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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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43
src/backend/optimizer/util/tlist.c
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@@ -8,7 +8,7 @@
*
*
* IDENTIFICATION
* $Header: /cvsroot/pgsql/src/backend/optimizer/util/tlist.c,v 1.42 2000/01/26 05:56:40 momjian Exp $
* $Header: /cvsroot/pgsql/src/backend/optimizer/util/tlist.c,v 1.43 2000/01/27 18:11:34 tgl Exp $
*
*-------------------------------------------------------------------------
*/
@@ -216,6 +216,33 @@ get_expr(TargetEntry *tle)
return (Var *) tle->expr;
}
/*
* get_sortgroupclause_tle
* Find the targetlist entry matching the given SortClause
* (or GroupClause) by ressortgroupref, and return it.
*
* Because GroupClause is typedef'd as SortClause, either kind of
* node can be passed without casting.
*/
TargetEntry *
get_sortgroupclause_tle(SortClause *sortClause,
List *targetList)
{
Index refnumber = sortClause->tleSortGroupRef;
List *l;
foreach(l, targetList)
{
TargetEntry *tle = (TargetEntry *) lfirst(l);
if (tle->resdom->ressortgroupref == refnumber)
return tle;
}
elog(ERROR, "get_sortgroupclause_tle: ORDER/GROUP BY expression not found in targetlist");
return NULL; /* keep compiler quiet */
}
/*
* get_sortgroupclause_expr
* Find the targetlist entry matching the given SortClause
@@ -227,17 +254,7 @@ get_expr(TargetEntry *tle)
Node *
get_sortgroupclause_expr(SortClause *sortClause, List *targetList)
{
Index refnumber = sortClause->tleSortGroupRef;
List *l;
TargetEntry *tle = get_sortgroupclause_tle(sortClause, targetList);
foreach(l, targetList)
{
TargetEntry *tle = (TargetEntry *) lfirst(l);
if (tle->resdom->ressortgroupref == refnumber)
return tle->expr;
}
elog(ERROR, "get_sortgroupclause_expr: ORDER/GROUP BY expression not found in targetlist");
return NULL; /* keep compiler quiet */
return tle->expr;
}