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postgresql/src/backend/executor/nodeIndexscan.c
Peter Geoghegan 5bf748b86b Enhance nbtree ScalarArrayOp execution. 
Commit 9e8da0f7 taught nbtree to handle ScalarArrayOpExpr quals
natively.  This works by pushing down the full context (the array keys)
to the nbtree index AM, enabling it to execute multiple primitive index
scans that the planner treats as one continuous index scan/index path.
This earlier enhancement enabled nbtree ScalarArrayOp index-only scans.
It also allowed scans with ScalarArrayOp quals to return ordered results
(with some notable restrictions, described further down).

Take this general approach a lot further: teach nbtree SAOP index scans
to decide how to execute ScalarArrayOp scans (when and where to start
the next primitive index scan) based on physical index characteristics.
This can be far more efficient.  All SAOP scans will now reliably avoid
duplicative leaf page accesses (just like any other nbtree index scan).
SAOP scans whose array keys are naturally clustered together now require
far fewer index descents, since we'll reliably avoid starting a new
primitive scan just to get to a later offset from the same leaf page.

The scan's arrays now advance using binary searches for the array
element that best matches the next tuple's attribute value.  Required
scan key arrays (i.e. arrays from scan keys that can terminate the scan)
ratchet forward in lockstep with the index scan.  Non-required arrays
(i.e. arrays from scan keys that can only exclude non-matching tuples)
"advance" without the process ever rolling over to a higher-order array.

Naturally, only required SAOP scan keys trigger skipping over leaf pages
(non-required arrays cannot safely end or start primitive index scans).
Consequently, even index scans of a composite index with a high-order
inequality scan key (which we'll mark required) and a low-order SAOP
scan key (which we won't mark required) now avoid repeating leaf page
accesses -- that benefit isn't limited to simpler equality-only cases.
In general, all nbtree index scans now output tuples as if they were one
continuous index scan -- even scans that mix a high-order inequality
with lower-order SAOP equalities reliably output tuples in index order.
This allows us to remove a couple of special cases that were applied
when building index paths with SAOP clauses during planning.

Bugfix commit 807a40c5 taught the planner to avoid generating unsafe
path keys: path keys on a multicolumn index path, with a SAOP clause on
any attribute beyond the first/most significant attribute.  These cases
are now all safe, so we go back to generating path keys without regard
for the presence of SAOP clauses (just like with any other clause type).
Affected queries can now exploit scan output order in all the usual ways
(e.g., certain "ORDER BY ... LIMIT n" queries can now terminate early).

Also undo changes from follow-up bugfix commit a4523c5a, which taught
the planner to produce alternative index paths, with path keys, but
without low-order SAOP index quals (filter quals were used instead).
We'll no longer generate these alternative paths, since they can no
longer offer any meaningful advantages over standard index qual paths.
Affected queries thereby avoid all of the disadvantages that come from
using filter quals within index scan nodes.  They can avoid extra heap
page accesses from using filter quals to exclude non-matching tuples
(index quals will never have that problem).  They can also skip over
irrelevant sections of the index in more cases (though only when nbtree
determines that starting another primitive scan actually makes sense).

There is a theoretical risk that removing restrictions on SAOP index
paths from the planner will break compatibility with amcanorder-based
index AMs maintained as extensions.  Such an index AM could have the
same limitations around ordered SAOP scans as nbtree had up until now.
Adding a pro forma incompatibility item about the issue to the Postgres
17 release notes seems like a good idea.

Author: Peter Geoghegan <pg@bowt.ie>
Author: Matthias van de Meent <boekewurm+postgres@gmail.com>
Reviewed-By: Heikki Linnakangas <hlinnaka@iki.fi>
Reviewed-By: Matthias van de Meent <boekewurm+postgres@gmail.com>
Reviewed-By: Tomas Vondra <tomas.vondra@enterprisedb.com>
Discussion: https://postgr.es/m/CAH2-Wz=ksvN_sjcnD1+Bt-WtifRA5ok48aDYnq3pkKhxgMQpcw@mail.gmail.com
2024-04-06 11:47:10 -04:00

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/*-------------------------------------------------------------------------
*
* nodeIndexscan.c
* Routines to support indexed scans of relations
*
* Portions Copyright (c) 1996-2024, PostgreSQL Global Development Group
* Portions Copyright (c) 1994, Regents of the University of California
*
*
* IDENTIFICATION
* src/backend/executor/nodeIndexscan.c
*
*-------------------------------------------------------------------------
*/
/*
* INTERFACE ROUTINES
* ExecIndexScan scans a relation using an index
* IndexNext retrieve next tuple using index
* IndexNextWithReorder same, but recheck ORDER BY expressions
* ExecInitIndexScan creates and initializes state info.
* ExecReScanIndexScan rescans the indexed relation.
* ExecEndIndexScan releases all storage.
* ExecIndexMarkPos marks scan position.
* ExecIndexRestrPos restores scan position.
* ExecIndexScanEstimate estimates DSM space needed for parallel index scan
* ExecIndexScanInitializeDSM initialize DSM for parallel indexscan
* ExecIndexScanReInitializeDSM reinitialize DSM for fresh scan
* ExecIndexScanInitializeWorker attach to DSM info in parallel worker
*/
#include "postgres.h"
#include "access/nbtree.h"
#include "access/relscan.h"
#include "access/tableam.h"
#include "catalog/pg_am.h"
#include "executor/executor.h"
#include "executor/nodeIndexscan.h"
#include "lib/pairingheap.h"
#include "miscadmin.h"
#include "nodes/nodeFuncs.h"
#include "utils/array.h"
#include "utils/datum.h"
#include "utils/lsyscache.h"
#include "utils/rel.h"
/*
* When an ordering operator is used, tuples fetched from the index that
* need to be reordered are queued in a pairing heap, as ReorderTuples.
*/
typedef struct
{
pairingheap_node ph_node;
HeapTuple htup;
Datum *orderbyvals;
bool *orderbynulls;
} ReorderTuple;
static TupleTableSlot *IndexNext(IndexScanState *node);
static TupleTableSlot *IndexNextWithReorder(IndexScanState *node);
static void EvalOrderByExpressions(IndexScanState *node, ExprContext *econtext);
static bool IndexRecheck(IndexScanState *node, TupleTableSlot *slot);
static int cmp_orderbyvals(const Datum *adist, const bool *anulls,
const Datum *bdist, const bool *bnulls,
IndexScanState *node);
static int reorderqueue_cmp(const pairingheap_node *a,
const pairingheap_node *b, void *arg);
static void reorderqueue_push(IndexScanState *node, TupleTableSlot *slot,
Datum *orderbyvals, bool *orderbynulls);
static HeapTuple reorderqueue_pop(IndexScanState *node);
/* ----------------------------------------------------------------
* IndexNext
*
* Retrieve a tuple from the IndexScan node's currentRelation
* using the index specified in the IndexScanState information.
* ----------------------------------------------------------------
*/
static TupleTableSlot *
IndexNext(IndexScanState *node)
{
EState *estate;
ExprContext *econtext;
ScanDirection direction;
IndexScanDesc scandesc;
TupleTableSlot *slot;
/*
* extract necessary information from index scan node
*/
estate = node->ss.ps.state;
/*
* Determine which direction to scan the index in based on the plan's scan
* direction and the current direction of execution.
*/
direction = ScanDirectionCombine(estate->es_direction,
((IndexScan *) node->ss.ps.plan)->indexorderdir);
scandesc = node->iss_ScanDesc;
econtext = node->ss.ps.ps_ExprContext;
slot = node->ss.ss_ScanTupleSlot;
if (scandesc == NULL)
{
/*
* We reach here if the index scan is not parallel, or if we're
* serially executing an index scan that was planned to be parallel.
*/
scandesc = index_beginscan(node->ss.ss_currentRelation,
node->iss_RelationDesc,
estate->es_snapshot,
node->iss_NumScanKeys,
node->iss_NumOrderByKeys);
node->iss_ScanDesc = scandesc;
/*
* If no run-time keys to calculate or they are ready, go ahead and
* pass the scankeys to the index AM.
*/
if (node->iss_NumRuntimeKeys == 0 || node->iss_RuntimeKeysReady)
index_rescan(scandesc,
node->iss_ScanKeys, node->iss_NumScanKeys,
node->iss_OrderByKeys, node->iss_NumOrderByKeys);
}
/*
* ok, now that we have what we need, fetch the next tuple.
*/
while (index_getnext_slot(scandesc, direction, slot))
{
CHECK_FOR_INTERRUPTS();
/*
* If the index was lossy, we have to recheck the index quals using
* the fetched tuple.
*/
if (scandesc->xs_recheck)
{
econtext->ecxt_scantuple = slot;
if (!ExecQualAndReset(node->indexqualorig, econtext))
{
/* Fails recheck, so drop it and loop back for another */
InstrCountFiltered2(node, 1);
continue;
}
}
return slot;
}
/*
* if we get here it means the index scan failed so we are at the end of
* the scan..
*/
node->iss_ReachedEnd = true;
return ExecClearTuple(slot);
}
/* ----------------------------------------------------------------
* IndexNextWithReorder
*
* Like IndexNext, but this version can also re-check ORDER BY
* expressions, and reorder the tuples as necessary.
* ----------------------------------------------------------------
*/
static TupleTableSlot *
IndexNextWithReorder(IndexScanState *node)
{
EState *estate;
ExprContext *econtext;
IndexScanDesc scandesc;
TupleTableSlot *slot;
ReorderTuple *topmost = NULL;
bool was_exact;
Datum *lastfetched_vals;
bool *lastfetched_nulls;
int cmp;
estate = node->ss.ps.state;
/*
* Only forward scan is supported with reordering. Note: we can get away
* with just Asserting here because the system will not try to run the
* plan backwards if ExecSupportsBackwardScan() says it won't work.
* Currently, that is guaranteed because no index AMs support both
* amcanorderbyop and amcanbackward; if any ever do,
* ExecSupportsBackwardScan() will need to consider indexorderbys
* explicitly.
*/
Assert(!ScanDirectionIsBackward(((IndexScan *) node->ss.ps.plan)->indexorderdir));
Assert(ScanDirectionIsForward(estate->es_direction));
scandesc = node->iss_ScanDesc;
econtext = node->ss.ps.ps_ExprContext;
slot = node->ss.ss_ScanTupleSlot;
if (scandesc == NULL)
{
/*
* We reach here if the index scan is not parallel, or if we're
* serially executing an index scan that was planned to be parallel.
*/
scandesc = index_beginscan(node->ss.ss_currentRelation,
node->iss_RelationDesc,
estate->es_snapshot,
node->iss_NumScanKeys,
node->iss_NumOrderByKeys);
node->iss_ScanDesc = scandesc;
/*
* If no run-time keys to calculate or they are ready, go ahead and
* pass the scankeys to the index AM.
*/
if (node->iss_NumRuntimeKeys == 0 || node->iss_RuntimeKeysReady)
index_rescan(scandesc,
node->iss_ScanKeys, node->iss_NumScanKeys,
node->iss_OrderByKeys, node->iss_NumOrderByKeys);
}
for (;;)
{
CHECK_FOR_INTERRUPTS();
/*
* Check the reorder queue first. If the topmost tuple in the queue
* has an ORDER BY value smaller than (or equal to) the value last
* returned by the index, we can return it now.
*/
if (!pairingheap_is_empty(node->iss_ReorderQueue))
{
topmost = (ReorderTuple *) pairingheap_first(node->iss_ReorderQueue);
if (node->iss_ReachedEnd ||
cmp_orderbyvals(topmost->orderbyvals,
topmost->orderbynulls,
scandesc->xs_orderbyvals,
scandesc->xs_orderbynulls,
node) <= 0)
{
HeapTuple tuple;
tuple = reorderqueue_pop(node);
/* Pass 'true', as the tuple in the queue is a palloc'd copy */
ExecForceStoreHeapTuple(tuple, slot, true);
return slot;
}
}
else if (node->iss_ReachedEnd)
{
/* Queue is empty, and no more tuples from index. We're done. */
return ExecClearTuple(slot);
}
/*
* Fetch next tuple from the index.
*/
next_indextuple:
if (!index_getnext_slot(scandesc, ForwardScanDirection, slot))
{
/*
* No more tuples from the index. But we still need to drain any
* remaining tuples from the queue before we're done.
*/
node->iss_ReachedEnd = true;
continue;
}
/*
* If the index was lossy, we have to recheck the index quals and
* ORDER BY expressions using the fetched tuple.
*/
if (scandesc->xs_recheck)
{
econtext->ecxt_scantuple = slot;
if (!ExecQualAndReset(node->indexqualorig, econtext))
{
/* Fails recheck, so drop it and loop back for another */
InstrCountFiltered2(node, 1);
/* allow this loop to be cancellable */
CHECK_FOR_INTERRUPTS();
goto next_indextuple;
}
}
if (scandesc->xs_recheckorderby)
{
econtext->ecxt_scantuple = slot;
ResetExprContext(econtext);
EvalOrderByExpressions(node, econtext);
/*
* Was the ORDER BY value returned by the index accurate? The
* recheck flag means that the index can return inaccurate values,
* but then again, the value returned for any particular tuple
* could also be exactly correct. Compare the value returned by
* the index with the recalculated value. (If the value returned
* by the index happened to be exact right, we can often avoid
* pushing the tuple to the queue, just to pop it back out again.)
*/
cmp = cmp_orderbyvals(node->iss_OrderByValues,
node->iss_OrderByNulls,
scandesc->xs_orderbyvals,
scandesc->xs_orderbynulls,
node);
if (cmp < 0)
elog(ERROR, "index returned tuples in wrong order");
else if (cmp == 0)
was_exact = true;
else
was_exact = false;
lastfetched_vals = node->iss_OrderByValues;
lastfetched_nulls = node->iss_OrderByNulls;
}
else
{
was_exact = true;
lastfetched_vals = scandesc->xs_orderbyvals;
lastfetched_nulls = scandesc->xs_orderbynulls;
}
/*
* Can we return this tuple immediately, or does it need to be pushed
* to the reorder queue? If the ORDER BY expression values returned
* by the index were inaccurate, we can't return it yet, because the
* next tuple from the index might need to come before this one. Also,
* we can't return it yet if there are any smaller tuples in the queue
* already.
*/
if (!was_exact || (topmost && cmp_orderbyvals(lastfetched_vals,
lastfetched_nulls,
topmost->orderbyvals,
topmost->orderbynulls,
node) > 0))
{
/* Put this tuple to the queue */
reorderqueue_push(node, slot, lastfetched_vals, lastfetched_nulls);
continue;
}
else
{
/* Can return this tuple immediately. */
return slot;
}
}
/*
* if we get here it means the index scan failed so we are at the end of
* the scan..
*/
return ExecClearTuple(slot);
}
/*
* Calculate the expressions in the ORDER BY clause, based on the heap tuple.
*/
static void
EvalOrderByExpressions(IndexScanState *node, ExprContext *econtext)
{
int i;
ListCell *l;
MemoryContext oldContext;
oldContext = MemoryContextSwitchTo(econtext->ecxt_per_tuple_memory);
i = 0;
foreach(l, node->indexorderbyorig)
{
ExprState *orderby = (ExprState *) lfirst(l);
node->iss_OrderByValues[i] = ExecEvalExpr(orderby,
econtext,
&node->iss_OrderByNulls[i]);
i++;
}
MemoryContextSwitchTo(oldContext);
}
/*
* IndexRecheck -- access method routine to recheck a tuple in EvalPlanQual
*/
static bool
IndexRecheck(IndexScanState *node, TupleTableSlot *slot)
{
ExprContext *econtext;
/*
* extract necessary information from index scan node
*/
econtext = node->ss.ps.ps_ExprContext;
/* Does the tuple meet the indexqual condition? */
econtext->ecxt_scantuple = slot;
return ExecQualAndReset(node->indexqualorig, econtext);
}
/*
* Compare ORDER BY expression values.
*/
static int
cmp_orderbyvals(const Datum *adist, const bool *anulls,
const Datum *bdist, const bool *bnulls,
IndexScanState *node)
{
int i;
int result;
for (i = 0; i < node->iss_NumOrderByKeys; i++)
{
SortSupport ssup = &node->iss_SortSupport[i];
/*
* Handle nulls. We only need to support NULLS LAST ordering, because
* match_pathkeys_to_index() doesn't consider indexorderby
* implementation otherwise.
*/
if (anulls[i] && !bnulls[i])
return 1;
else if (!anulls[i] && bnulls[i])
return -1;
else if (anulls[i] && bnulls[i])
return 0;
result = ssup->comparator(adist[i], bdist[i], ssup);
if (result != 0)
return result;
}
return 0;
}
/*
* Pairing heap provides getting topmost (greatest) element while KNN provides
* ascending sort. That's why we invert the sort order.
*/
static int
reorderqueue_cmp(const pairingheap_node *a, const pairingheap_node *b,
void *arg)
{
ReorderTuple *rta = (ReorderTuple *) a;
ReorderTuple *rtb = (ReorderTuple *) b;
IndexScanState *node = (IndexScanState *) arg;
/* exchange argument order to invert the sort order */
return cmp_orderbyvals(rtb->orderbyvals, rtb->orderbynulls,
rta->orderbyvals, rta->orderbynulls,
node);
}
/*
* Helper function to push a tuple to the reorder queue.
*/
static void
reorderqueue_push(IndexScanState *node, TupleTableSlot *slot,
Datum *orderbyvals, bool *orderbynulls)
{
IndexScanDesc scandesc = node->iss_ScanDesc;
EState *estate = node->ss.ps.state;
MemoryContext oldContext = MemoryContextSwitchTo(estate->es_query_cxt);
ReorderTuple *rt;
int i;
rt = (ReorderTuple *) palloc(sizeof(ReorderTuple));
rt->htup = ExecCopySlotHeapTuple(slot);
rt->orderbyvals =
(Datum *) palloc(sizeof(Datum) * scandesc->numberOfOrderBys);
rt->orderbynulls =
(bool *) palloc(sizeof(bool) * scandesc->numberOfOrderBys);
for (i = 0; i < node->iss_NumOrderByKeys; i++)
{
if (!orderbynulls[i])
rt->orderbyvals[i] = datumCopy(orderbyvals[i],
node->iss_OrderByTypByVals[i],
node->iss_OrderByTypLens[i]);
else
rt->orderbyvals[i] = (Datum) 0;
rt->orderbynulls[i] = orderbynulls[i];
}
pairingheap_add(node->iss_ReorderQueue, &rt->ph_node);
MemoryContextSwitchTo(oldContext);
}
/*
* Helper function to pop the next tuple from the reorder queue.
*/
static HeapTuple
reorderqueue_pop(IndexScanState *node)
{
HeapTuple result;
ReorderTuple *topmost;
int i;
topmost = (ReorderTuple *) pairingheap_remove_first(node->iss_ReorderQueue);
result = topmost->htup;
for (i = 0; i < node->iss_NumOrderByKeys; i++)
{
if (!node->iss_OrderByTypByVals[i] && !topmost->orderbynulls[i])
pfree(DatumGetPointer(topmost->orderbyvals[i]));
}
pfree(topmost->orderbyvals);
pfree(topmost->orderbynulls);
pfree(topmost);
return result;
}
/* ----------------------------------------------------------------
* ExecIndexScan(node)
* ----------------------------------------------------------------
*/
static TupleTableSlot *
ExecIndexScan(PlanState *pstate)
{
IndexScanState *node = castNode(IndexScanState, pstate);
/*
* If we have runtime keys and they've not already been set up, do it now.
*/
if (node->iss_NumRuntimeKeys != 0 && !node->iss_RuntimeKeysReady)
ExecReScan((PlanState *) node);
if (node->iss_NumOrderByKeys > 0)
return ExecScan(&node->ss,
(ExecScanAccessMtd) IndexNextWithReorder,
(ExecScanRecheckMtd) IndexRecheck);
else
return ExecScan(&node->ss,
(ExecScanAccessMtd) IndexNext,
(ExecScanRecheckMtd) IndexRecheck);
}
/* ----------------------------------------------------------------
* 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;
/* flush the reorder queue */
if (node->iss_ReorderQueue)
{
HeapTuple tuple;
while (!pairingheap_is_empty(node->iss_ReorderQueue))
{
tuple = reorderqueue_pop(node);
heap_freetuple(tuple);
}
}
/* reset index scan */
if (node->iss_ScanDesc)
index_rescan(node->iss_ScanDesc,
node->iss_ScanKeys, node->iss_NumScanKeys,
node->iss_OrderByKeys, node->iss_NumOrderByKeys);
node->iss_ReachedEnd = false;
ExecScanReScan(&node->ss);
}
/*
* ExecIndexEvalRuntimeKeys
* Evaluate any runtime key values, and update the scankeys.
*/
void
ExecIndexEvalRuntimeKeys(ExprContext *econtext,
IndexRuntimeKeyInfo *runtimeKeys, int numRuntimeKeys)
{
int j;
MemoryContext oldContext;
/* We want to keep the key values in per-tuple memory */
oldContext = MemoryContextSwitchTo(econtext->ecxt_per_tuple_memory);
for (j = 0; j < numRuntimeKeys; j++)
{
ScanKey scan_key = runtimeKeys[j].scan_key;
ExprState *key_expr = runtimeKeys[j].key_expr;
Datum scanvalue;
bool isNull;
/*
* For each run-time key, extract the run-time expression and evaluate
* it with respect to the current context. We then stick the result
* into the proper scan key.
*
* Note: the result of the eval could be a pass-by-ref value that's
* stored in some outer scan's tuple, not in
* econtext->ecxt_per_tuple_memory. We assume that the outer tuple
* will stay put throughout our scan. If this is wrong, we could copy
* the result into our context explicitly, but I think that's not
* necessary.
*
* It's also entirely possible that the result of the eval is a
* toasted value. In this case we should forcibly detoast it, to
* avoid repeat detoastings each time the value is examined by an
* index support function.
*/
scanvalue = ExecEvalExpr(key_expr,
econtext,
&isNull);
if (isNull)
{
scan_key->sk_argument = scanvalue;
scan_key->sk_flags |= SK_ISNULL;
}
else
{
if (runtimeKeys[j].key_toastable)
scanvalue = PointerGetDatum(PG_DETOAST_DATUM(scanvalue));
scan_key->sk_argument = scanvalue;
scan_key->sk_flags &= ~SK_ISNULL;
}
}
MemoryContextSwitchTo(oldContext);
}
/*
* ExecIndexEvalArrayKeys
* Evaluate any array key values, and set up to iterate through arrays.
*
* Returns true if there are array elements to consider; false means there
* is at least one null or empty array, so no match is possible. On true
* result, the scankeys are initialized with the first elements of the arrays.
*/
bool
ExecIndexEvalArrayKeys(ExprContext *econtext,
IndexArrayKeyInfo *arrayKeys, int numArrayKeys)
{
bool result = true;
int j;
MemoryContext oldContext;
/* We want to keep the arrays in per-tuple memory */
oldContext = MemoryContextSwitchTo(econtext->ecxt_per_tuple_memory);
for (j = 0; j < numArrayKeys; j++)
{
ScanKey scan_key = arrayKeys[j].scan_key;
ExprState *array_expr = arrayKeys[j].array_expr;
Datum arraydatum;
bool isNull;
ArrayType *arrayval;
int16 elmlen;
bool elmbyval;
char elmalign;
int num_elems;
Datum *elem_values;
bool *elem_nulls;
/*
* Compute and deconstruct the array expression. (Notes in
* ExecIndexEvalRuntimeKeys() apply here too.)
*/
arraydatum = ExecEvalExpr(array_expr,
econtext,
&isNull);
if (isNull)
{
result = false;
break; /* no point in evaluating more */
}
arrayval = DatumGetArrayTypeP(arraydatum);
/* We could cache this data, but not clear it's worth it */
get_typlenbyvalalign(ARR_ELEMTYPE(arrayval),
&elmlen, &elmbyval, &elmalign);
deconstruct_array(arrayval,
ARR_ELEMTYPE(arrayval),
elmlen, elmbyval, elmalign,
&elem_values, &elem_nulls, &num_elems);
if (num_elems <= 0)
{
result = false;
break; /* no point in evaluating more */
}
/*
* Note: we expect the previous array data, if any, to be
* automatically freed by resetting the per-tuple context; hence no
* pfree's here.
*/
arrayKeys[j].elem_values = elem_values;
arrayKeys[j].elem_nulls = elem_nulls;
arrayKeys[j].num_elems = num_elems;
scan_key->sk_argument = elem_values[0];
if (elem_nulls[0])
scan_key->sk_flags |= SK_ISNULL;
else
scan_key->sk_flags &= ~SK_ISNULL;
arrayKeys[j].next_elem = 1;
}
MemoryContextSwitchTo(oldContext);
return result;
}
/*
* ExecIndexAdvanceArrayKeys
* Advance to the next set of array key values, if any.
*
* Returns true if there is another set of values to consider, false if not.
* On true result, the scankeys are initialized with the next set of values.
*/
bool
ExecIndexAdvanceArrayKeys(IndexArrayKeyInfo *arrayKeys, int numArrayKeys)
{
bool found = false;
int j;
/*
* Note we advance the rightmost array key most quickly, since it will
* correspond to the lowest-order index column among the available
* qualifications. This is hypothesized to result in better locality of
* access in the index.
*/
for (j = numArrayKeys - 1; j >= 0; j--)
{
ScanKey scan_key = arrayKeys[j].scan_key;
int next_elem = arrayKeys[j].next_elem;
int num_elems = arrayKeys[j].num_elems;
Datum *elem_values = arrayKeys[j].elem_values;
bool *elem_nulls = arrayKeys[j].elem_nulls;
if (next_elem >= num_elems)
{
next_elem = 0;
found = false; /* need to advance next array key */
}
else
found = true;
scan_key->sk_argument = elem_values[next_elem];
if (elem_nulls[next_elem])
scan_key->sk_flags |= SK_ISNULL;
else
scan_key->sk_flags &= ~SK_ISNULL;
arrayKeys[j].next_elem = next_elem + 1;
if (found)
break;
}
return found;
}
/* ----------------------------------------------------------------
* ExecEndIndexScan
* ----------------------------------------------------------------
*/
void
ExecEndIndexScan(IndexScanState *node)
{
Relation indexRelationDesc;
IndexScanDesc indexScanDesc;
/*
* extract information from the node
*/
indexRelationDesc = node->iss_RelationDesc;
indexScanDesc = node->iss_ScanDesc;
/*
* close the index relation (no-op if we didn't open it)
*/
if (indexScanDesc)
index_endscan(indexScanDesc);
if (indexRelationDesc)
index_close(indexRelationDesc, NoLock);
}
/* ----------------------------------------------------------------
* ExecIndexMarkPos
*
* Note: we assume that no caller attempts to set a mark before having read
* at least one tuple. Otherwise, iss_ScanDesc might still be NULL.
* ----------------------------------------------------------------
*/
void
ExecIndexMarkPos(IndexScanState *node)
{
EState *estate = node->ss.ps.state;
EPQState *epqstate = estate->es_epq_active;
if (epqstate != NULL)
{
/*
* We are inside an EvalPlanQual recheck. If a test tuple exists for
* this relation, then we shouldn't access the index at all. We would
* instead need to save, and later restore, the state of the
* relsubs_done flag, so that re-fetching the test tuple is possible.
* However, given the assumption that no caller sets a mark at the
* start of the scan, we can only get here with relsubs_done[i]
* already set, and so no state need be saved.
*/
Index scanrelid = ((Scan *) node->ss.ps.plan)->scanrelid;
Assert(scanrelid > 0);
if (epqstate->relsubs_slot[scanrelid - 1] != NULL ||
epqstate->relsubs_rowmark[scanrelid - 1] != NULL)
{
/* Verify the claim above */
if (!epqstate->relsubs_done[scanrelid - 1])
elog(ERROR, "unexpected ExecIndexMarkPos call in EPQ recheck");
return;
}
}
index_markpos(node->iss_ScanDesc);
}
/* ----------------------------------------------------------------
* ExecIndexRestrPos
* ----------------------------------------------------------------
*/
void
ExecIndexRestrPos(IndexScanState *node)
{
EState *estate = node->ss.ps.state;
EPQState *epqstate = estate->es_epq_active;
if (estate->es_epq_active != NULL)
{
/* See comments in ExecIndexMarkPos */
Index scanrelid = ((Scan *) node->ss.ps.plan)->scanrelid;
Assert(scanrelid > 0);
if (epqstate->relsubs_slot[scanrelid - 1] != NULL ||
epqstate->relsubs_rowmark[scanrelid - 1] != NULL)
{
/* Verify the claim above */
if (!epqstate->relsubs_done[scanrelid - 1])
elog(ERROR, "unexpected ExecIndexRestrPos call in EPQ recheck");
return;
}
}
index_restrpos(node->iss_ScanDesc);
}
/* ----------------------------------------------------------------
* 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;
LOCKMODE lockmode;
/*
* create state structure
*/
indexstate = makeNode(IndexScanState);
indexstate->ss.ps.plan = (Plan *) node;
indexstate->ss.ps.state = estate;
indexstate->ss.ps.ExecProcNode = ExecIndexScan;
/*
* Miscellaneous initialization
*
* create expression context for node
*/
ExecAssignExprContext(estate, &indexstate->ss.ps);
/*
* open the scan relation
*/
currentRelation = ExecOpenScanRelation(estate, node->scan.scanrelid, eflags);
indexstate->ss.ss_currentRelation = currentRelation;
indexstate->ss.ss_currentScanDesc = NULL; /* no heap scan here */
/*
* get the scan type from the relation descriptor.
*/
ExecInitScanTupleSlot(estate, &indexstate->ss,
RelationGetDescr(currentRelation),
table_slot_callbacks(currentRelation));
/*
* Initialize result type and projection.
*/
ExecInitResultTypeTL(&indexstate->ss.ps);
ExecAssignScanProjectionInfo(&indexstate->ss);
/*
* 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.qual =
ExecInitQual(node->scan.plan.qual, (PlanState *) indexstate);
indexstate->indexqualorig =
ExecInitQual(node->indexqualorig, (PlanState *) indexstate);
indexstate->indexorderbyorig =
ExecInitExprList(node->indexorderbyorig, (PlanState *) indexstate);
/*
* 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. */
lockmode = exec_rt_fetch(node->scan.scanrelid, estate)->rellockmode;
indexstate->iss_RelationDesc = index_open(node->indexid, lockmode);
/*
* 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->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->indexorderby,
true,
&indexstate->iss_OrderByKeys,
&indexstate->iss_NumOrderByKeys,
&indexstate->iss_RuntimeKeys,
&indexstate->iss_NumRuntimeKeys,
NULL, /* no ArrayKeys */
NULL);
/* Initialize sort support, if we need to re-check ORDER BY exprs */
if (indexstate->iss_NumOrderByKeys > 0)
{
int numOrderByKeys = indexstate->iss_NumOrderByKeys;
int i;
ListCell *lco;
ListCell *lcx;
/*
* Prepare sort support, and look up the data type for each ORDER BY
* expression.
*/
Assert(numOrderByKeys == list_length(node->indexorderbyops));
Assert(numOrderByKeys == list_length(node->indexorderbyorig));
indexstate->iss_SortSupport = (SortSupportData *)
palloc0(numOrderByKeys * sizeof(SortSupportData));
indexstate->iss_OrderByTypByVals = (bool *)
palloc(numOrderByKeys * sizeof(bool));
indexstate->iss_OrderByTypLens = (int16 *)
palloc(numOrderByKeys * sizeof(int16));
i = 0;
forboth(lco, node->indexorderbyops, lcx, node->indexorderbyorig)
{
Oid orderbyop = lfirst_oid(lco);
Node *orderbyexpr = (Node *) lfirst(lcx);
Oid orderbyType = exprType(orderbyexpr);
Oid orderbyColl = exprCollation(orderbyexpr);
SortSupport orderbysort = &indexstate->iss_SortSupport[i];
/* Initialize sort support */
orderbysort->ssup_cxt = CurrentMemoryContext;
orderbysort->ssup_collation = orderbyColl;
/* See cmp_orderbyvals() comments on NULLS LAST */
orderbysort->ssup_nulls_first = false;
/* ssup_attno is unused here and elsewhere */
orderbysort->ssup_attno = 0;
/* No abbreviation */
orderbysort->abbreviate = false;
PrepareSortSupportFromOrderingOp(orderbyop, orderbysort);
get_typlenbyval(orderbyType,
&indexstate->iss_OrderByTypLens[i],
&indexstate->iss_OrderByTypByVals[i]);
i++;
}
/* allocate arrays to hold the re-calculated distances */
indexstate->iss_OrderByValues = (Datum *)
palloc(numOrderByKeys * sizeof(Datum));
indexstate->iss_OrderByNulls = (bool *)
palloc(numOrderByKeys * sizeof(bool));
/* and initialize the reorder queue */
indexstate->iss_ReorderQueue = pairingheap_allocate(reorderqueue_cmp,
indexstate);
}
/*
* 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;
}
/*
* all done.
*/
return indexstate;
}
/*
* ExecIndexBuildScanKeys
* Build the index scan keys from the index qualification expressions
*
* The index quals are passed to the index AM in the form of a ScanKey array.
* This routine sets up the ScanKeys, fills in all constant fields of the
* ScanKeys, and prepares information about the keys that have non-constant
* comparison values. We divide index qual expressions into five types:
*
* 1. Simple operator with constant comparison value ("indexkey op constant").
* For these, we just fill in a ScanKey containing the constant value.
*
* 2. Simple operator with non-constant value ("indexkey op expression").
* For these, we create a ScanKey with everything filled in except the
* expression value, and set up an IndexRuntimeKeyInfo struct to drive
* evaluation of the expression at the right times.
*
* 3. RowCompareExpr ("(indexkey, indexkey, ...) op (expr, expr, ...)").
* For these, we create a header ScanKey plus a subsidiary ScanKey array,
* as specified in access/skey.h. The elements of the row comparison
* can have either constant or non-constant comparison values.
*
* 4. ScalarArrayOpExpr ("indexkey op ANY (array-expression)"). If the index
* supports amsearcharray, we handle these the same as simple operators,
* setting the SK_SEARCHARRAY flag to tell the AM to handle them. Otherwise,
* we create a ScanKey with everything filled in except the comparison value,
* and set up an IndexArrayKeyInfo struct to drive processing of the qual.
* (Note that if we use an IndexArrayKeyInfo struct, the array expression is
* always treated as requiring runtime evaluation, even if it's a constant.)
*
* 5. NullTest ("indexkey IS NULL/IS NOT NULL"). We just fill in the
* ScanKey properly.
*
* This code is also used to prepare ORDER BY expressions for amcanorderbyop
* indexes. The behavior is exactly the same, except that we have to look up
* the operator differently. Note that only cases 1 and 2 are currently
* possible for ORDER BY.
*
* Input params are:
*
* planstate: executor state node we are working for
* index: the index we are building scan keys for
* quals: indexquals (or indexorderbys) expressions
* isorderby: true if processing ORDER BY exprs, false if processing quals
* *runtimeKeys: ptr to pre-existing IndexRuntimeKeyInfos, or NULL if none
* *numRuntimeKeys: number of pre-existing runtime keys
*
* Output params are:
*
* *scanKeys: receives ptr to array of ScanKeys
* *numScanKeys: receives number of scankeys
* *runtimeKeys: receives ptr to array of IndexRuntimeKeyInfos, or NULL if none
* *numRuntimeKeys: receives number of runtime keys
* *arrayKeys: receives ptr to array of IndexArrayKeyInfos, or NULL if none
* *numArrayKeys: receives number of array keys
*
* Caller may pass NULL for arrayKeys and numArrayKeys to indicate that
* IndexArrayKeyInfos are not supported.
*/
void
ExecIndexBuildScanKeys(PlanState *planstate, Relation index,
List *quals, bool isorderby,
ScanKey *scanKeys, int *numScanKeys,
IndexRuntimeKeyInfo **runtimeKeys, int *numRuntimeKeys,
IndexArrayKeyInfo **arrayKeys, int *numArrayKeys)
{
ListCell *qual_cell;
ScanKey scan_keys;
IndexRuntimeKeyInfo *runtime_keys;
IndexArrayKeyInfo *array_keys;
int n_scan_keys;
int n_runtime_keys;
int max_runtime_keys;
int n_array_keys;
int j;
/* Allocate array for ScanKey structs: one per qual */
n_scan_keys = list_length(quals);
scan_keys = (ScanKey) palloc(n_scan_keys * sizeof(ScanKeyData));
/*
* runtime_keys array is dynamically resized as needed. We handle it this
* way so that the same runtime keys array can be shared between
* indexquals and indexorderbys, which will be processed in separate calls
* of this function. Caller must be sure to pass in NULL/0 for first
* call.
*/
runtime_keys = *runtimeKeys;
n_runtime_keys = max_runtime_keys = *numRuntimeKeys;
/* Allocate array_keys as large as it could possibly need to be */
array_keys = (IndexArrayKeyInfo *)
palloc0(n_scan_keys * sizeof(IndexArrayKeyInfo));
n_array_keys = 0;
/*
* for each opclause in the given qual, convert the opclause into a single
* scan key
*/
j = 0;
foreach(qual_cell, quals)
{
Expr *clause = (Expr *) lfirst(qual_cell);
ScanKey this_scan_key = &scan_keys[j++];
Oid opno; /* operator's OID */
RegProcedure opfuncid; /* operator proc id used in scan */
Oid opfamily; /* opfamily of index column */
int op_strategy; /* operator's strategy number */
Oid op_lefttype; /* operator's declared input types */
Oid op_righttype;
Expr *leftop; /* expr on lhs of operator */
Expr *rightop; /* expr on rhs ... */
AttrNumber varattno; /* att number used in scan */
int indnkeyatts;
indnkeyatts = IndexRelationGetNumberOfKeyAttributes(index);
if (IsA(clause, OpExpr))
{
/* indexkey op const or indexkey op expression */
int flags = 0;
Datum scanvalue;
opno = ((OpExpr *) clause)->opno;
opfuncid = ((OpExpr *) clause)->opfuncid;
/*
* leftop should be the index key Var, possibly relabeled
*/
leftop = (Expr *) get_leftop(clause);
if (leftop && IsA(leftop, RelabelType))
leftop = ((RelabelType *) leftop)->arg;
Assert(leftop != NULL);
if (!(IsA(leftop, Var) &&
((Var *) leftop)->varno == INDEX_VAR))
elog(ERROR, "indexqual doesn't have key on left side");
varattno = ((Var *) leftop)->varattno;
if (varattno < 1 || varattno > indnkeyatts)
elog(ERROR, "bogus index qualification");
/*
* We have to look up the operator's strategy number. This
* provides a cross-check that the operator does match the index.
*/
opfamily = index->rd_opfamily[varattno - 1];
get_op_opfamily_properties(opno, opfamily, isorderby,
&op_strategy,
&op_lefttype,
&op_righttype);
if (isorderby)
flags |= SK_ORDER_BY;
/*
* rightop is the constant or variable comparison value
*/
rightop = (Expr *) get_rightop(clause);
if (rightop && IsA(rightop, RelabelType))
rightop = ((RelabelType *) rightop)->arg;
Assert(rightop != NULL);
if (IsA(rightop, Const))
{
/* OK, simple constant comparison value */
scanvalue = ((Const *) rightop)->constvalue;
if (((Const *) rightop)->constisnull)
flags |= SK_ISNULL;
}
else
{
/* Need to treat this one as a runtime key */
if (n_runtime_keys >= max_runtime_keys)
{
if (max_runtime_keys == 0)
{
max_runtime_keys = 8;
runtime_keys = (IndexRuntimeKeyInfo *)
palloc(max_runtime_keys * sizeof(IndexRuntimeKeyInfo));
}
else
{
max_runtime_keys *= 2;
runtime_keys = (IndexRuntimeKeyInfo *)
repalloc(runtime_keys, max_runtime_keys * sizeof(IndexRuntimeKeyInfo));
}
}
runtime_keys[n_runtime_keys].scan_key = this_scan_key;
runtime_keys[n_runtime_keys].key_expr =
ExecInitExpr(rightop, planstate);
runtime_keys[n_runtime_keys].key_toastable =
TypeIsToastable(op_righttype);
n_runtime_keys++;
scanvalue = (Datum) 0;
}
/*
* initialize the scan key's fields appropriately
*/
ScanKeyEntryInitialize(this_scan_key,
flags,
varattno, /* attribute number to scan */
op_strategy, /* op's strategy */
op_righttype, /* strategy subtype */
((OpExpr *) clause)->inputcollid, /* collation */
opfuncid, /* reg proc to use */
scanvalue); /* constant */
}
else if (IsA(clause, RowCompareExpr))
{
/* (indexkey, indexkey, ...) op (expression, expression, ...) */
RowCompareExpr *rc = (RowCompareExpr *) clause;
ScanKey first_sub_key;
int n_sub_key;
ListCell *largs_cell;
ListCell *rargs_cell;
ListCell *opnos_cell;
ListCell *collids_cell;
Assert(!isorderby);
first_sub_key = (ScanKey)
palloc(list_length(rc->opnos) * sizeof(ScanKeyData));
n_sub_key = 0;
/* Scan RowCompare columns and generate subsidiary ScanKey items */
forfour(largs_cell, rc->largs, rargs_cell, rc->rargs,
opnos_cell, rc->opnos, collids_cell, rc->inputcollids)
{
ScanKey this_sub_key = &first_sub_key[n_sub_key];
int flags = SK_ROW_MEMBER;
Datum scanvalue;
Oid inputcollation;
leftop = (Expr *) lfirst(largs_cell);
rightop = (Expr *) lfirst(rargs_cell);
opno = lfirst_oid(opnos_cell);
inputcollation = lfirst_oid(collids_cell);
/*
* leftop should be the index key Var, possibly relabeled
*/
if (leftop && IsA(leftop, RelabelType))
leftop = ((RelabelType *) leftop)->arg;
Assert(leftop != NULL);
if (!(IsA(leftop, Var) &&
((Var *) leftop)->varno == INDEX_VAR))
elog(ERROR, "indexqual doesn't have key on left side");
varattno = ((Var *) leftop)->varattno;
/*
* We have to look up the operator's associated btree support
* function
*/
if (index->rd_rel->relam != BTREE_AM_OID ||
varattno < 1 || varattno > indnkeyatts)
elog(ERROR, "bogus RowCompare index qualification");
opfamily = index->rd_opfamily[varattno - 1];
get_op_opfamily_properties(opno, opfamily, isorderby,
&op_strategy,
&op_lefttype,
&op_righttype);
if (op_strategy != rc->rctype)
elog(ERROR, "RowCompare index qualification contains wrong operator");
opfuncid = get_opfamily_proc(opfamily,
op_lefttype,
op_righttype,
BTORDER_PROC);
if (!RegProcedureIsValid(opfuncid))
elog(ERROR, "missing support function %d(%u,%u) in opfamily %u",
BTORDER_PROC, op_lefttype, op_righttype, opfamily);
/*
* rightop is the constant or variable comparison value
*/
if (rightop && IsA(rightop, RelabelType))
rightop = ((RelabelType *) rightop)->arg;
Assert(rightop != NULL);
if (IsA(rightop, Const))
{
/* OK, simple constant comparison value */
scanvalue = ((Const *) rightop)->constvalue;
if (((Const *) rightop)->constisnull)
flags |= SK_ISNULL;
}
else
{
/* Need to treat this one as a runtime key */
if (n_runtime_keys >= max_runtime_keys)
{
if (max_runtime_keys == 0)
{
max_runtime_keys = 8;
runtime_keys = (IndexRuntimeKeyInfo *)
palloc(max_runtime_keys * sizeof(IndexRuntimeKeyInfo));
}
else
{
max_runtime_keys *= 2;
runtime_keys = (IndexRuntimeKeyInfo *)
repalloc(runtime_keys, max_runtime_keys * sizeof(IndexRuntimeKeyInfo));
}
}
runtime_keys[n_runtime_keys].scan_key = this_sub_key;
runtime_keys[n_runtime_keys].key_expr =
ExecInitExpr(rightop, planstate);
runtime_keys[n_runtime_keys].key_toastable =
TypeIsToastable(op_righttype);
n_runtime_keys++;
scanvalue = (Datum) 0;
}
/*
* initialize the subsidiary scan key's fields appropriately
*/
ScanKeyEntryInitialize(this_sub_key,
flags,
varattno, /* attribute number */
op_strategy, /* op's strategy */
op_righttype, /* strategy subtype */
inputcollation, /* collation */
opfuncid, /* reg proc to use */
scanvalue); /* constant */
n_sub_key++;
}
/* Mark the last subsidiary scankey correctly */
first_sub_key[n_sub_key - 1].sk_flags |= SK_ROW_END;
/*
* We don't use ScanKeyEntryInitialize for the header because it
* isn't going to contain a valid sk_func pointer.
*/
MemSet(this_scan_key, 0, sizeof(ScanKeyData));
this_scan_key->sk_flags = SK_ROW_HEADER;
this_scan_key->sk_attno = first_sub_key->sk_attno;
this_scan_key->sk_strategy = rc->rctype;
/* sk_subtype, sk_collation, sk_func not used in a header */
this_scan_key->sk_argument = PointerGetDatum(first_sub_key);
}
else if (IsA(clause, ScalarArrayOpExpr))
{
/* indexkey op ANY (array-expression) */
ScalarArrayOpExpr *saop = (ScalarArrayOpExpr *) clause;
int flags = 0;
Datum scanvalue;
Assert(!isorderby);
Assert(saop->useOr);
opno = saop->opno;
opfuncid = saop->opfuncid;
/*
* leftop should be the index key Var, possibly relabeled
*/
leftop = (Expr *) linitial(saop->args);
if (leftop && IsA(leftop, RelabelType))
leftop = ((RelabelType *) leftop)->arg;
Assert(leftop != NULL);
if (!(IsA(leftop, Var) &&
((Var *) leftop)->varno == INDEX_VAR))
elog(ERROR, "indexqual doesn't have key on left side");
varattno = ((Var *) leftop)->varattno;
if (varattno < 1 || varattno > indnkeyatts)
elog(ERROR, "bogus index qualification");
/*
* We have to look up the operator's strategy number. This
* provides a cross-check that the operator does match the index.
*/
opfamily = index->rd_opfamily[varattno - 1];
get_op_opfamily_properties(opno, opfamily, isorderby,
&op_strategy,
&op_lefttype,
&op_righttype);
/*
* rightop is the constant or variable array value
*/
rightop = (Expr *) lsecond(saop->args);
if (rightop && IsA(rightop, RelabelType))
rightop = ((RelabelType *) rightop)->arg;
Assert(rightop != NULL);
if (index->rd_indam->amsearcharray)
{
/* Index AM will handle this like a simple operator */
flags |= SK_SEARCHARRAY;
if (IsA(rightop, Const))
{
/* OK, simple constant comparison value */
scanvalue = ((Const *) rightop)->constvalue;
if (((Const *) rightop)->constisnull)
flags |= SK_ISNULL;
}
else
{
/* Need to treat this one as a runtime key */
if (n_runtime_keys >= max_runtime_keys)
{
if (max_runtime_keys == 0)
{
max_runtime_keys = 8;
runtime_keys = (IndexRuntimeKeyInfo *)
palloc(max_runtime_keys * sizeof(IndexRuntimeKeyInfo));
}
else
{
max_runtime_keys *= 2;
runtime_keys = (IndexRuntimeKeyInfo *)
repalloc(runtime_keys, max_runtime_keys * sizeof(IndexRuntimeKeyInfo));
}
}
runtime_keys[n_runtime_keys].scan_key = this_scan_key;
runtime_keys[n_runtime_keys].key_expr =
ExecInitExpr(rightop, planstate);
/*
* Careful here: the runtime expression is not of
* op_righttype, but rather is an array of same; so
* TypeIsToastable() isn't helpful. However, we can
* assume that all array types are toastable.
*/
runtime_keys[n_runtime_keys].key_toastable = true;
n_runtime_keys++;
scanvalue = (Datum) 0;
}
}
else
{
/* Executor has to expand the array value */
array_keys[n_array_keys].scan_key = this_scan_key;
array_keys[n_array_keys].array_expr =
ExecInitExpr(rightop, planstate);
/* the remaining fields were zeroed by palloc0 */
n_array_keys++;
scanvalue = (Datum) 0;
}
/*
* initialize the scan key's fields appropriately
*/
ScanKeyEntryInitialize(this_scan_key,
flags,
varattno, /* attribute number to scan */
op_strategy, /* op's strategy */
op_righttype, /* strategy subtype */
saop->inputcollid, /* collation */
opfuncid, /* reg proc to use */
scanvalue); /* constant */
}
else if (IsA(clause, NullTest))
{
/* indexkey IS NULL or indexkey IS NOT NULL */
NullTest *ntest = (NullTest *) clause;
int flags;
Assert(!isorderby);
/*
* argument should be the index key Var, possibly relabeled
*/
leftop = ntest->arg;
if (leftop && IsA(leftop, RelabelType))
leftop = ((RelabelType *) leftop)->arg;
Assert(leftop != NULL);
if (!(IsA(leftop, Var) &&
((Var *) leftop)->varno == INDEX_VAR))
elog(ERROR, "NullTest indexqual has wrong key");
varattno = ((Var *) leftop)->varattno;
/*
* initialize the scan key's fields appropriately
*/
switch (ntest->nulltesttype)
{
case IS_NULL:
flags = SK_ISNULL | SK_SEARCHNULL;
break;
case IS_NOT_NULL:
flags = SK_ISNULL | SK_SEARCHNOTNULL;
break;
default:
elog(ERROR, "unrecognized nulltesttype: %d",
(int) ntest->nulltesttype);
flags = 0; /* keep compiler quiet */
break;
}
ScanKeyEntryInitialize(this_scan_key,
flags,
varattno, /* attribute number to scan */
InvalidStrategy, /* no strategy */
InvalidOid, /* no strategy subtype */
InvalidOid, /* no collation */
InvalidOid, /* no reg proc for this */
(Datum) 0); /* constant */
}
else
elog(ERROR, "unsupported indexqual type: %d",
(int) nodeTag(clause));
}
Assert(n_runtime_keys <= max_runtime_keys);
/* Get rid of any unused arrays */
if (n_array_keys == 0)
{
pfree(array_keys);
array_keys = NULL;
}
/*
* Return info to our caller.
*/
*scanKeys = scan_keys;
*numScanKeys = n_scan_keys;
*runtimeKeys = runtime_keys;
*numRuntimeKeys = n_runtime_keys;
if (arrayKeys)
{
*arrayKeys = array_keys;
*numArrayKeys = n_array_keys;
}
else if (n_array_keys != 0)
elog(ERROR, "ScalarArrayOpExpr index qual found where not allowed");
}
/* ----------------------------------------------------------------
* Parallel Scan Support
* ----------------------------------------------------------------
*/
/* ----------------------------------------------------------------
* ExecIndexScanEstimate
*
* Compute the amount of space we'll need in the parallel
* query DSM, and inform pcxt->estimator about our needs.
* ----------------------------------------------------------------
*/
void
ExecIndexScanEstimate(IndexScanState *node,
ParallelContext *pcxt)
{
EState *estate = node->ss.ps.state;
node->iss_PscanLen = index_parallelscan_estimate(node->iss_RelationDesc,
node->iss_NumScanKeys,
node->iss_NumOrderByKeys,
estate->es_snapshot);
shm_toc_estimate_chunk(&pcxt->estimator, node->iss_PscanLen);
shm_toc_estimate_keys(&pcxt->estimator, 1);
}
/* ----------------------------------------------------------------
* ExecIndexScanInitializeDSM
*
* Set up a parallel index scan descriptor.
* ----------------------------------------------------------------
*/
void
ExecIndexScanInitializeDSM(IndexScanState *node,
ParallelContext *pcxt)
{
EState *estate = node->ss.ps.state;
ParallelIndexScanDesc piscan;
piscan = shm_toc_allocate(pcxt->toc, node->iss_PscanLen);
index_parallelscan_initialize(node->ss.ss_currentRelation,
node->iss_RelationDesc,
estate->es_snapshot,
piscan);
shm_toc_insert(pcxt->toc, node->ss.ps.plan->plan_node_id, piscan);
node->iss_ScanDesc =
index_beginscan_parallel(node->ss.ss_currentRelation,
node->iss_RelationDesc,
node->iss_NumScanKeys,
node->iss_NumOrderByKeys,
piscan);
/*
* If no run-time keys to calculate or they are ready, go ahead and pass
* the scankeys to the index AM.
*/
if (node->iss_NumRuntimeKeys == 0 || node->iss_RuntimeKeysReady)
index_rescan(node->iss_ScanDesc,
node->iss_ScanKeys, node->iss_NumScanKeys,
node->iss_OrderByKeys, node->iss_NumOrderByKeys);
}
/* ----------------------------------------------------------------
* ExecIndexScanReInitializeDSM
*
* Reset shared state before beginning a fresh scan.
* ----------------------------------------------------------------
*/
void
ExecIndexScanReInitializeDSM(IndexScanState *node,
ParallelContext *pcxt)
{
index_parallelrescan(node->iss_ScanDesc);
}
/* ----------------------------------------------------------------
* ExecIndexScanInitializeWorker
*
* Copy relevant information from TOC into planstate.
* ----------------------------------------------------------------
*/
void
ExecIndexScanInitializeWorker(IndexScanState *node,
ParallelWorkerContext *pwcxt)
{
ParallelIndexScanDesc piscan;
piscan = shm_toc_lookup(pwcxt->toc, node->ss.ps.plan->plan_node_id, false);
node->iss_ScanDesc =
index_beginscan_parallel(node->ss.ss_currentRelation,
node->iss_RelationDesc,
node->iss_NumScanKeys,
node->iss_NumOrderByKeys,
piscan);
/*
* If no run-time keys to calculate or they are ready, go ahead and pass
* the scankeys to the index AM.
*/
if (node->iss_NumRuntimeKeys == 0 || node->iss_RuntimeKeysReady)
index_rescan(node->iss_ScanDesc,
node->iss_ScanKeys, node->iss_NumScanKeys,
node->iss_OrderByKeys, node->iss_NumOrderByKeys);
}
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