I started adding the Having Clause and it works quite fine for

sequential scans! (I think it will also work with hash, index, etc
but I did not check it out! I made some High level changes which
should work for all access methods, but maybe I'm wrong. Please
let me know.)

Now it is possible to make queries like:

select s.sname, max(p.pid), min(p.pid) from part p, supplier s
where s.sid=p.sid group by s.sname having max(pid)=6 and min(pid)=1
or avg(pid)=4;

Having does not work yet for queries that contain a subselect
statement in the Having clause, I'll try to fix this in the next
days.

If there are some bugs, please let me know, I'll start to read the
mailinglists now!

Now here is the patch against the original 6.3 version (no snapshot!!):

Stefan

src/backend/executor/execQual.c

@@ -7,7 +7,7 @@
  *
  *
  * IDENTIFICATION
- *	  $Header: /cvsroot/pgsql/src/backend/executor/execQual.c,v 1.26 1998/02/26 04:31:13 momjian Exp $
+ *	  $Header: /cvsroot/pgsql/src/backend/executor/execQual.c,v 1.27 1998/03/30 16:35:50 momjian Exp $
  *
  *-------------------------------------------------------------------------
  */
@@ -203,8 +203,7 @@ ExecEvalArrayRef(ArrayRef *arrayRef,
 static Datum
 ExecEvalAggreg(Aggreg *agg, ExprContext *econtext, bool *isNull)
 {
-
-	*isNull = econtext->ecxt_nulls[agg->aggno];
+	*isNull = econtext->ecxt_nulls[agg->aggno];	
 	return econtext->ecxt_values[agg->aggno];
 }
 
@@ -648,6 +647,8 @@ ExecEvalFuncArgs(FunctionCachePtr fcache,
 						 econtext,
 						 &argIsNull,
 						 argIsDone);
+
+
 		if (!(*argIsDone))
 		{
 			Assert(i == 0);
@@ -1356,8 +1357,11 @@ ExecQual(List *qual, ExprContext *econtext)
 	 * ----------------
 	 */
 	result = false;
+
 	foreach(clause, qual)
 	{
+	 
+	  
 		result = ExecQualClause((Node *) lfirst(clause), econtext);
 		if (result == true)
 			break;

src/backend/executor/nodeAgg.c

@@ -29,6 +29,7 @@
 #include "storage/bufmgr.h"
 #include "utils/palloc.h"
 #include "utils/syscache.h"
+#include "optimizer/clauses.h"
 
 /*
  * AggFuncInfo -
@@ -109,10 +110,16 @@ ExecAgg(Agg *node)
 				isNull1 = FALSE,
 				isNull2 = FALSE;
 
+
+	/***S*H***/
+	do { 
+
+
 	/* ---------------------
 	 *	get state info from node
 	 * ---------------------
 	 */
+
 	aggstate = node->aggstate;
 	if (aggstate->agg_done)
 		return NULL;
@@ -229,6 +236,7 @@ ExecAgg(Agg *node)
 			}
 		}
 	}
+	  
 
 	/* ----------------
 	 *	 for each tuple from the the outer plan, apply all the aggregates
@@ -477,11 +485,19 @@ ExecAgg(Agg *node)
 	 *	slot and return it.
 	 * ----------------
 	 */
+
+        /***S*H***/
+	}
+	while((ExecQual(fix_opids(node->plan.qual),econtext)!=true) && 
+	      (node->plan.qual!=NULL));
+
+	 
 	ExecStoreTuple(oneTuple,
 				   aggstate->csstate.css_ScanTupleSlot,
 				   InvalidBuffer,
 				   false);
 	econtext->ecxt_scantuple = aggstate->csstate.css_ScanTupleSlot;
+
 	resultSlot = ExecProject(projInfo, &isDone);
 
 	if (oneTuple)

src/backend/optimizer/plan/planner.c

@@ -7,7 +7,7 @@
  *
  *
  * IDENTIFICATION
- *	  $Header: /cvsroot/pgsql/src/backend/optimizer/plan/planner.c,v 1.23 1998/02/26 04:32:51 momjian Exp $
+ *	  $Header: /cvsroot/pgsql/src/backend/optimizer/plan/planner.c,v 1.24 1998/03/30 16:36:04 momjian Exp $
  *
  *-------------------------------------------------------------------------
  */
@@ -59,6 +59,115 @@ make_groupPlan(List **tlist, bool tuplePerGroup,
  *
  *****************************************************************************/
 
+
+/***S*H***/ /* Anfang */
+
+static List *
+check_having_qual_for_aggs(Node *clause, List *subplanTargetList)
+{
+	List	   *t;
+	List	   *agg_list = NIL;
+
+	if (IsA(clause, Var))
+	{
+	  TargetEntry *subplanVar;
+	  
+	  /*
+	   * Ha! A Var node!
+	   */
+	  subplanVar = match_varid((Var *) clause, subplanTargetList);
+	  
+	  /*
+	   * Change the varno & varattno fields of the var node.
+	   *
+	   */
+	  ((Var *) clause)->varattno = subplanVar->resdom->resno;
+	  return NIL;
+	}
+        /***S*H***/
+	else if (is_funcclause(clause) || not_clause(clause) || 
+		 or_clause(clause) || and_clause(clause))
+	{
+
+		/*
+		 * This is a function. Recursively call this routine for its
+		 * arguments...
+		 */
+		foreach(t, ((Expr *) clause)->args)
+		{
+			agg_list = nconc(agg_list,
+					   check_having_qual_for_aggs(lfirst(t), subplanTargetList));
+		}
+		return agg_list;
+	}
+	else if (IsA(clause, Aggreg))
+	{
+		return lcons(clause,
+		    check_having_qual_for_aggs(((Aggreg *) clause)->target, subplanTargetList));
+		
+	}
+	else if (IsA(clause, ArrayRef))
+	{
+		ArrayRef   *aref = (ArrayRef *) clause;
+
+		/*
+		 * This is an arrayref. Recursively call this routine for its
+		 * expression and its index expression...
+		 */
+		foreach(t, aref->refupperindexpr)
+		{
+			agg_list = nconc(agg_list,
+					 check_having_qual_for_aggs(lfirst(t), subplanTargetList));
+		}
+		foreach(t, aref->reflowerindexpr)
+		{
+			agg_list = nconc(agg_list,
+					 check_having_qual_for_aggs(lfirst(t), subplanTargetList));
+		}
+		agg_list = nconc(agg_list,
+				 check_having_qual_for_aggs(aref->refexpr, subplanTargetList));
+		agg_list = nconc(agg_list,
+				 check_having_qual_for_aggs(aref->refassgnexpr, subplanTargetList));
+
+		return agg_list;
+	}
+	else if (is_opclause(clause))
+	{
+
+		/*
+		 * This is an operator. Recursively call this routine for both its
+		 * left and right operands
+		 */
+		Node	   *left = (Node *) get_leftop((Expr *) clause);
+		Node	   *right = (Node *) get_rightop((Expr *) clause);
+
+		if (left != (Node *) NULL)
+			agg_list = nconc(agg_list,
+					 check_having_qual_for_aggs(left, subplanTargetList));
+		if (right != (Node *) NULL)
+			agg_list = nconc(agg_list,
+					 check_having_qual_for_aggs(right, subplanTargetList));
+
+		return agg_list;
+	}
+	else if (IsA(clause, Param) ||IsA(clause, Const))
+	{
+		/* do nothing! */
+		return NIL;
+	}
+	else
+	{
+
+		/*
+		 * Ooops! we can not handle that!
+		 */
+		elog(ERROR, "check_having_qual_for_aggs: Can not handle this having_qual!\n");
+		return NIL;
+	}
+}
+/***S*H***/ /* Ende */
+
+
 Plan *
 planner(Query *parse)
 {
@@ -181,7 +290,22 @@ union_planner(Query *parse)
 		 * the result tuple of the subplans.
 		 */
 		((Agg *) result_plan)->aggs =
-			set_agg_tlist_references((Agg *) result_plan);
+			set_agg_tlist_references((Agg *) result_plan); 
+
+		/***S*H***/
+		if(parse->havingQual!=NULL) {
+		  List	   *clause;
+
+		  /***S*H***/ /* set qpqual of having clause */
+		  ((Agg *) result_plan)->plan.qual=cnfify((Expr *)parse->havingQual,true);
+
+		  foreach(clause, ((Agg *) result_plan)->plan.qual)
+		    {
+		      ((Agg *) result_plan)->aggs = nconc(((Agg *) result_plan)->aggs,
+			 check_having_qual_for_aggs((Node *) lfirst(clause),
+				       ((Agg *) result_plan)->plan.lefttree->targetlist));
+		    }
+		}
 	}
 
 	/*
@@ -429,3 +553,6 @@ pg_checkretval(Oid rettype, QueryTreeList *queryTreeList)
 	/* success */
 	return;
 }
+
+
+

src/backend/optimizer/plan/setrefs.c

@@ -7,7 +7,7 @@
  *
  *
  * IDENTIFICATION
- *	  $Header: /cvsroot/pgsql/src/backend/optimizer/plan/setrefs.c,v 1.19 1998/02/26 04:32:53 momjian Exp $
+ *	  $Header: /cvsroot/pgsql/src/backend/optimizer/plan/setrefs.c,v 1.20 1998/03/30 16:36:14 momjian Exp $
  *
  *-------------------------------------------------------------------------
  */
@@ -839,6 +839,7 @@ replace_agg_clause(Node *clause, List *subplanTargetList)
 	}
 }
 
+
 /*
  * del_agg_tlist_references
  *	  Remove the Agg nodes from the target list

src/backend/parser/analyze.c

@@ -7,7 +7,7 @@
  *
  *
  * IDENTIFICATION
- *	  $Header: /cvsroot/pgsql/src/backend/parser/analyze.c,v 1.71 1998/02/26 04:33:26 momjian Exp $
+ *	  $Header: /cvsroot/pgsql/src/backend/parser/analyze.c,v 1.72 1998/03/30 16:36:23 momjian Exp $
  *
  *-------------------------------------------------------------------------
  */
@@ -781,6 +781,10 @@ transformSelectStmt(ParseState *pstate, SelectStmt *stmt)
 	qry->targetList = transformTargetList(pstate, stmt->targetList);
 
 	qry->qual = transformWhereClause(pstate, stmt->whereClause);
+
+        /***S*H***/
+	qry->havingQual = transformWhereClause(pstate, stmt->havingClause);
+
 	qry->hasSubLinks = pstate->p_hasSubLinks;
 
 	qry->sortClause = transformSortClause(pstate,

src/backend/parser/gram.c

@@ -216,7 +216,7 @@
  *
  *
  * IDENTIFICATION
- *	  $Header: /cvsroot/pgsql/src/backend/parser/Attic/gram.c,v 2.4 1998/03/18 16:50:15 thomas Exp $
+ *	  $Header: /cvsroot/pgsql/src/backend/parser/Attic/gram.c,v 2.5 1998/03/30 16:36:32 momjian Exp $
  *
  * HISTORY
  *	  AUTHOR			DATE			MAJOR EVENT
@@ -6700,7 +6700,7 @@ case 463:
 case 464:
 #line 2529 "gram.y"
 {
-					elog(NOTICE, "HAVING not yet supported; ignore clause");
+					/***S*H***/ /* elog(NOTICE, "HAVING not yet supported; ignore clause");*/
 					yyval.node = yyvsp[0].node;
 				;
     break;}

src/backend/parser/gram.y

@@ -10,7 +10,7 @@
  *
  *
  * IDENTIFICATION
- *	  $Header: /cvsroot/pgsql/src/backend/parser/gram.y,v 2.7 1998/03/18 16:50:19 thomas Exp $
+ *	  $Header: /cvsroot/pgsql/src/backend/parser/gram.y,v 2.8 1998/03/30 16:36:35 momjian Exp $
  *
  * HISTORY
  *	  AUTHOR			DATE			MAJOR EVENT
@@ -2527,7 +2527,7 @@ groupby:  ColId
 
 having_clause:  HAVING a_expr
 				{
-					elog(NOTICE, "HAVING not yet supported; ignore clause");
+					/***S*H***/ /* elog(NOTICE, "HAVING not yet supported; ignore clause");*/
 					$$ = $2;
 				}
 		| /*EMPTY*/								{ $$ = NULL; }

src/backend/parser/parse_agg.c

@@ -7,7 +7,7 @@
  *
  *
  * IDENTIFICATION
- *	  $Header: /cvsroot/pgsql/src/backend/parser/parse_agg.c,v 1.9 1998/02/26 04:33:28 momjian Exp $
+ *	  $Header: /cvsroot/pgsql/src/backend/parser/parse_agg.c,v 1.10 1998/03/30 16:36:36 momjian Exp $
  *
  *-------------------------------------------------------------------------
  */
@@ -331,7 +331,7 @@ ParseAgg(ParseState *pstate, char *aggname, Oid basetype,
 	aggreg->target = lfirst(target);
 	if (usenulls)
 		aggreg->usenulls = true;
-
+	
 	pstate->p_hasAggs = true;
 
 	return aggreg;

src/backend/rewrite/rewriteHandler.c

@@ -6,7 +6,7 @@
  *
  *
  * IDENTIFICATION
- *	  $Header: /cvsroot/pgsql/src/backend/rewrite/rewriteHandler.c,v 1.14 1998/02/26 04:35:16 momjian Exp $
+ *	  $Header: /cvsroot/pgsql/src/backend/rewrite/rewriteHandler.c,v 1.15 1998/03/30 16:36:43 momjian Exp $
  *
  *-------------------------------------------------------------------------
  */
@@ -195,7 +195,7 @@ FireRetrieveRulesAtQuery(Query *parsetree,
 	if ((rt_entry_locks = relation->rd_rules) == NULL)
 		return NIL;
 
-	locks = matchLocks(CMD_SELECT, rt_entry_locks, rt_index, parsetree);
+	locks = matchLocks(CMD_SELECT, rt_entry_locks, rt_index, parsetree);	
 
 	/* find all retrieve instead */
 	foreach(i, locks)
@@ -375,6 +375,7 @@ ProcessRetrieveQuery(Query *parsetree,
 	List	   *product_queries = NIL;
 	int			rt_index = 0;
 
+
 	foreach(rt, rtable)
 	{
 		RangeTblEntry *rt_entry = lfirst(rt);
@@ -384,6 +385,8 @@ ProcessRetrieveQuery(Query *parsetree,
 		rt_index++;
 		rt_entry_relation = heap_openr(rt_entry->relname);
 
+
+
 		if (rt_entry_relation->rd_rules != NULL)
 		{
 			result =
@@ -414,6 +417,7 @@ ProcessRetrieveQuery(Query *parsetree,
 		rt_entry_locks = rt_entry_relation->rd_rules;
 		heap_close(rt_entry_relation);
 
+
 		if (rt_entry_locks)
 		{
 			locks =
@@ -683,7 +687,6 @@ static int	numQueryRewriteInvoked = 0;
 List *
 QueryRewrite(Query *parsetree)
 {
-
 	QueryRewriteSubLink(parsetree->qual);
 	return QueryRewriteOne(parsetree);
 }
@@ -780,6 +783,8 @@ deepRewriteQuery(Query *parsetree)
 	bool		instead;
 	List	   *qual_products = NIL;
 
+
+
 	if (++numQueryRewriteInvoked > REWRITE_INVOKE_MAX)
 	{
 		elog(ERROR, "query rewritten %d times, may contain cycles",