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From: David Hartwig <daybee@bellatlantic.net> 

I put some extra checks to make sure a query was a good candidate for
rewrite into a UNION.    Besides the existing checks:

1.  Make sure the AND/OR tree was rectangular.  ( i.e.    3 X 4  or 10 X
3)
2.  Only one table.
3.  Must have an AND dimension.
4.  At least 9 OP expressions total

Also  cleaned up and commented.
This commit is contained in:
Marc G. Fournier 1998-09-04 12:52:23 +00:00
parent e9d0fa3762
commit 370d6cdb64
1 changed files with 54 additions and 54 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

108
src/backend/optimizer/prep/prepkeyset.c
View File

@ -11,35 +11,20 @@
#include <string.h>
#include "postgres.h"
#include "nodes/pg_list.h"
#include "nodes/parsenodes.h"
#include "utils/elog.h"
#include "nodes/nodes.h"
#include "nodes/execnodes.h"
#include "nodes/plannodes.h"
#include "nodes/primnodes.h"
#include "nodes/relation.h"
#include "catalog/pg_type.h"
#include "lib/stringinfo.h"
#include "optimizer/planmain.h"
/*
* Node_Copy--
* a macro to simplify calling of copyObject on the specified field
*/
#define Node_Copy(from, newnode, field) newnode->field = copyObject(from->field)
/***** DEBUG stuff
#define TABS {int i; printf("\n"); for (i = 0; i<level; i++) printf("\t"); }
static int level = 0;
******/
bool _use_keyset_query_optimizer = FALSE;
static int inspectOpNode(Expr *expr);
static int inspectAndNode(Expr *expr);
static int inspectOrNode(Expr *expr);
static int TotalExpr;
/**********************************************************************
* This routine transforms query trees with the following form:
@ -73,8 +58,7 @@ static int inspectOrNode(Expr *expr);
*
* daveh@insightdist.com 1998-08-31
*
* Needs to better identify the signeture WHERE clause.
* May want to also prune out duplicate where clauses.
* May want to also prune out duplicate terms.
**********************************************************************/
void
transformKeySetQuery(Query *origNode)
@ -92,18 +76,20 @@ transformKeySetQuery(Query *origNode)
return;
/* Qualify single table query */
if (length(origNode->rtable) != 1)
return;
/* Sorry about the global, not worth passing around */
/* 9 expressions seems like a good number. More than 9 */
/* and it starts to slow down quite a bit */
TotalExpr = 0;
/*************************/
/* Qualify where clause */
if ( ! inspectOrNode((Expr*)origNode->qual)) {
/*************************/
if ( ! inspectOrNode((Expr*)origNode->qual) || TotalExpr < 9)
return;
}
/* Copy essential elements into a union node */
/*
elog(NOTICE, "OR_EXPR=%d, OP_EXPR=%d, AND_EXPR=%d", OR_EXPR, OP_EXPR, AND_EXPR);
elog(NOTICE, "T_List=%d, T_Expr=%d, T_Var=%d, T_Const=%d", T_List, T_Expr, T_Var, T_Const);
elog(NOTICE, "opType=%d", ((Expr*)origNode->qual)->opType);
*/
while (((Expr*)origNode->qual)->opType == OR_EXPR) {
Query *unionNode = makeNode(Query);
@ -113,11 +99,6 @@ transformKeySetQuery(Query *origNode)
/* Pull up balance of tree */
origNode->qual = lfirst(((Expr*)origNode->qual)->args);
/*
elog(NOTICE, "origNode: opType=%d, nodeTag=%d", ((Expr*)origNode->qual)->opType, nodeTag(origNode->qual));
elog(NOTICE, "unionNode: opType=%d, nodeTag=%d", ((Expr*)unionNode->qual)->opType, nodeTag(unionNode->qual));
*/
unionNode->commandType = origNode->commandType;
unionNode->resultRelation = origNode->resultRelation;
unionNode->isPortal = origNode->isPortal;
@ -139,9 +120,14 @@ transformKeySetQuery(Query *origNode)
static int
/**********************************************************************
* Checks for 1 or more OR terms w/ 1 or more AND terms.
* AND terms must be equal in size.
* Returns the number of each AND term.
**********************************************************************/
inspectOrNode(Expr *expr)
{
int fr = 0, sr = 0;
int rc;
Expr *firstExpr, *secondExpr;
if ( ! (expr && nodeTag(expr) == T_Expr && expr->opType == OR_EXPR))
@ -152,27 +138,35 @@ inspectOrNode(Expr *expr)
if (nodeTag(firstExpr) != T_Expr || nodeTag(secondExpr) != T_Expr)
return 0;
if (firstExpr->opType == OR_EXPR)
fr = inspectOrNode(firstExpr);
else if (firstExpr->opType == OP_EXPR) /* Need to make sure it is last */
fr = inspectOpNode(firstExpr);
else if (firstExpr->opType == AND_EXPR) /* Need to make sure it is last */
fr = inspectAndNode(firstExpr);
if (firstExpr->opType == OR_EXPR && secondExpr->opType == AND_EXPR)
{
if ((rc = inspectOrNode(firstExpr)) == 0)
return 0;
if (secondExpr->opType == AND_EXPR)
sr = inspectAndNode(secondExpr);
else if (secondExpr->opType == OP_EXPR)
sr = inspectOpNode(secondExpr);
return (rc == inspectAndNode(secondExpr)) ? rc : 0;
}
else if (firstExpr->opType == AND_EXPR && secondExpr->opType == AND_EXPR)
{
if ((rc = inspectAndNode(firstExpr)) == 0)
return 0;
return (fr && sr);
return (rc == inspectAndNode(secondExpr)) ? rc : 0;
}
return 0;
}
static int
/**********************************************************************
* Check for one or more AND terms. Each sub-term must be a T_Const
* T_Var expression.
* Returns the number of AND terms.
**********************************************************************/
inspectAndNode(Expr *expr)
{
int fr = 0, sr = 0;
int rc;
Expr *firstExpr, *secondExpr;
if ( ! (expr && nodeTag(expr) == T_Expr && expr->opType == AND_EXPR))
@ -183,15 +177,19 @@ inspectAndNode(Expr *expr)
if (nodeTag(firstExpr) != T_Expr || nodeTag(secondExpr) != T_Expr)
return 0;
if (firstExpr->opType == AND_EXPR)
fr = inspectAndNode(firstExpr);
else if (firstExpr->opType == OP_EXPR)
fr = inspectOpNode(firstExpr);
if (firstExpr->opType == AND_EXPR &&
secondExpr->opType == OP_EXPR && inspectOpNode(secondExpr))
{
rc = inspectAndNode(firstExpr);
return ((rc) ? (rc + 1) : 0); /* Add up the AND nodes */
}
else if (firstExpr->opType == OP_EXPR && inspectOpNode(firstExpr) &&
secondExpr->opType == OP_EXPR && inspectOpNode(secondExpr))
{
return 1;
}
if (secondExpr->opType == OP_EXPR)
sr = inspectOpNode(secondExpr);
return (fr && sr);
return 0;
}
@ -205,7 +203,9 @@ inspectOpNode(Expr *expr)
Expr *firstExpr, *secondExpr;
if (nodeTag(expr) != T_Expr || expr->opType != OP_EXPR)
return 0;
return FALSE;
TotalExpr++;
firstExpr = lfirst(expr->args);
secondExpr = lsecond(expr->args);