*
*
* IDENTIFICATION
- * $Header: /cvsroot/pgsql/src/backend/optimizer/plan/createplan.c,v 1.68 1999/08/09 06:20:26 momjian Exp $
+ * $Header: /cvsroot/pgsql/src/backend/optimizer/plan/createplan.c,v 1.69 1999/08/10 02:58:56 tgl Exp $
*
*-------------------------------------------------------------------------
*/
Plan *inner_node,
List *inner_tlist)
{
- NestLoop *join_node = (NestLoop *) NULL;
+ NestLoop *join_node;
if (IsA(inner_node, IndexScan))
{
-
/*
* An index is being used to reduce the number of tuples scanned
- * in the inner relation. There will never be more than one index
- * used in the inner scan path, so we need only consider the first
- * set of qualifications in indxqual.
+ * in the inner relation. If there are join clauses being used
+ * with the index, we must update their outer-rel var nodes to
+ * refer to the outer relation.
*
- * But there may be more than one clause in this "first set" in the
- * case of multi-column indices. - vadim 03/18/97
- */
-
- List *inner_indxqual = lfirst(((IndexScan *) inner_node)->indxqual);
- List *inner_qual;
- bool found = false;
-
- foreach(inner_qual, inner_indxqual)
- {
- if (!qual_clause_p((Node *) lfirst(inner_qual)))
- {
- found = true;
- break;
- }
- }
-
- /*
- * If we have in fact found a join index qualification, remove
- * these index clauses from the nestloop's join clauses and reset
- * the inner(index) scan's qualification so that the var nodes
- * refer to the proper outer join relation attributes.
+ * We can also remove those join clauses from the list of clauses
+ * that have to be checked as qpquals at the join node, but only
+ * if there's just one indexscan in the inner path (otherwise,
+ * several different sets of clauses are being ORed together).
+ *
+ * Note: if the index is lossy, the same clauses may also be getting
+ * checked as qpquals in the indexscan. We can still remove them
+ * from the nestloop's qpquals, but we gotta update the outer-rel
+ * vars in the indexscan's qpquals too...
*
- * XXX Removing index clauses doesn't work properly: 1.
- * fix_indxqual_references may change varattno-s in
- * inner_indxqual; 2. clauses may be commuted I havn't time to fix
- * it at the moment. - vadim 04/24/97
+ * XXX as of 8/99, removal of redundant joinclauses doesn't work
+ * all the time, since it will fail to recognize clauses that have
+ * been commuted in the indexqual. I hope to make this problem go
+ * away soon by not commuting indexqual clauses --- tgl.
*/
- if (found)
+ IndexScan *innerscan = (IndexScan *) inner_node;
+ List *indxqualorig = innerscan->indxqualorig;
+
+ /* No work needed if indxqual refers only to its own relation... */
+ if (NumRelids((Node *) indxqualorig) > 1)
{
- List *new_inner_qual;
+ /* Remove redundant tests from my clauses, if possible.
+ * Note we must compare against indxqualorig not the "fixed"
+ * indxqual (which has index attnos instead of relation attnos).
+ */
+ if (length(indxqualorig) == 1) /* single indexscan? */
+ clauses = set_difference(clauses, lfirst(indxqualorig));
- clauses = set_difference(clauses, inner_indxqual); /* XXX */
/* only refs to outer vars get changed in the inner indexqual */
- new_inner_qual = join_references(inner_indxqual,
- outer_tlist,
- NIL);
- ((IndexScan *) inner_node)->indxqual = lcons(new_inner_qual, NIL);
+ innerscan->indxqualorig = join_references(indxqualorig,
+ outer_tlist,
+ NIL);
+ innerscan->indxqual = join_references(innerscan->indxqual,
+ outer_tlist,
+ NIL);
+ if (NumRelids((Node *) inner_node->qual) > 1)
+ inner_node->qual = join_references(inner_node->qual,
+ outer_tlist,
+ NIL);
}
}
else if (IsA_Join(inner_node))
*mergeclauses;
MergeJoin *join_node;
-
/*
- * Separate the mergeclauses from the other join qualification clauses
- * and set those clauses to contain references to lower attributes.
+ * Remove the mergeclauses from the list of join qual clauses,
+ * leaving the list of quals that must be checked as qpquals.
+ * Set those clauses to contain INNER/OUTER var references.
*/
qpqual = join_references(set_difference(clauses,
best_path->path_mergeclauses),
return join_node;
}
-/*
- * create_hashjoin_node-- XXX HASH
- *
- * Returns a new hashjoin node.
- *
- * XXX hash join ops are totally bogus -- how the hell do we choose
- * these?? at runtime? what about a hash index?
- */
static HashJoin *
create_hashjoin_node(HashPath *best_path,
List *tlist,
Var *innerhashkey;
/*
- * Separate the hashclauses from the other join qualification clauses
- * and set those clauses to contain references to lower attributes.
+ * NOTE: there will always be exactly one hashclause in the list
+ * best_path->path_hashclauses (cf. hash_inner_and_outer()).
+ * We represent it as a list anyway for convenience with routines
+ * that want to work on lists of clauses.
+ */
+
+ /*
+ * Remove the hashclauses from the list of join qual clauses,
+ * leaving the list of quals that must be checked as qpquals.
+ * Set those clauses to contain INNER/OUTER var references.
*/
qpqual = join_references(set_difference(clauses,
best_path->path_hashclauses),
outer_tlist,
inner_tlist));
+ /* Now the righthand op of the sole hashclause is the inner hash key. */
innerhashkey = get_rightop(lfirst(hashclauses));
+ /*
+ * Build the hash node and hash join node.
+ */
hash_node = make_hash(inner_tlist, innerhashkey, inner_node);
join_node = make_hashjoin(tlist,
qpqual,
Assert(is_opclause((Node *) clause));
op = (Node *) get_rightop(clause);
Assert(op != (Node *) NULL);
- if (IsA(op, ArrayRef))
+ if (IsA(op, ArrayRef)) /* I think this test is dead code ... tgl */
op = ((ArrayRef *) op)->refexpr;
Assert(IsA(op, Var));
if (var_is_outer((Var *) op))
projects / postgresql / commitdiff