postgresql/src/backend/executor/nodeBitmapIndexscan.c

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/*-------------------------------------------------------------------------
*
* nodeBitmapIndexscan.c
* Routines to support bitmapped index scans of relations
*
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* Portions Copyright (c) 1996-2017, PostgreSQL Global Development Group
* Portions Copyright (c) 1994, Regents of the University of California
*
*
* IDENTIFICATION
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* src/backend/executor/nodeBitmapIndexscan.c
*
*-------------------------------------------------------------------------
*/
/*
* INTERFACE ROUTINES
* MultiExecBitmapIndexScan scans a relation using index.
* ExecInitBitmapIndexScan creates and initializes state info.
* ExecReScanBitmapIndexScan prepares to rescan the plan.
* ExecEndBitmapIndexScan releases all storage.
*/
#include "postgres.h"
#include "executor/execdebug.h"
#include "executor/nodeBitmapIndexscan.h"
#include "executor/nodeIndexscan.h"
#include "miscadmin.h"
#include "utils/memutils.h"
/* ----------------------------------------------------------------
* MultiExecBitmapIndexScan(node)
* ----------------------------------------------------------------
*/
Node *
MultiExecBitmapIndexScan(BitmapIndexScanState *node)
{
TIDBitmap *tbm;
IndexScanDesc scandesc;
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;
/*
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* 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
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* 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);
doscan = node->biss_RuntimeKeysReady;
}
else
doscan = true;
/*
* Prepare the result bitmap. Normally we just create a new one to pass
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* 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;
Phase 2 of pgindent updates. Change pg_bsd_indent to follow upstream rules for placement of comments to the right of code, and remove pgindent hack that caused comments following #endif to not obey the general rule. Commit e3860ffa4dd0dad0dd9eea4be9cc1412373a8c89 wasn't actually using the published version of pg_bsd_indent, but a hacked-up version that tried to minimize the amount of movement of comments to the right of code. The situation of interest is where such a comment has to be moved to the right of its default placement at column 33 because there's code there. BSD indent has always moved right in units of tab stops in such cases --- but in the previous incarnation, indent was working in 8-space tab stops, while now it knows we use 4-space tabs. So the net result is that in about half the cases, such comments are placed one tab stop left of before. This is better all around: it leaves more room on the line for comment text, and it means that in such cases the comment uniformly starts at the next 4-space tab stop after the code, rather than sometimes one and sometimes two tabs after. Also, ensure that comments following #endif are indented the same as comments following other preprocessor commands such as #else. That inconsistency turns out to have been self-inflicted damage from a poorly-thought-through post-indent "fixup" in pgindent. This patch is much less interesting than the first round of indent changes, but also bulkier, so I thought it best to separate the effects. Discussion: https://postgr.es/m/E1dAmxK-0006EE-1r@gemulon.postgresql.org Discussion: https://postgr.es/m/30527.1495162840@sss.pgh.pa.us
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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,
((BitmapIndexScan *) node->ss.ps.plan)->isshared ?
node->ss.ps.state->es_query_dsa : NULL);
}
/*
* Get TIDs from index and insert into bitmap
*/
while (doscan)
{
nTuples += (double) index_getbitmap(scandesc, tbm);
CHECK_FOR_INTERRUPTS();
doscan = ExecIndexAdvanceArrayKeys(node->biss_ArrayKeys,
node->biss_NumArrayKeys);
if (doscan) /* reset index scan */
index_rescan(node->biss_ScanDesc,
node->biss_ScanKeys, node->biss_NumScanKeys,
NULL, 0);
}
/* must provide our own instrumentation support */
if (node->ss.ps.instrument)
InstrStopNode(node->ss.ps.instrument, nTuples);
return (Node *) tbm;
}
/* ----------------------------------------------------------------
* ExecReScanBitmapIndexScan(node)
*
* Recalculates the values of any scan keys whose value depends on
* information known at runtime, then rescans the indexed relation.
* ----------------------------------------------------------------
*/
void
ExecReScanBitmapIndexScan(BitmapIndexScanState *node)
{
ExprContext *econtext = node->biss_RuntimeContext;
/*
* 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.
*/
if (econtext)
ResetExprContext(econtext);
/*
* If we are doing runtime key calculations (ie, any of the index key
* values weren't simple Consts), compute the new key values.
*
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* 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, node->biss_NumScanKeys,
NULL, 0);
}
/* ----------------------------------------------------------------
* 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, true);
#endif
/*
* close the index relation (no-op if we didn't open it)
*/
if (indexScanDesc)
index_endscan(indexScanDesc);
if (indexRelationDesc)
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).
*/
/*
* We do not open or lock the base relation here. We assume that an
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* 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;
/*
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* If we are just doing EXPLAIN (ie, aren't going to run the plan), stop
* here. This allows an index-advisor plugin to EXPLAIN a plan containing
* references to nonexistent indexes.
*/
if (eflags & EXEC_FLAG_EXPLAIN_ONLY)
return indexstate;
/*
* 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;
indexstate->biss_RuntimeKeys = NULL;
indexstate->biss_NumRuntimeKeys = 0;
/*
* build the index scan keys from the index qualification
*/
ExecIndexBuildScanKeys((PlanState *) indexstate,
indexstate->biss_RelationDesc,
node->indexqual,
false,
&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_bitmap(indexstate->biss_RelationDesc,
estate->es_snapshot,
indexstate->biss_NumScanKeys);
/*
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* If no run-time keys to calculate, go ahead and pass the scankeys to the
* index AM.
*/
if (indexstate->biss_NumRuntimeKeys == 0 &&
indexstate->biss_NumArrayKeys == 0)
index_rescan(indexstate->biss_ScanDesc,
indexstate->biss_ScanKeys, indexstate->biss_NumScanKeys,
NULL, 0);
/*
* all done.
*/
return indexstate;
}