*
*
* IDENTIFICATION
- * $Header: /cvsroot/pgsql/src/backend/parser/parse_agg.c,v 1.21 1999/05/25 16:10:13 momjian Exp $
+ * $Header: /cvsroot/pgsql/src/backend/parser/parse_agg.c,v 1.22 1999/06/19 03:48:31 tgl Exp $
*
*-------------------------------------------------------------------------
*/
#include "utils/lsyscache.h"
static bool contain_agg_clause(Node *clause);
-static bool exprIsAggOrGroupCol(Node *expr, List *groupClause, List *tlist);
-static bool tleIsAggOrGroupCol(TargetEntry *tle, List *groupClause,
- List *tlist);
+static bool contain_agg_clause_walker(Node *node, void *context);
+static bool exprIsAggOrGroupCol(Node *expr, List *groupClauses);
+static bool exprIsAggOrGroupCol_walker(Node *node, List *groupClauses);
/*
* contain_agg_clause
- * Recursively find aggref nodes from a clause.
+ * Recursively find aggref nodes within a clause.
*
* Returns true if any aggregate found.
+ *
+ * NOTE: we assume that the given clause has been transformed suitably for
+ * parser output. This means we can use the planner's expression_tree_walker,
+ * except that we have to process SubLink nodes specially, since they haven't
+ * been turned into SubPlan nodes yet.
*/
static bool
contain_agg_clause(Node *clause)
{
- if (clause == NULL)
- return FALSE;
- else if (IsA(clause, Aggref))
- return TRUE;
- else if (IsA(clause, Iter))
- return contain_agg_clause(((Iter *) clause)->iterexpr);
- else if (single_node(clause))
- return FALSE;
- else if (or_clause(clause) || and_clause(clause))
- {
- List *temp;
-
- foreach(temp, ((Expr *) clause)->args)
- if (contain_agg_clause(lfirst(temp)))
- return TRUE;
- return FALSE;
- }
- else if (is_funcclause(clause))
- {
- List *temp;
+ return contain_agg_clause_walker(clause, NULL);
+}
- foreach(temp, ((Expr *) clause)->args)
- if (contain_agg_clause(lfirst(temp)))
- return TRUE;
- return FALSE;
- }
- else if (IsA(clause, ArrayRef))
+static bool
+contain_agg_clause_walker(Node *node, void *context)
+{
+ if (node == NULL)
+ return false;
+ if (IsA(node, Aggref))
+ return true; /* abort the tree traversal and return true */
+ if (IsA(node, SubLink))
{
- List *temp;
-
- foreach(temp, ((ArrayRef *) clause)->refupperindexpr)
- if (contain_agg_clause(lfirst(temp)))
- return TRUE;
- foreach(temp, ((ArrayRef *) clause)->reflowerindexpr)
- if (contain_agg_clause(lfirst(temp)))
- return TRUE;
- if (contain_agg_clause(((ArrayRef *) clause)->refexpr))
- return TRUE;
- if (contain_agg_clause(((ArrayRef *) clause)->refassgnexpr))
- return TRUE;
- return FALSE;
+ /* Examine the lefthand side, but not the oper list nor the subquery */
+ SubLink *sublink = (SubLink *) node;
+ return contain_agg_clause_walker((Node *) sublink->lefthand, context);
}
- else if (not_clause(clause))
- return contain_agg_clause((Node *) get_notclausearg((Expr *) clause));
- else if (is_opclause(clause))
- return (contain_agg_clause((Node *) get_leftop((Expr *) clause)) ||
- contain_agg_clause((Node *) get_rightop((Expr *) clause)));
-
- return FALSE;
+ return expression_tree_walker(node, contain_agg_clause_walker, context);
}
/*
* exprIsAggOrGroupCol -
- * returns true if the expression does not contain non-group columns.
+ * returns true if the expression does not contain non-group columns,
+ * other than within the arguments of aggregate functions.
+ *
+ * NOTE: we assume that the given clause has been transformed suitably for
+ * parser output. This means we can use the planner's expression_tree_walker,
+ * except that we have to process SubLink nodes specially, since they haven't
+ * been turned into SubPlan nodes yet.
+ *
+ * NOTE: in the case of a SubLink, we do not descend into the subquery. This
+ * means we will fail to detect ungrouped columns that appear as outer-level
+ * variables within a subquery. That seems unreasonably hard to handle here.
+ * Instead, we expect the planner to check for ungrouped columns after it's
+ * found all the outer-level references inside the subquery and converted
+ * them into a list of parameters for the subquery.
*/
static bool
-exprIsAggOrGroupCol(Node *expr, List *groupClause, List *tlist)
+exprIsAggOrGroupCol(Node *expr, List *groupClauses)
{
- List *gl;
-
- if (expr == NULL || IsA(expr, Const) ||
- IsA(expr, Param) ||IsA(expr, Aggref) ||
- IsA(expr, SubLink)) /* can't handle currently !!! */
- return TRUE;
-
- foreach(gl, groupClause)
- {
- GroupClause *grpcl = lfirst(gl);
-
- if (equal(expr, get_groupclause_expr(grpcl, tlist)))
- return TRUE;
- }
-
- if (IsA(expr, Expr))
- {
- List *temp;
-
- foreach(temp, ((Expr *) expr)->args)
- if (!exprIsAggOrGroupCol(lfirst(temp), groupClause, tlist))
- return FALSE;
- return TRUE;
- }
-
- return FALSE;
+ /* My walker returns TRUE if it finds a subexpression that is NOT
+ * acceptable (since we can abort the recursion at that point).
+ * So, invert its result.
+ */
+ return ! exprIsAggOrGroupCol_walker(expr, groupClauses);
}
-/*
- * tleIsAggOrGroupCol -
- * returns true if the TargetEntry is Agg or GroupCol.
- */
static bool
-tleIsAggOrGroupCol(TargetEntry *tle, List *groupClause, List *tlist)
+exprIsAggOrGroupCol_walker(Node *node, List *groupClauses)
{
- Node *expr = tle->expr;
List *gl;
- if (expr == NULL || IsA(expr, Const) ||IsA(expr, Param))
- return TRUE;
-
- foreach(gl, groupClause)
+ if (node == NULL)
+ return false;
+ if (IsA(node, Aggref))
+ return false; /* OK; do not examine argument of aggregate */
+ if (IsA(node, Const) || IsA(node, Param))
+ return false; /* constants are always acceptable */
+ /* Now check to see if expression as a whole matches any GROUP BY item.
+ * We need to do this at every recursion level so that we recognize
+ * GROUPed-BY expressions.
+ */
+ foreach(gl, groupClauses)
{
- GroupClause *grpcl = lfirst(gl);
-
- if (tle->resdom->resgroupref == grpcl->tleGroupref)
- {
- if (contain_agg_clause((Node *) expr))
- elog(ERROR, "Aggregates not allowed in GROUP BY clause");
- return TRUE;
- }
+ if (equal(node, lfirst(gl)))
+ return false; /* acceptable, do not descend more */
}
-
- if (IsA(expr, Aggref))
- return TRUE;
-
- if (IsA(expr, Expr))
+ /* If we have an ungrouped Var, we have a failure --- unless it is an
+ * outer-level Var. In that case it's a constant as far as this query
+ * level is concerned, and we can accept it. (If it's ungrouped as far
+ * as the upper query is concerned, that's someone else's problem...)
+ */
+ if (IsA(node, Var))
{
- List *temp;
-
- foreach(temp, ((Expr *) expr)->args)
- if (!exprIsAggOrGroupCol(lfirst(temp), groupClause, tlist))
- return FALSE;
- return TRUE;
+ if (((Var *) node)->varlevelsup == 0)
+ return true; /* found an ungrouped local variable */
+ return false; /* outer-level Var is acceptable */
}
-
- return FALSE;
+ /* Otherwise, recurse. */
+ if (IsA(node, SubLink))
+ {
+ /* Examine the lefthand side, but not the oper list nor the subquery */
+ SubLink *sublink = (SubLink *) node;
+ return exprIsAggOrGroupCol_walker((Node *) sublink->lefthand,
+ groupClauses);
+ }
+ return expression_tree_walker(node, exprIsAggOrGroupCol_walker,
+ (void *) groupClauses);
}
/*
void
parseCheckAggregates(ParseState *pstate, Query *qry)
{
+ List *groupClauses = NIL;
List *tl;
/* This should only be called if we found aggregates or grouping */
if (contain_agg_clause(qry->qual))
elog(ERROR, "Aggregates not allowed in WHERE clause");
+ /*
+ * No aggregates allowed in GROUP BY clauses, either.
+ *
+ * While we are at it, build a list of the acceptable GROUP BY expressions
+ * for use by exprIsAggOrGroupCol() (this avoids repeated scans of the
+ * targetlist within the recursive routines...)
+ */
+ foreach(tl, qry->groupClause)
+ {
+ GroupClause *grpcl = lfirst(tl);
+ Node *expr;
+
+ expr = (Node *) get_groupclause_expr(grpcl, qry->targetList);
+ if (contain_agg_clause(expr))
+ elog(ERROR, "Aggregates not allowed in GROUP BY clause");
+ groupClauses = lcons(expr, groupClauses);
+ }
+
/*
* The target list can only contain aggregates, group columns and
* functions thereof.
{
TargetEntry *tle = lfirst(tl);
- if (!tleIsAggOrGroupCol(tle, qry->groupClause, qry->targetList))
+ if (!exprIsAggOrGroupCol(tle->expr, groupClauses))
elog(ERROR,
"Illegal use of aggregates or non-group column in target list");
}
/*
- * the expression specified in the HAVING clause has the same
+ * The expression specified in the HAVING clause has the same
* restriction as those in the target list.
*/
-
- if (!exprIsAggOrGroupCol(qry->havingQual, qry->groupClause, qry->targetList))
+ if (!exprIsAggOrGroupCol(qry->havingQual, groupClauses))
elog(ERROR,
- "Illegal use of aggregates or non-group column in HAVING clause");
+ "Illegal use of aggregates or non-group column in HAVING clause");
+
+ /* Release the list storage (but not the pointed-to expressions!) */
+ freeList(groupClauses);
}
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