);
> > >   extern void simple_heap_delete(Relation relation, ItemPointer tid);
> > > diff -r -c postgresql-8.0.0rc2.orig/src/include/nodes/execnodes.h postgresql-8.0.0rc2/src/include/nodes/execnodes.h
> > > *** postgresql-8.0.0rc2.orig/src/include/nodes/execnodes.h	Sun Dec 12 00:26:49 2004
> > > --- postgresql-8.0.0rc2/src/include/nodes/execnodes.h	Mon Dec 27 10:56:52 2004
> > > ***************
> > > *** 308,313 ****
> > > --- 308,314 ----
> > >   	bool		es_instrument;	/* true requests runtime instrumentation */
> > >   	bool		es_select_into; /* true if doing SELECT INTO */
> > >   	bool		es_into_oids;	/* true to generate OIDs in SELECT INTO */
> > > + 	bool		es_nowait;	/* SELECT FOR UPDATE NOWAIT */
> > >   
> > >   	List	   *es_exprcontexts;	/* List of ExprContexts within EState */
> > >   
> > > diff -r -c postgresql-8.0.0rc2.orig/src/include/nodes/nodes.h postgresql-8.0.0rc2/src/include/nodes/nodes.h
> > > *** postgresql-8.0.0rc2.orig/src/include/nodes/nodes.h	Sun Dec 12 00:26:49 2004
> > > --- postgresql-8.0.0rc2/src/include/nodes/nodes.h	Mon Dec 27 10:56:52 2004
> > > ***************
> > > *** 302,307 ****
> > > --- 302,308 ----
> > >   	T_CompositeTypeStmt,
> > >   	T_InhRelation,
> > >   	T_FunctionParameter,
> > > + 	T_ForUpdate,
> > >   
> > >   	/*
> > >   	 * TAGS FOR FUNCTION-CALL CONTEXT AND RESULTINFO NODES (see fmgr.h)
> > > diff -r -c postgresql-8.0.0rc2.orig/src/include/nodes/parsenodes.h postgresql-8.0.0rc2/src/include/nodes/parsenodes.h
> > > *** postgresql-8.0.0rc2.orig/src/include/nodes/parsenodes.h	Fri Nov  5 20:16:38 2004
> > > --- postgresql-8.0.0rc2/src/include/nodes/parsenodes.h	Mon Dec 27 10:56:52 2004
> > > ***************
> > > *** 103,108 ****
> > > --- 103,110 ----
> > >   
> > >   	List	   *sortClause;		/* a list of SortClause's */
> > >   
> > > + 	bool	   nowait;		/* are we in NOWAIT mode? */
> > > + 
> > >   	Node	   *limitOffset;	/* # of result tuples to skip */
> > >   	Node	   *limitCount;		/* # of result tuples to return */
> > >   
> > > ***************
> > > *** 422,427 ****
> > > --- 424,439 ----
> > >   	Node	   *arg;			/* a (Value *) or a (TypeName *) */
> > >   } DefElem;
> > >   
> > > + /*
> > > +  * ForUpdate -
> > > +  *       used in raw parsetrees output only
> > > +  */
> > > + typedef struct ForUpdate
> > > + {
> > > + 	NodeTag		type;
> > > + 	List		*update_list;	/* list of tables */
> > > + 	bool		nowait;		/* NOWAIT option */
> > > + } ForUpdate;
> > >   
> > >   /****************************************************************************
> > >    *	Nodes for a Query tree
> > > ***************
> > > *** 686,692 ****
> > >   	List	   *sortClause;		/* sort clause (a list of SortBy's) */
> > >   	Node	   *limitOffset;	/* # of result tuples to skip */
> > >   	Node	   *limitCount;		/* # of result tuples to return */
> > > ! 	List	   *forUpdate;		/* FOR UPDATE clause */
> > >   
> > >   	/*
> > >   	 * These fields are used only in upper-level SelectStmts.
> > > --- 698,704 ----
> > >   	List	   *sortClause;		/* sort clause (a list of SortBy's) */
> > >   	Node	   *limitOffset;	/* # of result tuples to skip */
> > >   	Node	   *limitCount;		/* # of result tuples to return */
> > > ! 	Node	   *forupdateClause;	/* FOR UPDATE clause (ForUpdate node) */
> > >   
> > >   	/*
> > >   	 * These fields are used only in upper-level SelectStmts.
> > > diff -r -c postgresql-8.0.0rc2.orig/src/include/storage/lmgr.h postgresql-8.0.0rc2/src/include/storage/lmgr.h
> > > *** postgresql-8.0.0rc2.orig/src/include/storage/lmgr.h	Thu Sep 16 18:58:42 2004
> > > --- postgresql-8.0.0rc2/src/include/storage/lmgr.h	Mon Dec 27 10:56:52 2004
> > > ***************
> > > *** 60,64 ****
> > > --- 60,65 ----
> > >   extern void XactLockTableInsert(TransactionId xid);
> > >   extern void XactLockTableDelete(TransactionId xid);
> > >   extern void XactLockTableWait(TransactionId xid);
> > > + extern bool ConditionalXactLockTableWait(TransactionId xid);
> > >   
> > >   #endif   /* LMGR_H */
> > 
> > -- 
> >   Bruce Momjian                        |  http://candle.pha.pa.us
> >   pgman@candle.pha.pa.us               |  (610) 359-1001
> >   +  If your life is a hard drive,     |  13 Roberts Road
> >   +  Christ can be your backup.        |  Newtown Square, Pennsylvania 19073
> > 
> > ---------------------------(end of broadcast)---------------------------
> > TIP 4: Don't 'kill -9' the postmaster
> > 
> 
> -- 
>   Bruce Momjian                        |  http://candle.pha.pa.us
>   pgman@candle.pha.pa.us               |  (610) 359-1001
>   +  If your life is a hard drive,     |  13 Roberts Road
>   +  Christ can be your backup.        |  Newtown Square, Pennsylvania 19073
> 
> ---------------------------(end of broadcast)---------------------------
> TIP 9: In versions below 8.0, the planner will ignore your desire to
>        choose an index scan if your joining column's datatypes do not
>        match
-- 
Karel Zak 

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