database/postgres
database/postgres
1
0
Fork 0
mirror of https://github.com/postgres/postgres.git synced 2025-04-21 12:05:57 +03:00
Code

Support parallel bitmap heap scans.

Browse Source 
The index is scanned by a single process, but then all cooperating
processes can iterate jointly over the resulting set of heap blocks.
In the future, we might also want to support using a parallel bitmap
index scan to set up for a parallel bitmap heap scan, but that's a
job for another day.

Dilip Kumar, with some corrections and cosmetic changes by me.  The
larger patch set of which this is a part has been reviewed and tested
by (at least) Andres Freund, Amit Khandekar, Tushar Ahuja, Rafia
Sabih, Haribabu Kommi, Thomas Munro, and me.

Discussion: http://postgr.es/m/CAFiTN-uc4=0WxRGfCzs-xfkMYcSEWUC-Fon6thkJGjkh9i=13A@mail.gmail.com
This commit is contained in:
Robert Haas 2017-03-08 12:05:43 -05:00
parent 4eafdcc276
commit f35742ccb7
24 changed files with 615 additions and 58 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

6
doc/src/sgml/monitoring.sgml
View File

@ -1211,7 +1211,7 @@ postgres 27093 0.0 0.0 30096 2752 ? Ss 11:34 0:00 postgres: ser
<entry>Waiting in an extension.</entry>
</row>
<row>
<entry morerows="10"><literal>IPC</></entry>
<entry morerows="11"><literal>IPC</></entry>
<entry><literal>BgWorkerShutdown</></entry>
<entry>Waiting for background worker to shut down.</entry>
</row>
@ -1247,6 +1247,10 @@ postgres 27093 0.0 0.0 30096 2752 ? Ss 11:34 0:00 postgres: ser
<entry><literal>ParallelFinish</></entry>
<entry>Waiting for parallel workers to finish computing.</entry>
</row>
<row>
<entry><literal>ParallelBitmapPopulate</></entry>
<entry>Waiting for the leader to populate the TidBitmap.</entry>
</row>
<row>
<entry><literal>SafeSnapshot</></entry>
<entry>Waiting for a snapshot for a <literal>READ ONLY DEFERRABLE</> transaction.</entry>

16
src/backend/access/heap/heapam.c
View File

@ -1753,6 +1753,22 @@ retry:
return page;
}
/* ----------------
* heap_update_snapshot
*
* Update snapshot info in heap scan descriptor.
* ----------------
*/
void
heap_update_snapshot(HeapScanDesc scan, Snapshot snapshot)
{
Assert(IsMVCCSnapshot(snapshot));
RegisterSnapshot(snapshot);
scan->rs_snapshot = snapshot;
scan->rs_temp_snap = true;
}
/* ----------------
* heap_getnext - retrieve next tuple in scan
*

14
src/backend/executor/execParallel.c
View File

@ -25,6 +25,7 @@
#include "executor/execParallel.h"
#include "executor/executor.h"
#include "executor/nodeBitmapHeapscan.h"
#include "executor/nodeCustom.h"
#include "executor/nodeForeignscan.h"
#include "executor/nodeSeqscan.h"
@ -217,6 +218,10 @@ ExecParallelEstimate(PlanState *planstate, ExecParallelEstimateContext *e)
ExecCustomScanEstimate((CustomScanState *) planstate,
e->pcxt);
break;
case T_BitmapHeapScanState:
ExecBitmapHeapEstimate((BitmapHeapScanState *) planstate,
e->pcxt);
break;
default:
break;
}
@ -277,6 +282,11 @@ ExecParallelInitializeDSM(PlanState *planstate,
ExecCustomScanInitializeDSM((CustomScanState *) planstate,
d->pcxt);
break;
case T_BitmapHeapScanState:
ExecBitmapHeapInitializeDSM((BitmapHeapScanState *) planstate,
d->pcxt);
break;
default:
break;
}
@ -775,6 +785,10 @@ ExecParallelInitializeWorker(PlanState *planstate, shm_toc *toc)
ExecCustomScanInitializeWorker((CustomScanState *) planstate,
toc);
break;
case T_BitmapHeapScanState:
ExecBitmapHeapInitializeWorker(
(BitmapHeapScanState *) planstate, toc);
break;
default:
break;
}

428
src/backend/executor/nodeBitmapHeapscan.c
View File

@ -53,11 +53,15 @@
static TupleTableSlot *BitmapHeapNext(BitmapHeapScanState *node);
static void bitgetpage(HeapScanDesc scan, TBMIterateResult *tbmres);
static inline void BitmapDoneInitializingSharedState(
ParallelBitmapHeapState *pstate);
static inline void BitmapAdjustPrefetchIterator(BitmapHeapScanState *node,
TBMIterateResult *tbmres);
static inline void BitmapAdjustPrefetchTarget(BitmapHeapScanState *node);
static inline void BitmapPrefetch(BitmapHeapScanState *node,
HeapScanDesc scan);
static bool BitmapShouldInitializeSharedState(
ParallelBitmapHeapState *pstate);
/* ----------------------------------------------------------------
@ -73,9 +77,12 @@ BitmapHeapNext(BitmapHeapScanState *node)
HeapScanDesc scan;
TIDBitmap *tbm;
TBMIterator *tbmiterator;
TBMSharedIterator *shared_tbmiterator;
TBMIterateResult *tbmres;
OffsetNumber targoffset;
TupleTableSlot *slot;
ParallelBitmapHeapState *pstate = node->pstate;
dsa_area *dsa = node->ss.ps.state->es_query_dsa;
/*
* extract necessary information from index scan node
@ -84,7 +91,10 @@ BitmapHeapNext(BitmapHeapScanState *node)
slot = node->ss.ss_ScanTupleSlot;
scan = node->ss.ss_currentScanDesc;
tbm = node->tbm;
tbmiterator = node->tbmiterator;
if (pstate == NULL)
tbmiterator = node->tbmiterator;
else
shared_tbmiterator = node->shared_tbmiterator;
tbmres = node->tbmres;
/*
@ -99,25 +109,82 @@ BitmapHeapNext(BitmapHeapScanState *node)
* node->prefetch_maximum. This is to avoid doing a lot of prefetching in
* a scan that stops after a few tuples because of a LIMIT.
*/
if (tbm == NULL)
if (!node->initialized)
{
tbm = (TIDBitmap *) MultiExecProcNode(outerPlanState(node));
if (!pstate)
{
tbm = (TIDBitmap *) MultiExecProcNode(outerPlanState(node));
if (!tbm || !IsA(tbm, TIDBitmap))
elog(ERROR, "unrecognized result from subplan");
if (!tbm || !IsA(tbm, TIDBitmap))
elog(ERROR, "unrecognized result from subplan");
node->tbm = tbm;
node->tbmiterator = tbmiterator = tbm_begin_iterate(tbm);
node->tbmres = tbmres = NULL;
node->tbm = tbm;
node->tbmiterator = tbmiterator = tbm_begin_iterate(tbm);
node->tbmres = tbmres = NULL;
#ifdef USE_PREFETCH
if (node->prefetch_maximum > 0)
{
node->prefetch_iterator = tbm_begin_iterate(tbm);
node->prefetch_pages = 0;
node->prefetch_target = -1;
}
if (node->prefetch_maximum > 0)
{
node->prefetch_iterator = tbm_begin_iterate(tbm);
node->prefetch_pages = 0;
node->prefetch_target = -1;
}
#endif /* USE_PREFETCH */
}
else
{
/*
* The leader will immediately come out of the function, but
* others will be blocked until leader populates the TBM and wakes
* them up.
*/
if (BitmapShouldInitializeSharedState(pstate))
{
tbm = (TIDBitmap *) MultiExecProcNode(outerPlanState(node));
if (!tbm || !IsA(tbm, TIDBitmap))
elog(ERROR, "unrecognized result from subplan");
node->tbm = tbm;
/*
* Prepare to iterate over the TBM. This will return the
* dsa_pointer of the iterator state which will be used by
* multiple processes to iterate jointly.
*/
pstate->tbmiterator = tbm_prepare_shared_iterate(tbm);
#ifdef USE_PREFETCH
if (node->prefetch_maximum > 0)
{
pstate->prefetch_iterator =
tbm_prepare_shared_iterate(tbm);
/*
* We don't need the mutex here as we haven't yet woke up
* others.
*/
pstate->prefetch_pages = 0;
pstate->prefetch_target = -1;
}
#endif
/* We have initialized the shared state so wake up others. */
BitmapDoneInitializingSharedState(pstate);
}
/* Allocate a private iterator and attach the shared state to it */
node->shared_tbmiterator = shared_tbmiterator =
tbm_attach_shared_iterate(dsa, pstate->tbmiterator);
node->tbmres = tbmres = NULL;
#ifdef USE_PREFETCH
if (node->prefetch_maximum > 0)
{
node->shared_prefetch_iterator =
tbm_attach_shared_iterate(dsa, pstate->prefetch_iterator);
}
#endif /* USE_PREFETCH */
}
node->initialized = true;
}
for (;;)
@ -130,7 +197,10 @@ BitmapHeapNext(BitmapHeapScanState *node)
*/
if (tbmres == NULL)
{
node->tbmres = tbmres = tbm_iterate(tbmiterator);
if (!pstate)
node->tbmres = tbmres = tbm_iterate(tbmiterator);
else
node->tbmres = tbmres = tbm_shared_iterate(shared_tbmiterator);
if (tbmres == NULL)
{
/* no more entries in the bitmap */
@ -182,8 +252,19 @@ BitmapHeapNext(BitmapHeapScanState *node)
* Try to prefetch at least a few pages even before we get to the
* second page if we don't stop reading after the first tuple.
*/
if (node->prefetch_target < node->prefetch_maximum)
node->prefetch_target++;
if (!pstate)
{
if (node->prefetch_target < node->prefetch_maximum)
node->prefetch_target++;
}
else if (pstate->prefetch_target < node->prefetch_maximum)
{
/* take spinlock while updating shared state */
SpinLockAcquire(&pstate->mutex);
if (pstate->prefetch_target < node->prefetch_maximum)
pstate->prefetch_target++;
SpinLockRelease(&pstate->mutex);
}
#endif /* USE_PREFETCH */
}
@ -361,6 +442,21 @@ bitgetpage(HeapScanDesc scan, TBMIterateResult *tbmres)
scan->rs_ntuples = ntup;
}
/*
* BitmapDoneInitializingSharedState - Shared state is initialized
*
* By this time the leader has already populated the TBM and initialized the
* shared state so wake up other processes.
*/
static inline void
BitmapDoneInitializingSharedState(ParallelBitmapHeapState *pstate)
{
SpinLockAcquire(&pstate->mutex);
pstate->state = BM_FINISHED;
SpinLockRelease(&pstate->mutex);
ConditionVariableBroadcast(&pstate->cv);
}
/*
* BitmapAdjustPrefetchIterator - Adjust the prefetch iterator
*/
@ -369,20 +465,53 @@ BitmapAdjustPrefetchIterator(BitmapHeapScanState *node,
TBMIterateResult *tbmres)
{
#ifdef USE_PREFETCH
TBMIterator *prefetch_iterator = node->prefetch_iterator;
ParallelBitmapHeapState *pstate = node->pstate;
if (node->prefetch_pages > 0)
if (pstate == NULL)
{
/* The main iterator has closed the distance by one page */
node->prefetch_pages--;
TBMIterator *prefetch_iterator = node->prefetch_iterator;
if (node->prefetch_pages > 0)
{
/* The main iterator has closed the distance by one page */
node->prefetch_pages--;
}
else if (prefetch_iterator)
{
/* Do not let the prefetch iterator get behind the main one */
TBMIterateResult *tbmpre = tbm_iterate(prefetch_iterator);
if (tbmpre == NULL || tbmpre->blockno != tbmres->blockno)
elog(ERROR, "prefetch and main iterators are out of sync");
}
return;
}
else if (prefetch_iterator)
{
/* Do not let the prefetch iterator get behind the main one */
TBMIterateResult *tbmpre = tbm_iterate(prefetch_iterator);
if (tbmpre == NULL || tbmpre->blockno != tbmres->blockno)
elog(ERROR, "prefetch and main iterators are out of sync");
if (node->prefetch_maximum > 0)
{
TBMSharedIterator *prefetch_iterator = node->shared_prefetch_iterator;
SpinLockAcquire(&pstate->mutex);
if (pstate->prefetch_pages > 0)
{
node->prefetch_pages--;
SpinLockRelease(&pstate->mutex);
}
else
{
/* Release the mutex before iterating */
SpinLockRelease(&pstate->mutex);
/*
* In case of shared mode, we can not ensure that the current
* blockno of the main iterator and that of the prefetch iterator
* are same. It's possible that whatever blockno we are
* prefetching will be processed by another process. Therefore, we
* don't validate the blockno here as we do in non-parallel case.
*/
if (prefetch_iterator)
tbm_shared_iterate(prefetch_iterator);
}
}
#endif /* USE_PREFETCH */
}
@ -399,14 +528,35 @@ static inline void
BitmapAdjustPrefetchTarget(BitmapHeapScanState *node)
{
#ifdef USE_PREFETCH
if (node->prefetch_target >= node->prefetch_maximum)
/* don't increase any further */ ;
else if (node->prefetch_target >= node->prefetch_maximum / 2)
node->prefetch_target = node->prefetch_maximum;
else if (node->prefetch_target > 0)
node->prefetch_target *= 2;
else
node->prefetch_target++;
ParallelBitmapHeapState *pstate = node->pstate;
if (pstate == NULL)
{
if (node->prefetch_target >= node->prefetch_maximum)
/* don't increase any further */ ;
else if (node->prefetch_target >= node->prefetch_maximum / 2)
node->prefetch_target = node->prefetch_maximum;
else if (node->prefetch_target > 0)
node->prefetch_target *= 2;
else
node->prefetch_target++;
return;
}
/* Do an unlocked check first to save spinlock acquisitions. */
if (pstate->prefetch_target < node->prefetch_maximum)
{
SpinLockAcquire(&pstate->mutex);
if (pstate->prefetch_target >= node->prefetch_maximum)
/* don't increase any further */ ;
else if (pstate->prefetch_target >= node->prefetch_maximum / 2)
pstate->prefetch_target = node->prefetch_maximum;
else if (pstate->prefetch_target > 0)
pstate->prefetch_target *= 2;
else
pstate->prefetch_target++;
SpinLockRelease(&pstate->mutex);
}
#endif /* USE_PREFETCH */
}
@ -417,23 +567,70 @@ static inline void
BitmapPrefetch(BitmapHeapScanState *node, HeapScanDesc scan)
{
#ifdef USE_PREFETCH
TBMIterator *prefetch_iterator = node->prefetch_iterator;
ParallelBitmapHeapState *pstate = node->pstate;
if (prefetch_iterator)
if (pstate == NULL)
{
while (node->prefetch_pages < node->prefetch_target)
{
TBMIterateResult *tbmpre = tbm_iterate(prefetch_iterator);
TBMIterator *prefetch_iterator = node->prefetch_iterator;
if (tbmpre == NULL)
if (prefetch_iterator)
{
while (node->prefetch_pages < node->prefetch_target)
{
/* No more pages to prefetch */
tbm_end_iterate(prefetch_iterator);
node->prefetch_iterator = NULL;
break;
TBMIterateResult *tbmpre = tbm_iterate(prefetch_iterator);
if (tbmpre == NULL)
{
/* No more pages to prefetch */
tbm_end_iterate(prefetch_iterator);
node->prefetch_iterator = NULL;
break;
}
node->prefetch_pages++;
PrefetchBuffer(scan->rs_rd, MAIN_FORKNUM, tbmpre->blockno);
}
}
return;
}
if (pstate->prefetch_pages < pstate->prefetch_target)
{
TBMSharedIterator *prefetch_iterator = node->shared_prefetch_iterator;
if (prefetch_iterator)
{
while (1)
{
TBMIterateResult *tbmpre;
bool do_prefetch = false;
/*
* Recheck under the mutex. If some other process has already
* done enough prefetching then we need not to do anything.
*/
SpinLockAcquire(&pstate->mutex);
if (pstate->prefetch_pages < pstate->prefetch_target)
{
pstate->prefetch_pages++;
do_prefetch = true;
}
SpinLockRelease(&pstate->mutex);
if (!do_prefetch)
return;
tbmpre = tbm_shared_iterate(prefetch_iterator);
if (tbmpre == NULL)
{
/* No more pages to prefetch */
tbm_end_shared_iterate(prefetch_iterator);
node->shared_prefetch_iterator = NULL;
break;
}
PrefetchBuffer(scan->rs_rd, MAIN_FORKNUM, tbmpre->blockno);
}
node->prefetch_pages++;
PrefetchBuffer(scan->rs_rd, MAIN_FORKNUM, tbmpre->blockno);
}
}
#endif /* USE_PREFETCH */
@ -488,12 +685,36 @@ ExecReScanBitmapHeapScan(BitmapHeapScanState *node)
tbm_end_iterate(node->tbmiterator);
if (node->prefetch_iterator)
tbm_end_iterate(node->prefetch_iterator);
if (node->shared_tbmiterator)
tbm_end_shared_iterate(node->shared_tbmiterator);
if (node->shared_prefetch_iterator)
tbm_end_shared_iterate(node->shared_prefetch_iterator);
if (node->tbm)
tbm_free(node->tbm);
node->tbm = NULL;
node->tbmiterator = NULL;
node->tbmres = NULL;
node->prefetch_iterator = NULL;
node->initialized = false;
node->shared_tbmiterator = NULL;
node->shared_prefetch_iterator = NULL;
/* Reset parallel bitmap state, if present */
if (node->pstate)
{
dsa_area *dsa = node->ss.ps.state->es_query_dsa;
node->pstate->state = BM_INITIAL;
if (DsaPointerIsValid(node->pstate->tbmiterator))
tbm_free_shared_area(dsa, node->pstate->tbmiterator);
if (DsaPointerIsValid(node->pstate->prefetch_iterator))
tbm_free_shared_area(dsa, node->pstate->prefetch_iterator);
node->pstate->tbmiterator = InvalidDsaPointer;
node->pstate->prefetch_iterator = InvalidDsaPointer;
}
ExecScanReScan(&node->ss);
@ -546,6 +767,10 @@ ExecEndBitmapHeapScan(BitmapHeapScanState *node)
tbm_end_iterate(node->prefetch_iterator);
if (node->tbm)
tbm_free(node->tbm);
if (node->shared_tbmiterator)
tbm_end_shared_iterate(node->shared_tbmiterator);
if (node->shared_prefetch_iterator)
tbm_end_shared_iterate(node->shared_prefetch_iterator);
/*
* close heap scan
@ -597,6 +822,10 @@ ExecInitBitmapHeapScan(BitmapHeapScan *node, EState *estate, int eflags)
scanstate->prefetch_target = 0;
/* may be updated below */
scanstate->prefetch_maximum = target_prefetch_pages;
scanstate->pscan_len = 0;
scanstate->initialized = false;
scanstate->shared_tbmiterator = NULL;
scanstate->pstate = NULL;
/*
* Miscellaneous initialization
@ -681,3 +910,108 @@ ExecInitBitmapHeapScan(BitmapHeapScan *node, EState *estate, int eflags)
*/
return scanstate;
}
/*----------------
* BitmapShouldInitializeSharedState
*
* The first process to come here and see the state to the BM_INITIAL
* will become the leader for the parallel bitmap scan and will be
* responsible for populating the TIDBitmap. The other processes will
* be blocked by the condition variable until the leader wakes them up.
* ---------------
*/
static bool
BitmapShouldInitializeSharedState(ParallelBitmapHeapState *pstate)
{
SharedBitmapState state;
while (1)
{
SpinLockAcquire(&pstate->mutex);
state = pstate->state;
if (pstate->state == BM_INITIAL)
pstate->state = BM_INPROGRESS;
SpinLockRelease(&pstate->mutex);
/* Exit if bitmap is done, or if we're the leader. */
if (state != BM_INPROGRESS)
break;
/* Wait for the leader to wake us up. */
ConditionVariableSleep(&pstate->cv, WAIT_EVENT_PARALLEL_BITMAP_SCAN);
}
ConditionVariableCancelSleep();
return (state == BM_INITIAL);
}
/* ----------------------------------------------------------------
* ExecBitmapHeapEstimate
*
* estimates the space required to serialize bitmap scan node.
* ----------------------------------------------------------------
*/
void
ExecBitmapHeapEstimate(BitmapHeapScanState *node,
ParallelContext *pcxt)
{
EState *estate = node->ss.ps.state;
node->pscan_len = add_size(offsetof(ParallelBitmapHeapState,
phs_snapshot_data),
EstimateSnapshotSpace(estate->es_snapshot));
shm_toc_estimate_chunk(&pcxt->estimator, node->pscan_len);
shm_toc_estimate_keys(&pcxt->estimator, 1);
}
/* ----------------------------------------------------------------
* ExecBitmapHeapInitializeDSM
*
* Set up a parallel bitmap heap scan descriptor.
* ----------------------------------------------------------------
*/
void
ExecBitmapHeapInitializeDSM(BitmapHeapScanState *node,
ParallelContext *pcxt)
{
ParallelBitmapHeapState *pstate;
EState *estate = node->ss.ps.state;
pstate = shm_toc_allocate(pcxt->toc, node->pscan_len);
pstate->tbmiterator = 0;
pstate->prefetch_iterator = 0;
/* Initialize the mutex */
SpinLockInit(&pstate->mutex);
pstate->prefetch_pages = 0;
pstate->prefetch_target = 0;
pstate->state = BM_INITIAL;
ConditionVariableInit(&pstate->cv);
SerializeSnapshot(estate->es_snapshot, pstate->phs_snapshot_data);
shm_toc_insert(pcxt->toc, node->ss.ps.plan->plan_node_id, pstate);
node->pstate = pstate;
}
/* ----------------------------------------------------------------
* ExecBitmapHeapInitializeWorker
*
* Copy relevant information from TOC into planstate.
* ----------------------------------------------------------------
*/
void
ExecBitmapHeapInitializeWorker(BitmapHeapScanState *node, shm_toc *toc)
{
ParallelBitmapHeapState *pstate;
Snapshot snapshot;
pstate = shm_toc_lookup(toc, node->ss.ps.plan->plan_node_id);
node->pstate = pstate;
snapshot = RestoreSnapshot(pstate->phs_snapshot_data);
heap_update_snapshot(node->ss.ss_currentScanDesc, snapshot);
}

4
src/backend/executor/nodeBitmapIndexscan.c
View File

@ -78,7 +78,9 @@ MultiExecBitmapIndexScan(BitmapIndexScanState *node)
else
{
/* XXX should we use less than work_mem for this? */
tbm = tbm_create(work_mem * 1024L, NULL);
tbm = tbm_create(work_mem * 1024L,
((BitmapIndexScan *) node->ss.ps.plan)->isshared ?
node->ss.ps.state->es_query_dsa : NULL);
}
/*

4
src/backend/executor/nodeBitmapOr.c
View File

@ -129,7 +129,9 @@ MultiExecBitmapOr(BitmapOrState *node)
if (result == NULL) /* first subplan */
{
/* XXX should we use less than work_mem for this? */
result = tbm_create(work_mem * 1024L, NULL);
result = tbm_create(work_mem * 1024L,
((BitmapOr *) node->ps.plan)->isshared ?
node->ps.state->es_query_dsa : NULL);
}
((BitmapIndexScanState *) subnode)->biss_result = result;

2
src/backend/nodes/copyfuncs.c
View File

@ -331,6 +331,7 @@ _copyBitmapOr(const BitmapOr *from)
/*
* copy remainder of node
*/
COPY_SCALAR_FIELD(isshared);
COPY_NODE_FIELD(bitmapplans);
return newnode;
@ -496,6 +497,7 @@ _copyBitmapIndexScan(const BitmapIndexScan *from)
* copy remainder of node
*/
COPY_SCALAR_FIELD(indexid);
COPY_SCALAR_FIELD(isshared);
COPY_NODE_FIELD(indexqual);
COPY_NODE_FIELD(indexqualorig);

2
src/backend/nodes/outfuncs.c
View File

@ -441,6 +441,7 @@ _outBitmapOr(StringInfo str, const BitmapOr *node)
_outPlanInfo(str, (const Plan *) node);
WRITE_BOOL_FIELD(isshared);
WRITE_NODE_FIELD(bitmapplans);
}
@ -520,6 +521,7 @@ _outBitmapIndexScan(StringInfo str, const BitmapIndexScan *node)
_outScanInfo(str, (const Scan *) node);
WRITE_OID_FIELD(indexid);
WRITE_BOOL_FIELD(isshared);
WRITE_NODE_FIELD(indexqual);
WRITE_NODE_FIELD(indexqualorig);
}

2
src/backend/nodes/readfuncs.c
View File

@ -1633,6 +1633,7 @@ _readBitmapOr(void)
ReadCommonPlan(&local_node->plan);
READ_BOOL_FIELD(isshared);
READ_NODE_FIELD(bitmapplans);
READ_DONE();
@ -1744,6 +1745,7 @@ _readBitmapIndexScan(void)
ReadCommonScan(&local_node->scan);
READ_OID_FIELD(indexid);
READ_BOOL_FIELD(isshared);
READ_NODE_FIELD(indexqual);
READ_NODE_FIELD(indexqualorig);

24
src/backend/optimizer/path/allpaths.c
View File

@ -2911,6 +2911,30 @@ remove_unused_subquery_outputs(Query *subquery, RelOptInfo *rel)
}
}
/*
* create_partial_bitmap_paths
* Build partial bitmap heap path for the relation
*/
void
create_partial_bitmap_paths(PlannerInfo *root, RelOptInfo *rel,
Path *bitmapqual)
{
int parallel_workers;
double pages_fetched;
/* Compute heap pages for bitmap heap scan */
pages_fetched = compute_bitmap_pages(root, rel, bitmapqual, 1.0,
NULL, NULL);
parallel_workers = compute_parallel_worker(rel, pages_fetched, 0);
if (parallel_workers <= 0)
return;
add_partial_path(rel, (Path *) create_bitmap_heap_path(root, rel,
bitmapqual, rel->lateral_relids, 1.0, parallel_workers));
}
/*
* Compute the number of parallel workers that should be used to scan a
* relation. We compute the parallel workers based on the size of the heap to

16
src/backend/optimizer/path/costsize.c
View File

@ -860,6 +860,7 @@ cost_bitmap_heap_scan(Path *path, PlannerInfo *root, RelOptInfo *baserel,
QualCost qpqual_cost;
Cost cpu_per_tuple;
Cost cost_per_page;
Cost cpu_run_cost;
double tuples_fetched;
double pages_fetched;
double spc_seq_page_cost,
@ -921,8 +922,21 @@ cost_bitmap_heap_scan(Path *path, PlannerInfo *root, RelOptInfo *baserel,
startup_cost += qpqual_cost.startup;
cpu_per_tuple = cpu_tuple_cost + qpqual_cost.per_tuple;
cpu_run_cost = cpu_per_tuple * tuples_fetched;
run_cost += cpu_per_tuple * tuples_fetched;
/* Adjust costing for parallelism, if used. */
if (path->parallel_workers > 0)
{
double parallel_divisor = get_parallel_divisor(path);
/* The CPU cost is divided among all the workers. */
cpu_run_cost /= parallel_divisor;
path->rows = clamp_row_est(path->rows / parallel_divisor);
}
run_cost += cpu_run_cost;
/* tlist eval costs are paid per output row, not per tuple scanned */
startup_cost += path->pathtarget->cost.startup;

19
src/backend/optimizer/path/indxpath.c
View File

@ -337,8 +337,12 @@ create_index_paths(PlannerInfo *root, RelOptInfo *rel)
bitmapqual = choose_bitmap_and(root, rel, bitindexpaths);
bpath = create_bitmap_heap_path(root, rel, bitmapqual,
rel->lateral_relids, 1.0);
rel->lateral_relids, 1.0, 0);
add_path(rel, (Path *) bpath);
/* create a partial bitmap heap path */
if (rel->consider_parallel && rel->lateral_relids == NULL)
create_partial_bitmap_paths(root, rel, bitmapqual);
}
/*
@ -410,7 +414,7 @@ create_index_paths(PlannerInfo *root, RelOptInfo *rel)
required_outer = get_bitmap_tree_required_outer(bitmapqual);
loop_count = get_loop_count(root, rel->relid, required_outer);
bpath = create_bitmap_heap_path(root, rel, bitmapqual,
required_outer, loop_count);
required_outer, loop_count, 0);
add_path(rel, (Path *) bpath);
}
}
@ -1617,6 +1621,11 @@ bitmap_scan_cost_est(PlannerInfo *root, RelOptInfo *rel, Path *ipath)
bpath.path.pathkeys = NIL;
bpath.bitmapqual = ipath;
/*
* Check the cost of temporary path without considering parallelism.
* Parallel bitmap heap path will be considered at later stage.
*/
bpath.path.parallel_workers = 0;
cost_bitmap_heap_scan(&bpath.path, root, rel,
bpath.path.param_info,
ipath,
@ -1659,6 +1668,12 @@ bitmap_and_cost_est(PlannerInfo *root, RelOptInfo *rel, List *paths)
bpath.path.pathkeys = NIL;
bpath.bitmapqual = (Path *) &apath;
/*
* Check the cost of temporary path without considering parallelism.
* Parallel bitmap heap path will be considered at later stage.
*/
bpath.path.parallel_workers = 0;
/* Now we can do cost_bitmap_heap_scan */
cost_bitmap_heap_scan(&bpath.path, root, rel,
bpath.path.param_info,

22
src/backend/optimizer/plan/createplan.c
View File

@ -125,6 +125,7 @@ static BitmapHeapScan *create_bitmap_scan_plan(PlannerInfo *root,
List *tlist, List *scan_clauses);
static Plan *create_bitmap_subplan(PlannerInfo *root, Path *bitmapqual,
List **qual, List **indexqual, List **indexECs);
static void bitmap_subplan_mark_shared(Plan *plan);
static TidScan *create_tidscan_plan(PlannerInfo *root, TidPath *best_path,
List *tlist, List *scan_clauses);
static SubqueryScan *create_subqueryscan_plan(PlannerInfo *root,
@ -2590,6 +2591,9 @@ create_bitmap_scan_plan(PlannerInfo *root,
&bitmapqualorig, &indexquals,
&indexECs);
if (best_path->path.parallel_aware)
bitmap_subplan_mark_shared(bitmapqualplan);
/*
* The qpqual list must contain all restrictions not automatically handled
* by the index, other than pseudoconstant clauses which will be handled
@ -4756,6 +4760,24 @@ label_sort_with_costsize(PlannerInfo *root, Sort *plan, double limit_tuples)
plan->plan.parallel_aware = false;
}
/*
* bitmap_subplan_mark_shared
* Set isshared flag in bitmap subplan so that it will be created in
* shared memory.
*/
static void
bitmap_subplan_mark_shared(Plan *plan)
{
if (IsA(plan, BitmapAnd))
bitmap_subplan_mark_shared(
linitial(((BitmapAnd *) plan)->bitmapplans));
else if (IsA(plan, BitmapOr))
((BitmapOr *) plan)->isshared = true;
else if (IsA(plan, BitmapIndexScan))
((BitmapIndexScan *) plan)->isshared = true;
else
elog(ERROR, "unrecognized node type: %d", nodeTag(plan));
}
/*****************************************************************************
*

9
src/backend/optimizer/util/pathnode.c
View File

@ -1068,7 +1068,8 @@ create_bitmap_heap_path(PlannerInfo *root,
RelOptInfo *rel,
Path *bitmapqual,
Relids required_outer,
double loop_count)
double loop_count,
int parallel_degree)
{
BitmapHeapPath *pathnode = makeNode(BitmapHeapPath);
@ -1077,9 +1078,9 @@ create_bitmap_heap_path(PlannerInfo *root,
pathnode->path.pathtarget = rel->reltarget;
pathnode->path.param_info = get_baserel_parampathinfo(root, rel,
required_outer);
pathnode->path.parallel_aware = false;
pathnode->path.parallel_aware = parallel_degree > 0 ? true : false;
pathnode->path.parallel_safe = rel->consider_parallel;
pathnode->path.parallel_workers = 0;
pathnode->path.parallel_workers = parallel_degree;
pathnode->path.pathkeys = NIL; /* always unordered */
pathnode->bitmapqual = bitmapqual;
@ -3281,7 +3282,7 @@ reparameterize_path(PlannerInfo *root, Path *path,
rel,
bpath->bitmapqual,
required_outer,
loop_count);
loop_count, 0);
}
case T_SubqueryScan:
{

3
src/backend/postmaster/pgstat.c
View File

@ -3395,6 +3395,9 @@ pgstat_get_wait_ipc(WaitEventIPC w)
case WAIT_EVENT_PARALLEL_FINISH:
event_name = "ParallelFinish";
break;
case WAIT_EVENT_PARALLEL_BITMAP_SCAN:
event_name = "ParallelBitmapScan";
break;
case WAIT_EVENT_SAFE_SNAPSHOT:
event_name = "SafeSnapshot";
break;

1
src/include/access/heapam.h
View File

@ -179,6 +179,7 @@ extern void simple_heap_update(Relation relation, ItemPointer otid,
HeapTuple tup);
extern void heap_sync(Relation relation);
extern void heap_update_snapshot(HeapScanDesc scan, Snapshot snapshot);
/* in heap/pruneheap.c */
extern void heap_page_prune_opt(Relation relation, Buffer buffer);

7
src/include/executor/nodeBitmapHeapscan.h
View File

@ -15,10 +15,17 @@
#define NODEBITMAPHEAPSCAN_H
#include "nodes/execnodes.h"
#include "access/parallel.h"
extern BitmapHeapScanState *ExecInitBitmapHeapScan(BitmapHeapScan *node, EState *estate, int eflags);
extern TupleTableSlot *ExecBitmapHeapScan(BitmapHeapScanState *node);
extern void ExecEndBitmapHeapScan(BitmapHeapScanState *node);
extern void ExecReScanBitmapHeapScan(BitmapHeapScanState *node);
extern void ExecBitmapHeapEstimate(BitmapHeapScanState *node,
ParallelContext *pcxt);
extern void ExecBitmapHeapInitializeDSM(BitmapHeapScanState *node,
ParallelContext *pcxt);
extern void ExecBitmapHeapInitializeWorker(BitmapHeapScanState *node,
shm_toc *toc);
#endif /* NODEBITMAPHEAPSCAN_H */

57
src/include/nodes/execnodes.h
View File

@ -26,6 +26,8 @@
#include "utils/sortsupport.h"
#include "utils/tuplestore.h"
#include "utils/tuplesort.h"
#include "nodes/tidbitmap.h"
#include "storage/condition_variable.h"
/* ----------------
@ -1464,6 +1466,51 @@ typedef struct BitmapIndexScanState
IndexScanDesc biss_ScanDesc;
} BitmapIndexScanState;
/* ----------------
* SharedBitmapState information
*
* BM_INITIAL TIDBitmap creation is not yet started, so first worker
* to see this state will set the state to BM_INPROGRESS
* and that process will be responsible for creating
* TIDBitmap.
* BM_INPROGRESS TIDBitmap creation is in progress; workers need to
* sleep until it's finished.
* BM_FINISHED TIDBitmap creation is done, so now all workers can
* proceed to iterate over TIDBitmap.
* ----------------
*/
typedef enum
{
BM_INITIAL,
BM_INPROGRESS,
BM_FINISHED
} SharedBitmapState;
/* ----------------
* ParallelBitmapHeapState information
* tbmiterator iterator for scanning current pages
* prefetch_iterator iterator for prefetching ahead of current page
* mutex mutual exclusion for the prefetching variable
* and state
* prefetch_pages # pages prefetch iterator is ahead of current
* prefetch_target current target prefetch distance
* state current state of the TIDBitmap
* cv conditional wait variable
* phs_snapshot_data snapshot data shared to workers
* ----------------
*/
typedef struct ParallelBitmapHeapState
{
dsa_pointer tbmiterator;
dsa_pointer prefetch_iterator;
slock_t mutex;
int prefetch_pages;
int prefetch_target;
SharedBitmapState state;
ConditionVariable cv;
char phs_snapshot_data[FLEXIBLE_ARRAY_MEMBER];
} ParallelBitmapHeapState;
/* ----------------
* BitmapHeapScanState information
*
@ -1477,6 +1524,11 @@ typedef struct BitmapIndexScanState
* prefetch_pages # pages prefetch iterator is ahead of current
* prefetch_target current target prefetch distance
* prefetch_maximum maximum value for prefetch_target
* pscan_len size of the shared memory for parallel bitmap
* initialized is node is ready to iterate
* shared_tbmiterator shared iterator
* shared_prefetch_iterator shared iterator for prefetching
* pstate shared state for parallel bitmap scan
* ----------------
*/
typedef struct BitmapHeapScanState
@ -1492,6 +1544,11 @@ typedef struct BitmapHeapScanState
int prefetch_pages;
int prefetch_target;
int prefetch_maximum;
Size pscan_len;
bool initialized;
TBMSharedIterator *shared_tbmiterator;
TBMSharedIterator *shared_prefetch_iterator;
ParallelBitmapHeapState *pstate;
} BitmapHeapScanState;
/* ----------------

2
src/include/nodes/plannodes.h
View File

@ -292,6 +292,7 @@ typedef struct BitmapAnd
typedef struct BitmapOr
{
Plan plan;
bool isshared;
List *bitmapplans;
} BitmapOr;
@ -420,6 +421,7 @@ typedef struct BitmapIndexScan
{
Scan scan;
Oid indexid; /* OID of index to scan */
bool isshared; /* Create shared bitmap if set */
List *indexqual; /* list of index quals (OpExprs) */
List *indexqualorig; /* the same in original form */
} BitmapIndexScan;

3
src/include/optimizer/pathnode.h
View File

@ -53,7 +53,8 @@ extern BitmapHeapPath *create_bitmap_heap_path(PlannerInfo *root,
RelOptInfo *rel,
Path *bitmapqual,
Relids required_outer,
double loop_count);
double loop_count,
int parallel_degree);
extern BitmapAndPath *create_bitmap_and_path(PlannerInfo *root,
RelOptInfo *rel,
List *bitmapquals);

2
src/include/optimizer/paths.h
View File

@ -56,6 +56,8 @@ extern RelOptInfo *standard_join_search(PlannerInfo *root, int levels_needed,
extern void generate_gather_paths(PlannerInfo *root, RelOptInfo *rel);
extern int compute_parallel_worker(RelOptInfo *rel, BlockNumber heap_pages,
BlockNumber index_pages);
extern void create_partial_bitmap_paths(PlannerInfo *root, RelOptInfo *rel,
Path *bitmapqual);
#ifdef OPTIMIZER_DEBUG
extern void debug_print_rel(PlannerInfo *root, RelOptInfo *rel);

1
src/include/pgstat.h
View File

@ -787,6 +787,7 @@ typedef enum
WAIT_EVENT_MQ_RECEIVE,
WAIT_EVENT_MQ_SEND,
WAIT_EVENT_PARALLEL_FINISH,
WAIT_EVENT_PARALLEL_BITMAP_SCAN,
WAIT_EVENT_SAFE_SNAPSHOT,
WAIT_EVENT_SYNC_REP
} WaitEventIPC;

19
src/test/regress/expected/select_parallel.out
View File

@ -169,6 +169,25 @@ select count(*) from tenk1 where thousand > 95;
reset enable_seqscan;
reset enable_bitmapscan;
-- test parallel bitmap heap scan.
set enable_seqscan to off;
set enable_indexscan to off;
explain (costs off)
select count((unique1)) from tenk1 where hundred > 1;
QUERY PLAN
------------------------------------------------------------
Finalize Aggregate
-> Gather
Workers Planned: 4
-> Partial Aggregate
-> Parallel Bitmap Heap Scan on tenk1
Recheck Cond: (hundred > 1)
-> Bitmap Index Scan on tenk1_hundred
Index Cond: (hundred > 1)
(8 rows)
reset enable_seqscan;
reset enable_indexscan;
-- test parallel merge join path.
set enable_hashjoin to off;
set enable_nestloop to off;

10
src/test/regress/sql/select_parallel.sql
View File

@ -64,6 +64,16 @@ select count(*) from tenk1 where thousand > 95;
reset enable_seqscan;
reset enable_bitmapscan;
-- test parallel bitmap heap scan.
set enable_seqscan to off;
set enable_indexscan to off;
explain (costs off)
select count((unique1)) from tenk1 where hundred > 1;
reset enable_seqscan;
reset enable_indexscan;
-- test parallel merge join path.
set enable_hashjoin to off;
set enable_nestloop to off;