Adjust nodeBitmapIndexscan.c to not keep the index open across calls,

but just to open and close it during MultiExecBitmapIndexScan.  This
avoids acquiring duplicate resources (eg, multiple locks on the same
relation) in a tree with many bitmap scans.  Also, don't bother to
lock the parent heap at all here, since we must be underneath a
BitmapHeapScan node that will be holding a suitable lock.

src/backend/executor/nodeBitmapIndexscan.c

@@ -8,7 +8,7 @@
  *
  *
  * IDENTIFICATION
- *	  $PostgreSQL: pgsql/src/backend/executor/nodeBitmapIndexscan.c,v 1.5 2005/04/24 17:32:46 tgl Exp $
+ *	  $PostgreSQL: pgsql/src/backend/executor/nodeBitmapIndexscan.c,v 1.6 2005/04/24 18:16:38 tgl Exp $
  *
  *-------------------------------------------------------------------------
  */
@@ -41,6 +41,8 @@ MultiExecBitmapIndexScan(BitmapIndexScanState *node)
 {
 #define MAX_TIDS	1024
 	TIDBitmap  *tbm;
+	Oid			indxid;
+	Relation	indexRelation;
 	IndexScanDesc scandesc;
 	ItemPointerData tids[MAX_TIDS];
 	int32		ntids;
@@ -58,9 +60,22 @@ MultiExecBitmapIndexScan(BitmapIndexScanState *node)
 		ExecReScan((PlanState *) node, NULL);
 
 	/*
-	 * extract necessary information from index scan node
+	 * We do not open or lock the base relation here.  We assume that an
+	 * ancestor BitmapHeapScan node is holding AccessShareLock on the
+	 * heap relation throughout the execution of the plan tree.
 	 */
-	scandesc = node->biss_ScanDesc;
+
+	/*
+	 * open the index relation and initialize relation and scan
+	 * descriptors.  Note we acquire no locks here; the index machinery
+	 * does its own locks and unlocks.
+	 */
+	indxid = ((BitmapIndexScan *) node->ss.ps.plan)->indxid;
+	indexRelation = index_open(indxid);
+	scandesc = index_beginscan_multi(indexRelation,
+									 node->ss.ps.state->es_snapshot,
+									 node->biss_NumScanKeys,
+									 node->biss_ScanKeys);
 
 	/*
 	 * Prepare the result bitmap.  Normally we just create a new one to pass
@@ -98,6 +113,12 @@ MultiExecBitmapIndexScan(BitmapIndexScanState *node)
 		CHECK_FOR_INTERRUPTS();
 	}
 
+	/*
+	 * close the index relation
+	 */
+	index_endscan(scandesc);
+	index_close(indexRelation);
+
 	/* must provide our own instrumentation support */
 	if (node->ss.ps.instrument)
 		InstrStopNodeMulti(node->ss.ps.instrument, nTuples);
@@ -109,11 +130,7 @@ MultiExecBitmapIndexScan(BitmapIndexScanState *node)
  *		ExecBitmapIndexReScan(node)
  *
  *		Recalculates the value of the scan keys whose value depends on
- *		information known at runtime and rescans the indexed relation.
+ *		information known at runtime.
- *		Updating the scan key was formerly done separately in
- *		ExecUpdateIndexScanKeys. Integrating it into ReScan makes
- *		rescans of indices and relations/general streams more uniform.
- *
  * ----------------------------------------------------------------
  */
 void
@@ -121,12 +138,10 @@ ExecBitmapIndexReScan(BitmapIndexScanState *node, ExprContext *exprCtxt)
 {
 	ExprContext *econtext;
 	ExprState **runtimeKeyInfo;
-	Index		scanrelid;
 
 	econtext = node->biss_RuntimeContext;		/* context for runtime
 												 * keys */
 	runtimeKeyInfo = node->biss_RuntimeKeyInfo;
-	scanrelid = ((BitmapIndexScan *) node->ss.ps.plan)->scan.scanrelid;
 
 	if (econtext)
 	{
@@ -194,8 +209,6 @@ ExecBitmapIndexReScan(BitmapIndexScanState *node, ExprContext *exprCtxt)
 
 		node->biss_RuntimeKeysReady = true;
 	}
-
-	index_rescan(node->biss_ScanDesc, node->biss_ScanKeys);
 }
 
 /* ----------------------------------------------------------------
@@ -205,13 +218,6 @@ ExecBitmapIndexReScan(BitmapIndexScanState *node, ExprContext *exprCtxt)
 void
 ExecEndBitmapIndexScan(BitmapIndexScanState *node)
 {
-	Relation	relation;
-
-	/*
-	 * extract information from the node
-	 */
-	relation = node->ss.ss_currentRelation;
-
 	/*
 	 * Free the exprcontext ... now dead code, see ExecFreeExprContext
 	 */
@@ -219,44 +225,12 @@ ExecEndBitmapIndexScan(BitmapIndexScanState *node)
 	if (node->biss_RuntimeContext)
 		FreeExprContext(node->biss_RuntimeContext);
 #endif
-
-	/*
-	 * close the index relation
-	 */
-	if (node->biss_ScanDesc != NULL)
-		index_endscan(node->biss_ScanDesc);
-
-	if (node->biss_RelationDesc != NULL)
-		index_close(node->biss_RelationDesc);
-
-	/*
-	 * close the heap relation.
-	 *
-	 * Currently, we do not release the AccessShareLock acquired by
-	 * ExecInitBitmapIndexScan.  This lock should be held till end of
-	 * transaction. (There is a faction that considers this too much
-	 * locking, however.)
-	 */
-	heap_close(relation, NoLock);
 }
 
 /* ----------------------------------------------------------------
  *		ExecInitBitmapIndexScan
  *
- *		Initializes the index scan's state information, creates
+ *		Initializes the index scan's state information.
- *		scan keys, and opens the base and index relations.
- *
- *		Note: index scans have 2 sets of state information because
- *			  we have to keep track of the base relation and the
- *			  index relations.
- *
- * old comments
- *		Creates the run-time state information for the node and
- *		sets the relation id to contain relevant descriptors.
- *
- *		Parameters:
- *		  node: BitmapIndexNode node produced by the planner.
- *		  estate: the execution state initialized in InitPlan.
  * ----------------------------------------------------------------
  */
 BitmapIndexScanState *
@@ -265,10 +239,6 @@ ExecInitBitmapIndexScan(BitmapIndexScan *node, EState *estate)
 	BitmapIndexScanState *indexstate;
 	ExprState **runtimeKeyInfo;
 	bool		have_runtime_keys;
-	RangeTblEntry *rtentry;
-	Index		relid;
-	Oid			reloid;
-	Relation	currentRelation;
 
 	/*
 	 * create state structure
@@ -306,8 +276,6 @@ ExecInitBitmapIndexScan(BitmapIndexScan *node, EState *estate)
 	indexstate->biss_RuntimeKeyInfo = NULL;
 	indexstate->biss_RuntimeContext = NULL;
 	indexstate->biss_RuntimeKeysReady = false;
-	indexstate->biss_RelationDesc = NULL;
-	indexstate->biss_ScanDesc = NULL;
 
 	CXT1_printf("ExecInitBitmapIndexScan: context is %d\n", CurrentMemoryContext);
 
@@ -459,7 +427,6 @@ ExecInitBitmapIndexScan(BitmapIndexScan *node, EState *estate)
 		runtimeKeyInfo = run_keys;
 	}
 
-
 	/*
 	 * If all of our keys have the form (var op const), then we have no
 	 * runtime keys so we store NULL in the runtime key info. Otherwise
@@ -489,30 +456,9 @@ ExecInitBitmapIndexScan(BitmapIndexScan *node, EState *estate)
 			pfree(runtimeKeyInfo);
 	}
 
-	/*
+	/* We don't keep the table or index open across calls */
-	 * open the base relation and acquire AccessShareLock on it.
+	indexstate->ss.ss_currentRelation = NULL;
-	 */
+	indexstate->ss.ss_currentScanDesc = NULL;
-	relid = node->scan.scanrelid;
-	rtentry = rt_fetch(relid, estate->es_range_table);
-	reloid = rtentry->relid;
-
-	currentRelation = heap_open(reloid, AccessShareLock);
-
-	indexstate->ss.ss_currentRelation = currentRelation;
-	indexstate->ss.ss_currentScanDesc = NULL;	/* no heap scan here */
-
-	/*
-	 * open the index relation and initialize relation and scan
-	 * descriptors.  Note we acquire no locks here; the index machinery
-	 * does its own locks and unlocks.	(We rely on having AccessShareLock
-	 * on the parent table to ensure the index won't go away!)
-	 */
-	indexstate->biss_RelationDesc = index_open(node->indxid);
-	indexstate->biss_ScanDesc =
-		index_beginscan_multi(indexstate->biss_RelationDesc,
-							  estate->es_snapshot,
-							  indexstate->biss_NumScanKeys,
-							  indexstate->biss_ScanKeys);
 
 	/*
 	 * all done.

src/include/nodes/execnodes.h

@@ -7,7 +7,7 @@
  * Portions Copyright (c) 1996-2005, PostgreSQL Global Development Group
  * Portions Copyright (c) 1994, Regents of the University of California
  *
- * $PostgreSQL: pgsql/src/include/nodes/execnodes.h,v 1.127 2005/04/20 15:48:36 tgl Exp $
+ * $PostgreSQL: pgsql/src/include/nodes/execnodes.h,v 1.128 2005/04/24 18:16:38 tgl Exp $
  *
  *-------------------------------------------------------------------------
  */
@@ -908,8 +908,6 @@ typedef struct IndexScanState
  *						   that will be evaluated at runtime
  *		RuntimeContext	   expr context for evaling runtime Skeys
  *		RuntimeKeysReady   true if runtime Skeys have been computed
- *		RelationDesc	   relation descriptor
- *		ScanDesc		   scan descriptor
  * ----------------
  */
 typedef struct BitmapIndexScanState
@@ -921,8 +919,6 @@ typedef struct BitmapIndexScanState
 	ExprState **biss_RuntimeKeyInfo;
 	ExprContext *biss_RuntimeContext;
 	bool		biss_RuntimeKeysReady;
-	Relation	biss_RelationDesc;
-	IndexScanDesc biss_ScanDesc;
 } BitmapIndexScanState;
 
 /* ----------------