/*
* systable_beginscan_ordered --- set up for ordered catalog scan
*
* These routines have essentially the same API as systable_beginscan etc,
* except that they guarantee to return multiple matching tuples in
* index order. Also, for largely historical reasons, the index to use
* is opened and locked by the caller, not here.
*
* Currently we do not support non-index-based scans here. (In principle
* we could do a heapscan and sort, but the uses are in places that
* probably don't need to still work with corrupted catalog indexes.)
* For the moment, therefore, these functions are merely the thinnest of
* wrappers around index_beginscan/index_getnext. The main reason for their
* existence is to centralize possible future support of lossy operators
* in catalog scans.
*/
SysScanDesc
systable_beginscan_ordered(Relation heapRelation,
Relation indexRelation,
Snapshot snapshot,
int nkeys, ScanKey key)
{
SysScanDesc sysscan;
int i;
/* REINDEX can probably be a hard error here ... */
if (ReindexIsProcessingIndex(RelationGetRelid(indexRelation)))
elog(ERROR, "cannot do ordered scan on index \"%s\", because it is being reindexed",
RelationGetRelationName(indexRelation));
/* ... but we only throw a warning about violating IgnoreSystemIndexes */
if (IgnoreSystemIndexes)
elog(WARNING, "using index \"%s\" despite IgnoreSystemIndexes",
RelationGetRelationName(indexRelation));
sysscan = (SysScanDesc) palloc(sizeof(SysScanDescData));
sysscan->heap_rel = heapRelation;
sysscan->irel = indexRelation;
if (snapshot == NULL)
{
Oid relid = RelationGetRelid(heapRelation);
snapshot = RegisterSnapshot(GetCatalogSnapshot(relid));
sysscan->snapshot = snapshot;
}
else
{
/* Caller is responsible for any snapshot. */
sysscan->snapshot = NULL;
}
/* Change attribute numbers to be index column numbers. */
for (i = 0; i < nkeys; i++)
{
int j;
for (j = 0; j < indexRelation->rd_index->indnatts; j++)
{
if (key[i].sk_attno == indexRelation->rd_index->indkey.values[j])
{
key[i].sk_attno = j + 1;
break;
}
}
if (j == indexRelation->rd_index->indnatts)
elog(ERROR, "column is not in index");
}
sysscan->iscan = index_beginscan(heapRelation, indexRelation,
snapshot, nkeys, 0);
index_rescan(sysscan->iscan, key, nkeys, NULL, 0);
sysscan->scan = NULL;
return sysscan;
}
/* ----------------------------------------------------------------
* ExecReScanIndexScan(node)
*
* Recalculates the values of any scan keys whose value depends on
* information known at runtime, then rescans the indexed relation.
*
* Updating the scan key was formerly done separately in
* ExecUpdateIndexScanKeys. Integrating it into ReScan makes
* rescans of indices and relations/general streams more uniform.
* ----------------------------------------------------------------
*/
void
ExecReScanIndexScan(IndexScanState *node)
{
/*
* 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->iss_NumRuntimeKeys != 0)
{
ExprContext *econtext = node->iss_RuntimeContext;
ResetExprContext(econtext);
ExecIndexEvalRuntimeKeys(econtext,
node->iss_RuntimeKeys,
node->iss_NumRuntimeKeys);
}
node->iss_RuntimeKeysReady = true;
/* reset index scan */
index_rescan(node->iss_ScanDesc,
node->iss_ScanKeys, node->iss_NumScanKeys,
node->iss_OrderByKeys, node->iss_NumOrderByKeys);
ExecScanReScan(&node->ss);
}
/* ----------------------------------------------------------------
* ExecIndexOnlyScanInitializeDSM
*
* Set up a parallel index-only scan descriptor.
* ----------------------------------------------------------------
*/
void
ExecIndexOnlyScanInitializeDSM(IndexOnlyScanState *node,
ParallelContext *pcxt)
{
EState *estate = node->ss.ps.state;
ParallelIndexScanDesc piscan;
piscan = shm_toc_allocate(pcxt->toc, node->ioss_PscanLen);
index_parallelscan_initialize(node->ss.ss_currentRelation,
node->ioss_RelationDesc,
estate->es_snapshot,
piscan);
shm_toc_insert(pcxt->toc, node->ss.ps.plan->plan_node_id, piscan);
node->ioss_ScanDesc =
index_beginscan_parallel(node->ss.ss_currentRelation,
node->ioss_RelationDesc,
node->ioss_NumScanKeys,
node->ioss_NumOrderByKeys,
piscan);
node->ioss_ScanDesc->xs_want_itup = true;
node->ioss_VMBuffer = InvalidBuffer;
/*
* If no run-time keys to calculate or they are ready, go ahead and pass
* the scankeys to the index AM.
*/
if (node->ioss_NumRuntimeKeys == 0 || node->ioss_RuntimeKeysReady)
index_rescan(node->ioss_ScanDesc,
node->ioss_ScanKeys, node->ioss_NumScanKeys,
node->ioss_OrderByKeys, node->ioss_NumOrderByKeys);
}
/* ----------------------------------------------------------------
* ExecIndexReScan(node)
*
* Recalculates the value of the scan keys whose value depends on
* information known at runtime and rescans the indexed relation.
* Updating the scan key was formerly done separately in
* ExecUpdateIndexScanKeys. Integrating it into ReScan makes
* rescans of indices and relations/general streams more uniform.
* ----------------------------------------------------------------
*/
void
ExecIndexReScan(IndexScanState *node, ExprContext *exprCtxt)
{
EState *estate;
ExprContext *econtext;
Index scanrelid;
estate = node->ss.ps.state;
econtext = node->iss_RuntimeContext; /* context for runtime keys */
scanrelid = ((IndexScan *) node->ss.ps.plan)->scan.scanrelid;
node->ss.ps.ps_TupFromTlist = false;
if (econtext)
{
/*
* If we are being passed an outer tuple, save it for runtime key
* calc. We also need to link it into the "regular" per-tuple
* econtext, so it can be used during indexqualorig evaluations.
*/
if (exprCtxt != NULL)
{
ExprContext *stdecontext;
econtext->ecxt_outertuple = exprCtxt->ecxt_outertuple;
stdecontext = node->ss.ps.ps_ExprContext;
stdecontext->ecxt_outertuple = exprCtxt->ecxt_outertuple;
}
/*
* Reset the runtime-key context so we don't leak memory as each outer
* tuple is scanned. Note this assumes that we will recalculate *all*
* runtime keys on each call.
*/
ResetExprContext(econtext);
}
/*
* If we are doing runtime key calculations (ie, the index keys depend on
* data from an outer scan), compute the new key values
*/
if (node->iss_NumRuntimeKeys != 0)
ExecIndexEvalRuntimeKeys(econtext,
node->iss_RuntimeKeys,
node->iss_NumRuntimeKeys);
node->iss_RuntimeKeysReady = true;
/* If this is re-scanning of PlanQual ... */
if (estate->es_evTuple != NULL &&
estate->es_evTuple[scanrelid - 1] != NULL)
{
estate->es_evTupleNull[scanrelid - 1] = false;
return;
}
/* reset index scan */
index_rescan(node->iss_ScanDesc, node->iss_ScanKeys);
}
/* ----------------------------------------------------------------
* ExecBitmapIndexReScan(node)
*
* Recalculates the value of the scan keys whose value depends on
* information known at runtime and rescans the indexed relation.
* ----------------------------------------------------------------
*/
void
ExecBitmapIndexReScan(BitmapIndexScanState *node, ExprContext *exprCtxt)
{
ExprContext *econtext;
ExprState **runtimeKeyInfo;
econtext = node->biss_RuntimeContext; /* context for runtime keys */
runtimeKeyInfo = node->biss_RuntimeKeyInfo;
if (econtext)
{
/*
* If we are being passed an outer tuple, save it for runtime key
* calc.
*/
if (exprCtxt != NULL)
econtext->ecxt_outertuple = exprCtxt->ecxt_outertuple;
/*
* Reset the runtime-key context so we don't leak memory as each outer
* tuple is scanned. Note this assumes that we will recalculate *all*
* runtime keys on each call.
*/
ResetExprContext(econtext);
}
/*
* If we are doing runtime key calculations (ie, the index keys depend on
* data from an outer scan), compute the new key values
*/
if (runtimeKeyInfo)
{
ExecIndexEvalRuntimeKeys(econtext,
runtimeKeyInfo,
node->biss_ScanKeys,
node->biss_NumScanKeys);
node->biss_RuntimeKeysReady = true;
}
/* reset index scan */
index_rescan(node->biss_ScanDesc, node->biss_ScanKeys);
if (node->odbiss_ScanDesc != NULL)
index_rescan(node->odbiss_ScanDesc, node->biss_ScanKeys);
}
/* ----------------
* RelationGetIndexScan -- Create and fill an IndexScanDesc.
*
* This routine creates an index scan structure and sets its contents
* up correctly. This routine calls AMrescan to set up the scan with
* the passed key.
*
* Parameters:
* indexRelation -- index relation for scan.
* nkeys -- count of scan keys.
* key -- array of scan keys to restrict the index scan.
*
* Returns:
* An initialized IndexScanDesc.
* ----------------
*/
IndexScanDesc
RelationGetIndexScan(Relation indexRelation,
int nkeys, ScanKey key)
{
IndexScanDesc scan;
scan = (IndexScanDesc) palloc(sizeof(IndexScanDescData));
scan->heapRelation = NULL; /* may be set later */
scan->indexRelation = indexRelation;
scan->xs_snapshot = SnapshotNow; /* may be set later */
scan->numberOfKeys = nkeys;
/*
* We allocate the key space here, but the AM is responsible for
* actually filling it from the passed key array.
*/
if (nkeys > 0)
scan->keyData = (ScanKey) palloc(sizeof(ScanKeyData) * nkeys);
else
scan->keyData = NULL;
scan->kill_prior_tuple = false;
scan->ignore_killed_tuples = true; /* default setting */
scan->keys_are_unique = false; /* may be set by index AM */
scan->got_tuple = false;
scan->opaque = NULL;
ItemPointerSetInvalid(&scan->currentItemData);
ItemPointerSetInvalid(&scan->currentMarkData);
ItemPointerSetInvalid(&scan->xs_ctup.t_self);
scan->xs_ctup.t_datamcxt = NULL;
scan->xs_ctup.t_data = NULL;
scan->xs_cbuf = InvalidBuffer;
/* mark cached function lookup data invalid; it will be set later */
scan->fn_getnext.fn_oid = InvalidOid;
scan->unique_tuple_pos = 0;
scan->unique_tuple_mark = 0;
pgstat_initstats(&scan->xs_pgstat_info, indexRelation);
/*
* Let the AM fill in the key and any opaque data it wants.
*/
index_rescan(scan, key);
return scan;
}
/* ----------------
* RelationGetIndexScan -- Create and fill an IndexScanDesc.
*
* This routine creates an index scan structure and sets its contents
* up correctly. This routine calls AMrescan to set up the scan with
* the passed key.
*
* Parameters:
* indexRelation -- index relation for scan.
* nkeys -- count of scan keys.
* key -- array of scan keys to restrict the index scan.
*
* Returns:
* An initialized IndexScanDesc.
* ----------------
*/
IndexScanDesc
RelationGetIndexScan(Relation indexRelation,
int nkeys, ScanKey key)
{
IndexScanDesc scan;
scan = (IndexScanDesc) palloc(sizeof(IndexScanDescData));
scan->heapRelation = NULL; /* may be set later */
scan->indexRelation = indexRelation;
scan->xs_snapshot = SnapshotNow; /* may be set later */
scan->numberOfKeys = nkeys;
/*
* We allocate the key space here, but the AM is responsible for actually
* filling it from the passed key array.
*/
if (nkeys > 0)
scan->keyData = (ScanKey) palloc(sizeof(ScanKeyData) * nkeys);
else
scan->keyData = NULL;
/*
* During recovery we ignore killed tuples and don't bother to kill them
* either. We do this because the xmin on the primary node could easily be
* later than the xmin on the standby node, so that what the primary
* thinks is killed is supposed to be visible on standby. So for correct
* MVCC for queries during recovery we must ignore these hints and check
* all tuples. Do *not* set ignore_killed_tuples to true when running in a
* transaction that was started during recovery. xactStartedInRecovery
* should not be altered by index AMs.
*/
scan->kill_prior_tuple = false;
scan->xactStartedInRecovery = TransactionStartedDuringRecovery();
scan->ignore_killed_tuples = !scan->xactStartedInRecovery;
scan->opaque = NULL;
ItemPointerSetInvalid(&scan->xs_ctup.t_self);
scan->xs_ctup.t_data = NULL;
scan->xs_cbuf = InvalidBuffer;
scan->xs_hot_dead = false;
scan->xs_next_hot = InvalidOffsetNumber;
scan->xs_prev_xmax = InvalidTransactionId;
/*
* Let the AM fill in the key and any opaque data it wants.
*/
index_rescan(scan, key);
return scan;
}
/* ----------------------------------------------------------------
* ExecBitmapIndexReScan(node)
*
* Recalculates the value of the scan keys whose value depends on
* information known at runtime and rescans the indexed relation.
* ----------------------------------------------------------------
*/
void
ExecBitmapIndexReScan(BitmapIndexScanState *node, ExprContext *exprCtxt)
{
ExprContext *econtext;
econtext = node->biss_RuntimeContext; /* context for runtime keys */
if (econtext)
{
/*
* If we are being passed an outer tuple, save it for runtime key
* calc.
*/
if (exprCtxt != NULL)
econtext->ecxt_outertuple = exprCtxt->ecxt_outertuple;
/*
* Reset the runtime-key context so we don't leak memory as each outer
* tuple is scanned. Note this assumes that we will recalculate *all*
* runtime keys on each call.
*/
ResetExprContext(econtext);
}
/*
* If we are doing runtime key calculations (ie, the index keys depend on
* data from an outer scan), compute the new key values.
*
* Array keys are also treated as runtime keys; note that if we return
* with biss_RuntimeKeysReady still false, then there is an empty array
* key so no index scan is needed.
*/
if (node->biss_NumRuntimeKeys != 0)
ExecIndexEvalRuntimeKeys(econtext,
node->biss_RuntimeKeys,
node->biss_NumRuntimeKeys);
if (node->biss_NumArrayKeys != 0)
node->biss_RuntimeKeysReady =
ExecIndexEvalArrayKeys(econtext,
node->biss_ArrayKeys,
node->biss_NumArrayKeys);
else
node->biss_RuntimeKeysReady = true;
/* reset index scan */
if (node->biss_RuntimeKeysReady)
index_rescan(node->biss_ScanDesc, node->biss_ScanKeys);
}
/* ----------------------------------------------------------------
* ExecIndexReScan(node)
*
* Recalculates the value of the scan keys whose value depends on
* information known at runtime and rescans the indexed relation.
* Updating the scan key was formerly done separately in
* ExecUpdateIndexScanKeys. Integrating it into ReScan makes
* rescans of indices and relations/general streams more uniform.
* ----------------------------------------------------------------
*/
void
ExecIndexReScan(IndexScanState *node, ExprContext *exprCtxt)
{
ExprContext *econtext;
econtext = node->iss_RuntimeContext; /* context for runtime keys */
if (econtext)
{
/*
* If we are being passed an outer tuple, save it for runtime key
* calc. We also need to link it into the "regular" per-tuple
* econtext, so it can be used during indexqualorig evaluations.
*/
if (exprCtxt != NULL)
{
ExprContext *stdecontext;
econtext->ecxt_outertuple = exprCtxt->ecxt_outertuple;
stdecontext = node->ss.ps.ps_ExprContext;
stdecontext->ecxt_outertuple = exprCtxt->ecxt_outertuple;
}
/*
* Reset the runtime-key context so we don't leak memory as each outer
* tuple is scanned. Note this assumes that we will recalculate *all*
* runtime keys on each call.
*/
ResetExprContext(econtext);
}
/*
* If we are doing runtime key calculations (ie, the index keys depend on
* data from an outer scan), compute the new key values
*/
if (node->iss_NumRuntimeKeys != 0)
ExecIndexEvalRuntimeKeys(econtext,
node->iss_RuntimeKeys,
node->iss_NumRuntimeKeys);
node->iss_RuntimeKeysReady = true;
/* reset index scan */
index_rescan(node->iss_ScanDesc, node->iss_ScanKeys);
ExecScanReScan(&node->ss);
}
/* ----------------
* RelationGetIndexScan -- Create and fill an IndexScanDesc.
*
* This routine creates an index scan structure and sets its contents
* up correctly. This routine calls AMrescan to set up the scan with
* the passed key.
*
* Parameters:
* indexRelation -- index relation for scan.
* nkeys -- count of scan keys.
* key -- array of scan keys to restrict the index scan.
*
* Returns:
* An initialized IndexScanDesc.
* ----------------
*/
IndexScanDesc
RelationGetIndexScan(Relation indexRelation,
int nkeys, ScanKey key)
{
IndexScanDesc scan;
scan = (IndexScanDesc) palloc(sizeof(IndexScanDescData));
scan->heapRelation = NULL; /* may be set later */
scan->indexRelation = indexRelation;
scan->xs_snapshot = SnapshotNow; /* may be set later */
scan->numberOfKeys = nkeys;
/*
* We allocate the key space here, but the AM is responsible for actually
* filling it from the passed key array.
*/
if (nkeys > 0)
scan->keyData = (ScanKey) palloc(sizeof(ScanKeyData) * nkeys);
else
scan->keyData = NULL;
scan->is_multiscan = false; /* caller may change this */
scan->kill_prior_tuple = false;
scan->ignore_killed_tuples = true; /* default setting */
scan->opaque = NULL;
ItemPointerSetInvalid(&scan->currentItemData);
ItemPointerSetInvalid(&scan->currentMarkData);
ItemPointerSetInvalid(&scan->xs_ctup.t_self);
scan->xs_ctup.t_data = NULL;
scan->xs_cbuf = InvalidBuffer;
pgstat_initstats(&scan->xs_pgstat_info, indexRelation);
/*
* Let the AM fill in the key and any opaque data it wants.
*/
index_rescan(scan, key);
return scan;
}
/* ----------------------------------------------------------------
* ExecReScanIndexOnlyScan(node)
*
* Recalculates the values of any scan keys whose value depends on
* information known at runtime, then rescans the indexed relation.
*
* Updating the scan key was formerly done separately in
* ExecUpdateIndexScanKeys. Integrating it into ReScan makes
* rescans of indices and relations/general streams more uniform.
* ----------------------------------------------------------------
*/
void
ExecReScanIndexOnlyScan(IndexOnlyScanState *node)
{
bool reset_parallel_scan = true;
/*
* If we are here to just update the scan keys, then don't reset parallel
* scan. For detailed reason behind this look in the comments for
* ExecReScanIndexScan.
*/
if (node->ioss_NumRuntimeKeys != 0 && !node->ioss_RuntimeKeysReady)
reset_parallel_scan = false;
/*
* 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 */
if (node->ioss_ScanDesc)
{
index_rescan(node->ioss_ScanDesc,
node->ioss_ScanKeys, node->ioss_NumScanKeys,
node->ioss_OrderByKeys, node->ioss_NumOrderByKeys);
if (reset_parallel_scan && node->ioss_ScanDesc->parallel_scan)
index_parallelrescan(node->ioss_ScanDesc);
}
ExecScanReScan(&node->ss);
}
/*
* Starts a scan over the visimap store.
*
* Parameter keys may be NULL iff nkeys is zero.
*/
IndexScanDesc
AppendOnlyVisimapStore_BeginScan(AppendOnlyVisimapStore *visiMapStore,
int nkeys,
ScanKey keys)
{
IndexScanDesc scandesc;
Assert(visiMapStore);
Assert(RelationIsValid(visiMapStore->visimapRelation));
scandesc = index_beginscan(visiMapStore->visimapRelation,
visiMapStore->visimapIndex,
visiMapStore->snapshot,
nkeys,
0);
index_rescan(scandesc, keys, nkeys, NULL, 0);
return scandesc;
}
/* ----------------
* RelationGetIndexScan -- Create and fill an IndexScanDesc.
*
* This routine creates an index scan structure and sets its contents
* up correctly. This routine calls AMrescan to set up the scan with
* the passed key.
*
* Parameters:
* indexRelation -- index relation for scan.
* nkeys -- count of scan keys.
* key -- array of scan keys to restrict the index scan.
*
* Returns:
* An initialized IndexScanDesc.
* ----------------
*/
IndexScanDesc
RelationGetIndexScan(Relation indexRelation,
int nkeys, ScanKey key)
{
IndexScanDesc scan;
scan = (IndexScanDesc) palloc(sizeof(IndexScanDescData));
scan->heapRelation = NULL; /* may be set later */
scan->indexRelation = indexRelation;
scan->xs_snapshot = SnapshotNow; /* may be set later */
scan->numberOfKeys = nkeys;
/*
* We allocate the key space here, but the AM is responsible for actually
* filling it from the passed key array.
*/
if (nkeys > 0)
scan->keyData = (ScanKey) palloc(sizeof(ScanKeyData) * nkeys);
else
scan->keyData = NULL;
scan->kill_prior_tuple = false;
scan->ignore_killed_tuples = true; /* default setting */
scan->opaque = NULL;
ItemPointerSetInvalid(&scan->xs_ctup.t_self);
scan->xs_ctup.t_data = NULL;
scan->xs_cbuf = InvalidBuffer;
scan->xs_hot_dead = false;
scan->xs_next_hot = InvalidOffsetNumber;
scan->xs_prev_xmax = InvalidTransactionId;
/*
* Let the AM fill in the key and any opaque data it wants.
*/
index_rescan(scan, key);
return scan;
}
/* ----------------------------------------------------------------
* ExecReScanBitmapIndexScan(node)
*
* Recalculates the values of any scan keys whose value depends on
* information known at runtime, then rescans the indexed relation.
* ----------------------------------------------------------------
*/
void
ExecReScanBitmapIndexScan(BitmapIndexScanState *node)
{
ExprContext *econtext = node->biss_RuntimeContext;
/*
* Reset the runtime-key context so we don't leak memory as each outer
* tuple is scanned. Note this assumes that we will recalculate *all*
* runtime keys on each call.
*/
if (econtext)
ResetExprContext(econtext);
/*
* If we are doing runtime key calculations (ie, any of the index key
* values weren't simple Consts), compute the new key values.
*
* Array keys are also treated as runtime keys; note that if we return
* with biss_RuntimeKeysReady still false, then there is an empty array
* key so no index scan is needed.
*/
if (node->biss_NumRuntimeKeys != 0)
ExecIndexEvalRuntimeKeys(econtext,
node->biss_RuntimeKeys,
node->biss_NumRuntimeKeys);
if (node->biss_NumArrayKeys != 0)
node->biss_RuntimeKeysReady =
ExecIndexEvalArrayKeys(econtext,
node->biss_ArrayKeys,
node->biss_NumArrayKeys);
else
node->biss_RuntimeKeysReady = true;
/* reset index scan */
if (node->biss_RuntimeKeysReady)
index_rescan(node->biss_ScanDesc,
node->biss_ScanKeys, node->biss_NumScanKeys,
NULL, 0);
}
/* ----------------------------------------------------------------
* ExecIndexOnlyScanInitializeWorker
*
* Copy relevant information from TOC into planstate.
* ----------------------------------------------------------------
*/
void
ExecIndexOnlyScanInitializeWorker(IndexOnlyScanState *node, shm_toc *toc)
{
ParallelIndexScanDesc piscan;
piscan = shm_toc_lookup(toc, node->ss.ps.plan->plan_node_id, false);
node->ioss_ScanDesc =
index_beginscan_parallel(node->ss.ss_currentRelation,
node->ioss_RelationDesc,
node->ioss_NumScanKeys,
node->ioss_NumOrderByKeys,
piscan);
node->ioss_ScanDesc->xs_want_itup = true;
/*
* If no run-time keys to calculate or they are ready, go ahead and pass
* the scankeys to the index AM.
*/
if (node->ioss_NumRuntimeKeys == 0 || node->ioss_RuntimeKeysReady)
index_rescan(node->ioss_ScanDesc,
node->ioss_ScanKeys, node->ioss_NumScanKeys,
node->ioss_OrderByKeys, node->ioss_NumOrderByKeys);
}
/* ----------------------------------------------------------------
* MultiExecBitmapIndexScan(node)
* ----------------------------------------------------------------
*/
Node *
MultiExecBitmapIndexScan(BitmapIndexScanState *node)
{
TIDBitmap *tbm;
IndexScanDesc scandesc;
double nTuples = 0;
bool doscan;
/* must provide our own instrumentation support */
if (node->ss.ps.instrument)
InstrStartNode(node->ss.ps.instrument);
/*
* extract necessary information from index scan node
*/
scandesc = node->biss_ScanDesc;
/*
* If we have runtime keys and they've not already been set up, do it now.
* Array keys are also treated as runtime keys; note that if ExecReScan
* returns with biss_RuntimeKeysReady still false, then there is an empty
* array key so we should do nothing.
*/
if (!node->biss_RuntimeKeysReady &&
(node->biss_NumRuntimeKeys != 0 || node->biss_NumArrayKeys != 0))
{
ExecReScan((PlanState *) node);
doscan = node->biss_RuntimeKeysReady;
}
else
doscan = true;
/*
* Prepare the result bitmap. Normally we just create a new one to pass
* back; however, our parent node is allowed to store a pre-made one into
* node->biss_result, in which case we just OR our tuple IDs into the
* existing bitmap. (This saves needing explicit UNION steps.)
*/
if (node->biss_result)
{
tbm = node->biss_result;
node->biss_result = NULL; /* reset for next time */
}
else
{
/* XXX should we use less than work_mem for this? */
tbm = tbm_create(work_mem * 1024L);
}
/*
* Get TIDs from index and insert into bitmap
*/
while (doscan)
{
nTuples += (double) index_getbitmap(scandesc, tbm);
CHECK_FOR_INTERRUPTS();
doscan = ExecIndexAdvanceArrayKeys(node->biss_ArrayKeys,
node->biss_NumArrayKeys);
if (doscan) /* reset index scan */
index_rescan(node->biss_ScanDesc,
node->biss_ScanKeys, node->biss_NumScanKeys,
NULL, 0);
}
/* must provide our own instrumentation support */
if (node->ss.ps.instrument)
InstrStopNode(node->ss.ps.instrument, nTuples);
return (Node *) tbm;
}
/* ----------------------------------------------------------------
* ExecInitBitmapIndexScan
*
* Initializes the index scan's state information.
* ----------------------------------------------------------------
*/
BitmapIndexScanState *
ExecInitBitmapIndexScan(BitmapIndexScan *node, EState *estate, int eflags)
{
BitmapIndexScanState *indexstate;
bool relistarget;
/* check for unsupported flags */
Assert(!(eflags & (EXEC_FLAG_BACKWARD | EXEC_FLAG_MARK)));
/*
* create state structure
*/
indexstate = makeNode(BitmapIndexScanState);
indexstate->ss.ps.plan = (Plan *) node;
indexstate->ss.ps.state = estate;
/* normally we don't make the result bitmap till runtime */
indexstate->biss_result = NULL;
/*
* Miscellaneous initialization
*
* We do not need a standard exprcontext for this node, though we may
* decide below to create a runtime-key exprcontext
*/
/*
* initialize child expressions
*
* We don't need to initialize targetlist or qual since neither are used.
*
* Note: we don't initialize all of the indexqual expression, only the
* sub-parts corresponding to runtime keys (see below).
*/
/*
* We do not open or lock the base relation here. We assume that an
* ancestor BitmapHeapScan node is holding AccessShareLock (or better) on
* the heap relation throughout the execution of the plan tree.
*/
indexstate->ss.ss_currentRelation = NULL;
indexstate->ss.ss_currentScanDesc = NULL;
/*
* If we are just doing EXPLAIN (ie, aren't going to run the plan), stop
* here. This allows an index-advisor plugin to EXPLAIN a plan containing
* references to nonexistent indexes.
*/
if (eflags & EXEC_FLAG_EXPLAIN_ONLY)
return indexstate;
/*
* Open the index relation.
*
* If the parent table is one of the target relations of the query, then
* InitPlan already opened and write-locked the index, so we can avoid
* taking another lock here. Otherwise we need a normal reader's lock.
*/
relistarget = ExecRelationIsTargetRelation(estate, node->scan.scanrelid);
indexstate->biss_RelationDesc = index_open(node->indexid,
relistarget ? NoLock : AccessShareLock);
/*
* Initialize index-specific scan state
*/
indexstate->biss_RuntimeKeysReady = false;
indexstate->biss_RuntimeKeys = NULL;
indexstate->biss_NumRuntimeKeys = 0;
/*
* build the index scan keys from the index qualification
*/
ExecIndexBuildScanKeys((PlanState *) indexstate,
indexstate->biss_RelationDesc,
node->indexqual,
false,
&indexstate->biss_ScanKeys,
&indexstate->biss_NumScanKeys,
&indexstate->biss_RuntimeKeys,
&indexstate->biss_NumRuntimeKeys,
&indexstate->biss_ArrayKeys,
&indexstate->biss_NumArrayKeys);
/*
* If we have runtime keys or array keys, we need an ExprContext to
* evaluate them. We could just create a "standard" plan node exprcontext,
* but to keep the code looking similar to nodeIndexscan.c, it seems
* better to stick with the approach of using a separate ExprContext.
*/
if (indexstate->biss_NumRuntimeKeys != 0 ||
indexstate->biss_NumArrayKeys != 0)
{
ExprContext *stdecontext = indexstate->ss.ps.ps_ExprContext;
ExecAssignExprContext(estate, &indexstate->ss.ps);
indexstate->biss_RuntimeContext = indexstate->ss.ps.ps_ExprContext;
indexstate->ss.ps.ps_ExprContext = stdecontext;
}
else
{
indexstate->biss_RuntimeContext = NULL;
}
/*
* Initialize scan descriptor.
*/
indexstate->biss_ScanDesc =
index_beginscan_bitmap(indexstate->biss_RelationDesc,
estate->es_snapshot,
indexstate->biss_NumScanKeys);
/*
* If no run-time keys to calculate, go ahead and pass the scankeys to the
* index AM.
*/
if (indexstate->biss_NumRuntimeKeys == 0 &&
indexstate->biss_NumArrayKeys == 0)
index_rescan(indexstate->biss_ScanDesc,
indexstate->biss_ScanKeys, indexstate->biss_NumScanKeys,
NULL, 0);
/*
* all done.
*/
return indexstate;
}
/*
* systable_beginscan --- set up for heap-or-index scan
*
* rel: catalog to scan, already opened and suitably locked
* indexId: OID of index to conditionally use
* indexOK: if false, forces a heap scan (see notes below)
* snapshot: time qual to use (NULL for a recent catalog snapshot)
* nkeys, key: scan keys
*
* The attribute numbers in the scan key should be set for the heap case.
* If we choose to index, we reset them to 1..n to reference the index
* columns. Note this means there must be one scankey qualification per
* index column! This is checked by the Asserts in the normal, index-using
* case, but won't be checked if the heapscan path is taken.
*
* The routine checks the normal cases for whether an indexscan is safe,
* but caller can make additional checks and pass indexOK=false if needed.
* In standard case indexOK can simply be constant TRUE.
*/
SysScanDesc
systable_beginscan(Relation heapRelation,
Oid indexId,
bool indexOK,
Snapshot snapshot,
int nkeys, ScanKey key)
{
SysScanDesc sysscan;
Relation irel;
if (indexOK &&
!IgnoreSystemIndexes &&
!ReindexIsProcessingIndex(indexId))
irel = index_open(indexId, AccessShareLock);
else
irel = NULL;
sysscan = (SysScanDesc) palloc(sizeof(SysScanDescData));
sysscan->heap_rel = heapRelation;
sysscan->irel = irel;
if (snapshot == NULL)
{
Oid relid = RelationGetRelid(heapRelation);
snapshot = RegisterSnapshot(GetCatalogSnapshot(relid));
sysscan->snapshot = snapshot;
}
else
{
/* Caller is responsible for any snapshot. */
sysscan->snapshot = NULL;
}
if (irel)
{
int i;
/* Change attribute numbers to be index column numbers. */
for (i = 0; i < nkeys; i++)
{
int j;
for (j = 0; j < irel->rd_index->indnatts; j++)
{
if (key[i].sk_attno == irel->rd_index->indkey.values[j])
{
key[i].sk_attno = j + 1;
break;
}
}
if (j == irel->rd_index->indnatts)
elog(ERROR, "column is not in index");
}
sysscan->iscan = index_beginscan(heapRelation, irel,
snapshot, nkeys, 0);
index_rescan(sysscan->iscan, key, nkeys, NULL, 0);
sysscan->scan = NULL;
}
else
{
/*
* We disallow synchronized scans when forced to use a heapscan on a
* catalog. In most cases the desired rows are near the front, so
* that the unpredictable start point of a syncscan is a serious
* disadvantage; and there are no compensating advantages, because
* it's unlikely that such scans will occur in parallel.
*/
sysscan->scan = heap_beginscan_strat(heapRelation, snapshot,
nkeys, key,
true, false);
sysscan->iscan = NULL;
}
return sysscan;
}
/* ----------------------------------------------------------------
* ExecInitIndexOnlyScan
*
* Initializes the index scan's state information, creates
* scan keys, and opens the base and index relations.
*
* Note: index scans have 2 sets of state information because
* we have to keep track of the base relation and the
* index relation.
* ----------------------------------------------------------------
*/
IndexOnlyScanState *
ExecInitIndexOnlyScan(IndexOnlyScan *node, EState *estate, int eflags)
{
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. The node's
* targetlist will contain Vars with varno = INDEX_VAR, referencing the
* scan tuple.
*/
ExecAssignResultTypeFromTL(&indexstate->ss.ps);
ExecAssignScanProjectionInfoWithVarno(&indexstate->ss, INDEX_VAR);
/*
* 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;
}
/* ----------------------------------------------------------------
* MultiExecBitmapIndexScan(node)
* ----------------------------------------------------------------
*/
Node *
MultiExecBitmapIndexScan(BitmapIndexScanState *node)
{
IndexScanState *scanState = (IndexScanState*)node;
Node *bitmap = NULL;
/* must provide our own instrumentation support */
if (scanState->ss.ps.instrument)
{
InstrStartNode(scanState->ss.ps.instrument);
}
bool partitionIsReady = DynamicScan_BeginIndexPartition(scanState, false /* initQual */,
false /* initTargetList */, true /* supportsArrayKeys */,
true /* isMultiScan */);
Assert(partitionIsReady);
if (!partitionIsReady)
{
DynamicScan_EndIndexPartition(scanState);
return NULL;
}
bool doscan = node->indexScanState.iss_RuntimeKeysReady;
IndexScanDesc scandesc = scanState->iss_ScanDesc;
/* Get bitmap from index */
while (doscan)
{
bitmap = index_getmulti(scandesc, node->bitmap);
if ((NULL != bitmap) &&
!(IsA(bitmap, HashBitmap) || IsA(bitmap, StreamBitmap)))
{
elog(ERROR, "unrecognized result from bitmap index scan");
}
CHECK_FOR_INTERRUPTS();
/* CDB: If EXPLAIN ANALYZE, let bitmap share our Instrumentation. */
if (scanState->ss.ps.instrument)
{
tbm_bitmap_set_instrument(bitmap, scanState->ss.ps.instrument);
}
if(node->bitmap == NULL)
{
node->bitmap = (Node *)bitmap;
}
doscan = ExecIndexAdvanceArrayKeys(scanState->iss_ArrayKeys,
scanState->iss_NumArrayKeys);
if (doscan)
{
/* reset index scan */
index_rescan(scanState->iss_ScanDesc, scanState->iss_ScanKeys);
}
}
DynamicScan_EndIndexPartition(scanState);
/* must provide our own instrumentation support */
if (scanState->ss.ps.instrument)
{
InstrStopNode(scanState->ss.ps.instrument, 1 /* nTuples */);
}
return (Node *) bitmap;
}
/* ----------------------------------------------------------------
* IndexOnlyNext
*
* Retrieve a tuple from the IndexOnlyScan node's index.
* ----------------------------------------------------------------
*/
static TupleTableSlot *
IndexOnlyNext(IndexOnlyScanState *node)
{
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;
if (scandesc == NULL)
{
/*
* We reach here if the index only scan is not parallel, or if we're
* serially executing an index only scan that was planned to be
* parallel.
*/
scandesc = index_beginscan(node->ss.ss_currentRelation,
node->ioss_RelationDesc,
estate->es_snapshot,
node->ioss_NumScanKeys,
node->ioss_NumOrderByKeys);
node->ioss_ScanDesc = scandesc;
/* Set it up for index-only scan */
node->ioss_ScanDesc->xs_want_itup = true;
node->ioss_VMBuffer = InvalidBuffer;
/*
* If no run-time keys to calculate or they are ready, go ahead and
* pass the scankeys to the index AM.
*/
if (node->ioss_NumRuntimeKeys == 0 || node->ioss_RuntimeKeysReady)
index_rescan(scandesc,
node->ioss_ScanKeys,
node->ioss_NumScanKeys,
node->ioss_OrderByKeys,
node->ioss_NumOrderByKeys);
}
/*
* OK, now that we have what we need, fetch the next tuple.
*/
while ((tid = index_getnext_tid(scandesc, direction)) != NULL)
{
HeapTuple tuple = NULL;
CHECK_FOR_INTERRUPTS();
/*
* 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_get_status 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.
*
* We need to detect clearing a VM bit due to an insert right away,
* because the tuple is present in the index page but not visible. The
* reading of the TID by this scan (using a shared lock on the index
* buffer) is serialized with the insert of the TID into the index
* (using an exclusive lock on the index buffer). Because the VM bit
* is cleared before updating the index, and locking/unlocking of the
* index page acts as a full memory barrier, we are sure to see the
* cleared bit if we see a recently-inserted TID.
*
* Deletes do not update the index page (only VACUUM will clear out
* the TID), so the clearing of the VM bit by a delete is not
* serialized with this test below, and we may see a value that is
* significantly stale. However, we don't care about the delete right
* away, because the tuple is still visible until the deleting
* transaction commits or the statement ends (if it's our
* transaction). In either case, the lock on the VM buffer will have
* been released (acting as a write barrier) after clearing the bit.
* And for us to have a snapshot that includes the deleting
* transaction (making the tuple invisible), we must have acquired
* ProcArrayLock after that time, acting as a read barrier.
*
* It's worth going through this complexity to avoid needing to lock
* the VM buffer, which could cause significant contention.
*/
if (!VM_ALL_VISIBLE(scandesc->heapRelation,
ItemPointerGetBlockNumber(tid),
&node->ioss_VMBuffer))
{
/*
* Rats, we have to visit the heap to check visibility.
*/
InstrCountTuples2(node, 1);
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. This might be
* provided in either HeapTuple or IndexTuple format. Conceivably an
* index AM might fill both fields, in which case we prefer the heap
* format, since it's probably a bit cheaper to fill a slot from.
*/
if (scandesc->xs_hitup)
{
/*
* We don't take the trouble to verify that the provided tuple has
* exactly the slot's format, but it seems worth doing a quick
* check on the number of fields.
*/
Assert(slot->tts_tupleDescriptor->natts ==
scandesc->xs_hitupdesc->natts);
ExecStoreHeapTuple(scandesc->xs_hitup, slot, false);
}
else if (scandesc->xs_itup)
StoreIndexTuple(slot, scandesc->xs_itup, scandesc->xs_itupdesc);
else
elog(ERROR, "no data returned for index-only scan");
/*
* 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;
if (!ExecQualAndReset(node->indexqual, econtext))
{
/* Fails recheck, so drop it and loop back for another */
InstrCountFiltered2(node, 1);
continue;
}
}
/*
* We don't currently support rechecking ORDER BY distances. (In
* principle, if the index can support retrieval of the originally
* indexed value, it should be able to produce an exact distance
* calculation too. So it's not clear that adding code here for
* recheck/re-sort would be worth the trouble. But we should at least
* throw an error if someone tries it.)
*/
if (scandesc->numberOfOrderBys > 0 && scandesc->xs_recheckorderby)
ereport(ERROR,
(errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
errmsg("lossy distance functions are not supported in index-only scans")));
/*
* 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);
}
/*
* Search the relation 'rel' for tuple using the index.
*
* If a matching tuple is found, lock it with lockmode, fill the slot with its
* contents, and return true. Return false otherwise.
*/
bool
RelationFindReplTupleByIndex(Relation rel, Oid idxoid,
LockTupleMode lockmode,
TupleTableSlot *searchslot,
TupleTableSlot *outslot)
{
HeapTuple scantuple;
ScanKeyData skey[INDEX_MAX_KEYS];
IndexScanDesc scan;
SnapshotData snap;
TransactionId xwait;
Relation idxrel;
bool found;
/* Open the index. */
idxrel = index_open(idxoid, RowExclusiveLock);
/* Start an index scan. */
InitDirtySnapshot(snap);
scan = index_beginscan(rel, idxrel, &snap,
RelationGetNumberOfAttributes(idxrel),
0);
/* Build scan key. */
build_replindex_scan_key(skey, rel, idxrel, searchslot);
retry:
found = false;
index_rescan(scan, skey, RelationGetNumberOfAttributes(idxrel), NULL, 0);
/* Try to find the tuple */
if ((scantuple = index_getnext(scan, ForwardScanDirection)) != NULL)
{
found = true;
ExecStoreTuple(scantuple, outslot, InvalidBuffer, false);
ExecMaterializeSlot(outslot);
xwait = TransactionIdIsValid(snap.xmin) ?
snap.xmin : snap.xmax;
/*
* If the tuple is locked, wait for locking transaction to finish and
* retry.
*/
if (TransactionIdIsValid(xwait))
{
XactLockTableWait(xwait, NULL, NULL, XLTW_None);
goto retry;
}
}
/* Found tuple, try to lock it in the lockmode. */
if (found)
{
Buffer buf;
HeapUpdateFailureData hufd;
HTSU_Result res;
HeapTupleData locktup;
ItemPointerCopy(&outslot->tts_tuple->t_self, &locktup.t_self);
PushActiveSnapshot(GetLatestSnapshot());
res = heap_lock_tuple(rel, &locktup, GetCurrentCommandId(false),
lockmode,
LockWaitBlock,
false /* don't follow updates */ ,
&buf, &hufd);
/* the tuple slot already has the buffer pinned */
ReleaseBuffer(buf);
PopActiveSnapshot();
switch (res)
{
case HeapTupleMayBeUpdated:
break;
case HeapTupleUpdated:
/* XXX: Improve handling here */
ereport(LOG,
(errcode(ERRCODE_T_R_SERIALIZATION_FAILURE),
errmsg("concurrent update, retrying")));
goto retry;
case HeapTupleInvisible:
elog(ERROR, "attempted to lock invisible tuple");
default:
elog(ERROR, "unexpected heap_lock_tuple status: %u", res);
break;
}
}
index_endscan(scan);
/* Don't release lock until commit. */
index_close(idxrel, NoLock);
return found;
}
/* ----------------------------------------------------------------
* ExecInitIndexScan
*
* Initializes the index scan's state information, creates
* scan keys, and opens the base and index relations.
*
* Note: index scans have 2 sets of state information because
* we have to keep track of the base relation and the
* index relation.
* ----------------------------------------------------------------
*/
IndexScanState *
ExecInitIndexScan(IndexScan *node, EState *estate, int eflags)
{
IndexScanState *indexstate;
Relation currentRelation;
bool relistarget;
/*
* create state structure
*/
indexstate = makeNode(IndexScanState);
indexstate->ss.ps.plan = (Plan *) node;
indexstate->ss.ps.state = estate;
/*
* 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 indexqual expression, only the
* sub-parts corresponding to runtime keys (see below). Likewise for
* indexorderby, if any. But the indexqualorig expression is always
* initialized even though it will only be used in some uncommon cases ---
* would be nice to improve that. (Problem is that any SubPlans present
* in the expression must be found now...)
*/
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->indexqualorig = (List *)
ExecInitExpr((Expr *) node->indexqualorig,
(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);
indexstate->ss.ss_currentRelation = currentRelation;
indexstate->ss.ss_currentScanDesc = NULL; /* no heap scan here */
/*
* get the scan type from the relation descriptor.
*/
ExecAssignScanType(&indexstate->ss, RelationGetDescr(currentRelation));
/*
* 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->iss_RelationDesc = index_open(node->indexid,
relistarget ? NoLock : AccessShareLock);
/*
* Initialize index-specific scan state
*/
indexstate->iss_RuntimeKeysReady = false;
indexstate->iss_RuntimeKeys = NULL;
indexstate->iss_NumRuntimeKeys = 0;
/*
* build the index scan keys from the index qualification
*/
ExecIndexBuildScanKeys((PlanState *) indexstate,
indexstate->iss_RelationDesc,
node->scan.scanrelid,
node->indexqual,
false,
&indexstate->iss_ScanKeys,
&indexstate->iss_NumScanKeys,
&indexstate->iss_RuntimeKeys,
&indexstate->iss_NumRuntimeKeys,
NULL, /* no ArrayKeys */
NULL);
/*
* any ORDER BY exprs have to be turned into scankeys in the same way
*/
ExecIndexBuildScanKeys((PlanState *) indexstate,
indexstate->iss_RelationDesc,
node->scan.scanrelid,
node->indexorderby,
true,
&indexstate->iss_OrderByKeys,
&indexstate->iss_NumOrderByKeys,
&indexstate->iss_RuntimeKeys,
&indexstate->iss_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->iss_NumRuntimeKeys != 0)
{
ExprContext *stdecontext = indexstate->ss.ps.ps_ExprContext;
ExecAssignExprContext(estate, &indexstate->ss.ps);
indexstate->iss_RuntimeContext = indexstate->ss.ps.ps_ExprContext;
indexstate->ss.ps.ps_ExprContext = stdecontext;
}
else
{
indexstate->iss_RuntimeContext = NULL;
}
/*
* Initialize scan descriptor.
*/
indexstate->iss_ScanDesc = index_beginscan(currentRelation,
indexstate->iss_RelationDesc,
estate->es_snapshot,
indexstate->iss_NumScanKeys,
indexstate->iss_NumOrderByKeys);
/*
* If no run-time keys to calculate, go ahead and pass the scankeys to the
* index AM.
*/
if (indexstate->iss_NumRuntimeKeys == 0)
index_rescan(indexstate->iss_ScanDesc,
indexstate->iss_ScanKeys, indexstate->iss_NumScanKeys,
indexstate->iss_OrderByKeys, indexstate->iss_NumOrderByKeys);
/*
* all done.
*/
return indexstate;
}
/* ----------------
* index_getnext - get the next heap tuple from a scan
*
* The result is the next heap tuple satisfying the scan keys and the
* snapshot, or NULL if no more matching tuples exist. On success,
* the buffer containing the heap tuple is pinned (the pin will be dropped
* at the next index_getnext or index_endscan). The index TID corresponding
* to the heap tuple can be obtained if needed from scan->currentItemData.
* ----------------
*/
HeapTuple
index_getnext(IndexScanDesc scan, ScanDirection direction)
{
HeapTuple heapTuple = &scan->xs_ctup;
SCAN_CHECKS;
/* Release any previously held pin */
if (BufferIsValid(scan->xs_cbuf))
{
ReleaseBuffer(scan->xs_cbuf);
scan->xs_cbuf = InvalidBuffer;
}
/*
* If we already got a tuple and it must be unique, there's no need to
* make the index AM look through any additional tuples. (This can
* save a useful amount of work in scenarios where there are many dead
* tuples due to heavy update activity.)
*
* To do this we must keep track of the logical scan position
* (before/on/after tuple). Also, we have to be sure to release scan
* resources before returning NULL; if we fail to do so then a
* multi-index scan can easily run the system out of free buffers. We
* can release index-level resources fairly cheaply by calling
* index_rescan. This means there are two persistent states as far as
* the index AM is concerned: on-tuple and rescanned. If we are
* actually asked to re-fetch the single tuple, we have to go through
* a fresh indexscan startup, which penalizes that (infrequent) case.
*/
if (scan->keys_are_unique && scan->got_tuple)
{
int new_tuple_pos = scan->unique_tuple_pos;
if (ScanDirectionIsForward(direction))
{
if (new_tuple_pos <= 0)
new_tuple_pos++;
}
else
{
if (new_tuple_pos >= 0)
new_tuple_pos--;
}
if (new_tuple_pos == 0)
{
/*
* We are moving onto the unique tuple from having been off
* it. We just fall through and let the index AM do the work.
* Note we should get the right answer regardless of scan
* direction.
*/
scan->unique_tuple_pos = 0; /* need to update position */
}
else
{
/*
* Moving off the tuple; must do amrescan to release
* index-level pins before we return NULL. Since index_rescan
* will reset my state, must save and restore...
*/
int unique_tuple_mark = scan->unique_tuple_mark;
index_rescan(scan, NULL /* no change to key */ );
scan->keys_are_unique = true;
scan->got_tuple = true;
scan->unique_tuple_pos = new_tuple_pos;
scan->unique_tuple_mark = unique_tuple_mark;
return NULL;
}
}
/* just make sure this is false... */
scan->kill_prior_tuple = false;
for (;;)
{
bool found;
uint16 sv_infomask;
pgstat_count_index_scan(&scan->xs_pgstat_info);
/*
* The AM's gettuple proc finds the next tuple matching the scan
* keys. index_beginscan already set up fn_getnext.
*/
found = DatumGetBool(FunctionCall2(&scan->fn_getnext,
PointerGetDatum(scan),
Int32GetDatum(direction)));
/* Reset kill flag immediately for safety */
scan->kill_prior_tuple = false;
if (!found)
return NULL; /* failure exit */
/*
* Fetch the heap tuple and see if it matches the snapshot.
*/
if (heap_fetch(scan->heapRelation, scan->xs_snapshot,
heapTuple, &scan->xs_cbuf, true,
&scan->xs_pgstat_info))
break;
/* Skip if no tuple at this location */
if (heapTuple->t_data == NULL)
continue; /* should we raise an error instead? */
/*
* If we can't see it, maybe no one else can either. Check to see
* if the tuple is dead to all transactions. If so, signal the
* index AM to not return it on future indexscans.
*
* We told heap_fetch to keep a pin on the buffer, so we can
* re-access the tuple here. But we must re-lock the buffer
* first. Also, it's just barely possible for an update of hint
* bits to occur here.
*/
LockBuffer(scan->xs_cbuf, BUFFER_LOCK_SHARE);
sv_infomask = heapTuple->t_data->t_infomask;
if (HeapTupleSatisfiesVacuum(heapTuple->t_data, RecentGlobalXmin) ==
HEAPTUPLE_DEAD)
scan->kill_prior_tuple = true;
if (sv_infomask != heapTuple->t_data->t_infomask)
SetBufferCommitInfoNeedsSave(scan->xs_cbuf);
LockBuffer(scan->xs_cbuf, BUFFER_LOCK_UNLOCK);
ReleaseBuffer(scan->xs_cbuf);
scan->xs_cbuf = InvalidBuffer;
}
/* Success exit */
scan->got_tuple = true;
/*
* If we just fetched a known-unique tuple, then subsequent calls will
* go through the short-circuit code above. unique_tuple_pos has been
* initialized to 0, which is the correct state ("on row").
*/
pgstat_count_index_getnext(&scan->xs_pgstat_info);
return heapTuple;
}