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> > Prevent sorting if result is already sorted
> > > > was implemented by Jan Wieck. > > His work is for ascending order cases. > > > > Here is a patch to prevent sorting also in descending > > order cases. > > Because I had already changed _bt_first() to position > > backward correctly before v6.5,this patch would work. > > Hiroshi Inoue Inoue@tpf.co.jp
1 parent 5efe312 commit 158fd5f

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9 files changed

+78
-28
lines changed

9 files changed

+78
-28
lines changed

‎src/backend/commands/explain.c

Lines changed: 3 additions & 1 deletion
Original file line numberDiff line numberDiff line change
@@ -4,7 +4,7 @@
44
*
55
* Copyright (c) 1994-5, Regents of the University of California
66
*
7-
* $Id: explain.c,v 1.43 1999/07/17 20:16:52 momjian Exp $
7+
* $Id: explain.c,v 1.44 1999/08/09 06:20:21 momjian Exp $
88
*
99
*/
1010

@@ -200,6 +200,8 @@ explain_outNode(StringInfo str, Plan *plan, int indent, ExplainState *es)
200200
switch (nodeTag(plan))
201201
{
202202
case T_IndexScan:
203+
if (ScanDirectionIsBackward(((IndexScan *)plan)->indxorderdir))
204+
appendStringInfo(str, " Backward");
203205
appendStringInfo(str, " using ");
204206
i = 0;
205207
foreach(l, ((IndexScan *) plan)->indxid)

‎src/backend/executor/nodeIndexscan.c

Lines changed: 12 additions & 1 deletion
Original file line numberDiff line numberDiff line change
@@ -7,7 +7,7 @@
77
*
88
*
99
* IDENTIFICATION
10-
* $Header: /cvsroot/pgsql/src/backend/executor/nodeIndexscan.c,v 1.40 1999/07/16 04:58:50 momjian Exp $
10+
* $Header: /cvsroot/pgsql/src/backend/executor/nodeIndexscan.c,v 1.41 1999/08/09 06:20:22 momjian Exp $
1111
*
1212
*-------------------------------------------------------------------------
1313
*/
@@ -99,6 +99,13 @@ IndexNext(IndexScan *node)
9999
*/
100100
estate = node->scan.plan.state;
101101
direction = estate->es_direction;
102+
if (ScanDirectionIsBackward(node->indxorderdir))
103+
{
104+
if (ScanDirectionIsForward(direction))
105+
direction = BackwardScanDirection;
106+
else if (ScanDirectionIsBackward(direction))
107+
direction = ForwardScanDirection;
108+
}
102109
snapshot = estate->es_snapshot;
103110
scanstate = node->scan.scanstate;
104111
indexstate = node->indxstate;
@@ -316,6 +323,8 @@ ExecIndexReScan(IndexScan *node, ExprContext *exprCtxt, Plan *parent)
316323
indxqual = node->indxqual;
317324
numScanKeys = indexstate->iss_NumScanKeys;
318325
indexstate->iss_IndexPtr = -1;
326+
if (ScanDirectionIsBackward(node->indxorderdir))
327+
indexstate->iss_IndexPtr = numIndices;
319328

320329
/* If this is re-scanning of PlanQual ... */
321330
if (estate->es_evTuple != NULL &&
@@ -966,6 +975,8 @@ ExecInitIndexScan(IndexScan *node, EState *estate, Plan *parent)
966975
}
967976

968977
indexstate->iss_NumIndices = numIndices;
978+
if (ScanDirectionIsBackward(node->indxorderdir))
979+
indexPtr = numIndices;
969980
indexstate->iss_IndexPtr = indexPtr;
970981
indexstate->iss_ScanKeys = scanKeys;
971982
indexstate->iss_NumScanKeys = numScanKeys;

‎src/backend/nodes/copyfuncs.c

Lines changed: 2 additions & 1 deletion
Original file line numberDiff line numberDiff line change
@@ -7,7 +7,7 @@
77
*
88
*
99
* IDENTIFICATION
10-
* $Header: /cvsroot/pgsql/src/backend/nodes/copyfuncs.c,v 1.89 1999/07/27 03:51:07 tgl Exp $
10+
* $Header: /cvsroot/pgsql/src/backend/nodes/copyfuncs.c,v 1.90 1999/08/09 06:20:23 momjian Exp $
1111
*
1212
*-------------------------------------------------------------------------
1313
*/
@@ -238,6 +238,7 @@ _copyIndexScan(IndexScan *from)
238238
newnode->indxid = listCopy(from->indxid);
239239
Node_Copy(from, newnode, indxqual);
240240
Node_Copy(from, newnode, indxqualorig);
241+
newnode->indxorderdir = from->indxorderdir;
241242

242243
return newnode;
243244
}

‎src/backend/nodes/equalfuncs.c

Lines changed: 4 additions & 1 deletion
Original file line numberDiff line numberDiff line change
@@ -7,7 +7,7 @@
77
*
88
*
99
* IDENTIFICATION
10-
* $Header: /cvsroot/pgsql/src/backend/nodes/equalfuncs.c,v 1.45 1999/07/29 02:45:36 tgl Exp $
10+
* $Header: /cvsroot/pgsql/src/backend/nodes/equalfuncs.c,v 1.46 1999/08/09 06:20:24 momjian Exp $
1111
*
1212
*-------------------------------------------------------------------------
1313
*/
@@ -437,6 +437,9 @@ _equalIndexScan(IndexScan *a, IndexScan *b)
437437
if (a->scan.scanrelid != b->scan.scanrelid)
438438
return false;
439439

440+
if (a->indxorderdir != b->indxorderdir)
441+
return false;
442+
440443
if (!equali(a->indxid, b->indxid))
441444
return false;
442445
return true;

‎src/backend/nodes/outfuncs.c

Lines changed: 2 additions & 1 deletion
Original file line numberDiff line numberDiff line change
@@ -5,7 +5,7 @@
55
*
66
* Copyright (c) 1994, Regents of the University of California
77
*
8-
* $Id: outfuncs.c,v 1.91 1999/07/24 23:21:07 tgl Exp $
8+
* $Id: outfuncs.c,v 1.92 1999/08/09 06:20:24 momjian Exp $
99
*
1010
* NOTES
1111
* Every (plan) node in POSTGRES has an associated "out" routine which
@@ -445,6 +445,7 @@ _outIndexScan(StringInfo str, IndexScan *node)
445445
appendStringInfo(str, " :indxqualorig ");
446446
_outNode(str, node->indxqualorig);
447447

448+
appendStringInfo(str, " :indxorderdir %d ", node->indxorderdir);
448449
}
449450

450451
/*

‎src/backend/nodes/readfuncs.c

Lines changed: 6 additions & 1 deletion
Original file line numberDiff line numberDiff line change
@@ -7,7 +7,7 @@
77
*
88
*
99
* IDENTIFICATION
10-
* $Header: /cvsroot/pgsql/src/backend/nodes/readfuncs.c,v 1.70 1999/07/24 23:21:08 tgl Exp $
10+
* $Header: /cvsroot/pgsql/src/backend/nodes/readfuncs.c,v 1.71 1999/08/09 06:20:24 momjian Exp $
1111
*
1212
* NOTES
1313
* Most of the read functions for plan nodes are tested. (In fact, they
@@ -532,6 +532,11 @@ _readIndexScan()
532532
token = lsptok(NULL, &length); /* eat :indxqualorig */
533533
local_node->indxqualorig = nodeRead(true); /* now read it */
534534

535+
token = lsptok(NULL, &length); /* eat :indxorderdir */
536+
token = lsptok(NULL, &length); /* get indxorderdir */
537+
538+
local_node->indxorderdir = atoi(token);
539+
535540
return local_node;
536541
}
537542

‎src/backend/optimizer/plan/createplan.c

Lines changed: 2 additions & 1 deletion
Original file line numberDiff line numberDiff line change
@@ -7,7 +7,7 @@
77
*
88
*
99
* IDENTIFICATION
10-
* $Header: /cvsroot/pgsql/src/backend/optimizer/plan/createplan.c,v 1.67 1999/08/09 01:01:42 tgl Exp $
10+
* $Header: /cvsroot/pgsql/src/backend/optimizer/plan/createplan.c,v 1.68 1999/08/09 06:20:26 momjian Exp $
1111
*
1212
*-------------------------------------------------------------------------
1313
*/
@@ -1024,6 +1024,7 @@ make_indexscan(List *qptlist,
10241024
node->indxid = indxid;
10251025
node->indxqual = indxqual;
10261026
node->indxqualorig = indxqualorig;
1027+
node->indxorderdir = NoMovementScanDirection;
10271028
node->scan.scanstate = (CommonScanState *) NULL;
10281029

10291030
return node;

‎src/backend/optimizer/plan/planner.c

Lines changed: 45 additions & 20 deletions
Original file line numberDiff line numberDiff line change
@@ -7,7 +7,7 @@
77
*
88
*
99
* IDENTIFICATION
10-
* $Header: /cvsroot/pgsql/src/backend/optimizer/plan/planner.c,v 1.61 1999/07/17 20:17:15 momjian Exp $
10+
* $Header: /cvsroot/pgsql/src/backend/optimizer/plan/planner.c,v 1.62 1999/08/09 06:20:26 momjian Exp $
1111
*
1212
*-------------------------------------------------------------------------
1313
*/
@@ -39,7 +39,7 @@ static List *make_subplanTargetList(Query *parse, List *tlist,
3939
static Plan *make_groupplan(List *group_tlist, bool tuplePerGroup,
4040
List *groupClause, AttrNumber *grpColIdx,
4141
Plan *subplan);
42-
static bool need_sortplan(List *sortcls, Plan *plan);
42+
static ScanDirection get_dir_to_omit_sortplan(List *sortcls, Plan *plan);
4343
static Plan *make_sortplan(List *tlist, List *sortcls, Plan *plannode);
4444

4545
/*****************************************************************************
@@ -303,8 +303,17 @@ union_planner(Query *parse)
303303
}
304304
else
305305
{
306-
if (parse->sortClause && need_sortplan(parse->sortClause, result_plan))
307-
return (make_sortplan(tlist, parse->sortClause, result_plan));
306+
if (parse->sortClause)
307+
{
308+
ScanDirection dir = get_dir_to_omit_sortplan(parse->sortClause, result_plan);
309+
if (ScanDirectionIsNoMovement(dir))
310+
return (make_sortplan(tlist, parse->sortClause, result_plan));
311+
else
312+
{
313+
((IndexScan *)result_plan)->indxorderdir = dir;
314+
return ((Plan *) result_plan);
315+
}
316+
}
308317
else
309318
return ((Plan *) result_plan);
310319
}
@@ -822,7 +831,7 @@ pg_checkretval(Oid rettype, List *queryTreeList)
822831

823832

824833
/* ----------
825-
* Support function for need_sortplan
834+
* Support function for get scan direction to omit sortplan
826835
* ----------
827836
*/
828837
static TargetEntry *
@@ -845,11 +854,13 @@ get_matching_tle(Plan *plan, Resdom *resdom)
845854
* Check if a user requested ORDER BY is already satisfied by
846855
* the choosen index scan.
847856
*
848-
* Returns TRUE if sort is required, FALSE if can be omitted.
857+
* Returns the direction of Index scan to omit sort,
858+
* if sort is required returns NoMovementScanDirection
859+
*
849860
* ----------
850861
*/
851-
static bool
852-
need_sortplan(List *sortcls, Plan *plan)
862+
static ScanDirection
863+
get_dir_to_omit_sortplan(List *sortcls, Plan *plan)
853864
{
854865
Relation indexRel;
855866
IndexScan *indexScan;
@@ -858,13 +869,15 @@ need_sortplan(List *sortcls, Plan *plan)
858869
HeapTuple htup;
859870
Form_pg_index index_tup;
860871
int key_no = 0;
872+
ScanDirection dir, nodir = NoMovementScanDirection;
861873

874+
dir = nodir;
862875
/* ----------
863876
* Must be an IndexScan
864877
* ----------
865878
*/
866879
if (nodeTag(plan) != T_IndexScan)
867-
return TRUE;
880+
return nodir;
868881

869882
indexScan = (IndexScan *) plan;
870883

@@ -873,24 +886,24 @@ need_sortplan(List *sortcls, Plan *plan)
873886
* ----------
874887
*/
875888
if (plan->lefttree != NULL)
876-
return TRUE;
889+
return nodir;
877890
if (plan->righttree != NULL)
878-
return TRUE;
891+
return nodir;
879892

880893
/* ----------
881894
* Must be a single index scan
882895
* ----------
883896
*/
884897
if (length(indexScan->indxid) != 1)
885-
return TRUE;
898+
return nodir;
886899

887900
/* ----------
888901
* Indices can only have up to 8 attributes. So an ORDER BY using
889902
* more that 8 attributes could never be satisfied by an index.
890903
* ----------
891904
*/
892905
if (length(sortcls) > 8)
893-
return TRUE;
906+
return nodir;
894907

895908
/* ----------
896909
* The choosen Index must be a btree
@@ -902,7 +915,7 @@ need_sortplan(List *sortcls, Plan *plan)
902915
if (strcmp(nameout(&(indexRel->rd_am->amname)), "btree") != 0)
903916
{
904917
heap_close(indexRel);
905-
return TRUE;
918+
return nodir;
906919
}
907920
heap_close(indexRel);
908921

@@ -937,7 +950,7 @@ need_sortplan(List *sortcls, Plan *plan)
937950
* Could this happen?
938951
* ----------
939952
*/
940-
return TRUE;
953+
return nodir;
941954
}
942955
if (nodeTag(tle->expr) != T_Var)
943956
{
@@ -946,7 +959,7 @@ need_sortplan(List *sortcls, Plan *plan)
946959
* cannot be the indexed attribute
947960
* ----------
948961
*/
949-
return TRUE;
962+
return nodir;
950963
}
951964
var = (Var *) (tle->expr);
952965

@@ -957,7 +970,7 @@ need_sortplan(List *sortcls, Plan *plan)
957970
* that of the index
958971
* ----------
959972
*/
960-
return TRUE;
973+
return nodir;
961974
}
962975

963976
if (var->varattno != index_tup->indkey[key_no])
@@ -966,7 +979,7 @@ need_sortplan(List *sortcls, Plan *plan)
966979
* It isn't the indexed attribute.
967980
* ----------
968981
*/
969-
return TRUE;
982+
return nodir;
970983
}
971984

972985
if (oprid(oper("<", resdom->restype, resdom->restype, FALSE)) != sortcl->opoid)
@@ -975,7 +988,19 @@ need_sortplan(List *sortcls, Plan *plan)
975988
* Sort order isn't in ascending order.
976989
* ----------
977990
*/
978-
return TRUE;
991+
if (ScanDirectionIsForward(dir))
992+
return nodir;
993+
dir = BackwardScanDirection;
994+
}
995+
else
996+
{
997+
/* ----------
998+
* Sort order is in ascending order.
999+
* ----------
1000+
*/
1001+
if (ScanDirectionIsBackward(dir))
1002+
return nodir;
1003+
dir = ForwardScanDirection;
9791004
}
9801005

9811006
key_no++;
@@ -985,5 +1010,5 @@ need_sortplan(List *sortcls, Plan *plan)
9851010
* Index matches ORDER BY - sort not required
9861011
* ----------
9871012
*/
988-
return FALSE;
1013+
return dir;
9891014
}

‎src/include/nodes/plannodes.h

Lines changed: 2 additions & 1 deletion
Original file line numberDiff line numberDiff line change
@@ -6,7 +6,7 @@
66
*
77
* Copyright (c) 1994, Regents of the University of California
88
*
9-
* $Id: plannodes.h,v 1.28 1999/07/15 23:03:55 momjian Exp $
9+
* $Id: plannodes.h,v 1.29 1999/08/09 06:20:27 momjian Exp $
1010
*
1111
*-------------------------------------------------------------------------
1212
*/
@@ -175,6 +175,7 @@ typedef struct IndexScan
175175
List *indxid;
176176
List *indxqual;
177177
List *indxqualorig;
178+
ScanDirection indxorderdir;
178179
IndexScanState *indxstate;
179180
} IndexScan;
180181

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