71ed7eb494
pghackers discussion of 5-Jan-2000. The amopselect and amopnpages estimators are gone, and in their place is a per-AM amcostestimate procedure (linked to from pg_am, not pg_amop).
355 lines
10 KiB
C
355 lines
10 KiB
C
/*-------------------------------------------------------------------------
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*
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* initsplan.c
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* Target list, qualification, joininfo initialization routines
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*
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* Copyright (c) 1994, Regents of the University of California
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*
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*
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* IDENTIFICATION
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* $Header: /cvsroot/pgsql/src/backend/optimizer/plan/initsplan.c,v 1.42 2000/01/22 23:50:16 tgl Exp $
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*
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*-------------------------------------------------------------------------
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*/
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#include <sys/types.h>
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#include "postgres.h"
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#include "catalog/pg_type.h"
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#include "nodes/makefuncs.h"
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#include "optimizer/clauses.h"
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#include "optimizer/cost.h"
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#include "optimizer/joininfo.h"
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#include "optimizer/pathnode.h"
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#include "optimizer/planmain.h"
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#include "optimizer/tlist.h"
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#include "optimizer/var.h"
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#include "utils/lsyscache.h"
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static void add_restrict_and_join_to_rel(Query *root, Node *clause);
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static void add_join_info_to_rels(Query *root, RestrictInfo *restrictinfo,
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Relids join_relids);
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static void add_vars_to_targetlist(Query *root, List *vars);
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static void set_restrictinfo_joininfo(RestrictInfo *restrictinfo);
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static void check_mergejoinable(RestrictInfo *restrictinfo);
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static void check_hashjoinable(RestrictInfo *restrictinfo);
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/*****************************************************************************
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*
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* TARGET LISTS
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*
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*****************************************************************************/
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/*
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* make_var_only_tlist
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* Creates rel nodes for every relation mentioned in the target list
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* 'tlist' (if a node hasn't already been created) and adds them to
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* *query_relation_list*. Creates targetlist entries for each member of
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* 'tlist' and adds them to the tlist field of the appropriate rel node.
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*/
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void
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make_var_only_tlist(Query *root, List *tlist)
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{
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List *tlist_vars = pull_var_clause((Node *) tlist, false);
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add_vars_to_targetlist(root, tlist_vars);
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freeList(tlist_vars);
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}
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/*
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* add_vars_to_targetlist
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* For each variable appearing in the list, add it to the relation's
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* targetlist if not already present. Rel nodes will also be created
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* if not already present.
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*/
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static void
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add_vars_to_targetlist(Query *root, List *vars)
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{
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List *temp;
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foreach(temp, vars)
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{
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Var *var = (Var *) lfirst(temp);
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RelOptInfo *rel = get_base_rel(root, var->varno);
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add_var_to_tlist(rel, var);
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}
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}
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/*
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* add_missing_rels_to_query
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*
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* If we have a range variable in the FROM clause that does not appear
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* in the target list nor qualifications, we must add it to the base
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* relation list so that it will be joined. For instance, "select f.x
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* from foo f, foo f2" is a join of f and f2. Note that if we have
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* "select foo.x from foo f", it also gets turned into a join (between
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* foo as foo and foo as f).
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*
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* To avoid putting useless entries into the per-relation targetlists,
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* this should only be called after all the variables in the targetlist
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* and quals have been processed by the routines above.
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*/
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void
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add_missing_rels_to_query(Query *root)
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{
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int varno = 1;
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List *l;
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foreach(l, root->rtable)
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{
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RangeTblEntry *rte = (RangeTblEntry *) lfirst(l);
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if (rte->inJoinSet)
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{
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RelOptInfo *rel = get_base_rel(root, varno);
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/* If the rel isn't otherwise referenced, give it a dummy
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* targetlist consisting of its own OID.
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*/
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if (rel->targetlist == NIL)
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{
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Var *var = makeVar(varno, ObjectIdAttributeNumber,
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OIDOID, -1, 0);
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add_var_to_tlist(rel, var);
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}
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}
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varno++;
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}
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}
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/*****************************************************************************
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*
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* QUALIFICATIONS
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*
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*****************************************************************************/
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/*
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* add_restrict_and_join_to_rels
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* Fill RestrictInfo and JoinInfo lists of relation entries for all
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* relations appearing within clauses. Creates new relation entries if
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* necessary, adding them to *query_relation_list*.
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*
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* 'clauses': the list of clauses in the cnfify'd query qualification.
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*/
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void
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add_restrict_and_join_to_rels(Query *root, List *clauses)
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{
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List *clause;
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foreach(clause, clauses)
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add_restrict_and_join_to_rel(root, (Node*) lfirst(clause));
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}
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/*
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* add_restrict_and_join_to_rel
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* Add clause information to either the 'RestrictInfo' or 'JoinInfo' field
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* (depending on whether the clause is a join) of each base relation
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* mentioned in the clause. A RestrictInfo node is created and added to
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* the appropriate list for each rel.
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*/
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static void
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add_restrict_and_join_to_rel(Query *root, Node *clause)
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{
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RestrictInfo *restrictinfo = makeNode(RestrictInfo);
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Relids relids;
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List *vars;
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restrictinfo->clause = (Expr *) clause;
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restrictinfo->subclauseindices = NIL;
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restrictinfo->mergejoinoperator = InvalidOid;
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restrictinfo->left_sortop = InvalidOid;
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restrictinfo->right_sortop = InvalidOid;
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restrictinfo->hashjoinoperator = InvalidOid;
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/*
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* Retrieve all relids and vars contained within the clause.
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*/
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clause_get_relids_vars(clause, &relids, &vars);
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if (length(relids) == 1)
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{
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/*
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* There is only one relation participating in 'clause', so
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* 'clause' must be a restriction clause for that relation.
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*/
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RelOptInfo *rel = get_base_rel(root, lfirsti(relids));
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rel->restrictinfo = lcons(restrictinfo, rel->restrictinfo);
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}
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else
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{
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/*
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* 'clause' is a join clause, since there is more than one atom in
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* the relid list. Set additional RestrictInfo fields for joining.
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*/
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set_restrictinfo_joininfo(restrictinfo);
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/*
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* Add clause to the join lists of all the relevant
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* relations. (If, perchance, 'clause' contains NO vars, then
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* nothing will happen...)
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*/
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add_join_info_to_rels(root, restrictinfo, relids);
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/*
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* Add vars used in the join clause to targetlists of member relations,
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* so that they will be emitted by the plan nodes that scan those
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* relations (else they won't be available at the join node!).
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*/
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add_vars_to_targetlist(root, vars);
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}
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}
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/*
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* add_join_info_to_rels
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* For every relation participating in a join clause, add 'restrictinfo' to
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* the appropriate joininfo list (creating a new list and adding it to the
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* appropriate rel node if necessary).
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*
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* 'restrictinfo' describes the join clause
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* 'join_relids' is the list of relations participating in the join clause
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*/
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static void
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add_join_info_to_rels(Query *root, RestrictInfo *restrictinfo,
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Relids join_relids)
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{
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List *join_relid;
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/* For every relid, find the joininfo, and add the proper join entries */
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foreach(join_relid, join_relids)
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{
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int cur_relid = lfirsti(join_relid);
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Relids unjoined_relids = NIL;
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JoinInfo *joininfo;
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List *otherrel;
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/* Get the relids not equal to the current relid */
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foreach(otherrel, join_relids)
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{
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if (lfirsti(otherrel) != cur_relid)
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unjoined_relids = lappendi(unjoined_relids, lfirsti(otherrel));
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}
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/*
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* Find or make the joininfo node for this combination of rels,
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* and add the restrictinfo node to it.
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*/
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joininfo = find_joininfo_node(get_base_rel(root, cur_relid),
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unjoined_relids);
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joininfo->jinfo_restrictinfo = lcons(restrictinfo,
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joininfo->jinfo_restrictinfo);
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}
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}
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/*****************************************************************************
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*
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* JOININFO
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*
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*****************************************************************************/
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/*
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* set_restrictinfo_joininfo
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* Examine a RestrictInfo that has been determined to be a join clause,
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* and set the merge and hash info fields if it can be merge/hash joined.
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*/
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static void
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set_restrictinfo_joininfo(RestrictInfo *restrictinfo)
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{
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if (enable_mergejoin)
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check_mergejoinable(restrictinfo);
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if (enable_hashjoin)
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check_hashjoinable(restrictinfo);
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}
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/*
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* check_mergejoinable
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* If the restrictinfo's clause is mergejoinable, set the mergejoin
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* info fields in the restrictinfo.
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*
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* Currently, we support mergejoin for binary opclauses where
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* both operands are simple Vars and the operator is a mergejoinable
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* operator. (Note: since we are only examining clauses that were
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* classified as joins, it is certain that the two Vars belong to
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* different relations... if we accepted more general clause structures
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* we might need to check that the two sides refer to different rels...)
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*/
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static void
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check_mergejoinable(RestrictInfo *restrictinfo)
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{
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Expr *clause = restrictinfo->clause;
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Var *left,
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*right;
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Oid opno,
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leftOp,
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rightOp;
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if (! is_opclause((Node *) clause))
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return;
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left = get_leftop(clause);
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right = get_rightop(clause);
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/* caution: is_opclause accepts more than I do, so check it */
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if (! right)
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return; /* unary opclauses need not apply */
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if (!IsA(left, Var) || !IsA(right, Var))
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return;
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opno = ((Oper *) clause->oper)->opno;
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if (op_mergejoinable(opno,
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left->vartype,
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right->vartype,
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&leftOp,
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&rightOp))
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{
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restrictinfo->mergejoinoperator = opno;
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restrictinfo->left_sortop = leftOp;
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restrictinfo->right_sortop = rightOp;
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}
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}
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/*
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* check_hashjoinable
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* If the restrictinfo's clause is hashjoinable, set the hashjoin
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* info fields in the restrictinfo.
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*
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* Currently, we support hashjoin for binary opclauses where
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* both operands are simple Vars and the operator is a hashjoinable
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* operator. (Note: since we are only examining clauses that were
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* classified as joins, it is certain that the two Vars belong to
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* different relations... if we accepted more general clause structures
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* we might need to check that the two sides refer to different rels...)
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*/
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static void
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check_hashjoinable(RestrictInfo *restrictinfo)
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{
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Expr *clause = restrictinfo->clause;
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Var *left,
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*right;
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Oid opno;
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if (! is_opclause((Node *) clause))
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return;
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left = get_leftop(clause);
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right = get_rightop(clause);
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/* caution: is_opclause accepts more than I do, so check it */
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if (! right)
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return; /* unary opclauses need not apply */
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if (!IsA(left, Var) || !IsA(right, Var))
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return;
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opno = ((Oper *) clause->oper)->opno;
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if (op_hashjoinable(opno,
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left->vartype,
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right->vartype))
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{
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restrictinfo->hashjoinoperator = opno;
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}
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}
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