8000 Teach nodeSort and nodeMaterial to optimize out unnecessary overhead · postgrespro/postgres_cluster@d2c555e · GitHub
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Teach nodeSort and nodeMaterial to optimize out unnecessary overhead
when the passed-down eflags indicate they can. Simon Riggs and Tom Lane
1 parent 2c0ef97 commit d2c555e

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3 files changed

+80
-31
lines changed

3 files changed

+80
-31
lines changed
10000

‎src/backend/executor/nodeMaterial.c

Lines changed: 57 additions & 26 deletions
Original file line numberDiff line numberDiff line change
@@ -8,7 +8,7 @@
88
*
99
*
1010
* IDENTIFICATION
11-
* $PostgreSQL: pgsql/src/backend/executor/nodeMaterial.c,v 1.52 2006/02/28 04:10:27 tgl Exp $
11+
* $PostgreSQL: pgsql/src/backend/executor/nodeMaterial.c,v 1.53 2006/02/28 05:48:44 tgl Exp $
1212
*
1313
*-------------------------------------------------------------------------
1414
*/
@@ -58,9 +58,9 @@ ExecMaterial(MaterialState *node)
5858
tuplestorestate = (Tuplestorestate *) node->tuplestorestate;
5959

6060
/*
61-
* If first time through, initialize the tuplestore.
61+
* If first time through, and we need a tuplestore, initialize it.
6262
*/
63-
if (tuplestorestate == NULL)
63+
if (tuplestorestate == NULL && node->randomAccess)
6464
{
6565
tuplestorestate = tuplestore_begin_heap(true, false, work_mem);
6666

@@ -71,7 +71,8 @@ ExecMaterial(MaterialState *node)
7171
* If we are not at the end of the tuplestore, or are going backwards, try
7272
* to fetch a tuple from tuplestore.
7373
*/
74-
eof_tuplestore = tuplestore_ateof(tuplestorestate);
74+
eof_tuplestore = (tuplestorestate == NULL) ||
75+
tuplestore_ateof(tuplestorestate);
7576

7677
if (!forward && eof_tuplestore)
7778
{
@@ -135,7 +136,8 @@ ExecMaterial(MaterialState *node)
135136
* tuplestore is certainly in EOF state, its read position will move
136137
* forward over the added tuple. This is what we want.
137138
*/
138-
tuplestore_puttuple(tuplestorestate, (void *) heapTuple);
139+
if (tuplestorestate)
140+
tuplestore_puttuple(tuplestorestate, (void *) heapTuple);
139141
}
140142

141143
/*
@@ -165,8 +167,18 @@ ExecInitMaterial(Material *node, EState *estate, int eflags)
165167
matstate->ss.ps.plan = (Plan *) node;
166168
matstate->ss.ps.state = estate;
167169

168-
matstate->tuplestorestate = NULL;
170+
/*
171+
* We must have random access to the subplan output to do backward scan
172+
* or mark/restore. We also prefer to materialize the subplan output
173+
* if we might be called on to rewind and replay it many times.
174+
* However, if none of these cases apply, we can skip storing the data.
175+
*/
176+
matstate->randomAccess = (eflags & (EXEC_FLAG_REWIND |
177+
EXEC_FLAG_BACKWARD |
178+
EXEC_FLAG_MARK)) != 0;
179+
169180
matstate->eof_underlying = false;
181+
matstate->tuplestorestate = NULL;
170182

171183
/*
172184
* Miscellaneous initialization
@@ -249,6 +261,8 @@ ExecEndMaterial(MaterialState *node)
249261
void
250262
ExecMaterialMarkPos(MaterialState *node)
251263
{
264+
Assert(node->randomAccess);
265+
252266
/*
253267
* if we haven't materialized yet, just return.
254268
*/
@@ -267,6 +281,8 @@ ExecMaterialMarkPos(MaterialState *node)
267281
void
268282
ExecMaterialRestrPos(MaterialState *node)
269283
{
284+
Assert(node->randomAccess);
285+
270286
/*
271287
* if we haven't materialized yet, just return.
272288
*/
@@ -288,29 +304,44 @@ ExecMaterialRestrPos(MaterialState *node)
288304
void
289305
ExecMaterialReScan(MaterialState *node, ExprContext *exprCtxt)
290306
{
291-
/*
292-
* If we haven't materialized yet, just return. If outerplan' chgParam is
293-
* not NULL then it will be re-scanned by ExecProcNode, else - no reason
294-
* to re-scan it at all.
295-
*/
296-
if (!node->tuplestorestate)
297-
return;
298-
299307
ExecClearTuple(node->ss.ps.ps_ResultTupleSlot);
300308

301-
/*
302-
* If subnode is to be rescanned then we forget previous stored results;
303-
* we have to re-read the subplan and re-store.
304-
*
305-
* Otherwise we can just rewind and rescan the stored output. The state of
306-
* the subnode does not change.
307-
*/
308-
if (((PlanState *) node)->lefttree->chgParam != NULL)
309+
if (node->randomAccess)
309310
{
310-
tuplestore_end((Tuplestorestate *) node->tuplestorestate);
311-
node->tuplestorestate = NULL;
312-
node->eof_underlying = false;
311+
/*
312+
* If we haven't materialized yet, just return. If outerplan' chgParam
313+
* is not NULL then it will be re-scanned by ExecProcNode, else - no
314+
* reason to re-scan it at all.
315+
*/
316+
if (!node->tuplestorestate)
317+
return;
318+
319+
/*
320+
* If subnode is to be rescanned then we forget previous stored
321+
* results; we have to re-read the subplan and re-store.
322+
*
323+
* Otherwise we can just rewind and rescan the stored output. The
324+
* state of the subnode does not change.
325+
*/
326+
if (((PlanState *) node)->lefttree->chgParam != NULL)
327+
{
328+
tuplestore_end((Tuplestorestate *) node->tuplestorestate);
329+
node->tuplestorestate = NULL;
330+
node->eof_underlying = false;
331+
}
332+
else
333+
tuplestore_rescan((Tuplestorestate *) node->tuplestorestate);
313334
}
314335
else
315-
tuplestore_rescan((Tuplestorestate *) node->tuplestorestate);
336+
{
337+
/* In this case we are just passing on the subquery's output */
338+
339+
/*
340+
* if chgParam of subnode is not null then plan will be re-scanned by
341+
* first ExecProcNode.
342+
*/
343+
if (((PlanState *) node)->lefttree->chgParam == NULL)
344+
ExecReScan(((PlanState *) node)->lefttree, exprCtxt);
345+
node->eof_underlying = false;
346+
}
316347
}

‎src/backend/executor/nodeSort.c

Lines changed: 19 additions & 3 deletions
Original file line numberDiff line numberDiff line change
@@ -8,7 +8,7 @@
88
*
99
*
1010
* IDENTIFICATION
11-
* $PostgreSQL: pgsql/src/backend/executor/nodeSort.c,v 1.54 2006/02/28 04:10:27 tgl Exp $
11+
* $PostgreSQL: pgsql/src/backend/executor/nodeSort.c,v 1.55 2006/02/28 05:48:44 tgl Exp $
1212
*
1313
*-------------------------------------------------------------------------
1414
*/
@@ -89,7 +89,7 @@ ExecSort(SortState *node)
8989
plannode->sortOperators,
9090
plannode->sortColIdx,
9191
work_mem,
92-
true /* randomAccess */ );
92+
node->randomAccess);
9393
node->tuplesortstate = (void *) tuplesortstate;
9494

9595
/*
@@ -164,6 +164,15 @@ ExecInitSort(Sort *node, EState *estate, int eflags)
164164
sortstate->ss.ps.plan = (Plan *) node;
165165
sortstate->ss.ps.state = estate;
166166

167+
/*
168+
* We must have random access to the sort output to do backward scan
169+
* or mark/restore. We also prefer to materialize the sort output
170+
* if we might be called on to rewind and replay it many times.
171+
*/
172+
sortstate->randomAccess = (eflags & (EXEC_FLAG_REWIND |
173+
EXEC_FLAG_BACKWARD |
174+
EXEC_FLAG_MARK)) != 0;
175+
167176
sortstate->sort_Done = false;
168177
sortstate->tuplesortstate = NULL;
169178

@@ -308,11 +317,18 @@ ExecReScanSort(SortState *node, ExprContext *exprCtxt)
308317
*
309318
* Otherwise we can just rewind and rescan the sorted output.
310319
*/
311-
if (((PlanState *) node)->lefttree->chgParam != NULL)
320+
if (((PlanState *) node)->lefttree->chgParam != NULL ||
321+
!node->randomAccess)
312322
{
313323
node->sort_Done = false;
314324
tuplesort_end((Tuplesortstate *) node->tuplesortstate);
315325
node->tuplesortstate = NULL;
326+
/*
327+
* if chgParam of subnode is not null then plan will be re-scanned by
328+
* first ExecProcNode.
329+
*/
330+
if (((PlanState *) node)->lefttree->chgParam == NULL)
331+
ExecReScan(((PlanState *) node)->lefttree, exprCtxt);
316332
}
317333
else
318334
tuplesort_rescan((Tuplesortstate *) node->tuplesortstate);

‎src/include/nodes/execnodes.h

Lines changed: 4 additions & 2 deletions
Original file line numberDiff line numberDiff line change
@@ -7,7 +7,7 @@
77
* Portions Copyright (c) 1996-2005, PostgreSQL Global Development Group
88
* Portions Copyright (c) 1994, Regents of the University of California
99
*
10-
* $PostgreSQL: pgsql/src/include/nodes/execnodes.h,v 1.147 2005/12/28 01:30:01 tgl Exp $
10+
* $PostgreSQL: pgsql/src/include/nodes/execnodes.h,v 1.148 2006/02/28 05:48:44 tgl Exp $
1111
*
1212
*-------------------------------------------------------------------------
1313
*/
@@ -1185,8 +1185,9 @@ typedef struct HashJoinState
11851185
typedef struct MaterialState
11861186
{
11871187
ScanState ss; /* its first field is NodeTag */
1188-
void *tuplestorestate; /* private state of tuplestore.c */
1188+
bool randomAccess; /* need random access to subplan output? */
11891189
bool eof_underlying; /* reached end of underlying plan? */
1190+
void *tuplestorestate; /* private state of tuplestore.c */
11901191
} MaterialState;
11911192

11921193
/* ----------------
@@ -1196,6 +1197,7 @@ typedef struct MaterialState
11961197
typedef struct SortState
11971198
{
11981199
ScanState ss; /* its first field is NodeTag */
1200+
bool randomAccess; /* need random access to sort output? */
11991201
bool sort_Done; /* sort completed yet? */
12001202
void *tuplesortstate; /* private state of tuplesort.c */
12011203
} SortState;

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