From 60be6da7310ba5bc1bd3c03d25f5d5992bf96d0f Mon Sep 17 00:00:00 2001
From: Tom Lane <tgl@sss.pgh.pa.us>
Date: Sat, 5 Feb 2000 23:19:44 +0000
Subject: [PATCH] Replace nth() calls in inner loops with traversal of the list
via lnext, to eliminate O(N^2) behavior with lots of indexquals.
---
src/backend/executor/nodeIndexscan.c | 60 +++++++++++++++-------------
1 file changed, 32 insertions(+), 28 deletions(-)
diff --git a/src/backend/executor/nodeIndexscan.c b/src/backend/executor/nodeIndexscan.c
index b9a54cb938a..e5f7642c85c 100644
--- a/src/backend/executor/nodeIndexscan.c
+++ b/src/backend/executor/nodeIndexscan.c
@@ -8,7 +8,7 @@
*
*
* IDENTIFICATION
- * $Header: /cvsroot/pgsql/src/backend/executor/nodeIndexscan.c,v 1.45 2000/01/26 05:56:23 momjian Exp $
+ * $Header: /cvsroot/pgsql/src/backend/executor/nodeIndexscan.c,v 1.46 2000/02/05 23:19:44 tgl Exp $
*
*-------------------------------------------------------------------------
*/
@@ -124,7 +124,7 @@ IndexNext(IndexScan *node)
if (estate->es_evTuple != NULL &&
estate->es_evTuple[node->scan.scanrelid - 1] != NULL)
{
- int iptr;
+ List *qual;
ExecClearTuple(slot);
if (estate->es_evTupleNull[node->scan.scanrelid - 1])
@@ -134,20 +134,23 @@ IndexNext(IndexScan *node)
slot->val = estate->es_evTuple[node->scan.scanrelid - 1];
slot->ttc_shouldFree = false;
- for (iptr = 0; iptr < numIndices; iptr++)
+ scanstate->cstate.cs_ExprContext->ecxt_scantuple = slot;
+
+ /* Does the tuple meet any of the OR'd indxqual conditions? */
+ foreach(qual, node->indxqualorig)
{
- scanstate->cstate.cs_ExprContext->ecxt_scantuple = slot;
- if (ExecQual(nth(iptr, node->indxqualorig),
+ if (ExecQual((List *) lfirst(qual),
scanstate->cstate.cs_ExprContext,
false))
break;
}
- if (iptr == numIndices) /* would not be returned by indices */
+ if (qual == NIL) /* would not be returned by indices */
slot->val = NULL;
/* Flag for the next call that no more tuples */
estate->es_evTupleNull[node->scan.scanrelid - 1] = true;
- return (slot);
+
+ return slot;
}
tuple = &(indexstate->iss_htup);
@@ -189,14 +192,14 @@ IndexNext(IndexScan *node)
{
bool prev_matches = false;
int prev_index;
+ List *qual;
- /* ----------------
+ /*
* store the scanned tuple in the scan tuple slot of
* the scan state. Eventually we will only do this and not
* return a tuple. Note: we pass 'false' because tuples
* returned by amgetnext are pointers onto disk pages and
* must not be pfree()'d.
- * ----------------
*/
ExecStoreTuple(tuple, /* tuple to store */
slot, /* slot to store in */
@@ -211,28 +214,29 @@ IndexNext(IndexScan *node)
ReleaseBuffer(buffer);
/*
- * We must check to see if the current tuple would have
- * been matched by an earlier index, so we don't double
- * report it. We do this by passing the tuple through
- * ExecQual and look for failure with all previous
- * qualifications.
+ * We must check to see if the current tuple was already
+ * matched by an earlier index, so we don't double-report it.
+ * We do this by passing the tuple through ExecQual and
+ * checking for failure with all previous qualifications.
*/
+ scanstate->cstate.cs_ExprContext->ecxt_scantuple = slot;
+ qual = node->indxqualorig;
for (prev_index = 0; prev_index < indexstate->iss_IndexPtr;
prev_index++)
{
- scanstate->cstate.cs_ExprContext->ecxt_scantuple = slot;
- if (ExecQual(nth(prev_index, node->indxqualorig),
+ if (ExecQual((List *) lfirst(qual),
scanstate->cstate.cs_ExprContext,
false))
{
prev_matches = true;
break;
}
+ qual = lnext(qual);
}
if (!prev_matches)
- return slot;
- else
- ExecClearTuple(slot);
+ return slot; /* OK to return tuple */
+ /* Duplicate tuple, so drop it and loop back for another */
+ ExecClearTuple(slot);
}
}
if (indexNumber < numIndices)
@@ -329,7 +333,6 @@ ExecIndexReScan(IndexScan *node, ExprContext *exprCtxt, Plan *parent)
scanDescs = indexstate->iss_ScanDescs;
scanKeys = indexstate->iss_ScanKeys;
runtimeKeyInfo = (Pointer *) indexstate->iss_RuntimeKeyInfo;
- indxqual = node->indxqual;
numScanKeys = indexstate->iss_NumScanKeys;
indexstate->iss_IndexPtr = -1;
if (ScanDirectionIsBackward(node->indxorderdir))
@@ -352,9 +355,11 @@ ExecIndexReScan(IndexScan *node, ExprContext *exprCtxt, Plan *parent)
/*
* get the index qualifications and recalculate the appropriate values
*/
+ indxqual = node->indxqual;
for (i = 0; i < numIndices; i++)
{
- qual = nth(i, indxqual);
+ qual = lfirst(indxqual);
+ indxqual = lnext(indxqual);
n_keys = numScanKeys[i];
scan_keys = (ScanKey) scanKeys[i];
@@ -672,7 +677,6 @@ ExecInitIndexScan(IndexScan *node, EState *estate, Plan *parent)
* ----------------
*/
indxid = node->indxid;
- indxqual = node->indxqual;
numIndices = length(indxid);
indexPtr = -1;
@@ -701,6 +705,7 @@ ExecInitIndexScan(IndexScan *node, EState *estate, Plan *parent)
* build the index scan keys from the index qualification
* ----------------
*/
+ indxqual = node->indxqual;
for (i = 0; i < numIndices; i++)
{
int j;
@@ -709,7 +714,8 @@ ExecInitIndexScan(IndexScan *node, EState *estate, Plan *parent)
ScanKey scan_keys;
int *run_keys;
- qual = nth(i, indxqual);
+ qual = lfirst(indxqual);
+ indxqual = lnext(indxqual);
n_keys = length(qual);
scan_keys = (n_keys <= 0) ? NULL :
(ScanKey) palloc(n_keys * sizeof(ScanKeyData));
@@ -743,8 +749,8 @@ ExecInitIndexScan(IndexScan *node, EState *estate, Plan *parent)
clause = nth(j, qual);
op = (Oper *) clause->oper;
- if (!IsA(op, Oper))
- elog(ERROR, "ExecInitIndexScan: op not an Oper!");
+ if (!IsA(clause, Expr) || !IsA(op, Oper))
+ elog(ERROR, "ExecInitIndexScan: indxqual not an opclause!");
opid = op->opid;
@@ -1066,9 +1072,7 @@ ExecInitIndexScan(IndexScan *node, EState *estate, Plan *parent)
*/
for (i = 0; i < numIndices; i++)
{
- Oid indexOid;
-
- indexOid = (Oid) nthi(i, indxid);
+ Oid indexOid = (Oid) nthi(i, indxid);
if (indexOid != 0)
{
--
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