From db70a312941d7e20d9fff6bbe7d6e9ccf59294e0 Mon Sep 17 00:00:00 2001
From: Tom Lane <tgl@sss.pgh.pa.us>
Date: Thu, 5 May 2005 03:37:23 +0000
Subject: [PATCH] Adjust nodeBitmapIndexscan to keep the target index opened
from plan startup to end, rather than re-opening it in each
MultiExecBitmapIndexScan call. I had foolishly thought that opening/closing
wouldn't be much more expensive than a rescan call, but that was sheer brain
fade.
This seems to fix about half of the performance lossage reported by
Sergey Koposov. I'm still not sure where the other half went.
---
src/backend/executor/nodeBitmapIndexscan.c | 72 +++++++++++++---------
src/include/nodes/execnodes.h | 6 +-
2 files changed, 48 insertions(+), 30 deletions(-)
diff --git a/src/backend/executor/nodeBitmapIndexscan.c b/src/backend/executor/nodeBitmapIndexscan.c
index 19915a60599..ecb5a63013c 100644
--- a/src/backend/executor/nodeBitmapIndexscan.c
+++ b/src/backend/executor/nodeBitmapIndexscan.c
@@ -8,7 +8,7 @@
*
*
* IDENTIFICATION
- * $PostgreSQL: pgsql/src/backend/executor/nodeBitmapIndexscan.c,v 1.7 2005/04/25 01:30:12 tgl Exp $
+ * $PostgreSQL: pgsql/src/backend/executor/nodeBitmapIndexscan.c,v 1.8 2005/05/05 03:37:23 tgl Exp $
*
*-------------------------------------------------------------------------
*/
@@ -38,8 +38,6 @@ MultiExecBitmapIndexScan(BitmapIndexScanState *node)
{
#define MAX_TIDS 1024
TIDBitmap *tbm;
- Oid indexid;
- Relation indexRelation;
IndexScanDesc scandesc;
ItemPointerData tids[MAX_TIDS];
int32 ntids;
@@ -49,6 +47,11 @@ MultiExecBitmapIndexScan(BitmapIndexScanState *node)
if (node->ss.ps.instrument)
InstrStartNode(node->ss.ps.instrument);
+ /*
+ * extract necessary information from index scan node
+ */
+ scandesc = node->biss_ScanDesc;
+
/*
* If we have runtime keys and they've not already been set up, do it
* now.
@@ -56,24 +59,6 @@ MultiExecBitmapIndexScan(BitmapIndexScanState *node)
if (node->biss_RuntimeKeyInfo && !node->biss_RuntimeKeysReady)
ExecReScan((PlanState *) node, NULL);
- /*
- * 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.
- */
-
- /*
- * 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.
- */
- indexid = ((BitmapIndexScan *) node->ss.ps.plan)->indexid;
- indexRelation = index_open(indexid);
- 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
* back; however, our parent node is allowed to store a pre-made one
@@ -110,12 +95,6 @@ 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);
@@ -127,7 +106,7 @@ MultiExecBitmapIndexScan(BitmapIndexScanState *node)
* ExecBitmapIndexReScan(node)
*
* Recalculates the value of the scan keys whose value depends on
- * information known at runtime.
+ * information known at runtime and rescans the indexed relation.
* ----------------------------------------------------------------
*/
void
@@ -169,6 +148,9 @@ ExecBitmapIndexReScan(BitmapIndexScanState *node, ExprContext *exprCtxt)
node->biss_NumScanKeys);
node->biss_RuntimeKeysReady = true;
}
+
+ /* reset index scan */
+ index_rescan(node->biss_ScanDesc, node->biss_ScanKeys);
}
/* ----------------------------------------------------------------
@@ -178,6 +160,15 @@ ExecBitmapIndexReScan(BitmapIndexScanState *node, ExprContext *exprCtxt)
void
ExecEndBitmapIndexScan(BitmapIndexScanState *node)
{
+ Relation indexRelationDesc;
+ IndexScanDesc indexScanDesc;
+
+ /*
+ * extract information from the node
+ */
+ indexRelationDesc = node->biss_RelationDesc;
+ indexScanDesc = node->biss_ScanDesc;
+
/*
* Free the exprcontext ... now dead code, see ExecFreeExprContext
*/
@@ -185,6 +176,12 @@ ExecEndBitmapIndexScan(BitmapIndexScanState *node)
if (node->biss_RuntimeContext)
FreeExprContext(node->biss_RuntimeContext);
#endif
+
+ /*
+ * close the index relation
+ */
+ index_endscan(indexScanDesc);
+ index_close(indexRelationDesc);
}
/* ----------------------------------------------------------------
@@ -272,10 +269,27 @@ ExecInitBitmapIndexScan(BitmapIndexScan *node, EState *estate)
indexstate->biss_RuntimeContext = NULL;
}
- /* We don't keep the table or index open across calls */
+ /*
+ * 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.
+ */
+
indexstate->ss.ss_currentRelation = NULL;
indexstate->ss.ss_currentScanDesc = NULL;
+ /*
+ * 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.
+ */
+ indexstate->biss_RelationDesc = index_open(node->indexid);
+ indexstate->biss_ScanDesc =
+ index_beginscan_multi(indexstate->biss_RelationDesc,
+ estate->es_snapshot,
+ numScanKeys,
+ scanKeys);
+
/*
* all done.
*/
diff --git a/src/include/nodes/execnodes.h b/src/include/nodes/execnodes.h
index 1280aff0ca0..2d74d25a361 100644
--- a/src/include/nodes/execnodes.h
+++ b/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 1.130 2005/04/28 21:47:17 tgl Exp $
+ * $PostgreSQL: pgsql/src/include/nodes/execnodes.h,v 1.131 2005/05/05 03:37:23 tgl Exp $
*
*-------------------------------------------------------------------------
*/
@@ -897,6 +897,8 @@ 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 index relation descriptor
+ * ScanDesc index scan descriptor
* ----------------
*/
typedef struct BitmapIndexScanState
@@ -908,6 +910,8 @@ typedef struct BitmapIndexScanState
ExprState **biss_RuntimeKeyInfo;
ExprContext *biss_RuntimeContext;
bool biss_RuntimeKeysReady;
+ Relation biss_RelationDesc;
+ IndexScanDesc biss_ScanDesc;
} BitmapIndexScanState;
/* ----------------
--
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