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> > Prevent sorting if result is already sorted

Browse Source 
> >
> > 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
This commit is contained in:
Bruce Momjian 1999-08-09 06:20:27 +00:00
parent 5efe31214a
commit 158fd5f1c4
9 changed files with 78 additions and 28 deletions
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4
src/backend/commands/explain.c
View File

@ -4,7 +4,7 @@
*
* Copyright (c) 1994-5, Regents of the University of California
*
* $Id: explain.c,v 1.43 1999/07/17 20:16:52 momjian Exp $
* $Id: explain.c,v 1.44 1999/08/09 06:20:21 momjian Exp $
*
*/
@ -200,6 +200,8 @@ explain_outNode(StringInfo str, Plan *plan, int indent, ExplainState *es)
switch (nodeTag(plan))
{
case T_IndexScan:
if (ScanDirectionIsBackward(((IndexScan *)plan)->indxorderdir))
appendStringInfo(str, " Backward");
appendStringInfo(str, " using ");
i = 0;
foreach(l, ((IndexScan *) plan)->indxid)

13
src/backend/executor/nodeIndexscan.c
View File

@ -7,7 +7,7 @@
*
*
* IDENTIFICATION
* $Header: /cvsroot/pgsql/src/backend/executor/nodeIndexscan.c,v 1.40 1999/07/16 04:58:50 momjian Exp $
* $Header: /cvsroot/pgsql/src/backend/executor/nodeIndexscan.c,v 1.41 1999/08/09 06:20:22 momjian Exp $
*
*-------------------------------------------------------------------------
*/
@ -99,6 +99,13 @@ IndexNext(IndexScan *node)
*/
estate = node->scan.plan.state;
direction = estate->es_direction;
if (ScanDirectionIsBackward(node->indxorderdir))
{
if (ScanDirectionIsForward(direction))
direction = BackwardScanDirection;
else if (ScanDirectionIsBackward(direction))
direction = ForwardScanDirection;
}
snapshot = estate->es_snapshot;
scanstate = node->scan.scanstate;
indexstate = node->indxstate;
@ -316,6 +323,8 @@ ExecIndexReScan(IndexScan *node, ExprContext *exprCtxt, Plan *parent)
indxqual = node->indxqual;
numScanKeys = indexstate->iss_NumScanKeys;
indexstate->iss_IndexPtr = -1;
if (ScanDirectionIsBackward(node->indxorderdir))
indexstate->iss_IndexPtr = numIndices;
/* If this is re-scanning of PlanQual ... */
if (estate->es_evTuple != NULL &&
@ -966,6 +975,8 @@ ExecInitIndexScan(IndexScan *node, EState *estate, Plan *parent)
}
indexstate->iss_NumIndices = numIndices;
if (ScanDirectionIsBackward(node->indxorderdir))
indexPtr = numIndices;
indexstate->iss_IndexPtr = indexPtr;
indexstate->iss_ScanKeys = scanKeys;
indexstate->iss_NumScanKeys = numScanKeys;

3
src/backend/nodes/copyfuncs.c
View File

@ -7,7 +7,7 @@
*
*
* IDENTIFICATION
* $Header: /cvsroot/pgsql/src/backend/nodes/copyfuncs.c,v 1.89 1999/07/27 03:51:07 tgl Exp $
* $Header: /cvsroot/pgsql/src/backend/nodes/copyfuncs.c,v 1.90 1999/08/09 06:20:23 momjian Exp $
*
*-------------------------------------------------------------------------
*/
@ -238,6 +238,7 @@ _copyIndexScan(IndexScan *from)
newnode->indxid = listCopy(from->indxid);
Node_Copy(from, newnode, indxqual);
Node_Copy(from, newnode, indxqualorig);
newnode->indxorderdir = from->indxorderdir;
return newnode;
}

5
src/backend/nodes/equalfuncs.c
View File

@ -7,7 +7,7 @@
*
*
* IDENTIFICATION
* $Header: /cvsroot/pgsql/src/backend/nodes/equalfuncs.c,v 1.45 1999/07/29 02:45:36 tgl Exp $
* $Header: /cvsroot/pgsql/src/backend/nodes/equalfuncs.c,v 1.46 1999/08/09 06:20:24 momjian Exp $
*
*-------------------------------------------------------------------------
*/
@ -437,6 +437,9 @@ _equalIndexScan(IndexScan *a, IndexScan *b)
if (a->scan.scanrelid != b->scan.scanrelid)
return false;
if (a->indxorderdir != b->indxorderdir)
return false;
if (!equali(a->indxid, b->indxid))
return false;
return true;

3
src/backend/nodes/outfuncs.c
View File

@ -5,7 +5,7 @@
*
* Copyright (c) 1994, Regents of the University of California
*
* $Id: outfuncs.c,v 1.91 1999/07/24 23:21:07 tgl Exp $
* $Id: outfuncs.c,v 1.92 1999/08/09 06:20:24 momjian Exp $
*
* NOTES
* Every (plan) node in POSTGRES has an associated "out" routine which
@ -445,6 +445,7 @@ _outIndexScan(StringInfo str, IndexScan *node)
appendStringInfo(str, " :indxqualorig ");
_outNode(str, node->indxqualorig);
appendStringInfo(str, " :indxorderdir %d ", node->indxorderdir);
}
/*

7
src/backend/nodes/readfuncs.c
View File

@ -7,7 +7,7 @@
*
*
* IDENTIFICATION
* $Header: /cvsroot/pgsql/src/backend/nodes/readfuncs.c,v 1.70 1999/07/24 23:21:08 tgl Exp $
* $Header: /cvsroot/pgsql/src/backend/nodes/readfuncs.c,v 1.71 1999/08/09 06:20:24 momjian Exp $
*
* NOTES
* Most of the read functions for plan nodes are tested. (In fact, they
@ -532,6 +532,11 @@ _readIndexScan()
token = lsptok(NULL, &length); /* eat :indxqualorig */
local_node->indxqualorig = nodeRead(true); /* now read it */
token = lsptok(NULL, &length); /* eat :indxorderdir */
token = lsptok(NULL, &length); /* get indxorderdir */
local_node->indxorderdir = atoi(token);
return local_node;
}

3
src/backend/optimizer/plan/createplan.c
View File

@ -7,7 +7,7 @@
*
*
* IDENTIFICATION
* $Header: /cvsroot/pgsql/src/backend/optimizer/plan/createplan.c,v 1.67 1999/08/09 01:01:42 tgl Exp $
* $Header: /cvsroot/pgsql/src/backend/optimizer/plan/createplan.c,v 1.68 1999/08/09 06:20:26 momjian Exp $
*
*-------------------------------------------------------------------------
*/
@ -1024,6 +1024,7 @@ make_indexscan(List *qptlist,
node->indxid = indxid;
node->indxqual = indxqual;
node->indxqualorig = indxqualorig;
node->indxorderdir = NoMovementScanDirection;
node->scan.scanstate = (CommonScanState *) NULL;
return node;

65
src/backend/optimizer/plan/planner.c
View File

@ -7,7 +7,7 @@
*
*
* IDENTIFICATION
* $Header: /cvsroot/pgsql/src/backend/optimizer/plan/planner.c,v 1.61 1999/07/17 20:17:15 momjian Exp $
* $Header: /cvsroot/pgsql/src/backend/optimizer/plan/planner.c,v 1.62 1999/08/09 06:20:26 momjian Exp $
*
*-------------------------------------------------------------------------
*/
@ -39,7 +39,7 @@ static List *make_subplanTargetList(Query *parse, List *tlist,
static Plan *make_groupplan(List *group_tlist, bool tuplePerGroup,
List *groupClause, AttrNumber *grpColIdx,
Plan *subplan);
static bool need_sortplan(List *sortcls, Plan *plan);
static ScanDirection get_dir_to_omit_sortplan(List *sortcls, Plan *plan);
static Plan *make_sortplan(List *tlist, List *sortcls, Plan *plannode);
/*****************************************************************************
@ -303,8 +303,17 @@ union_planner(Query *parse)
}
else
{
if (parse->sortClause && need_sortplan(parse->sortClause, result_plan))
return (make_sortplan(tlist, parse->sortClause, result_plan));
if (parse->sortClause)
{
ScanDirection dir = get_dir_to_omit_sortplan(parse->sortClause, result_plan);
if (ScanDirectionIsNoMovement(dir))
return (make_sortplan(tlist, parse->sortClause, result_plan));
else
{
((IndexScan *)result_plan)->indxorderdir = dir;
return ((Plan *) result_plan);
}
}
else
return ((Plan *) result_plan);
}
@ -822,7 +831,7 @@ pg_checkretval(Oid rettype, List *queryTreeList)
/* ----------
* Support function for need_sortplan
* Support function for get scan direction to omit sortplan
* ----------
*/
static TargetEntry *
@ -845,11 +854,13 @@ get_matching_tle(Plan *plan, Resdom *resdom)
* Check if a user requested ORDER BY is already satisfied by
* the choosen index scan.
*
* Returns TRUE if sort is required, FALSE if can be omitted.
* Returns the direction of Index scan to omit sort,
* if sort is required returns NoMovementScanDirection
*
* ----------
*/
static bool
need_sortplan(List *sortcls, Plan *plan)
static ScanDirection
get_dir_to_omit_sortplan(List *sortcls, Plan *plan)
{
Relation indexRel;
IndexScan *indexScan;
@ -858,13 +869,15 @@ need_sortplan(List *sortcls, Plan *plan)
HeapTuple htup;
Form_pg_index index_tup;
int key_no = 0;
ScanDirection dir, nodir = NoMovementScanDirection;
dir = nodir;
/* ----------
* Must be an IndexScan
* ----------
*/
if (nodeTag(plan) != T_IndexScan)
return TRUE;
return nodir;
indexScan = (IndexScan *) plan;
@ -873,16 +886,16 @@ need_sortplan(List *sortcls, Plan *plan)
* ----------
*/
if (plan->lefttree != NULL)
return TRUE;
return nodir;
if (plan->righttree != NULL)
return TRUE;
return nodir;
/* ----------
* Must be a single index scan
* ----------
*/
if (length(indexScan->indxid) != 1)
return TRUE;
return nodir;
/* ----------
* Indices can only have up to 8 attributes. So an ORDER BY using
@ -890,7 +903,7 @@ need_sortplan(List *sortcls, Plan *plan)
* ----------
*/
if (length(sortcls) > 8)
return TRUE;
return nodir;
/* ----------
* The choosen Index must be a btree
@ -902,7 +915,7 @@ need_sortplan(List *sortcls, Plan *plan)
if (strcmp(nameout(&(indexRel->rd_am->amname)), "btree") != 0)
{
heap_close(indexRel);
return TRUE;
return nodir;
}
heap_close(indexRel);
@ -937,7 +950,7 @@ need_sortplan(List *sortcls, Plan *plan)
* Could this happen?
* ----------
*/
return TRUE;
return nodir;
}
if (nodeTag(tle->expr) != T_Var)
{
@ -946,7 +959,7 @@ need_sortplan(List *sortcls, Plan *plan)
* cannot be the indexed attribute
* ----------
*/
return TRUE;
return nodir;
}
var = (Var *) (tle->expr);
@ -957,7 +970,7 @@ need_sortplan(List *sortcls, Plan *plan)
* that of the index
* ----------
*/
return TRUE;
return nodir;
}
if (var->varattno != index_tup->indkey[key_no])
@ -966,7 +979,7 @@ need_sortplan(List *sortcls, Plan *plan)
* It isn't the indexed attribute.
* ----------
*/
return TRUE;
return nodir;
}
if (oprid(oper("<", resdom->restype, resdom->restype, FALSE)) != sortcl->opoid)
@ -975,7 +988,19 @@ need_sortplan(List *sortcls, Plan *plan)
* Sort order isn't in ascending order.
* ----------
*/
return TRUE;
if (ScanDirectionIsForward(dir))
return nodir;
dir = BackwardScanDirection;
}
else
{
/* ----------
* Sort order is in ascending order.
* ----------
*/
if (ScanDirectionIsBackward(dir))
return nodir;
dir = ForwardScanDirection;
}
key_no++;
@ -985,5 +1010,5 @@ need_sortplan(List *sortcls, Plan *plan)
* Index matches ORDER BY - sort not required
* ----------
*/
return FALSE;
return dir;
}

3
src/include/nodes/plannodes.h
View File

@ -6,7 +6,7 @@
*
* Copyright (c) 1994, Regents of the University of California
*
* $Id: plannodes.h,v 1.28 1999/07/15 23:03:55 momjian Exp $
* $Id: plannodes.h,v 1.29 1999/08/09 06:20:27 momjian Exp $
*
*-------------------------------------------------------------------------
*/
@ -175,6 +175,7 @@ typedef struct IndexScan
List *indxid;
List *indxqual;
List *indxqualorig;
ScanDirection indxorderdir;
IndexScanState *indxstate;
} IndexScan;