mirror of
https://git.postgresql.org/git/postgresql.git
synced 2024-08-31 12:57:21 +02:00
The previous comment (which was copied as boilerplate from one file to the next) implied that it was the executor node itself which was being serialized, but that's not right. We're not serializing the executor nodes; we're just allowing them to store some additional information in DSM. Adjusts the comment to reflect this. Discussion: http://postgr.es/m/CA+TgmoaHVinxG=3h6qBAsyV8xaDyQwbzK7YZnYfE8nJFMK1=FA@mail.gmail.com
1029 lines
28 KiB
C
1029 lines
28 KiB
C
/*-------------------------------------------------------------------------
|
|
*
|
|
* nodeBitmapHeapscan.c
|
|
* Routines to support bitmapped scans of relations
|
|
*
|
|
* NOTE: it is critical that this plan type only be used with MVCC-compliant
|
|
* snapshots (ie, regular snapshots, not SnapshotAny or one of the other
|
|
* special snapshots). The reason is that since index and heap scans are
|
|
* decoupled, there can be no assurance that the index tuple prompting a
|
|
* visit to a particular heap TID still exists when the visit is made.
|
|
* Therefore the tuple might not exist anymore either (which is OK because
|
|
* heap_fetch will cope) --- but worse, the tuple slot could have been
|
|
* re-used for a newer tuple. With an MVCC snapshot the newer tuple is
|
|
* certain to fail the time qual and so it will not be mistakenly returned,
|
|
* but with anything else we might return a tuple that doesn't meet the
|
|
* required index qual conditions.
|
|
*
|
|
*
|
|
* Portions Copyright (c) 1996-2017, PostgreSQL Global Development Group
|
|
* Portions Copyright (c) 1994, Regents of the University of California
|
|
*
|
|
*
|
|
* IDENTIFICATION
|
|
* src/backend/executor/nodeBitmapHeapscan.c
|
|
*
|
|
*-------------------------------------------------------------------------
|
|
*/
|
|
/*
|
|
* INTERFACE ROUTINES
|
|
* ExecBitmapHeapScan scans a relation using bitmap info
|
|
* ExecBitmapHeapNext workhorse for above
|
|
* ExecInitBitmapHeapScan creates and initializes state info.
|
|
* ExecReScanBitmapHeapScan prepares to rescan the plan.
|
|
* ExecEndBitmapHeapScan releases all storage.
|
|
*/
|
|
#include "postgres.h"
|
|
|
|
#include <math.h>
|
|
|
|
#include "access/relscan.h"
|
|
#include "access/transam.h"
|
|
#include "executor/execdebug.h"
|
|
#include "executor/nodeBitmapHeapscan.h"
|
|
#include "miscadmin.h"
|
|
#include "pgstat.h"
|
|
#include "storage/bufmgr.h"
|
|
#include "storage/predicate.h"
|
|
#include "utils/memutils.h"
|
|
#include "utils/rel.h"
|
|
#include "utils/spccache.h"
|
|
#include "utils/snapmgr.h"
|
|
#include "utils/tqual.h"
|
|
|
|
|
|
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);
|
|
|
|
|
|
/* ----------------------------------------------------------------
|
|
* BitmapHeapNext
|
|
*
|
|
* Retrieve next tuple from the BitmapHeapScan node's currentRelation
|
|
* ----------------------------------------------------------------
|
|
*/
|
|
static TupleTableSlot *
|
|
BitmapHeapNext(BitmapHeapScanState *node)
|
|
{
|
|
ExprContext *econtext;
|
|
HeapScanDesc scan;
|
|
TIDBitmap *tbm;
|
|
TBMIterator *tbmiterator = NULL;
|
|
TBMSharedIterator *shared_tbmiterator = NULL;
|
|
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
|
|
*/
|
|
econtext = node->ss.ps.ps_ExprContext;
|
|
slot = node->ss.ss_ScanTupleSlot;
|
|
scan = node->ss.ss_currentScanDesc;
|
|
tbm = node->tbm;
|
|
if (pstate == NULL)
|
|
tbmiterator = node->tbmiterator;
|
|
else
|
|
shared_tbmiterator = node->shared_tbmiterator;
|
|
tbmres = node->tbmres;
|
|
|
|
/*
|
|
* If we haven't yet performed the underlying index scan, do it, and begin
|
|
* the iteration over the bitmap.
|
|
*
|
|
* For prefetching, we use *two* iterators, one for the pages we are
|
|
* actually scanning and another that runs ahead of the first for
|
|
* prefetching. node->prefetch_pages tracks exactly how many pages ahead
|
|
* the prefetch iterator is. Also, node->prefetch_target tracks the
|
|
* desired prefetch distance, which starts small and increases up to the
|
|
* 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 (!node->initialized)
|
|
{
|
|
if (!pstate)
|
|
{
|
|
tbm = (TIDBitmap *) MultiExecProcNode(outerPlanState(node));
|
|
|
|
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;
|
|
|
|
#ifdef USE_PREFETCH
|
|
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 (;;)
|
|
{
|
|
Page dp;
|
|
ItemId lp;
|
|
|
|
CHECK_FOR_INTERRUPTS();
|
|
|
|
/*
|
|
* Get next page of results if needed
|
|
*/
|
|
if (tbmres == NULL)
|
|
{
|
|
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 */
|
|
break;
|
|
}
|
|
|
|
BitmapAdjustPrefetchIterator(node, tbmres);
|
|
|
|
/*
|
|
* Ignore any claimed entries past what we think is the end of the
|
|
* relation. (This is probably not necessary given that we got at
|
|
* least AccessShareLock on the table before performing any of the
|
|
* indexscans, but let's be safe.)
|
|
*/
|
|
if (tbmres->blockno >= scan->rs_nblocks)
|
|
{
|
|
node->tbmres = tbmres = NULL;
|
|
continue;
|
|
}
|
|
|
|
/*
|
|
* Fetch the current heap page and identify candidate tuples.
|
|
*/
|
|
bitgetpage(scan, tbmres);
|
|
|
|
if (tbmres->ntuples >= 0)
|
|
node->exact_pages++;
|
|
else
|
|
node->lossy_pages++;
|
|
|
|
/*
|
|
* Set rs_cindex to first slot to examine
|
|
*/
|
|
scan->rs_cindex = 0;
|
|
|
|
/* Adjust the prefetch target */
|
|
BitmapAdjustPrefetchTarget(node);
|
|
}
|
|
else
|
|
{
|
|
/*
|
|
* Continuing in previously obtained page; advance rs_cindex
|
|
*/
|
|
scan->rs_cindex++;
|
|
|
|
#ifdef USE_PREFETCH
|
|
|
|
/*
|
|
* 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 (!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 */
|
|
}
|
|
|
|
/*
|
|
* Out of range? If so, nothing more to look at on this page
|
|
*/
|
|
if (scan->rs_cindex < 0 || scan->rs_cindex >= scan->rs_ntuples)
|
|
{
|
|
node->tbmres = tbmres = NULL;
|
|
continue;
|
|
}
|
|
|
|
/*
|
|
* We issue prefetch requests *after* fetching the current page to try
|
|
* to avoid having prefetching interfere with the main I/O. Also, this
|
|
* should happen only when we have determined there is still something
|
|
* to do on the current page, else we may uselessly prefetch the same
|
|
* page we are just about to request for real.
|
|
*/
|
|
BitmapPrefetch(node, scan);
|
|
|
|
/*
|
|
* Okay to fetch the tuple
|
|
*/
|
|
targoffset = scan->rs_vistuples[scan->rs_cindex];
|
|
dp = (Page) BufferGetPage(scan->rs_cbuf);
|
|
lp = PageGetItemId(dp, targoffset);
|
|
Assert(ItemIdIsNormal(lp));
|
|
|
|
scan->rs_ctup.t_data = (HeapTupleHeader) PageGetItem((Page) dp, lp);
|
|
scan->rs_ctup.t_len = ItemIdGetLength(lp);
|
|
scan->rs_ctup.t_tableOid = scan->rs_rd->rd_id;
|
|
ItemPointerSet(&scan->rs_ctup.t_self, tbmres->blockno, targoffset);
|
|
|
|
pgstat_count_heap_fetch(scan->rs_rd);
|
|
|
|
/*
|
|
* Set up the result slot to point to this tuple. Note that the slot
|
|
* acquires a pin on the buffer.
|
|
*/
|
|
ExecStoreTuple(&scan->rs_ctup,
|
|
slot,
|
|
scan->rs_cbuf,
|
|
false);
|
|
|
|
/*
|
|
* If we are using lossy info, we have to recheck the qual conditions
|
|
* at every tuple.
|
|
*/
|
|
if (tbmres->recheck)
|
|
{
|
|
econtext->ecxt_scantuple = slot;
|
|
ResetExprContext(econtext);
|
|
|
|
if (!ExecQual(node->bitmapqualorig, econtext))
|
|
{
|
|
/* Fails recheck, so drop it and loop back for another */
|
|
InstrCountFiltered2(node, 1);
|
|
ExecClearTuple(slot);
|
|
continue;
|
|
}
|
|
}
|
|
|
|
/* OK to return this tuple */
|
|
return slot;
|
|
}
|
|
|
|
/*
|
|
* if we get here it means we are at the end of the scan..
|
|
*/
|
|
return ExecClearTuple(slot);
|
|
}
|
|
|
|
/*
|
|
* bitgetpage - subroutine for BitmapHeapNext()
|
|
*
|
|
* This routine reads and pins the specified page of the relation, then
|
|
* builds an array indicating which tuples on the page are both potentially
|
|
* interesting according to the bitmap, and visible according to the snapshot.
|
|
*/
|
|
static void
|
|
bitgetpage(HeapScanDesc scan, TBMIterateResult *tbmres)
|
|
{
|
|
BlockNumber page = tbmres->blockno;
|
|
Buffer buffer;
|
|
Snapshot snapshot;
|
|
int ntup;
|
|
|
|
/*
|
|
* Acquire pin on the target heap page, trading in any pin we held before.
|
|
*/
|
|
Assert(page < scan->rs_nblocks);
|
|
|
|
scan->rs_cbuf = ReleaseAndReadBuffer(scan->rs_cbuf,
|
|
scan->rs_rd,
|
|
page);
|
|
buffer = scan->rs_cbuf;
|
|
snapshot = scan->rs_snapshot;
|
|
|
|
ntup = 0;
|
|
|
|
/*
|
|
* Prune and repair fragmentation for the whole page, if possible.
|
|
*/
|
|
heap_page_prune_opt(scan->rs_rd, buffer);
|
|
|
|
/*
|
|
* We must hold share lock on the buffer content while examining tuple
|
|
* visibility. Afterwards, however, the tuples we have found to be
|
|
* visible are guaranteed good as long as we hold the buffer pin.
|
|
*/
|
|
LockBuffer(buffer, BUFFER_LOCK_SHARE);
|
|
|
|
/*
|
|
* We need two separate strategies for lossy and non-lossy cases.
|
|
*/
|
|
if (tbmres->ntuples >= 0)
|
|
{
|
|
/*
|
|
* Bitmap is non-lossy, so we just look through the offsets listed in
|
|
* tbmres; but we have to follow any HOT chain starting at each such
|
|
* offset.
|
|
*/
|
|
int curslot;
|
|
|
|
for (curslot = 0; curslot < tbmres->ntuples; curslot++)
|
|
{
|
|
OffsetNumber offnum = tbmres->offsets[curslot];
|
|
ItemPointerData tid;
|
|
HeapTupleData heapTuple;
|
|
|
|
ItemPointerSet(&tid, page, offnum);
|
|
if (heap_hot_search_buffer(&tid, scan->rs_rd, buffer, snapshot,
|
|
&heapTuple, NULL, true))
|
|
scan->rs_vistuples[ntup++] = ItemPointerGetOffsetNumber(&tid);
|
|
}
|
|
}
|
|
else
|
|
{
|
|
/*
|
|
* Bitmap is lossy, so we must examine each item pointer on the page.
|
|
* But we can ignore HOT chains, since we'll check each tuple anyway.
|
|
*/
|
|
Page dp = (Page) BufferGetPage(buffer);
|
|
OffsetNumber maxoff = PageGetMaxOffsetNumber(dp);
|
|
OffsetNumber offnum;
|
|
|
|
for (offnum = FirstOffsetNumber; offnum <= maxoff; offnum = OffsetNumberNext(offnum))
|
|
{
|
|
ItemId lp;
|
|
HeapTupleData loctup;
|
|
bool valid;
|
|
|
|
lp = PageGetItemId(dp, offnum);
|
|
if (!ItemIdIsNormal(lp))
|
|
continue;
|
|
loctup.t_data = (HeapTupleHeader) PageGetItem((Page) dp, lp);
|
|
loctup.t_len = ItemIdGetLength(lp);
|
|
loctup.t_tableOid = scan->rs_rd->rd_id;
|
|
ItemPointerSet(&loctup.t_self, page, offnum);
|
|
valid = HeapTupleSatisfiesVisibility(&loctup, snapshot, buffer);
|
|
if (valid)
|
|
{
|
|
scan->rs_vistuples[ntup++] = offnum;
|
|
PredicateLockTuple(scan->rs_rd, &loctup, snapshot);
|
|
}
|
|
CheckForSerializableConflictOut(valid, scan->rs_rd, &loctup,
|
|
buffer, snapshot);
|
|
}
|
|
}
|
|
|
|
LockBuffer(buffer, BUFFER_LOCK_UNLOCK);
|
|
|
|
Assert(ntup <= MaxHeapTuplesPerPage);
|
|
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
|
|
*/
|
|
static inline void
|
|
BitmapAdjustPrefetchIterator(BitmapHeapScanState *node,
|
|
TBMIterateResult *tbmres)
|
|
{
|
|
#ifdef USE_PREFETCH
|
|
ParallelBitmapHeapState *pstate = node->pstate;
|
|
|
|
if (pstate == NULL)
|
|
{
|
|
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;
|
|
}
|
|
|
|
if (node->prefetch_maximum > 0)
|
|
{
|
|
TBMSharedIterator *prefetch_iterator = node->shared_prefetch_iterator;
|
|
|
|
SpinLockAcquire(&pstate->mutex);
|
|
if (pstate->prefetch_pages > 0)
|
|
{
|
|
pstate->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 */
|
|
}
|
|
|
|
/*
|
|
* BitmapAdjustPrefetchTarget - Adjust the prefetch target
|
|
*
|
|
* Increase prefetch target if it's not yet at the max. Note that
|
|
* we will increase it to zero after fetching the very first
|
|
* page/tuple, then to one after the second tuple is fetched, then
|
|
* it doubles as later pages are fetched.
|
|
*/
|
|
static inline void
|
|
BitmapAdjustPrefetchTarget(BitmapHeapScanState *node)
|
|
{
|
|
#ifdef USE_PREFETCH
|
|
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 */
|
|
}
|
|
|
|
/*
|
|
* BitmapPrefetch - Prefetch, if prefetch_pages are behind prefetch_target
|
|
*/
|
|
static inline void
|
|
BitmapPrefetch(BitmapHeapScanState *node, HeapScanDesc scan)
|
|
{
|
|
#ifdef USE_PREFETCH
|
|
ParallelBitmapHeapState *pstate = node->pstate;
|
|
|
|
if (pstate == NULL)
|
|
{
|
|
TBMIterator *prefetch_iterator = node->prefetch_iterator;
|
|
|
|
if (prefetch_iterator)
|
|
{
|
|
while (node->prefetch_pages < node->prefetch_target)
|
|
{
|
|
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);
|
|
}
|
|
}
|
|
}
|
|
#endif /* USE_PREFETCH */
|
|
}
|
|
|
|
/*
|
|
* BitmapHeapRecheck -- access method routine to recheck a tuple in EvalPlanQual
|
|
*/
|
|
static bool
|
|
BitmapHeapRecheck(BitmapHeapScanState *node, TupleTableSlot *slot)
|
|
{
|
|
ExprContext *econtext;
|
|
|
|
/*
|
|
* extract necessary information from index scan node
|
|
*/
|
|
econtext = node->ss.ps.ps_ExprContext;
|
|
|
|
/* Does the tuple meet the original qual conditions? */
|
|
econtext->ecxt_scantuple = slot;
|
|
|
|
ResetExprContext(econtext);
|
|
|
|
return ExecQual(node->bitmapqualorig, econtext);
|
|
}
|
|
|
|
/* ----------------------------------------------------------------
|
|
* ExecBitmapHeapScan(node)
|
|
* ----------------------------------------------------------------
|
|
*/
|
|
static TupleTableSlot *
|
|
ExecBitmapHeapScan(PlanState *pstate)
|
|
{
|
|
BitmapHeapScanState *node = castNode(BitmapHeapScanState, pstate);
|
|
|
|
return ExecScan(&node->ss,
|
|
(ExecScanAccessMtd) BitmapHeapNext,
|
|
(ExecScanRecheckMtd) BitmapHeapRecheck);
|
|
}
|
|
|
|
/* ----------------------------------------------------------------
|
|
* ExecReScanBitmapHeapScan(node)
|
|
* ----------------------------------------------------------------
|
|
*/
|
|
void
|
|
ExecReScanBitmapHeapScan(BitmapHeapScanState *node)
|
|
{
|
|
PlanState *outerPlan = outerPlanState(node);
|
|
|
|
/* rescan to release any page pin */
|
|
heap_rescan(node->ss.ss_currentScanDesc, NULL);
|
|
|
|
if (node->tbmiterator)
|
|
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;
|
|
|
|
ExecScanReScan(&node->ss);
|
|
|
|
/*
|
|
* if chgParam of subnode is not null then plan will be re-scanned by
|
|
* first ExecProcNode.
|
|
*/
|
|
if (outerPlan->chgParam == NULL)
|
|
ExecReScan(outerPlan);
|
|
}
|
|
|
|
/* ----------------------------------------------------------------
|
|
* ExecEndBitmapHeapScan
|
|
* ----------------------------------------------------------------
|
|
*/
|
|
void
|
|
ExecEndBitmapHeapScan(BitmapHeapScanState *node)
|
|
{
|
|
Relation relation;
|
|
HeapScanDesc scanDesc;
|
|
|
|
/*
|
|
* extract information from the node
|
|
*/
|
|
relation = node->ss.ss_currentRelation;
|
|
scanDesc = node->ss.ss_currentScanDesc;
|
|
|
|
/*
|
|
* Free the exprcontext
|
|
*/
|
|
ExecFreeExprContext(&node->ss.ps);
|
|
|
|
/*
|
|
* clear out tuple table slots
|
|
*/
|
|
ExecClearTuple(node->ss.ps.ps_ResultTupleSlot);
|
|
ExecClearTuple(node->ss.ss_ScanTupleSlot);
|
|
|
|
/*
|
|
* close down subplans
|
|
*/
|
|
ExecEndNode(outerPlanState(node));
|
|
|
|
/*
|
|
* release bitmap if any
|
|
*/
|
|
if (node->tbmiterator)
|
|
tbm_end_iterate(node->tbmiterator);
|
|
if (node->prefetch_iterator)
|
|
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
|
|
*/
|
|
heap_endscan(scanDesc);
|
|
|
|
/*
|
|
* close the heap relation.
|
|
*/
|
|
ExecCloseScanRelation(relation);
|
|
}
|
|
|
|
/* ----------------------------------------------------------------
|
|
* ExecInitBitmapHeapScan
|
|
*
|
|
* Initializes the scan's state information.
|
|
* ----------------------------------------------------------------
|
|
*/
|
|
BitmapHeapScanState *
|
|
ExecInitBitmapHeapScan(BitmapHeapScan *node, EState *estate, int eflags)
|
|
{
|
|
BitmapHeapScanState *scanstate;
|
|
Relation currentRelation;
|
|
int io_concurrency;
|
|
|
|
/* check for unsupported flags */
|
|
Assert(!(eflags & (EXEC_FLAG_BACKWARD | EXEC_FLAG_MARK)));
|
|
|
|
/*
|
|
* Assert caller didn't ask for an unsafe snapshot --- see comments at
|
|
* head of file.
|
|
*/
|
|
Assert(IsMVCCSnapshot(estate->es_snapshot));
|
|
|
|
/*
|
|
* create state structure
|
|
*/
|
|
scanstate = makeNode(BitmapHeapScanState);
|
|
scanstate->ss.ps.plan = (Plan *) node;
|
|
scanstate->ss.ps.state = estate;
|
|
scanstate->ss.ps.ExecProcNode = ExecBitmapHeapScan;
|
|
|
|
scanstate->tbm = NULL;
|
|
scanstate->tbmiterator = NULL;
|
|
scanstate->tbmres = NULL;
|
|
scanstate->exact_pages = 0;
|
|
scanstate->lossy_pages = 0;
|
|
scanstate->prefetch_iterator = NULL;
|
|
scanstate->prefetch_pages = 0;
|
|
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
|
|
*
|
|
* create expression context for node
|
|
*/
|
|
ExecAssignExprContext(estate, &scanstate->ss.ps);
|
|
|
|
/*
|
|
* initialize child expressions
|
|
*/
|
|
scanstate->ss.ps.qual =
|
|
ExecInitQual(node->scan.plan.qual, (PlanState *) scanstate);
|
|
scanstate->bitmapqualorig =
|
|
ExecInitQual(node->bitmapqualorig, (PlanState *) scanstate);
|
|
|
|
/*
|
|
* tuple table initialization
|
|
*/
|
|
ExecInitResultTupleSlot(estate, &scanstate->ss.ps);
|
|
ExecInitScanTupleSlot(estate, &scanstate->ss);
|
|
|
|
/*
|
|
* open the base relation and acquire appropriate lock on it.
|
|
*/
|
|
currentRelation = ExecOpenScanRelation(estate, node->scan.scanrelid, eflags);
|
|
|
|
/*
|
|
* Determine the maximum for prefetch_target. If the tablespace has a
|
|
* specific IO concurrency set, use that to compute the corresponding
|
|
* maximum value; otherwise, we already initialized to the value computed
|
|
* by the GUC machinery.
|
|
*/
|
|
io_concurrency =
|
|
get_tablespace_io_concurrency(currentRelation->rd_rel->reltablespace);
|
|
if (io_concurrency != effective_io_concurrency)
|
|
{
|
|
double maximum;
|
|
|
|
if (ComputeIoConcurrency(io_concurrency, &maximum))
|
|
scanstate->prefetch_maximum = rint(maximum);
|
|
}
|
|
|
|
scanstate->ss.ss_currentRelation = currentRelation;
|
|
|
|
/*
|
|
* Even though we aren't going to do a conventional seqscan, it is useful
|
|
* to create a HeapScanDesc --- most of the fields in it are usable.
|
|
*/
|
|
scanstate->ss.ss_currentScanDesc = heap_beginscan_bm(currentRelation,
|
|
estate->es_snapshot,
|
|
0,
|
|
NULL);
|
|
|
|
/*
|
|
* get the scan type from the relation descriptor.
|
|
*/
|
|
ExecAssignScanType(&scanstate->ss, RelationGetDescr(currentRelation));
|
|
|
|
/*
|
|
* Initialize result tuple type and projection info.
|
|
*/
|
|
ExecAssignResultTypeFromTL(&scanstate->ss.ps);
|
|
ExecAssignScanProjectionInfo(&scanstate->ss);
|
|
|
|
/*
|
|
* initialize child nodes
|
|
*
|
|
* We do this last because the child nodes will open indexscans on our
|
|
* relation's indexes, and we want to be sure we have acquired a lock on
|
|
* the relation first.
|
|
*/
|
|
outerPlanState(scanstate) = ExecInitNode(outerPlan(node), estate, eflags);
|
|
|
|
/*
|
|
* all done.
|
|
*/
|
|
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
|
|
*
|
|
* Compute the amount of space we'll need in the parallel
|
|
* query DSM, and inform pcxt->estimator about our needs.
|
|
* ----------------------------------------------------------------
|
|
*/
|
|
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;
|
|
}
|
|
|
|
/* ----------------------------------------------------------------
|
|
* ExecBitmapHeapReInitializeDSM
|
|
*
|
|
* Reset shared state before beginning a fresh scan.
|
|
* ----------------------------------------------------------------
|
|
*/
|
|
void
|
|
ExecBitmapHeapReInitializeDSM(BitmapHeapScanState *node,
|
|
ParallelContext *pcxt)
|
|
{
|
|
ParallelBitmapHeapState *pstate = node->pstate;
|
|
dsa_area *dsa = node->ss.ps.state->es_query_dsa;
|
|
|
|
pstate->state = BM_INITIAL;
|
|
|
|
if (DsaPointerIsValid(pstate->tbmiterator))
|
|
tbm_free_shared_area(dsa, pstate->tbmiterator);
|
|
|
|
if (DsaPointerIsValid(pstate->prefetch_iterator))
|
|
tbm_free_shared_area(dsa, pstate->prefetch_iterator);
|
|
|
|
pstate->tbmiterator = InvalidDsaPointer;
|
|
pstate->prefetch_iterator = InvalidDsaPointer;
|
|
}
|
|
|
|
/* ----------------------------------------------------------------
|
|
* 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, false);
|
|
node->pstate = pstate;
|
|
|
|
snapshot = RestoreSnapshot(pstate->phs_snapshot_data);
|
|
heap_update_snapshot(node->ss.ss_currentScanDesc, snapshot);
|
|
}
|