Header And Logo
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#include "postgres.h"#include "access/relscan.h"#include "access/visibilitymap.h"#include "executor/execdebug.h"#include "executor/nodeIndexonlyscan.h"#include "executor/nodeIndexscan.h"#include "storage/bufmgr.h"#include "storage/predicate.h"#include "utils/memutils.h"#include "utils/rel.h"
Go to the source code of this file.
Functions | |
| static TupleTableSlot * | IndexOnlyNext (IndexOnlyScanState *node) |
| static void | StoreIndexTuple (TupleTableSlot *slot, IndexTuple itup, TupleDesc itupdesc) |
| static bool | IndexOnlyRecheck (IndexOnlyScanState *node, TupleTableSlot *slot) |
| TupleTableSlot * | ExecIndexOnlyScan (IndexOnlyScanState *node) |
| void | ExecReScanIndexOnlyScan (IndexOnlyScanState *node) |
| void | ExecEndIndexOnlyScan (IndexOnlyScanState *node) |
| void | ExecIndexOnlyMarkPos (IndexOnlyScanState *node) |
| void | ExecIndexOnlyRestrPos (IndexOnlyScanState *node) |
| IndexOnlyScanState * | ExecInitIndexOnlyScan (IndexOnlyScan *node, EState *estate, int eflags) |
| void ExecEndIndexOnlyScan | ( | IndexOnlyScanState * | node | ) |
Definition at line 283 of file nodeIndexonlyscan.c.
References ExecClearTuple(), ExecCloseScanRelation(), ExecFreeExprContext(), FreeExprContext(), index_close(), index_endscan(), InvalidBuffer, IndexOnlyScanState::ioss_RelationDesc, IndexOnlyScanState::ioss_RuntimeContext, IndexOnlyScanState::ioss_ScanDesc, IndexOnlyScanState::ioss_VMBuffer, NoLock, ScanState::ps, PlanState::ps_ResultTupleSlot, ReleaseBuffer(), IndexOnlyScanState::ss, ScanState::ss_currentRelation, and ScanState::ss_ScanTupleSlot.
Referenced by ExecEndNode().
{
Relation indexRelationDesc;
IndexScanDesc indexScanDesc;
Relation relation;
/*
* extract information from the node
*/
indexRelationDesc = node->ioss_RelationDesc;
indexScanDesc = node->ioss_ScanDesc;
relation = node->ss.ss_currentRelation;
/* Release VM buffer pin, if any. */
if (node->ioss_VMBuffer != InvalidBuffer)
{
ReleaseBuffer(node->ioss_VMBuffer);
node->ioss_VMBuffer = InvalidBuffer;
}
/*
* Free the exprcontext(s) ... now dead code, see ExecFreeExprContext
*/
#ifdef NOT_USED
ExecFreeExprContext(&node->ss.ps);
if (node->ioss_RuntimeContext)
FreeExprContext(node->ioss_RuntimeContext, true);
#endif
/*
* clear out tuple table slots
*/
ExecClearTuple(node->ss.ps.ps_ResultTupleSlot);
ExecClearTuple(node->ss.ss_ScanTupleSlot);
/*
* close the index relation (no-op if we didn't open it)
*/
if (indexScanDesc)
index_endscan(indexScanDesc);
if (indexRelationDesc)
index_close(indexRelationDesc, NoLock);
/*
* close the heap relation.
*/
ExecCloseScanRelation(relation);
}
| void ExecIndexOnlyMarkPos | ( | IndexOnlyScanState * | node | ) |
Definition at line 337 of file nodeIndexonlyscan.c.
References index_markpos(), and IndexOnlyScanState::ioss_ScanDesc.
Referenced by ExecMarkPos().
{
index_markpos(node->ioss_ScanDesc);
}
| void ExecIndexOnlyRestrPos | ( | IndexOnlyScanState * | node | ) |
Definition at line 347 of file nodeIndexonlyscan.c.
References index_restrpos(), and IndexOnlyScanState::ioss_ScanDesc.
Referenced by ExecRestrPos().
{
index_restrpos(node->ioss_ScanDesc);
}
| TupleTableSlot* ExecIndexOnlyScan | ( | IndexOnlyScanState * | node | ) |
Definition at line 224 of file nodeIndexonlyscan.c.
References ExecReScan(), ExecScan(), IndexOnlyNext(), IndexOnlyRecheck(), IndexOnlyScanState::ioss_NumRuntimeKeys, and IndexOnlyScanState::ioss_RuntimeKeysReady.
Referenced by ExecProcNode().
{
/*
* If we have runtime keys and they've not already been set up, do it now.
*/
if (node->ioss_NumRuntimeKeys != 0 && !node->ioss_RuntimeKeysReady)
ExecReScan((PlanState *) node);
return ExecScan(&node->ss,
(ExecScanAccessMtd) IndexOnlyNext,
(ExecScanRecheckMtd) IndexOnlyRecheck);
}
| IndexOnlyScanState* ExecInitIndexOnlyScan | ( | IndexOnlyScan * | node, | |
| EState * | estate, | |||
| int | eflags | |||
| ) |
Definition at line 364 of file nodeIndexonlyscan.c.
References AccessShareLock, EState::es_snapshot, EXEC_FLAG_EXPLAIN_ONLY, ExecAssignExprContext(), ExecAssignResultTypeFromTL(), ExecAssignScanProjectionInfo(), ExecAssignScanType(), ExecIndexBuildScanKeys(), ExecInitExpr(), ExecInitResultTupleSlot(), ExecInitScanTupleSlot(), ExecOpenScanRelation(), ExecRelationIsTargetRelation(), ExecTypeFromTL(), index_beginscan(), index_open(), index_rescan(), IndexOnlyScan::indexid, IndexOnlyScan::indexorderby, IndexOnlyScan::indexqual, IndexOnlyScanState::indexqual, IndexOnlyScan::indextlist, IndexOnlyScanState::ioss_HeapFetches, IndexOnlyScanState::ioss_NumRuntimeKeys, IndexOnlyScanState::ioss_RelationDesc, IndexOnlyScanState::ioss_RuntimeKeys, IndexOnlyScanState::ioss_RuntimeKeysReady, makeNode, NoLock, NULL, Scan::plan, PlanState::plan, ScanState::ps, PlanState::ps_ExprContext, PlanState::ps_TupFromTlist, Plan::qual, PlanState::qual, IndexOnlyScan::scan, Scan::scanrelid, IndexOnlyScanState::ss, ScanState::ss_currentRelation, ScanState::ss_currentScanDesc, PlanState::state, Plan::targetlist, and PlanState::targetlist.
Referenced by ExecInitNode().
{
IndexOnlyScanState *indexstate;
Relation currentRelation;
bool relistarget;
TupleDesc tupDesc;
/*
* create state structure
*/
indexstate = makeNode(IndexOnlyScanState);
indexstate->ss.ps.plan = (Plan *) node;
indexstate->ss.ps.state = estate;
indexstate->ioss_HeapFetches = 0;
/*
* Miscellaneous initialization
*
* create expression context for node
*/
ExecAssignExprContext(estate, &indexstate->ss.ps);
indexstate->ss.ps.ps_TupFromTlist = false;
/*
* initialize child expressions
*
* Note: we don't initialize all of the indexorderby expression, only the
* sub-parts corresponding to runtime keys (see below).
*/
indexstate->ss.ps.targetlist = (List *)
ExecInitExpr((Expr *) node->scan.plan.targetlist,
(PlanState *) indexstate);
indexstate->ss.ps.qual = (List *)
ExecInitExpr((Expr *) node->scan.plan.qual,
(PlanState *) indexstate);
indexstate->indexqual = (List *)
ExecInitExpr((Expr *) node->indexqual,
(PlanState *) indexstate);
/*
* tuple table initialization
*/
ExecInitResultTupleSlot(estate, &indexstate->ss.ps);
ExecInitScanTupleSlot(estate, &indexstate->ss);
/*
* open the base relation and acquire appropriate lock on it.
*/
currentRelation = ExecOpenScanRelation(estate, node->scan.scanrelid, eflags);
indexstate->ss.ss_currentRelation = currentRelation;
indexstate->ss.ss_currentScanDesc = NULL; /* no heap scan here */
/*
* Build the scan tuple type using the indextlist generated by the
* planner. We use this, rather than the index's physical tuple
* descriptor, because the latter contains storage column types not the
* types of the original datums. (It's the AM's responsibility to return
* suitable data anyway.)
*/
tupDesc = ExecTypeFromTL(node->indextlist, false);
ExecAssignScanType(&indexstate->ss, tupDesc);
/*
* Initialize result tuple type and projection info.
*/
ExecAssignResultTypeFromTL(&indexstate->ss.ps);
ExecAssignScanProjectionInfo(&indexstate->ss);
/*
* If we are just doing EXPLAIN (ie, aren't going to run the plan), stop
* here. This allows an index-advisor plugin to EXPLAIN a plan containing
* references to nonexistent indexes.
*/
if (eflags & EXEC_FLAG_EXPLAIN_ONLY)
return indexstate;
/*
* Open the index relation.
*
* If the parent table is one of the target relations of the query, then
* InitPlan already opened and write-locked the index, so we can avoid
* taking another lock here. Otherwise we need a normal reader's lock.
*/
relistarget = ExecRelationIsTargetRelation(estate, node->scan.scanrelid);
indexstate->ioss_RelationDesc = index_open(node->indexid,
relistarget ? NoLock : AccessShareLock);
/*
* Initialize index-specific scan state
*/
indexstate->ioss_RuntimeKeysReady = false;
indexstate->ioss_RuntimeKeys = NULL;
indexstate->ioss_NumRuntimeKeys = 0;
/*
* build the index scan keys from the index qualification
*/
ExecIndexBuildScanKeys((PlanState *) indexstate,
indexstate->ioss_RelationDesc,
node->indexqual,
false,
&indexstate->ioss_ScanKeys,
&indexstate->ioss_NumScanKeys,
&indexstate->ioss_RuntimeKeys,
&indexstate->ioss_NumRuntimeKeys,
NULL, /* no ArrayKeys */
NULL);
/*
* any ORDER BY exprs have to be turned into scankeys in the same way
*/
ExecIndexBuildScanKeys((PlanState *) indexstate,
indexstate->ioss_RelationDesc,
node->indexorderby,
true,
&indexstate->ioss_OrderByKeys,
&indexstate->ioss_NumOrderByKeys,
&indexstate->ioss_RuntimeKeys,
&indexstate->ioss_NumRuntimeKeys,
NULL, /* no ArrayKeys */
NULL);
/*
* If we have runtime keys, we need an ExprContext to evaluate them. The
* node's standard context won't do because we want to reset that context
* for every tuple. So, build another context just like the other one...
* -tgl 7/11/00
*/
if (indexstate->ioss_NumRuntimeKeys != 0)
{
ExprContext *stdecontext = indexstate->ss.ps.ps_ExprContext;
ExecAssignExprContext(estate, &indexstate->ss.ps);
indexstate->ioss_RuntimeContext = indexstate->ss.ps.ps_ExprContext;
indexstate->ss.ps.ps_ExprContext = stdecontext;
}
else
{
indexstate->ioss_RuntimeContext = NULL;
}
/*
* Initialize scan descriptor.
*/
indexstate->ioss_ScanDesc = index_beginscan(currentRelation,
indexstate->ioss_RelationDesc,
estate->es_snapshot,
indexstate->ioss_NumScanKeys,
indexstate->ioss_NumOrderByKeys);
/* Set it up for index-only scan */
indexstate->ioss_ScanDesc->xs_want_itup = true;
indexstate->ioss_VMBuffer = InvalidBuffer;
/*
* If no run-time keys to calculate, go ahead and pass the scankeys to the
* index AM.
*/
if (indexstate->ioss_NumRuntimeKeys == 0)
index_rescan(indexstate->ioss_ScanDesc,
indexstate->ioss_ScanKeys,
indexstate->ioss_NumScanKeys,
indexstate->ioss_OrderByKeys,
indexstate->ioss_NumOrderByKeys);
/*
* all done.
*/
return indexstate;
}
| void ExecReScanIndexOnlyScan | ( | IndexOnlyScanState * | node | ) |
Definition at line 249 of file nodeIndexonlyscan.c.
References ExecIndexEvalRuntimeKeys(), ExecScanReScan(), index_rescan(), IndexOnlyScanState::ioss_NumOrderByKeys, IndexOnlyScanState::ioss_NumRuntimeKeys, IndexOnlyScanState::ioss_NumScanKeys, IndexOnlyScanState::ioss_OrderByKeys, IndexOnlyScanState::ioss_RuntimeContext, IndexOnlyScanState::ioss_RuntimeKeys, IndexOnlyScanState::ioss_RuntimeKeysReady, IndexOnlyScanState::ioss_ScanDesc, IndexOnlyScanState::ioss_ScanKeys, ResetExprContext, and IndexOnlyScanState::ss.
Referenced by ExecReScan().
{
/*
* If we are doing runtime key calculations (ie, any of the index key
* values weren't simple Consts), compute the new key values. But first,
* reset the context so we don't leak memory as each outer tuple is
* scanned. Note this assumes that we will recalculate *all* runtime keys
* on each call.
*/
if (node->ioss_NumRuntimeKeys != 0)
{
ExprContext *econtext = node->ioss_RuntimeContext;
ResetExprContext(econtext);
ExecIndexEvalRuntimeKeys(econtext,
node->ioss_RuntimeKeys,
node->ioss_NumRuntimeKeys);
}
node->ioss_RuntimeKeysReady = true;
/* reset index scan */
index_rescan(node->ioss_ScanDesc,
node->ioss_ScanKeys, node->ioss_NumScanKeys,
node->ioss_OrderByKeys, node->ioss_NumOrderByKeys);
ExecScanReScan(&node->ss);
}
| static TupleTableSlot * IndexOnlyNext | ( | IndexOnlyScanState * | node | ) | [static] |
Definition at line 50 of file nodeIndexonlyscan.c.
References ExprContext::ecxt_scantuple, elog, ERROR, EState::es_direction, EState::es_snapshot, ExecClearTuple(), ExecQual(), IndexScanDescData::heapRelation, index_fetch_heap(), index_getnext_tid(), IndexOnlyScanState::indexqual, InstrCountFiltered2, IndexOnlyScanState::ioss_HeapFetches, IndexOnlyScanState::ioss_ScanDesc, IndexOnlyScanState::ioss_VMBuffer, ItemPointerGetBlockNumber, NULL, PlanState::plan, PredicateLockPage(), ScanState::ps, PlanState::ps_ExprContext, ResetExprContext, ScanDirectionIsBackward, ScanDirectionIsForward, IndexOnlyScanState::ss, ScanState::ss_ScanTupleSlot, PlanState::state, StoreIndexTuple(), visibilitymap_test(), IndexScanDescData::xs_continue_hot, IndexScanDescData::xs_itup, IndexScanDescData::xs_itupdesc, and IndexScanDescData::xs_recheck.
Referenced by ExecIndexOnlyScan().
{
EState *estate;
ExprContext *econtext;
ScanDirection direction;
IndexScanDesc scandesc;
TupleTableSlot *slot;
ItemPointer tid;
/*
* extract necessary information from index scan node
*/
estate = node->ss.ps.state;
direction = estate->es_direction;
/* flip direction if this is an overall backward scan */
if (ScanDirectionIsBackward(((IndexOnlyScan *) node->ss.ps.plan)->indexorderdir))
{
if (ScanDirectionIsForward(direction))
direction = BackwardScanDirection;
else if (ScanDirectionIsBackward(direction))
direction = ForwardScanDirection;
}
scandesc = node->ioss_ScanDesc;
econtext = node->ss.ps.ps_ExprContext;
slot = node->ss.ss_ScanTupleSlot;
/*
* OK, now that we have what we need, fetch the next tuple.
*/
while ((tid = index_getnext_tid(scandesc, direction)) != NULL)
{
HeapTuple tuple = NULL;
/*
* We can skip the heap fetch if the TID references a heap page on
* which all tuples are known visible to everybody. In any case,
* we'll use the index tuple not the heap tuple as the data source.
*
* Note on Memory Ordering Effects: visibilitymap_test does not lock
* the visibility map buffer, and therefore the result we read here
* could be slightly stale. However, it can't be stale enough to
* matter. It suffices to show that (1) there is a read barrier
* between the time we read the index TID and the time we test the
* visibility map; and (2) there is a write barrier between the time
* some other concurrent process clears the visibility map bit and the
* time it inserts the index TID. Since acquiring or releasing a
* LWLock interposes a full barrier, this is easy to show: (1) is
* satisfied by the release of the index buffer content lock after
* reading the TID; and (2) is satisfied by the acquisition of the
* buffer content lock in order to insert the TID.
*/
if (!visibilitymap_test(scandesc->heapRelation,
ItemPointerGetBlockNumber(tid),
&node->ioss_VMBuffer))
{
/*
* Rats, we have to visit the heap to check visibility.
*/
node->ioss_HeapFetches++;
tuple = index_fetch_heap(scandesc);
if (tuple == NULL)
continue; /* no visible tuple, try next index entry */
/*
* Only MVCC snapshots are supported here, so there should be no
* need to keep following the HOT chain once a visible entry has
* been found. If we did want to allow that, we'd need to keep
* more state to remember not to call index_getnext_tid next time.
*/
if (scandesc->xs_continue_hot)
elog(ERROR, "non-MVCC snapshots are not supported in index-only scans");
/*
* Note: at this point we are holding a pin on the heap page, as
* recorded in scandesc->xs_cbuf. We could release that pin now,
* but it's not clear whether it's a win to do so. The next index
* entry might require a visit to the same heap page.
*/
}
/*
* Fill the scan tuple slot with data from the index.
*/
StoreIndexTuple(slot, scandesc->xs_itup, scandesc->xs_itupdesc);
/*
* If the index was lossy, we have to recheck the index quals.
* (Currently, this can never happen, but we should support the case
* for possible future use, eg with GiST indexes.)
*/
if (scandesc->xs_recheck)
{
econtext->ecxt_scantuple = slot;
ResetExprContext(econtext);
if (!ExecQual(node->indexqual, econtext, false))
{
/* Fails recheck, so drop it and loop back for another */
InstrCountFiltered2(node, 1);
continue;
}
}
/*
* Predicate locks for index-only scans must be acquired at the page
* level when the heap is not accessed, since tuple-level predicate
* locks need the tuple's xmin value. If we had to visit the tuple
* anyway, then we already have the tuple-level lock and can skip the
* page lock.
*/
if (tuple == NULL)
PredicateLockPage(scandesc->heapRelation,
ItemPointerGetBlockNumber(tid),
estate->es_snapshot);
return slot;
}
/*
* if we get here it means the index scan failed so we are at the end of
* the scan..
*/
return ExecClearTuple(slot);
}
| static bool IndexOnlyRecheck | ( | IndexOnlyScanState * | node, | |
| TupleTableSlot * | slot | |||
| ) | [static] |
Definition at line 213 of file nodeIndexonlyscan.c.
Referenced by ExecIndexOnlyScan().
| static void StoreIndexTuple | ( | TupleTableSlot * | slot, | |
| IndexTuple | itup, | |||
| TupleDesc | itupdesc | |||
| ) | [static] |
Definition at line 182 of file nodeIndexonlyscan.c.
References Assert, ExecClearTuple(), ExecStoreVirtualTuple(), i, index_getattr, tupleDesc::natts, TupleTableSlot::tts_isnull, TupleTableSlot::tts_tupleDescriptor, TupleTableSlot::tts_values, and values.
Referenced by IndexOnlyNext().
{
int nindexatts = itupdesc->natts;
Datum *values = slot->tts_values;
bool *isnull = slot->tts_isnull;
int i;
/*
* Note: we must use the tupdesc supplied by the AM in index_getattr, not
* the slot's tupdesc, in case the latter has different datatypes (this
* happens for btree name_ops in particular). They'd better have the same
* number of columns though, as well as being datatype-compatible which is
* something we can't so easily check.
*/
Assert(slot->tts_tupleDescriptor->natts == nindexatts);
ExecClearTuple(slot);
for (i = 0; i < nindexatts; i++)
values[i] = index_getattr(itup, i + 1, itupdesc, &isnull[i]);
ExecStoreVirtualTuple(slot);
}
1.7.1