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Redesign DISTINCT ON as discussed in pgsql-sql 1/25/00: syntax is now

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SELECT DISTINCT ON (expr [, expr ...]) targetlist ...
and there is a check to make sure that the user didn't specify an ORDER BY
that's incompatible with the DISTINCT operation.
Reimplement nodeUnique and nodeGroup to use the proper datatype-specific
equality function for each column being compared --- they used to do
bitwise comparisons or convert the data to text strings and strcmp().
(To add insult to injury, they'd look up the conversion functions once
for each tuple...)  Parse/plan representation of DISTINCT is now a list
of SortClause nodes.
initdb forced by querytree change...
This commit is contained in:
Tom Lane
2000-01-27 18:11:50 +00:00
parent 3f0074e403
commit dd979f66be
32 changed files with 638 additions and 576 deletions
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4
src/backend/rewrite/rewriteDefine.c
View File

@ -8,7 +8,7 @@
*
*
* IDENTIFICATION
* $Header: /cvsroot/pgsql/src/backend/rewrite/rewriteDefine.c,v 1.41 2000/01/26 05:56:49 momjian Exp $
* $Header: /cvsroot/pgsql/src/backend/rewrite/rewriteDefine.c,v 1.42 2000/01/27 18:11:36 tgl Exp $
*
*-------------------------------------------------------------------------
*/
@ -312,7 +312,7 @@ DefineQueryRewrite(RuleStmt *stmt)
/*
* DISTINCT on view is not supported
*/
if (query->uniqueFlag != NULL)
if (query->distinctClause != NIL)
elog(ERROR, "DISTINCT not supported in views");
/*

20
src/backend/rewrite/rewriteHandler.c
View File

@ -7,7 +7,7 @@
*
*
* IDENTIFICATION
* $Header: /cvsroot/pgsql/src/backend/rewrite/rewriteHandler.c,v 1.66 2000/01/26 05:56:49 momjian Exp $
* $Header: /cvsroot/pgsql/src/backend/rewrite/rewriteHandler.c,v 1.67 2000/01/27 18:11:37 tgl Exp $
*
*-------------------------------------------------------------------------
*/
@ -536,8 +536,8 @@ modifyAggrefMakeSublink(Aggref *aggref, Query *parsetree)
subquery->isBinary = FALSE;
subquery->isTemp = FALSE;
subquery->unionall = FALSE;
subquery->uniqueFlag = NULL;
subquery->sortClause = NULL;
subquery->distinctClause = NIL;
subquery->sortClause = NIL;
subquery->rtable = lcons(copyObject(rte), NIL);
subquery->targetList = lcons(tle, NIL);
subquery->qual = modifyAggrefDropQual((Node *) parsetree->qual,
@ -1725,7 +1725,7 @@ check_targetlists_are_compatible(List *prev_target, List *current_target)
* The operator tree is attached to 'intersectClause' (see rule
* 'SelectStmt' in gram.y) of the 'parsetree' given as an
* argument. First we remember some clauses (the sortClause, the
* unique flag etc.) Then we translate the operator tree to DNF
* distinctClause etc.) Then we translate the operator tree to DNF
* (disjunctive normal form) by 'cnfify'. (Note that 'cnfify' produces
* CNF but as we exchanged ANDs with ORs in function A_Expr_to_Expr()
* earlier we get DNF after exchanging ANDs and ORs again in the
@ -1736,8 +1736,8 @@ check_targetlists_are_compatible(List *prev_target, List *current_target)
* union list is handed back but before that the remembered clauses
* (sortClause etc) are attached to the new top Node (Note that the
* new top Node can differ from the parsetree given as argument because of
* the translation to DNF. That's why we have to remember the sortClause or
* unique flag!) */
* the translation to DNF. That's why we have to remember the sortClause
* and so on!) */
static Query *
Except_Intersect_Rewrite(Query *parsetree)
{
@ -1750,12 +1750,12 @@ Except_Intersect_Rewrite(Query *parsetree)
*intersect,
*intersectClause;
List *union_list = NIL,
*sortClause;
*sortClause,
*distinctClause;
List *left_expr,
*right_expr,
*resnames = NIL;
char *op,
*uniqueFlag,
*into;
bool isBinary,
isPortal,
@ -1806,7 +1806,7 @@ Except_Intersect_Rewrite(Query *parsetree)
* node at the end of the function
*/
sortClause = parsetree->sortClause;
uniqueFlag = parsetree->uniqueFlag;
distinctClause = parsetree->distinctClause;
into = parsetree->into;
isBinary = parsetree->isBinary;
isPortal = parsetree->isPortal;
@ -2009,7 +2009,7 @@ Except_Intersect_Rewrite(Query *parsetree)
result->unionClause = lnext(union_list);
/* Attach all the items remembered in the beginning of the function */
result->sortClause = sortClause;
result->uniqueFlag = uniqueFlag;
result->distinctClause = distinctClause;
result->into = into;
result->isPortal = isPortal;
result->isBinary = isBinary;

21
src/backend/rewrite/rewriteManip.c
View File

@ -7,13 +7,14 @@
*
*
* IDENTIFICATION
* $Header: /cvsroot/pgsql/src/backend/rewrite/rewriteManip.c,v 1.43 2000/01/26 05:56:49 momjian Exp $
* $Header: /cvsroot/pgsql/src/backend/rewrite/rewriteManip.c,v 1.44 2000/01/27 18:11:37 tgl Exp $
*
*-------------------------------------------------------------------------
*/
#include "postgres.h"
#include "optimizer/clauses.h"
#include "optimizer/tlist.h"
#include "parser/parsetree.h"
#include "parser/parse_clause.h"
#include "rewrite/rewriteManip.h"
@ -286,22 +287,10 @@ AddGroupClause(Query *parsetree, List *group_by, List *tlist)
foreach(l, group_by)
{
GroupClause *groupclause = (GroupClause *) copyObject(lfirst(l));
Index refnumber = groupclause->tleSortGroupRef;
TargetEntry *tle = NULL;
List *tl;
TargetEntry *tle = get_sortgroupclause_tle(groupclause, tlist);
/* Find and copy the groupclause's TLE in the old tlist */
foreach(tl, tlist)
{
if (((TargetEntry *) lfirst(tl))->resdom->ressortgroupref ==
refnumber)
{
tle = (TargetEntry *) copyObject(lfirst(tl));
break;
}
}
if (tle == NULL)
elog(ERROR, "AddGroupClause(): GROUP BY entry not found in rules targetlist");
/* copy the groupclause's TLE from the old tlist */
tle = (TargetEntry *) copyObject(tle);
/* The ressortgroupref number in the old tlist might be already
* taken in the new tlist, so force assignment of a new number.