Improve the representation of FOR UPDATE/FOR SHARE so that we can

support both FOR UPDATE and FOR SHARE in one command, as well as both
NOWAIT and normal WAIT behavior.  The more general code is actually
simpler and cleaner.

Author: tglsfdc

doc/src/sgml/ref/select.sgml

@@ -1,5 +1,5 @@
 <!--
-$PostgreSQL: pgsql/doc/src/sgml/ref/select.sgml,v 1.90 2005/11/01 21:09:51 tgl Exp $
+$PostgreSQL: pgsql/doc/src/sgml/ref/select.sgml,v 1.91 2006/04/30 18:30:38 tgl Exp $
 PostgreSQL documentation
 -->
 
@@ -30,7 +30,7 @@ SELECT [ ALL | DISTINCT [ ON ( <replaceable class="parameter">expression</replac
     [ ORDER BY <replaceable class="parameter">expression</replaceable> [ ASC | DESC | USING <replaceable class="parameter">operator</replaceable> ] [, ...] ]
     [ LIMIT { <replaceable class="parameter">count</replaceable> | ALL } ]
     [ OFFSET <replaceable class="parameter">start</replaceable> ]
-    [ FOR { UPDATE | SHARE } [ OF <replaceable class="parameter">table_name</replaceable> [, ...] ] [ NOWAIT ] ]
+    [ FOR { UPDATE | SHARE } [ OF <replaceable class="parameter">table_name</replaceable> [, ...] ] [ NOWAIT ] [...] ]
 
 where <replaceable class="parameter">from_item</replaceable> can be one of:
 
@@ -142,8 +142,8 @@ where <replaceable class="parameter">from_item</replaceable> can be one of:
 
     <listitem>
      <para>
-      If the <literal>FOR UPDATE</literal> or <literal>FOR SHARE</literal>
-      clause is specified, the
+      If <literal>FOR UPDATE</literal> or <literal>FOR SHARE</literal>
+      is specified, the
       <command>SELECT</command> statement locks the selected rows
       against concurrent updates.  (See <xref linkend="sql-for-update-share"
       endterm="sql-for-update-share-title"> below.)
@@ -852,19 +852,27 @@ FOR SHARE [ OF <replaceable class="parameter">table_name</replaceable> [, ...] ]
     from performing <command>SELECT FOR SHARE</command>.
    </para>
 
-   <para>
-    It is currently not allowed for a single <command>SELECT</command>
-    statement to include both <literal>FOR UPDATE</literal> and
-    <literal>FOR SHARE</literal>, nor can different parts of the statement use
-    both <literal>NOWAIT</> and normal waiting mode.
-   </para>
-
    <para>
     If specific tables are named in <literal>FOR UPDATE</literal>
     or <literal>FOR SHARE</literal>,
     then only rows coming from those tables are locked; any other
     tables used in the <command>SELECT</command> are simply read as
-    usual.
+    usual.  A <literal>FOR UPDATE</literal> or <literal>FOR SHARE</literal>
+    clause without a table list affects all tables used in the command.
+    If <literal>FOR UPDATE</literal> or <literal>FOR SHARE</literal> is
+    applied to a view or sub-query, it affects all tables used in
+    the view or sub-query.
+   </para>
+
+   <para>
+    Multiple <literal>FOR UPDATE</literal> and <literal>FOR SHARE</literal>
+    clauses can be written if it is necessary to specify different locking
+    behavior for different tables.  If the same table is mentioned (or
+    implicitly affected) by both <literal>FOR UPDATE</literal> and
+    <literal>FOR SHARE</literal> clauses, then it is processed as
+    <literal>FOR UPDATE</literal>.  Similarly, a table is processed
+    as <literal>NOWAIT</> if that is specified in any of the clauses
+    affecting it.
    </para>
 
    <para>

doc/src/sgml/ref/select_into.sgml

@@ -1,5 +1,5 @@
 <!--
-$PostgreSQL: pgsql/doc/src/sgml/ref/select_into.sgml,v 1.36 2005/08/01 20:31:04 tgl Exp $
+$PostgreSQL: pgsql/doc/src/sgml/ref/select_into.sgml,v 1.37 2006/04/30 18:30:38 tgl Exp $
 PostgreSQL documentation
 -->
 
@@ -31,7 +31,7 @@ SELECT [ ALL | DISTINCT [ ON ( <replaceable class="PARAMETER">expression</replac
     [ ORDER BY <replaceable class="PARAMETER">expression</replaceable> [ ASC | DESC | USING <replaceable class="PARAMETER">operator</replaceable> ] [, ...] ]
     [ LIMIT { <replaceable class="PARAMETER">count</replaceable> | ALL } ]
     [ OFFSET <replaceable class="PARAMETER">start</replaceable> ]
-    [ FOR { UPDATE | SHARE } [ OF <replaceable class="parameter">table_name</replaceable> [, ...] ] [ NOWAIT ] ]
+    [ FOR { UPDATE | SHARE } [ OF <replaceable class="parameter">table_name</replaceable> [, ...] ] [ NOWAIT ] [...] ]
 </synopsis>
  </refsynopsisdiv>
 

doc/src/sgml/sql.sgml

@@ -1,4 +1,4 @@
-<!-- $PostgreSQL: pgsql/doc/src/sgml/sql.sgml,v 1.39 2006/03/10 19:10:49 momjian Exp $ -->
+<!-- $PostgreSQL: pgsql/doc/src/sgml/sql.sgml,v 1.40 2006/04/30 18:30:38 tgl Exp $ -->
 
  <chapter id="sql-intro">
   <title>SQL</title>
@@ -863,7 +863,7 @@ SELECT [ ALL | DISTINCT [ ON ( <replaceable class="PARAMETER">expression</replac
     [ ORDER BY <replaceable class="PARAMETER">expression</replaceable> [ ASC | DESC | USING <replaceable class="PARAMETER">operator</replaceable> ] [, ...] ]
     [ LIMIT { <replaceable class="PARAMETER">count</replaceable> | ALL } ]
     [ OFFSET <replaceable class="PARAMETER">start</replaceable> ]
-    [ FOR { UPDATE | SHARE } [ OF <replaceable class="parameter">table_name</replaceable> [, ...] ] [ NOWAIT ] ]
+    [ FOR { UPDATE | SHARE } [ OF <replaceable class="parameter">table_name</replaceable> [, ...] ] [ NOWAIT ] [...] ]
      </synopsis>
     </para>
 

src/backend/executor/execMain.c

@@ -26,7 +26,7 @@
  *
  *
  * IDENTIFICATION
- *	  $PostgreSQL: pgsql/src/backend/executor/execMain.c,v 1.269 2006/03/05 15:58:25 momjian Exp $
+ *	  $PostgreSQL: pgsql/src/backend/executor/execMain.c,v 1.270 2006/04/30 18:30:38 tgl Exp $
  *
  *-------------------------------------------------------------------------
  */
@@ -452,6 +452,7 @@ InitPlan(QueryDesc *queryDesc, int eflags)
 	Relation	intoRelationDesc;
 	bool		do_select_into;
 	TupleDesc	tupType;
+	ListCell   *l;
 
 	/*
 	 * Do permissions checks.  It's sufficient to examine the query's top
@@ -486,7 +487,6 @@ InitPlan(QueryDesc *queryDesc, int eflags)
 			 * parseTree->resultRelations identifies them all
 			 */
 			ResultRelInfo *resultRelInfo;
-			ListCell   *l;
 
 			numResultRelations = list_length(resultRelations);
 			resultRelInfos = (ResultRelInfo *)
@@ -549,26 +549,21 @@ InitPlan(QueryDesc *queryDesc, int eflags)
 	 * Have to lock relations selected FOR UPDATE/FOR SHARE
 	 */
 	estate->es_rowMarks = NIL;
-	estate->es_forUpdate = parseTree->forUpdate;
-	estate->es_rowNoWait = parseTree->rowNoWait;
-	if (parseTree->rowMarks != NIL)
+	foreach(l, parseTree->rowMarks)
 	{
-		ListCell   *l;
-
-		foreach(l, parseTree->rowMarks)
-		{
-			Index		rti = lfirst_int(l);
-			Oid			relid = getrelid(rti, rangeTable);
-			Relation	relation;
-			ExecRowMark *erm;
-
-			relation = heap_open(relid, RowShareLock);
-			erm = (ExecRowMark *) palloc(sizeof(ExecRowMark));
-			erm->relation = relation;
-			erm->rti = rti;
-			snprintf(erm->resname, sizeof(erm->resname), "ctid%u", rti);
-			estate->es_rowMarks = lappend(estate->es_rowMarks, erm);
-		}
+		RowMarkClause *rc = (RowMarkClause *) lfirst(l);
+		Oid			relid = getrelid(rc->rti, rangeTable);
+		Relation	relation;
+		ExecRowMark *erm;
+
+		relation = heap_open(relid, RowShareLock);
+		erm = (ExecRowMark *) palloc(sizeof(ExecRowMark));
+		erm->relation = relation;
+		erm->rti = rc->rti;
+		erm->forUpdate = rc->forUpdate;
+		erm->noWait = rc->noWait;
+		snprintf(erm->resname, sizeof(erm->resname), "ctid%u", rc->rti);
+		estate->es_rowMarks = lappend(estate->es_rowMarks, erm);
 	}
 
 	/*
@@ -1222,15 +1217,15 @@ lnext:	;
 
 					tuple.t_self = *((ItemPointer) DatumGetPointer(datum));
 
-					if (estate->es_forUpdate)
+					if (erm->forUpdate)
 						lockmode = LockTupleExclusive;
 					else
 						lockmode = LockTupleShared;
 
 					test = heap_lock_tuple(erm->relation, &tuple, &buffer,
 										   &update_ctid, &update_xmax,
 										   estate->es_snapshot->curcid,
-										   lockmode, estate->es_rowNoWait);
+										   lockmode, erm->noWait);
 					ReleaseBuffer(buffer);
 					switch (test)
 					{
@@ -2258,8 +2253,6 @@ EvalPlanQualStart(evalPlanQual *epq, EState *estate, evalPlanQual *priorepq)
 		epqstate->es_param_exec_vals = (ParamExecData *)
 			palloc0(estate->es_topPlan->nParamExec * sizeof(ParamExecData));
 	epqstate->es_rowMarks = estate->es_rowMarks;
-	epqstate->es_forUpdate = estate->es_forUpdate;
-	epqstate->es_rowNoWait = estate->es_rowNoWait;
 	epqstate->es_instrument = estate->es_instrument;
 	epqstate->es_select_into = estate->es_select_into;
 	epqstate->es_into_oids = estate->es_into_oids;

src/backend/executor/execUtils.c

@@ -8,7 +8,7 @@
  *
  *
  * IDENTIFICATION
- *	  $PostgreSQL: pgsql/src/backend/executor/execUtils.c,v 1.133 2006/03/05 15:58:26 momjian Exp $
+ *	  $PostgreSQL: pgsql/src/backend/executor/execUtils.c,v 1.134 2006/04/30 18:30:38 tgl Exp $
  *
  *-------------------------------------------------------------------------
  */
@@ -204,8 +204,6 @@ CreateExecutorState(void)
 	estate->es_processed = 0;
 	estate->es_lastoid = InvalidOid;
 	estate->es_rowMarks = NIL;
-	estate->es_forUpdate = false;
-	estate->es_rowNoWait = false;
 
 	estate->es_instrument = false;
 	estate->es_select_into = false;

src/backend/nodes/copyfuncs.c

@@ -15,7 +15,7 @@
  * Portions Copyright (c) 1994, Regents of the University of California
  *
  * IDENTIFICATION
- *	  $PostgreSQL: pgsql/src/backend/nodes/copyfuncs.c,v 1.334 2006/04/22 01:25:58 tgl Exp $
+ *	  $PostgreSQL: pgsql/src/backend/nodes/copyfuncs.c,v 1.335 2006/04/30 18:30:38 tgl Exp $
  *
  *-------------------------------------------------------------------------
  */
@@ -1409,6 +1409,18 @@ _copyGroupClause(GroupClause *from)
 	return newnode;
 }
 
+static RowMarkClause *
+_copyRowMarkClause(RowMarkClause *from)
+{
+	RowMarkClause *newnode = makeNode(RowMarkClause);
+
+	COPY_SCALAR_FIELD(rti);
+	COPY_SCALAR_FIELD(forUpdate);
+	COPY_SCALAR_FIELD(noWait);
+
+	return newnode;
+}
+
 static A_Expr *
 _copyAExpr(A_Expr *from)
 {
@@ -1650,7 +1662,7 @@ _copyLockingClause(LockingClause *from)
 
 	COPY_NODE_FIELD(lockedRels);
 	COPY_SCALAR_FIELD(forUpdate);
-	COPY_SCALAR_FIELD(nowait);
+	COPY_SCALAR_FIELD(noWait);
 
 	return newnode;
 }
@@ -1673,16 +1685,14 @@ _copyQuery(Query *from)
 	COPY_SCALAR_FIELD(hasSubLinks);
 	COPY_NODE_FIELD(rtable);
 	COPY_NODE_FIELD(jointree);
-	COPY_NODE_FIELD(rowMarks);
-	COPY_SCALAR_FIELD(forUpdate);
-	COPY_SCALAR_FIELD(rowNoWait);
 	COPY_NODE_FIELD(targetList);
 	COPY_NODE_FIELD(groupClause);
 	COPY_NODE_FIELD(havingQual);
 	COPY_NODE_FIELD(distinctClause);
 	COPY_NODE_FIELD(sortClause);
 	COPY_NODE_FIELD(limitOffset);
 	COPY_NODE_FIELD(limitCount);
+	COPY_NODE_FIELD(rowMarks);
 	COPY_NODE_FIELD(setOperations);
 	COPY_NODE_FIELD(resultRelations);
 
@@ -3284,6 +3294,9 @@ copyObject(void *from)
 		case T_GroupClause:
 			retval = _copyGroupClause(from);
 			break;
+		case T_RowMarkClause:
+			retval = _copyRowMarkClause(from);
+			break;
 		case T_FkConstraint:
 			retval = _copyFkConstraint(from);
 			break;

src/backend/nodes/equalfuncs.c

@@ -18,7 +18,7 @@
  * Portions Copyright (c) 1994, Regents of the University of California
  *
  * IDENTIFICATION
- *	  $PostgreSQL: pgsql/src/backend/nodes/equalfuncs.c,v 1.270 2006/04/22 01:25:59 tgl Exp $
+ *	  $PostgreSQL: pgsql/src/backend/nodes/equalfuncs.c,v 1.271 2006/04/30 18:30:38 tgl Exp $
  *
  *-------------------------------------------------------------------------
  */
@@ -665,16 +665,14 @@ _equalQuery(Query *a, Query *b)
 	COMPARE_SCALAR_FIELD(hasSubLinks);
 	COMPARE_NODE_FIELD(rtable);
 	COMPARE_NODE_FIELD(jointree);
-	COMPARE_NODE_FIELD(rowMarks);
-	COMPARE_SCALAR_FIELD(forUpdate);
-	COMPARE_SCALAR_FIELD(rowNoWait);
 	COMPARE_NODE_FIELD(targetList);
 	COMPARE_NODE_FIELD(groupClause);
 	COMPARE_NODE_FIELD(havingQual);
 	COMPARE_NODE_FIELD(distinctClause);
 	COMPARE_NODE_FIELD(sortClause);
 	COMPARE_NODE_FIELD(limitOffset);
 	COMPARE_NODE_FIELD(limitCount);
+	COMPARE_NODE_FIELD(rowMarks);
 	COMPARE_NODE_FIELD(setOperations);
 	COMPARE_NODE_FIELD(resultRelations);
 
@@ -1688,7 +1686,7 @@ _equalLockingClause(LockingClause *a, LockingClause *b)
 {
 	COMPARE_NODE_FIELD(lockedRels);
 	COMPARE_SCALAR_FIELD(forUpdate);
-	COMPARE_SCALAR_FIELD(nowait);
+	COMPARE_SCALAR_FIELD(noWait);
 
 	return true;
 }
@@ -1723,6 +1721,16 @@ _equalSortClause(SortClause *a, SortClause *b)
 	return true;
 }
 
+static bool
+_equalRowMarkClause(RowMarkClause *a, RowMarkClause *b)
+{
+	COMPARE_SCALAR_FIELD(rti);
+	COMPARE_SCALAR_FIELD(forUpdate);
+	COMPARE_SCALAR_FIELD(noWait);
+
+	return true;
+}
+
 static bool
 _equalFkConstraint(FkConstraint *a, FkConstraint *b)
 {
@@ -2297,6 +2305,9 @@ equal(void *a, void *b)
 			/* GroupClause is equivalent to SortClause */
 			retval = _equalSortClause(a, b);
 			break;
+		case T_RowMarkClause:
+			retval = _equalRowMarkClause(a, b);
+			break;
 		case T_FkConstraint:
 			retval = _equalFkConstraint(a, b);
 			break;

src/backend/nodes/outfuncs.c

@@ -8,7 +8,7 @@
  *
  *
  * IDENTIFICATION
- *	  $PostgreSQL: pgsql/src/backend/nodes/outfuncs.c,v 1.273 2006/04/22 01:25:59 tgl Exp $
+ *	  $PostgreSQL: pgsql/src/backend/nodes/outfuncs.c,v 1.274 2006/04/30 18:30:39 tgl Exp $
  *
  * NOTES
  *	  Every node type that can appear in stored rules' parsetrees *must*
@@ -1418,7 +1418,7 @@ _outLockingClause(StringInfo str, LockingClause *node)
 
 	WRITE_NODE_FIELD(lockedRels);
 	WRITE_BOOL_FIELD(forUpdate);
-	WRITE_BOOL_FIELD(nowait);
+	WRITE_BOOL_FIELD(noWait);
 }
 
 static void
@@ -1514,16 +1514,14 @@ _outQuery(StringInfo str, Query *node)
 	WRITE_BOOL_FIELD(hasSubLinks);
 	WRITE_NODE_FIELD(rtable);
 	WRITE_NODE_FIELD(jointree);
-	WRITE_NODE_FIELD(rowMarks);
-	WRITE_BOOL_FIELD(forUpdate);
-	WRITE_BOOL_FIELD(rowNoWait);
 	WRITE_NODE_FIELD(targetList);
 	WRITE_NODE_FIELD(groupClause);
 	WRITE_NODE_FIELD(havingQual);
 	WRITE_NODE_FIELD(distinctClause);
 	WRITE_NODE_FIELD(sortClause);
 	WRITE_NODE_FIELD(limitOffset);
 	WRITE_NODE_FIELD(limitCount);
+	WRITE_NODE_FIELD(rowMarks);
 	WRITE_NODE_FIELD(setOperations);
 	WRITE_NODE_FIELD(resultRelations);
 }
@@ -1546,6 +1544,16 @@ _outGroupClause(StringInfo str, GroupClause *node)
 	WRITE_OID_FIELD(sortop);
 }
 
+static void
+_outRowMarkClause(StringInfo str, RowMarkClause *node)
+{
+	WRITE_NODE_TYPE("ROWMARKCLAUSE");
+
+	WRITE_UINT_FIELD(rti);
+	WRITE_BOOL_FIELD(forUpdate);
+	WRITE_BOOL_FIELD(noWait);
+}
+
 static void
 _outSetOperationStmt(StringInfo str, SetOperationStmt *node)
 {
@@ -2113,6 +2121,9 @@ _outNode(StringInfo str, void *obj)
 			case T_GroupClause:
 				_outGroupClause(str, obj);
 				break;
+			case T_RowMarkClause:
+				_outRowMarkClause(str, obj);
+				break;
 			case T_SetOperationStmt:
 				_outSetOperationStmt(str, obj);
 				break;