Revise create_nestloop_node's handling of inner indexscan to
work under a wider range of scenarios than it did --- it formerly did not handle a multi-pass inner scan, nor cases in which the inner scan's indxqualorig or non-index qual contained outer var references. I am not sure that these limitations could be hit in the existing optimizer, but they need to be fixed for future expansion.
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@ -7,7 +7,7 @@
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*
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*
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* IDENTIFICATION
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* $Header: /cvsroot/pgsql/src/backend/optimizer/plan/createplan.c,v 1.68 1999/08/09 06:20:26 momjian Exp $
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* $Header: /cvsroot/pgsql/src/backend/optimizer/plan/createplan.c,v 1.69 1999/08/10 02:58:56 tgl Exp $
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*
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*-------------------------------------------------------------------------
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*/
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@ -426,55 +426,55 @@ create_nestloop_node(NestPath *best_path,
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Plan *inner_node,
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List *inner_tlist)
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{
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NestLoop *join_node = (NestLoop *) NULL;
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NestLoop *join_node;
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if (IsA(inner_node, IndexScan))
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{
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/*
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* An index is being used to reduce the number of tuples scanned
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* in the inner relation. There will never be more than one index
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* used in the inner scan path, so we need only consider the first
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* set of qualifications in indxqual.
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* in the inner relation. If there are join clauses being used
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* with the index, we must update their outer-rel var nodes to
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* refer to the outer relation.
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*
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* But there may be more than one clause in this "first set" in the
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* case of multi-column indices. - vadim 03/18/97
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*/
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List *inner_indxqual = lfirst(((IndexScan *) inner_node)->indxqual);
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List *inner_qual;
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bool found = false;
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foreach(inner_qual, inner_indxqual)
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{
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if (!qual_clause_p((Node *) lfirst(inner_qual)))
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{
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found = true;
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break;
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}
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}
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/*
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* If we have in fact found a join index qualification, remove
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* these index clauses from the nestloop's join clauses and reset
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* the inner(index) scan's qualification so that the var nodes
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* refer to the proper outer join relation attributes.
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* We can also remove those join clauses from the list of clauses
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* that have to be checked as qpquals at the join node, but only
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* if there's just one indexscan in the inner path (otherwise,
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* several different sets of clauses are being ORed together).
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*
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* XXX Removing index clauses doesn't work properly: 1.
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* fix_indxqual_references may change varattno-s in
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* inner_indxqual; 2. clauses may be commuted I havn't time to fix
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* it at the moment. - vadim 04/24/97
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* Note: if the index is lossy, the same clauses may also be getting
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* checked as qpquals in the indexscan. We can still remove them
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* from the nestloop's qpquals, but we gotta update the outer-rel
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* vars in the indexscan's qpquals too...
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*
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* XXX as of 8/99, removal of redundant joinclauses doesn't work
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* all the time, since it will fail to recognize clauses that have
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* been commuted in the indexqual. I hope to make this problem go
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* away soon by not commuting indexqual clauses --- tgl.
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*/
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if (found)
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{
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List *new_inner_qual;
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IndexScan *innerscan = (IndexScan *) inner_node;
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List *indxqualorig = innerscan->indxqualorig;
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/* No work needed if indxqual refers only to its own relation... */
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if (NumRelids((Node *) indxqualorig) > 1)
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{
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/* Remove redundant tests from my clauses, if possible.
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* Note we must compare against indxqualorig not the "fixed"
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* indxqual (which has index attnos instead of relation attnos).
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*/
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if (length(indxqualorig) == 1) /* single indexscan? */
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clauses = set_difference(clauses, lfirst(indxqualorig));
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clauses = set_difference(clauses, inner_indxqual); /* XXX */
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/* only refs to outer vars get changed in the inner indexqual */
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new_inner_qual = join_references(inner_indxqual,
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outer_tlist,
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NIL);
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((IndexScan *) inner_node)->indxqual = lcons(new_inner_qual, NIL);
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innerscan->indxqualorig = join_references(indxqualorig,
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outer_tlist,
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NIL);
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innerscan->indxqual = join_references(innerscan->indxqual,
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outer_tlist,
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NIL);
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if (NumRelids((Node *) inner_node->qual) > 1)
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inner_node->qual = join_references(inner_node->qual,
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outer_tlist,
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NIL);
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}
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}
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else if (IsA_Join(inner_node))
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@ -512,10 +512,10 @@ create_mergejoin_node(MergePath *best_path,
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*mergeclauses;
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MergeJoin *join_node;
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/*
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* Separate the mergeclauses from the other join qualification clauses
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* and set those clauses to contain references to lower attributes.
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* Remove the mergeclauses from the list of join qual clauses,
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* leaving the list of quals that must be checked as qpquals.
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* Set those clauses to contain INNER/OUTER var references.
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*/
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qpqual = join_references(set_difference(clauses,
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best_path->path_mergeclauses),
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@ -571,14 +571,6 @@ create_mergejoin_node(MergePath *best_path,
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return join_node;
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}
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/*
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* create_hashjoin_node-- XXX HASH
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*
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* Returns a new hashjoin node.
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*
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* XXX hash join ops are totally bogus -- how the hell do we choose
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* these?? at runtime? what about a hash index?
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*/
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static HashJoin *
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create_hashjoin_node(HashPath *best_path,
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List *tlist,
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@ -595,8 +587,16 @@ create_hashjoin_node(HashPath *best_path,
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Var *innerhashkey;
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/*
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* Separate the hashclauses from the other join qualification clauses
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* and set those clauses to contain references to lower attributes.
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* NOTE: there will always be exactly one hashclause in the list
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* best_path->path_hashclauses (cf. hash_inner_and_outer()).
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* We represent it as a list anyway for convenience with routines
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* that want to work on lists of clauses.
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*/
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/*
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* Remove the hashclauses from the list of join qual clauses,
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* leaving the list of quals that must be checked as qpquals.
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* Set those clauses to contain INNER/OUTER var references.
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*/
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qpqual = join_references(set_difference(clauses,
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best_path->path_hashclauses),
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@ -611,8 +611,12 @@ create_hashjoin_node(HashPath *best_path,
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outer_tlist,
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inner_tlist));
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/* Now the righthand op of the sole hashclause is the inner hash key. */
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innerhashkey = get_rightop(lfirst(hashclauses));
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/*
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* Build the hash node and hash join node.
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*/
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hash_node = make_hash(inner_tlist, innerhashkey, inner_node);
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join_node = make_hashjoin(tlist,
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qpqual,
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@ -791,7 +795,7 @@ switch_outer(List *clauses)
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Assert(is_opclause((Node *) clause));
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op = (Node *) get_rightop(clause);
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Assert(op != (Node *) NULL);
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if (IsA(op, ArrayRef))
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if (IsA(op, ArrayRef)) /* I think this test is dead code ... tgl */
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op = ((ArrayRef *) op)->refexpr;
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Assert(IsA(op, Var));
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if (var_is_outer((Var *) op))
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