/*-------------------------------------------------------------------------
*
* nodeBitmapIndexscan.c
* Routines to support bitmapped index scans of relations
*
* Portions Copyright (c) 1996-2006, PostgreSQL Global Development Group
* Portions Copyright (c) 1994, Regents of the University of California
*
*
* IDENTIFICATION
* $PostgreSQL: pgsql/src/backend/executor/nodeBitmapIndexscan.c,v 1.20 2006/07/31 20:09:04 tgl Exp $
*
*-------------------------------------------------------------------------
*/
/*
* INTERFACE ROUTINES
* MultiExecBitmapIndexScan scans a relation using index.
* ExecInitBitmapIndexScan creates and initializes state info.
* ExecBitmapIndexReScan prepares to rescan the plan.
* ExecEndBitmapIndexScan releases all storage.
*/
#include "postgres.h"
#include "access/genam.h"
#include "executor/execdebug.h"
#include "executor/instrument.h"
#include "executor/nodeBitmapIndexscan.h"
#include "executor/nodeIndexscan.h"
#include "miscadmin.h"
#include "utils/memutils.h"
/* ----------------------------------------------------------------
* MultiExecBitmapIndexScan(node)
* ----------------------------------------------------------------
*/
Node *
MultiExecBitmapIndexScan(BitmapIndexScanState *node)
{
#define MAX_TIDS 1024
TIDBitmap *tbm;
IndexScanDesc scandesc;
ItemPointerData tids[MAX_TIDS];
int32 ntids;
double nTuples = 0;
bool doscan;
/* must provide our own instrumentation support */
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.
* Array keys are also treated as runtime keys; note that if ExecReScan
* returns with biss_RuntimeKeysReady still false, then there is an
* empty array key so we should do nothing.
*/
if (!node->biss_RuntimeKeysReady &&
(node->biss_NumRuntimeKeys != 0 || node->biss_NumArrayKeys != 0))
{
ExecReScan((PlanState *) node, NULL);
doscan = node->biss_RuntimeKeysReady;
}
else
doscan = true;
/*
* 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 into
* node->biss_result, in which case we just OR our tuple IDs into the
* existing bitmap. (This saves needing explicit UNION steps.)
*/
if (node->biss_result)
{
tbm = node->biss_result;
node->biss_result = NULL; /* reset for next time */
}
else
{
/* XXX should we use less than work_mem for this? */
tbm = tbm_create(work_mem * 1024L);
}
/*
* Get TIDs from index and insert into bitmap
*/
while (doscan)
{
bool more = index_getmulti(scandesc, tids, MAX_TIDS, &ntids);
if (ntids > 0)
{
tbm_add_tuples(tbm, tids, ntids);
nTuples += ntids;
}
CHECK_FOR_INTERRUPTS();
if (!more)
{
doscan = ExecIndexAdvanceArrayKeys(node->biss_ArrayKeys,
node->biss_NumArrayKeys);
if (doscan) /* reset index scan */
index_rescan(node->biss_ScanDesc, node->biss_ScanKeys);
}
}
/* must provide our own instrumentation support */
if (node->ss.ps.instrument)
InstrStopNode(node->ss.ps.instrument, nTuples);
return (Node *) tbm;
}
/* ----------------------------------------------------------------
* ExecBitmapIndexReScan(node)
*
* Recalculates the value of the scan keys whose value depends on
* information known at runtime and rescans the indexed relation.
* ----------------------------------------------------------------
*/
void
ExecBitmapIndexReScan(BitmapIndexScanState *node, ExprContext *exprCtxt)
{
ExprContext *econtext;
econtext = node->biss_RuntimeContext; /* context for runtime keys */
if (econtext)
{
/*
* If we are being passed an outer tuple, save it for runtime key
* calc.
*/
if (exprCtxt != NULL)
econtext->ecxt_outertuple = exprCtxt->ecxt_outertuple;
/*
* Reset the runtime-key context so we don't leak memory as each outer
* tuple is scanned. Note this assumes that we will recalculate *all*
* runtime keys on each call.
*/
ResetExprContext(econtext);
}
/*
* If we are doing runtime key calculations (ie, the index keys depend on
* data from an outer scan), compute the new key values.
*
* Array keys are also treated as runtime keys; note that if we
* return with biss_RuntimeKeysReady still false, then there is an
* empty array key so no index scan is needed.
*/
if (node->biss_NumRuntimeKeys != 0)
ExecIndexEvalRuntimeKeys(econtext,
node->biss_RuntimeKeys,
node->biss_NumRuntimeKeys);
if (node->biss_NumArrayKeys != 0)
node->biss_RuntimeKeysReady =
ExecIndexEvalArrayKeys(econtext,
node->biss_ArrayKeys,
node->biss_NumArrayKeys);
else
node->biss_RuntimeKeysReady = true;
/* reset index scan */
if (node->biss_RuntimeKeysReady)
index_rescan(node->biss_ScanDesc, node->biss_ScanKeys);
}
/* ----------------------------------------------------------------
* ExecEndBitmapIndexScan
* ----------------------------------------------------------------
*/
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
*/
#ifdef NOT_USED
if (node->biss_RuntimeContext)
FreeExprContext(node->biss_RuntimeContext);
#endif
/*
* close the index relation
*/
index_endscan(indexScanDesc);
index_close(indexRelationDesc, NoLock);
}
/* ----------------------------------------------------------------
* ExecInitBitmapIndexScan
*
* Initializes the index scan's state information.
* ----------------------------------------------------------------
*/
BitmapIndexScanState *
ExecInitBitmapIndexScan(BitmapIndexScan *node, EState *estate, int eflags)
{
BitmapIndexScanState *indexstate;
bool relistarget;
/* check for unsupported flags */
Assert(!(eflags & (EXEC_FLAG_BACKWARD | EXEC_FLAG_MARK)));
/*
* create state structure
*/
indexstate = makeNode(BitmapIndexScanState);
indexstate->ss.ps.plan = (Plan *) node;
indexstate->ss.ps.state = estate;
/* normally we don't make the result bitmap till runtime */
indexstate->biss_result = NULL;
/*
* Miscellaneous initialization
*
* We do not need a standard exprcontext for this node, though we may
* decide below to create a runtime-key exprcontext
*/
/*
* initialize child expressions
*
* We don't need to initialize targetlist or qual since neither are used.
*
* Note: we don't initialize all of the indexqual expression, only the
* sub-parts corresponding to runtime keys (see below).
*/
#define BITMAPINDEXSCAN_NSLOTS 0
/*
* We do not open or lock the base relation here. We assume that an
* ancestor BitmapHeapScan node is holding AccessShareLock (or better)
* 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.
*
* If the parent table is one of the target relations of the query, then
* InitPlan already opened and write-locked the index, so we can avoid
* taking another lock here. Otherwise we need a normal reader's lock.
*/
relistarget = ExecRelationIsTargetRelation(estate, node->scan.scanrelid);
indexstate->biss_RelationDesc = index_open(node->indexid,
relistarget ? NoLock : AccessShareLock);
/*
* Initialize index-specific scan state
*/
indexstate->biss_RuntimeKeysReady = false;
/*
* build the index scan keys from the index qualification
*/
ExecIndexBuildScanKeys((PlanState *) indexstate,
indexstate->biss_RelationDesc,
node->indexqual,
node->indexstrategy,
node->indexsubtype,
&indexstate->biss_ScanKeys,
&indexstate->biss_NumScanKeys,
&indexstate->biss_RuntimeKeys,
&indexstate->biss_NumRuntimeKeys,
&indexstate->biss_ArrayKeys,
&indexstate->biss_NumArrayKeys);
/*
* If we have runtime keys or array keys, we need an ExprContext to
* evaluate them. We could just create a "standard" plan node exprcontext,
* but to keep the code looking similar to nodeIndexscan.c, it seems
* better to stick with the approach of using a separate ExprContext.
*/
if (indexstate->biss_NumRuntimeKeys != 0 ||
indexstate->biss_NumArrayKeys != 0)
{
ExprContext *stdecontext = indexstate->ss.ps.ps_ExprContext;
ExecAssignExprContext(estate, &indexstate->ss.ps);
indexstate->biss_RuntimeContext = indexstate->ss.ps.ps_ExprContext;
indexstate->ss.ps.ps_ExprContext = stdecontext;
}
else
{
indexstate->biss_RuntimeContext = NULL;
}
/*
* Initialize scan descriptor.
*/
indexstate->biss_ScanDesc =
index_beginscan_multi(indexstate->biss_RelationDesc,
estate->es_snapshot,
indexstate->biss_NumScanKeys,
indexstate->biss_ScanKeys);
/*
* all done.
*/
return indexstate;
}
int
ExecCountSlotsBitmapIndexScan(BitmapIndexScan *node)
{
return ExecCountSlotsNode(outerPlan((Plan *) node)) +
ExecCountSlotsNode(innerPlan((Plan *) node)) + BITMAPINDEXSCAN_NSLOTS;
}