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openGauss-server/src/gausskernel/runtime/executor/nodeBitmapHeapscan.cpp

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/* -------------------------------------------------------------------------
*
* nodeBitmapHeapscan.cpp
* 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 SnapshotNow 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.
* With SnapshotNow we might return a tuple that doesn't meet the required
* index qual conditions.
*
*
* Portions Copyright (c) 2020 Huawei Technologies Co.,Ltd.
* Portions Copyright (c) 1996-2012, PostgreSQL Global Development Group
* Portions Copyright (c) 1994, Regents of the University of California
* Portions Copyright (c) 2021, openGauss Contributors
*
*
* IDENTIFICATION
* src/gausskernel/runtime/executor/nodeBitmapHeapscan.cpp
*
* -------------------------------------------------------------------------
*
* 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 "knl/knl_variable.h"
#include "access/relscan.h"
#include "access/tableam.h"
#include "access/transam.h"
#include "catalog/pg_partition_fn.h"
#include "commands/cluster.h"
#include "executor/exec/execdebug.h"
#include "executor/node/nodeBitmapHeapscan.h"
#include "pgstat.h"
#include "storage/buf/bufmgr.h"
#include "storage/predicate.h"
#include "storage/tcap.h"
#include "utils/memutils.h"
#include "utils/rel.h"
#include "utils/rel_gs.h"
#include "utils/snapmgr.h"
#include "gstrace/gstrace_infra.h"
#include "gstrace/access_gstrace.h"
#include "nodes/execnodes.h"
#include "access/ustore/knl_uscan.h"
#include "nodes/makefuncs.h"
#include "optimizer/pruning.h"
#include "nodes/makefuncs.h"
#include "optimizer/pruning.h"
static TupleTableSlot* ExecBitmapHeapScan(PlanState* state);
static TupleTableSlot* BitmapHbucketTblNext(BitmapHeapScanState* node);
static TupleTableSlot* BitmapHeapTblNext(BitmapHeapScanState* node);
bool heapam_scan_bitmap_next_block(TableScanDesc scan, TBMIterateResult* tbmres,
bool* has_cur_xact_write = NULL);
static void ExecInitPartitionForBitmapHeapScan(BitmapHeapScanState* scanstate, EState* estate);
static void ExecInitNextPartitionForBitmapHeapScan(BitmapHeapScanState* node);
void BitmapHeapPrefetchNext(
BitmapHeapScanState* node, TableScanDesc scan, const TIDBitmap* tbm, TBMIterator** prefetch_iterator);
/* This struct is used for partition switch while prefetch pages */
typedef struct PrefetchNode {
BlockNumber blockNum;
Oid partOid;
int2 bktId;
} PrefetchNode;
void BitmapHeapFree(BitmapHeapScanState* node)
{
if (node->tbmiterator != NULL) {
tbm_end_iterate(node->tbmiterator);
node->tbmiterator = NULL;
}
if (node->prefetch_iterator != NULL) {
tbm_end_iterate(node->prefetch_iterator);
node->prefetch_iterator = NULL;
}
if (node->tbm != NULL) {
tbm_free(node->tbm);
node->tbm = NULL;
}
node->tbmres = NULL;
}
static TupleTableSlot* BitmapHbucketTblNext(BitmapHeapScanState* node)
{
Assert(node->ss.ss_currentScanDesc != NULL);
HBktTblScanDesc hpScan = (HBktTblScanDesc)node->ss.ss_currentScanDesc;
TupleTableSlot* slot = NULL;
while (true) {
node->ss.ps.hbktScanSlot.currSlot = hpScan->curr_slot;
node->ss.ps.lefttree->hbktScanSlot.currSlot = hpScan->curr_slot;
slot = BitmapHeapTblNext(node);
/* for crossbucket index */
if (tbm_is_crossbucket(node->tbm)) {
return slot;
}
/* for non-crossbucket index */
if (!TupIsNull(slot)) {
return slot;
}
if (!hbkt_bitmapheap_scan_nextbucket(hpScan)) {
return NULL;
}
BitmapHeapFree(node);
}
}
bool HeapamScanBitmapNextTuple(TableScanDesc scan,
TBMIterateResult *tbmres,
TupleTableSlot *slot)
{
HeapScanDesc hscan = (HeapScanDesc) scan;
OffsetNumber targoffset;
Page dp;
ItemId lp;
/*
* Out of range? If so, nothing more to look at on this page
*/
if (hscan->rs_base.rs_cindex < 0 || hscan->rs_base.rs_cindex >= hscan->rs_base.rs_ntuples)
return false;
/*
* Okay to fetch the tuple
*/
targoffset = hscan->rs_base.rs_vistuples[hscan->rs_base.rs_cindex];
dp = (Page)BufferGetPage(hscan->rs_base.rs_cbuf);
lp = PageGetItemId(dp, targoffset);
Assert(ItemIdIsNormal(lp));
hscan->rs_ctup.t_data = (HeapTupleHeader)PageGetItem((Page)dp, lp);
hscan->rs_ctup.t_len = ItemIdGetLength(lp);
hscan->rs_ctup.t_tableOid = RelationGetRelid(hscan->rs_base.rs_rd);
hscan->rs_ctup.t_bucketId = RelationGetBktid(hscan->rs_base.rs_rd);
HeapTupleCopyBaseFromPage(&hscan->rs_ctup, dp);
ItemPointerSet(&hscan->rs_ctup.t_self, tbmres->blockno, targoffset);
pgstat_count_heap_fetch(hscan->rs_base.rs_rd);
/*
* Set up the result slot to point to this tuple. Note that the slot
* acquires a pin on the buffer.
*/
(void)ExecStoreTuple(&hscan->rs_ctup, slot, hscan->rs_base.rs_cbuf, false);
hscan->rs_base.rs_cindex++;
return true;
}
static bool TableScanBitmapNextTuple(TableScanDesc scan, TBMIterateResult *tbmres, TupleTableSlot *slot)
{
bool isUstore = RelationIsUstoreFormat(scan->rs_rd);
if (isUstore) {
return UHeapScanBitmapNextTuple(scan, tbmres, slot);
} else {
return HeapamScanBitmapNextTuple(scan, tbmres, slot);
}
}
static bool TableScanBitmapNextBlock(TableScanDesc scan, TBMIterateResult *tbmres, bool* has_cur_xact_write)
{
bool isUstore = RelationIsUstoreFormat(scan->rs_rd);
if (isUstore) {
return UHeapScanBitmapNextBlock(scan, tbmres, has_cur_xact_write);
} else {
return heapam_scan_bitmap_next_block(scan, tbmres, has_cur_xact_write);
}
}
/*
* This is intended to locate the target child relation (partition or bucket).
* It is only applied to the underlying scan is a global index scan (GPI or GPI+CBI).
*
* Return values: 0: success; -1: fail; 1: need to prefetch.
*/
static int TableScanBitmapNextTargetRel(TableScanDesc scan, BitmapHeapScanState *node)
{
Assert(scan != NULL);
Assert(node != NULL);
Assert(node->tbm != NULL);
Assert(node->tbmres != NULL);
bool result = true;
TIDBitmap *tbm = node->tbm;
TBMIterateResult *tbmres = node->tbmres;
int2 bucketid = InvalidBktId;
bool need_reset_bucketid = false;
/* Check whether switch partition-fake-rel, use rd_rel save. */
if (BitmapNodeNeedSwitchPartRel(node)) { /* for global partitioned index */
GPISetCurrPartOid(node->gpi_scan, tbmres->partitionOid);
if (!GPIGetNextPartRelation(node->gpi_scan, CurrentMemoryContext, AccessShareLock)) {
/* return 1 to indicate caller may need to call prefetch */
return 1;
}
scan->rs_rd = node->gpi_scan->fakePartRelation;
scan->rs_nblocks = RelationGetNumberOfBlocks(scan->rs_rd);
/*
* Reset the scanning bucketid to force reloading
* the target bucket relation in this new partition.
*/
need_reset_bucketid = true;
}
/*
* Check whether need to switch bucket, if the underlying
* indexscan is a cross-bucket indexscan.
*/
if (tbm_is_crossbucket(tbm)) { /* for crossbucket index */
bucketid = tbmres->bucketid; /* set to the current iterating bucketid */
Assert(BUCKET_NODE_IS_VALID(bucketid));
need_reset_bucketid = (need_reset_bucketid || (scan->rs_rd->rd_node.bucketNode != bucketid));
if (need_reset_bucketid ) {
cbi_set_bucketid(node->cbi_scan, InvalidBktId);
}
if (cbi_scan_need_change_bucket(node->cbi_scan, bucketid)) {
cbi_set_bucketid(node->cbi_scan, bucketid);
result = cbi_bitmapheap_scan_nextbucket((HBktTblScanDesc)node->ss.ss_currentScanDesc, node->gpi_scan,
node->cbi_scan);
}
}
return (result ? 0 : -1);
}
/* ----------------------------------------------------------------
* BitmapHeapNext
*
* Retrieve next tuple from the BitmapHeapScan node's currentRelation
* ----------------------------------------------------------------
*/
static TupleTableSlot* BitmapHeapTblNext(BitmapHeapScanState* node)
{
ExprContext* econtext = NULL;
TableScanDesc scan = NULL;
TIDBitmap* tbm = NULL;
TBMHandler tbm_handler;
TBMIterator* tbmiterator = NULL;
TBMIterateResult* tbmres = NULL;
HBktTblScanDesc hpscan = NULL;
#ifdef USE_PREFETCH
TBMIterator* prefetch_iterator = NULL;
#endif
TupleTableSlot* slot = NULL;
/*
* extract necessary information from index scan node
*/
econtext = node->ss.ps.ps_ExprContext;
slot = node->ss.ss_ScanTupleSlot;
if (node->ss.ss_currentRelation != NULL && RelationIsPartitionedHashBucketTable(node->ss.ss_currentRelation)) {
Assert(node->ss.ss_currentScanDesc != NULL);
hpscan = (HBktTblScanDesc)node->ss.ss_currentScanDesc;
scan = (TableScanDesc)hpscan->currBktScan;
} else {
scan = GetTableScanDesc(node->ss.ss_currentScanDesc, node->ss.ss_currentRelation);
}
tbm = node->tbm;
tbmiterator = node->tbmiterator;
tbmres = node->tbmres;
#ifdef USE_PREFETCH
prefetch_iterator = node->prefetch_iterator;
#endif
/*
* 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
* GUC-controlled maximum, target_prefetch_pages. 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) {
tbm = (TIDBitmap*)MultiExecProcNode(outerPlanState(node));
tbm_handler = tbm_get_handler(tbm);
if (tbm == NULL || !IsA(tbm, TIDBitmap)) {
ereport(ERROR,
(errcode(ERRCODE_UNRECOGNIZED_NODE_TYPE),
errmodule(MOD_EXECUTOR),
errmsg("unrecognized result from subplan for BitmapHeapScan.")));
}
node->tbm = tbm;
node->tbmiterator = tbmiterator = tbm_handler._begin_iterate(tbm);
node->tbmres = tbmres = NULL;
#ifdef USE_PREFETCH
if (u_sess->storage_cxt.target_prefetch_pages > 0) {
node->prefetch_iterator = prefetch_iterator = tbm_handler._begin_iterate(tbm);
node->prefetch_pages = 0;
node->prefetch_target = -1;
}
#endif
}
/*
* Now tbm is not NULL, we have enough information to
* determine whether need to assign hpscan. Also need
* to make sure we are not scanning a virtual hashbucket
* table.
*/
if (hpscan == NULL && tbm_is_crossbucket(tbm) && RELATION_OWN_BUCKET(node->ss.ss_currentScanDesc->rs_rd)) {
hpscan = (HBktTblScanDesc)node->ss.ss_currentScanDesc;
}
for (;;) {
/*
* Get next page of results if needed
*/
if (tbmres == NULL) {
node->tbmres = tbmres = tbm_iterate(tbmiterator);
if (tbmres == NULL) {
/* no more entries in the bitmap */
break;
}
#ifdef USE_PREFETCH
if (node->prefetch_pages > 0) {
/* The main iterator has closed the distance by one page */
node->prefetch_pages--;
} else if (prefetch_iterator != NULL) {
/* Do not let the prefetch iterator get behind the main one */
TBMIterateResult* tbmpre = tbm_iterate(prefetch_iterator);
if (tbmpre == NULL || tbmpre->blockno != tbmres->blockno) {
ereport(ERROR,
(errcode(ERRCODE_DATA_EXCEPTION),
errmodule(MOD_EXECUTOR),
errmsg("prefetch and main iterators are out of sync for BitmapHeapScan.")));
}
}
#endif /* USE_PREFETCH */
int rc = TableScanBitmapNextTargetRel(scan, node);
if (rc != 0) {
/*
* If the current partition is invalid,
* the next page is directly processed.
*/
tbmres = NULL;
#ifdef USE_PREFETCH
if (rc == 1) {
BitmapHeapPrefetchNext(node, scan, tbm, &prefetch_iterator);
}
#endif /* USE_PREFETCH */
continue;
}
/* update bucket scan */
if (hpscan != NULL && scan != hpscan->currBktScan) {
scan = hpscan->currBktScan;
}
/*
* Fetch the current table page and identify candidate tuples.
*/
if (!TableScanBitmapNextBlock(scan, tbmres, &node->ss.ps.state->have_current_xact_date)) {
node->tbmres = tbmres = NULL;
continue;
}
if (tbmres->ntuples >= 0) {
node->exact_pages++;
} else {
node->lossy_pages++;
}
#ifdef USE_PREFETCH
/*
* 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.
*/
if (node->prefetch_target >= u_sess->storage_cxt.target_prefetch_pages)
/* don't increase any further */;
else if (node->prefetch_target >= u_sess->storage_cxt.target_prefetch_pages / 2)
node->prefetch_target = u_sess->storage_cxt.target_prefetch_pages;
else if (node->prefetch_target > 0)
node->prefetch_target *= 2;
else
node->prefetch_target++;
#endif /* USE_PREFETCH */
} else {
/*
* Continuing in previously obtained page.
*/
#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 (node->prefetch_target < u_sess->storage_cxt.target_prefetch_pages)
node->prefetch_target++;
#endif /* USE_PREFETCH */
}
#ifdef USE_PREFETCH
BitmapHeapPrefetchNext(node, scan, tbm, &prefetch_iterator);
#endif /* USE_PREFETCH */
/*
* Attempt to fetch tuple from AM.
*/
if (!TableScanBitmapNextTuple(scan, tbmres, slot)) {
/* nothing more to look at on this page */
node->tbmres = tbmres = NULL;
continue;
}
/*
* 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);
(void)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.
*/
bool heapam_scan_bitmap_next_block(TableScanDesc scan, TBMIterateResult* tbmres, bool* has_cur_xact_write)
{
HeapScanDesc hscan = (HeapScanDesc) scan;
BlockNumber page = tbmres->blockno;
Buffer buffer;
Snapshot snapshot;
int ntup;
hscan->rs_base.rs_cindex = 0;
hscan->rs_base.rs_ntuples = 0;
/*
* Ignore any claimed entries past what we think is the end of the
* relation. It may have been extended after the start of our scan (we
* only hold an AccessShareLock, and it could be inserts from this
* backend).
*/
if (page >= hscan->rs_base.rs_nblocks)
return false;
/*
* Acquire pin on the target heap page, trading in any pin we held before.
*/
hscan->rs_base.rs_cbuf = ReleaseAndReadBuffer(hscan->rs_base.rs_cbuf, hscan->rs_base.rs_rd, page);
/* In hot standby, we may get a null buffer if index
* replayed before the tid replayed. This is acceptable, so we return
* directly without reporting error.
*/
if (!BufferIsValid(hscan->rs_base.rs_cbuf)) {
return false;
}
hscan->rs_base.rs_cblock = page;
buffer = hscan->rs_base.rs_cbuf;
snapshot = hscan->rs_base.rs_snapshot;
ntup = 0;
/*
* Prune and repair fragmentation for the whole page, if possible.
*/
heap_page_prune_opt(hscan->rs_base.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, hscan->rs_base.rs_rd, buffer, snapshot, &heapTuple, NULL, NULL, true,
has_cur_xact_write))
hscan->rs_base.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 = false;
lp = PageGetItemId(dp, offnum);
if (!ItemIdIsNormal(lp))
continue;
loctup.t_data = (HeapTupleHeader)PageGetItem((Page)dp, lp);
loctup.t_len = ItemIdGetLength(lp);
loctup.t_tableOid = RelationGetRelid(hscan->rs_base.rs_rd);
loctup.t_bucketId = RelationGetBktid(hscan->rs_base.rs_rd);
HeapTupleCopyBaseFromPage(&hscan->rs_ctup, dp);
HeapTupleCopyBaseFromPage(&loctup, dp);
ItemPointerSet(&loctup.t_self, page, offnum);
valid = HeapTupleSatisfiesVisibility(&loctup, snapshot, buffer);
if (valid) {
hscan->rs_base.rs_vistuples[ntup++] = offnum;
PredicateLockTuple(hscan->rs_base.rs_rd, &loctup, snapshot);
}
CheckForSerializableConflictOut(valid, hscan->rs_base.rs_rd, (void *) &loctup, buffer, snapshot);
}
}
LockBuffer(buffer, BUFFER_LOCK_UNLOCK);
Assert(ntup <= MaxHeapTuplesPerPage);
hscan->rs_base.rs_ntuples = ntup;
return ntup > 0;
}
/*
* BitmapHeapRecheck -- access method routine to recheck a tuple in EvalPlanQual
*/
static bool BitmapHeapRecheck(BitmapHeapScanState* node, TupleTableSlot* slot)
{
ExprContext* econtext = NULL;
/*
* 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* state)
{
BitmapHeapScanState* node = castNode(BitmapHeapScanState, state);
return ExecScan(&node->ss, node->ss.ScanNextMtd, (ExecScanRecheckMtd)BitmapHeapRecheck);
}
/* ----------------------------------------------------------------
* ExecReScanBitmapHeapScan(node)
* ----------------------------------------------------------------
*/
void ExecReScanBitmapHeapScan(BitmapHeapScanState* node)
{
/*
* deal with partitioned table
*/
if (node->ss.isPartTbl && !(((Scan *)node->ss.ps.plan)->partition_iterator_elimination)) {
if (!PointerIsValid(node->ss.partitions)) {
return;
}
/*
* if there are partitions for scaning, switch to the next partition;
* else return with doing nothing
*/
scan_handler_tbl_endscan(node->ss.ss_currentScanDesc);
/* switch to next partition for scan */
ExecInitNextPartitionForBitmapHeapScan(node);
} else {
/* rescan to release any page pin */
scan_handler_tbl_rescan(node->ss.ss_currentScanDesc, NULL, node->ss.ss_currentRelation, true);
}
/* rescan to release any page pin */
BitmapHeapFree(node);
ExecScanReScan(&node->ss);
/*
* if chgParam of subnode is not null or the relation is a partitioned table
* then plan will be re-scanned by first ExecProcNode.
*/
if (node->ss.isPartTbl || !PointerIsValid(node->ss.ps.lefttree->chgParam))
ExecReScan(node->ss.ps.lefttree);
}
/* ----------------------------------------------------------------
* ExecEndBitmapHeapScan
* ----------------------------------------------------------------
*/
void ExecEndBitmapHeapScan(BitmapHeapScanState* node)
{
/*
* extract information from the node
*/
Relation relation = node->ss.ss_currentRelation;
/*
* Free the exprcontext
*/
ExecFreeExprContext(&node->ss.ps);
/*
* clear out tuple table slots
*/
(void)ExecClearTuple(node->ss.ps.ps_ResultTupleSlot);
(void)ExecClearTuple(node->ss.ss_ScanTupleSlot);
/*
* close down subplans
*/
ExecEndNode(outerPlanState(node));
/*
* release bitmap if any
*/
BitmapHeapFree(node);
if (node->ss.ss_currentScanDesc != NULL) {
scan_handler_tbl_endscan(node->ss.ss_currentScanDesc);
}
if (node->gpi_scan != NULL) {
GPIScanEnd(node->gpi_scan);
}
if (node->cbi_scan != NULL) {
cbi_scan_end(node->cbi_scan);
}
/* close heap scan */
if (node->ss.isPartTbl && PointerIsValid(node->ss.partitions)) {
/* close table partition */
Assert(node->ss.ss_currentPartition);
releaseDummyRelation(&(node->ss.ss_currentPartition));
releaseSubPartitionList(node->ss.ss_currentRelation, &(node->ss.subpartitions), NoLock);
releasePartitionList(node->ss.ss_currentRelation, &(node->ss.partitions), NoLock);
}
/*
* close the heap relation.
*/
ExecCloseScanRelation(relation);
}
static inline void InitBitmapHeapScanNextMtd(BitmapHeapScanState* bmstate)
{
if (RELATION_OWN_BUCKET(bmstate->ss.ss_currentRelation)) {
bmstate->ss.ScanNextMtd = (ExecScanAccessMtd)BitmapHbucketTblNext;
return;
}
bmstate->ss.ScanNextMtd = (ExecScanAccessMtd)BitmapHeapTblNext;
}
TableScanDesc UHeapBeginScan(Relation relation, Snapshot snapshot, int nkeys, ParallelHeapScanDesc parallel_scan);
/* ----------------------------------------------------------------
* ExecInitBitmapHeapScan
*
* Initializes the scan's state information.
* ----------------------------------------------------------------
*/
BitmapHeapScanState* ExecInitBitmapHeapScan(BitmapHeapScan* node, EState* estate, int eflags)
{
BitmapHeapScanState* scanstate = NULL;
Relation currentRelation;
bool isUstoreRel = false;
Snapshot scanSnap;
/* 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->tbm = NULL;
scanstate->tbmiterator = NULL;
scanstate->tbmres = NULL;
scanstate->exact_pages = 0.0;
scanstate->lossy_pages = 0.0;
scanstate->prefetch_iterator = NULL;
scanstate->prefetch_pages = 0;
scanstate->prefetch_target = 0;
scanstate->ss.isPartTbl = node->scan.isPartTbl;
scanstate->ss.currentSlot = 0;
scanstate->ss.partScanDirection = node->scan.partScanDirection;
scanstate->ss.ps.ExecProcNode = ExecBitmapHeapScan;
/* initialize Global partition index scan information */
GPIScanInit(&scanstate->gpi_scan);
/* initialize cross-bucket index scan information */
cbi_scan_init(&scanstate->cbi_scan);
/*
* Miscellaneous initialization
*
* create expression context for node
*/
ExecAssignExprContext(estate, &scanstate->ss.ps);
/*
* initialize child expressions
*/
if (estate->es_is_flt_frame) {
scanstate->ss.ps.qual = (List*)ExecInitQualByFlatten(node->scan.plan.qual, (PlanState*)scanstate);
scanstate->bitmapqualorig = (List*)ExecInitQualByFlatten(node->bitmapqualorig, (PlanState*)scanstate);
} else {
scanstate->ss.ps.targetlist = (List*)ExecInitExprByRecursion((Expr*)node->scan.plan.targetlist, (PlanState*)scanstate);
scanstate->ss.ps.qual = (List*)ExecInitExprByRecursion((Expr*)node->scan.plan.qual, (PlanState*)scanstate);
scanstate->bitmapqualorig = (List*)ExecInitExprByRecursion((Expr*)node->bitmapqualorig, (PlanState*)scanstate);
}
/*
* open the base relation and acquire appropriate lock on it.
*/
currentRelation = ExecOpenScanRelation(estate, node->scan.scanrelid);
scanstate->ss.ss_currentRelation = currentRelation;
scanstate->gpi_scan->parentRelation = currentRelation;
isUstoreRel = RelationIsUstoreFormat(currentRelation);
/*
* tuple table initialization
*/
ExecInitResultTupleSlot(estate, &scanstate->ss.ps, currentRelation->rd_tam_ops);
ExecInitScanTupleSlot(estate, &scanstate->ss, currentRelation->rd_tam_ops);
InitBitmapHeapScanNextMtd(scanstate);
/*
* Choose user-specified snapshot if TimeCapsule clause exists, otherwise
* estate->es_snapshot instead.
*/
scanSnap = TvChooseScanSnap(currentRelation, &node->scan, &scanstate->ss);
/*
* 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.
*/
if (scanstate->ss.isPartTbl) {
scanstate->ss.ss_currentScanDesc = NULL;
ExecInitPartitionForBitmapHeapScan(scanstate, estate);
if (node->scan.itrs > 0) {
Partition partition = NULL;
Relation partitiontrel = NULL;
if (scanstate->ss.partitions != NIL) {
/* construct a dummy table relation with the next table partition for scan */
partition = (Partition)list_nth(scanstate->ss.partitions, 0);
partitiontrel = partitionGetRelation(currentRelation, partition);
scanstate->ss.ss_currentPartition = partitiontrel;
/*
* Verify if a DDL operation that froze all tuples in the relation
* occured after taking the snapshot. Skip for explain only commands.
*/
if (isUstoreRel && !(eflags & EXEC_FLAG_EXPLAIN_ONLY)) {
TransactionId relfrozenxid64 = InvalidTransactionId;
getPartitionRelxids(partitiontrel, &relfrozenxid64);
if (TransactionIdPrecedes(FirstNormalTransactionId, scanSnap->xmax) &&
!TransactionIdIsCurrentTransactionId(relfrozenxid64) &&
TransactionIdPrecedes(scanSnap->xmax, relfrozenxid64)) {
ereport(ERROR, (errcode(ERRCODE_SNAPSHOT_INVALID),
(errmsg("Snapshot too old, BitmapHeapScan is PartTbl, the info: snapxmax is %lu, "
"snapxmin is %lu, csn is %lu, relfrozenxid64 is %lu, globalRecycleXid is %lu.",
scanSnap->xmax, scanSnap->xmin, scanSnap->snapshotcsn, relfrozenxid64,
g_instance.undo_cxt.globalRecycleXid))));
}
}
scanstate->ss.ss_currentScanDesc =
scan_handler_tbl_beginscan_bm(partitiontrel, scanSnap, 0, NULL, &scanstate->ss);
}
}
} else {
if (!isUstoreRel) {
scanstate->ss.ss_currentScanDesc =
scan_handler_tbl_beginscan_bm(currentRelation, scanSnap, 0, NULL, &scanstate->ss);
} else {
/*
* Verify if a DDL operation that froze all tuples in the relation
* occured after taking the snapshot. Skip for explain only commands.
*/
if (!(eflags & EXEC_FLAG_EXPLAIN_ONLY)) {
TransactionId relfrozenxid64 = InvalidTransactionId;
getRelationRelxids(currentRelation, &relfrozenxid64);
if (TransactionIdPrecedes(FirstNormalTransactionId, scanSnap->xmax) &&
!TransactionIdIsCurrentTransactionId(relfrozenxid64) &&
TransactionIdPrecedes(scanSnap->xmax, relfrozenxid64)) {
ereport(ERROR, (errcode(ERRCODE_SNAPSHOT_INVALID),
(errmsg("Snapshot too old, BitmapHeapScan is not PartTbl, the info: snapxmax is %lu, "
"snapxmin is %lu, csn is %lu, relfrozenxid64 is %lu, globalRecycleXid is %lu.",
scanSnap->xmax, scanSnap->xmin, scanSnap->snapshotcsn, relfrozenxid64,
g_instance.undo_cxt.globalRecycleXid))));
}
}
scanstate->ss.ss_currentScanDesc = UHeapBeginScan(currentRelation, scanSnap, 0, NULL);
}
}
if (scanstate->ss.ss_currentScanDesc == NULL) {
scanstate->ss.ps.stubType = PST_Scan;
}
/*
* get the scan type from the relation descriptor.
*/
ExecAssignScanType(&scanstate->ss, RelationGetDescr(currentRelation));
/*
* Initialize result tuple type and projection info.
*/
ExecAssignResultTypeFromTL(
&scanstate->ss.ps,
scanstate->ss.ss_ScanTupleSlot->tts_tupleDescriptor->td_tam_ops);
ExecAssignScanProjectionInfo(&scanstate->ss);
Assert(scanstate->ss.ps.ps_ResultTupleSlot->tts_tupleDescriptor->td_tam_ops);
/*
* 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;
}
/*
* @@GaussDB@@
* Target : data partition
* Brief : Initialize the table partition and the index partition for
* : index sacn
* Description :
* Input :
* Output :
* Notes :
*/
static void ExecInitNextPartitionForBitmapHeapScan(BitmapHeapScanState* node)
{
Partition currentpartition = NULL;
Relation currentpartitionrel = NULL;
BitmapHeapScan* plan = NULL;
int paramno = -1;
ParamExecData* param = NULL;
int subPartParamno = -1;
ParamExecData* SubPrtParam = NULL;
plan = (BitmapHeapScan*)(node->ss.ps.plan);
/* get partition sequnce */
paramno = plan->scan.plan.paramno;
param = &(node->ss.ps.state->es_param_exec_vals[paramno]);
node->ss.currentSlot = (int)param->value;
subPartParamno = plan->scan.plan.subparamno;
SubPrtParam = &(node->ss.ps.state->es_param_exec_vals[subPartParamno]);
/* construct a dummy relation with the nextl table partition */
currentpartition = (Partition)list_nth(node->ss.partitions, node->ss.currentSlot);
currentpartitionrel = partitionGetRelation(node->ss.ss_currentRelation, currentpartition);
/* switch the partition that needs to be scanned */
Assert(PointerIsValid(node->ss.ss_currentPartition));
releaseDummyRelation(&(node->ss.ss_currentPartition));
BitmapHeapScanState* bitmapState = node;
BitmapHeapScan* bitmpHeapScan = (BitmapHeapScan*)node->ss.ps.plan;
Snapshot scanSnap;
scanSnap = TvChooseScanSnap(currentpartitionrel, &bitmpHeapScan->scan, &bitmapState->ss);
if (currentpartitionrel->partMap != NULL) {
Partition currentSubPartition = NULL;
List* currentSubPartitionList = NULL;
Relation currentSubPartitionRel = NULL;
Assert(SubPrtParam != NULL);
currentSubPartitionList = (List *)list_nth(node->ss.subpartitions, node->ss.currentSlot);
currentSubPartition = (Partition)list_nth(currentSubPartitionList, (int)SubPrtParam->value);
currentSubPartitionRel = partitionGetRelation(currentpartitionrel, currentSubPartition);
releaseDummyRelation(&(currentpartitionrel));
node->ss.ss_currentPartition = currentSubPartitionRel;
node->gpi_scan->parentRelation = currentpartitionrel;
/* Initialize scan descriptor. */
node->ss.ss_currentScanDesc =
scan_handler_tbl_beginscan_bm(currentSubPartitionRel, scanSnap, 0, NULL, &node->ss);
} else {
node->ss.ss_currentPartition = currentpartitionrel;
/* Initialize scan descriptor. */
node->ss.ss_currentScanDesc =
scan_handler_tbl_beginscan_bm(currentpartitionrel, scanSnap, 0, NULL, &node->ss);
}
}
/*
* @@GaussDB@@
* Target : data partition
* Brief : get the table partition that need to be scanned, and add it
* : the list for the following scanning
* Description :
* Input :
* Output :
* Notes :
*/
static void ExecInitPartitionForBitmapHeapScan(BitmapHeapScanState* scanstate, EState* estate)
{
BitmapHeapScan* plan = NULL;
Relation currentRelation = NULL;
plan = (BitmapHeapScan*)scanstate->ss.ps.plan;
currentRelation = scanstate->ss.ss_currentRelation;
scanstate->ss.partitions = NIL;
scanstate->ss.ss_currentPartition = NULL;
if (plan->scan.itrs > 0) {
LOCKMODE lock = NoLock;
Partition tablepartition = NULL;
bool relistarget = false;
PruningResult* resultPlan = NULL;
if (plan->scan.pruningInfo->expr) {
resultPlan = GetPartitionInfo(plan->scan.pruningInfo, estate, currentRelation);
if (ENABLE_SQL_BETA_FEATURE(PARTITION_OPFUSION)) {
if (estate->pruningResult) {
destroyPruningResult(estate->pruningResult);
}
estate->pruningResult = resultPlan;
}
} else {
resultPlan = plan->scan.pruningInfo;
}
if (resultPlan->ls_rangeSelectedPartitions != NULL) {
scanstate->ss.part_id = resultPlan->ls_rangeSelectedPartitions->length;
} else {
scanstate->ss.part_id = 0;
}
ListCell* cell1 = NULL;
ListCell* cell2 = NULL;
List* part_seqs = resultPlan->ls_rangeSelectedPartitions;
List* partitionnos = resultPlan->ls_selectedPartitionnos;
Assert(list_length(part_seqs) == list_length(partitionnos));
relistarget = ExecRelationIsTargetRelation(estate, plan->scan.scanrelid);
lock = (relistarget ? RowExclusiveLock : AccessShareLock);
scanstate->ss.lockMode = lock;
forboth (cell1, part_seqs, cell2, partitionnos) {
Oid tablepartitionid = InvalidOid;
int partSeq = lfirst_int(cell1);
int partitionno = lfirst_int(cell2);
/* add table partition to list */
tablepartitionid = getPartitionOidFromSequence(currentRelation, partSeq, partitionno);
tablepartition = PartitionOpenWithPartitionno(currentRelation, tablepartitionid, partitionno, lock);
scanstate->ss.partitions = lappend(scanstate->ss.partitions, tablepartition);
if (resultPlan->ls_selectedSubPartitions != NIL) {
Relation partRelation = partitionGetRelation(currentRelation, tablepartition);
SubPartitionPruningResult* subPartPruningResult =
GetSubPartitionPruningResult(resultPlan->ls_selectedSubPartitions, partSeq, partitionno);
if (subPartPruningResult == NULL) {
continue;
}
List *subpart_seqs = subPartPruningResult->ls_selectedSubPartitions;
List *subpartitionnos = subPartPruningResult->ls_selectedSubPartitionnos;
Assert(list_length(subpart_seqs) == list_length(subpartitionnos));
List *subpartition = NULL;
ListCell *lc1 = NULL;
ListCell *lc2 = NULL;
forboth (lc1, subpart_seqs, lc2, subpartitionnos) {
Oid subpartitionid = InvalidOid;
int subpartSeq = lfirst_int(lc1);
int subpartitionno = lfirst_int(lc2);
subpartitionid = getPartitionOidFromSequence(partRelation, subpartSeq, subpartitionno);
Partition subpart =
PartitionOpenWithPartitionno(partRelation, subpartitionid, subpartitionno, lock);
subpartition = lappend(subpartition, subpart);
}
releaseDummyRelation(&(partRelation));
scanstate->ss.subPartLengthList =
lappend_int(scanstate->ss.subPartLengthList, list_length(subpartition));
scanstate->ss.subpartitions = lappend(scanstate->ss.subpartitions, subpartition);
}
}
}
}
static Relation BitmapHeapPrefetchTargetRel(BitmapHeapScanState* node, Oid partoid, bool partmatched,
int2 bucketid, bool bktmatched)
{
Relation targetheap = NULL;
HBktTblScanDesc hpscan = (HBktTblScanDesc)node->ss.ss_currentScanDesc;
bool partchanged = false;
bool bktchanged = false;
bool isgpi = OidIsValid(partoid);
bool iscbi = BUCKET_NODE_IS_VALID(bucketid);
if (isgpi && !partmatched) {
GPISetCurrPartOid(node->gpi_scan, partoid);
partchanged = GPIGetNextPartRelation(node->gpi_scan, CurrentMemoryContext, AccessShareLock);
targetheap = node->gpi_scan->fakePartRelation;
}
if (iscbi) {
if (partchanged) {
cbi_set_bucketid(node->cbi_scan, InvalidBktId);
} else if (!bktmatched) {
cbi_set_bucketid(node->cbi_scan, bucketid);
}
targetheap = cbi_bitmapheap_scan_getbucket(hpscan, node->gpi_scan, node->cbi_scan, bucketid);
bktchanged = (targetheap != hpscan->currBktRel);
}
if (!partchanged && !bktchanged) {
return NULL;
}
return targetheap;
}
/* First sort by partition oid, then call PageListPrefetch to get the pages under each partition */
void BitmapHeapPrefetchWithCrossLevelIndex(BitmapHeapScanState* node, int prefetchNow, PrefetchNode* prefetchNode,
BlockNumber* blockList)
{
/*
* we must save part Oid before switch relation, and recover it after prefetch.
* The reason for this is to assure correctness while getting a new tbmres.
*/
HBktTblScanDesc hpscan = (HBktTblScanDesc)node->ss.ss_currentScanDesc;
Oid originOid = GPIGetCurrPartOid(node->gpi_scan);
int2 originBktId = cbi_get_current_bucketid(node->cbi_scan);
int blkCount = 0;
Oid prevOid = prefetchNode[0].partOid;
int2 prevBktId = prefetchNode[0].bktId;
bool isgpi = OidIsValid(prevOid);
bool iscbi = BUCKET_NODE_IS_VALID(prevBktId);
bool partmatched, bktmatched;
Relation targetheap = NULL;
for (int i = 0; i < prefetchNow; i++) {
partmatched = bktmatched = false;
if (isgpi && prefetchNode[i].partOid == prevOid) {
partmatched = true;
}
if (iscbi && prefetchNode[i].bktId == prevBktId) {
bktmatched = true;
}
targetheap = BitmapHeapPrefetchTargetRel(node, prevOid, partmatched, prevBktId, bktmatched);
if (RelationIsValid(targetheap)) {
PageListPrefetch(targetheap, MAIN_FORKNUM, blockList, blkCount, 0, 0);
}
if (isgpi && !partmatched) {
blkCount = 0;
prevOid = prefetchNode[i].partOid;
}
if (iscbi && !bktmatched) {
blkCount = 0;
prevBktId = prefetchNode[i].bktId;
if (RelationIsValid(targetheap) && targetheap != hpscan->currBktRel) {
bucketCloseRelation(targetheap);
}
}
blockList[blkCount++] = prefetchNode[i].blockNum;
}
targetheap = BitmapHeapPrefetchTargetRel(node, prevOid, false, prevBktId, false);
if (RelationIsValid(targetheap)) {
PageListPrefetch(targetheap, MAIN_FORKNUM, blockList, blkCount, 0, 0);
if (targetheap != hpscan->currBktRel) {
bucketCloseRelation(targetheap);
}
}
/* recover old oid after prefetch switch */
GPISetCurrPartOid(node->gpi_scan, originOid);
cbi_set_bucketid(node->cbi_scan, originBktId);
}
Relation BitmapHeapPrefetchNextTargetHeap(BitmapHeapScanState* node, TBMIterateResult* tbmpre, Relation curr_targetheap)
{
bool need_reset_bucketid = false;
Relation targetheap = NULL;
Relation next_targetheap = curr_targetheap;
if (tbm_is_global(node->tbm) && GPIScanCheckPartOid(node->gpi_scan, tbmpre->partitionOid)) {
GPISetCurrPartOid(node->gpi_scan, tbmpre->partitionOid);
if (!GPIGetNextPartRelation(node->gpi_scan, CurrentMemoryContext, AccessShareLock)) {
/* If the current partition is invalid, the next page is directly processed */
return NULL;
}
next_targetheap = node->gpi_scan->fakePartRelation;
need_reset_bucketid = true;
}
if (tbm_is_crossbucket(node->tbm)) { /* for crossbucket index */
HBktTblScanDesc hpscan = (HBktTblScanDesc)node->ss.ss_currentScanDesc;
int2 bucketid = tbmpre->bucketid; /* set to the current iterating bucketid */
Assert(BUCKET_NODE_IS_VALID(bucketid));
if (need_reset_bucketid) {
cbi_set_bucketid(node->cbi_scan, InvalidBktId);
}
targetheap = cbi_bitmapheap_scan_getbucket(hpscan, node->gpi_scan, node->cbi_scan, bucketid);
if (targetheap == NULL) {
return NULL;
}
/* update target relation to prefetch */
next_targetheap = targetheap;
}
return next_targetheap;
}
void BitmapHeapPrefetchNextAsync(BitmapHeapScanState* node, TableScanDesc scan, const TIDBitmap* tbm,
TBMIterator** prefetch_iterator)
{
BlockNumber* blockList = NULL;
BlockNumber* blockListPtr = NULL;
PrefetchNode* prefetchNode = NULL;
PrefetchNode* prefetchNodePtr = NULL;
int prefetchNow = 0;
int prefetchWindow = node->prefetch_target - node->prefetch_pages;
/* We expect to prefetch at most prefetchWindow pages */
if (prefetchWindow > 0) {
if (tbm_is_global(tbm) || tbm_is_crossbucket(tbm)) {
prefetchNode = (PrefetchNode*)malloc(sizeof(PrefetchNode) * prefetchWindow);
prefetchNodePtr = prefetchNode;
}
blockList = (BlockNumber*)palloc(sizeof(BlockNumber) * prefetchWindow);
blockListPtr = blockList;
}
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 = *prefetch_iterator = NULL;
break;
}
node->prefetch_pages++;
/* we use PrefetchNode here to store relations between blockno and partition Oid */
if ((tbm_is_global(tbm) || tbm_is_crossbucket(tbm)) && prefetchNodePtr != NULL) {
prefetchNodePtr->blockNum = tbmpre->blockno;
prefetchNodePtr->partOid = tbmpre->partitionOid;
prefetchNodePtr->bktId = tbmpre->bucketid;
prefetchNodePtr++;
}
/* For Async Direct I/O we accumulate a list and send it */
if (blockListPtr != NULL) {
*blockListPtr++ = tbmpre->blockno;
}
prefetchNow++;
}
/* Send the list we generated and free it */
if (prefetchNow && blockList != NULL) {
if (tbm_is_global(tbm) || tbm_is_crossbucket(tbm)) {
BitmapHeapPrefetchWithCrossLevelIndex(node, prefetchNow, prefetchNode, blockList);
} else {
PageListPrefetch(scan->rs_rd, MAIN_FORKNUM, blockList, prefetchNow, 0, 0);
}
}
if (prefetchWindow > 0) {
pfree_ext(blockList);
if (tbm_is_global(tbm) || tbm_is_crossbucket(tbm)) {
pfree_ext(prefetchNode);
}
}
}
/*
* 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.
*/
void BitmapHeapPrefetchNext(
BitmapHeapScanState* node, TableScanDesc scan, const TIDBitmap* tbm, TBMIterator** prefetch_iterator)
{
if (*prefetch_iterator == NULL) {
return;
}
Assert(node->tbm == tbm);
ADIO_RUN()
{
/* prefetch next asynchronously */
BitmapHeapPrefetchNextAsync(node, scan, tbm, prefetch_iterator);
}
ADIO_ELSE()
{
/* prefetch next synchronously */
if (unlikely(tbm_is_crossbucket(tbm) || tbm_is_global(tbm))) {
HBktTblScanDesc hpscan = NULL;
Oid oldOid = GPIGetCurrPartOid(node->gpi_scan);
int2 oldBktId = cbi_get_current_bucketid(node->cbi_scan);
Relation oldheap = NULL;
Relation prefetchRel = scan->rs_rd;
while (node->prefetch_pages < node->prefetch_target) {
TBMIterateResult* tbmpre = tbm_iterate(*prefetch_iterator);
hpscan = (tbm_is_crossbucket(node->tbm) ? (HBktTblScanDesc)node->ss.ss_currentScanDesc : NULL);
if (tbmpre == NULL) {
/* No more pages to prefetch */
tbm_end_iterate(*prefetch_iterator);
node->prefetch_iterator = *prefetch_iterator = NULL;
break;
}
node->prefetch_pages++;
prefetchRel = BitmapHeapPrefetchNextTargetHeap(node, tbmpre, prefetchRel);
if (prefetchRel == NULL) {
tbmpre = NULL;
continue;
}
/* For posix_fadvise() we just send the one request */
PrefetchBuffer(prefetchRel, MAIN_FORKNUM, tbmpre->blockno);
if (RelationIsValid(oldheap) && oldheap != prefetchRel && PointerIsValid(hpscan) &&
oldheap != hpscan->currBktRel) {
/* release previous bucket fake relation except the current scanning one */
bucketCloseRelation(oldheap);
/* now oldheap is NULL */
}
oldheap = prefetchRel;
}
if (RelationIsValid(oldheap) && PointerIsValid(hpscan) && oldheap != hpscan->currBktRel) {
/* release previous bucket fake relation except the current scanning one */
bucketCloseRelation(oldheap);
}
/* recover old oid after prefetch switch */
GPISetCurrPartOid(node->gpi_scan, oldOid);
cbi_set_bucketid(node->cbi_scan, oldBktId);
} else {
while (node->prefetch_pages < node->prefetch_target) {
TBMIterateResult* tbmpre = tbm_iterate(*prefetch_iterator);
Relation prefetchRel = scan->rs_rd;
if (tbmpre == NULL) {
/* No more pages to prefetch */
tbm_end_iterate(*prefetch_iterator);
node->prefetch_iterator = *prefetch_iterator = NULL;
break;
}
node->prefetch_pages++;
/* For posix_fadvise() we just send the one request */
PrefetchBuffer(prefetchRel, MAIN_FORKNUM, tbmpre->blockno);
}
}
}
ADIO_END();
}
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