* relnode.c
* Relation-node lookup/construction routines
*
- * Portions Copyright (c) 1996-2001, PostgreSQL Global Development Group
+ * Portions Copyright (c) 1996-2003, PostgreSQL Global Development Group
* Portions Copyright (c) 1994, Regents of the University of California
*
*
* IDENTIFICATION
- * $Header: /cvsroot/pgsql/src/backend/optimizer/util/relnode.c,v 1.32 2001/02/16 00:03:08 tgl Exp $
+ * $PostgreSQL: pgsql/src/backend/optimizer/util/relnode.c,v 1.59 2004/06/01 03:03:02 tgl Exp $
*
*-------------------------------------------------------------------------
*/
#include "optimizer/joininfo.h"
#include "optimizer/pathnode.h"
#include "optimizer/plancat.h"
+#include "optimizer/restrictinfo.h"
#include "optimizer/tlist.h"
#include "parser/parsetree.h"
-static List *new_join_tlist(List *tlist, int first_resdomno);
-static List *build_joinrel_restrictlist(RelOptInfo *joinrel,
+static RelOptInfo *make_base_rel(Query *root, int relid);
+static void build_joinrel_tlist(Query *root, RelOptInfo *joinrel);
+static List *build_joinrel_restrictlist(Query *root,
+ RelOptInfo *joinrel,
RelOptInfo *outer_rel,
- RelOptInfo *inner_rel);
+ RelOptInfo *inner_rel,
+ JoinType jointype);
static void build_joinrel_joinlist(RelOptInfo *joinrel,
RelOptInfo *outer_rel,
RelOptInfo *inner_rel);
/*
- * get_base_rel
- * Returns relation entry corresponding to 'relid', creating a new one
- * if necessary. This is for base relations.
+ * build_base_rel
+ * Construct a new base relation RelOptInfo, and put it in the query's
+ * base_rel_list.
*/
-RelOptInfo *
-get_base_rel(Query *root, int relid)
+void
+build_base_rel(Query *root, int relid)
{
- List *baserels;
+ ListCell *l;
RelOptInfo *rel;
- foreach(baserels, root->base_rel_list)
+ /* Rel should not exist already */
+ foreach(l, root->base_rel_list)
{
- rel = (RelOptInfo *) lfirst(baserels);
+ rel = (RelOptInfo *) lfirst(l);
+ if (relid == rel->relid)
+ elog(ERROR, "rel already exists");
+ }
- /*
- * We know length(rel->relids) == 1 for all members of
- * base_rel_list
- */
- if (lfirsti(rel->relids) == relid)
- return rel;
+ /* It should not exist as an "other" rel, either */
+ foreach(l, root->other_rel_list)
+ {
+ rel = (RelOptInfo *) lfirst(l);
+ if (relid == rel->relid)
+ elog(ERROR, "rel already exists as \"other\" rel");
}
/* No existing RelOptInfo for this base rel, so make a new one */
/* and add it to the list */
root->base_rel_list = lcons(rel, root->base_rel_list);
+}
+
+/*
+ * build_other_rel
+ * Returns relation entry corresponding to 'relid', creating a new one
+ * if necessary. This is for 'other' relations, which are much like
+ * base relations except that they live in a different list.
+ */
+RelOptInfo *
+build_other_rel(Query *root, int relid)
+{
+ ListCell *l;
+ RelOptInfo *rel;
+
+ /* Already made? */
+ foreach(l, root->other_rel_list)
+ {
+ rel = (RelOptInfo *) lfirst(l);
+ if (relid == rel->relid)
+ return rel;
+ }
+
+ /* It should not exist as a base rel */
+ foreach(l, root->base_rel_list)
+ {
+ rel = (RelOptInfo *) lfirst(l);
+ if (relid == rel->relid)
+ elog(ERROR, "rel already exists as base rel");
+ }
+
+ /* No existing RelOptInfo for this other rel, so make a new one */
+ rel = make_base_rel(root, relid);
+
+ /* presently, must be an inheritance child rel */
+ Assert(rel->reloptkind == RELOPT_BASEREL);
+ rel->reloptkind = RELOPT_OTHER_CHILD_REL;
+
+ /* and add it to the list */
+ root->other_rel_list = lcons(rel, root->other_rel_list);
return rel;
}
* make_base_rel
* Construct a base-relation RelOptInfo for the specified rangetable index.
*
- * This is split out of get_base_rel so that inheritance-tree processing can
- * construct baserel nodes for child tables. We need a RelOptInfo so we can
- * plan a suitable access path for each child table, but we do NOT want to
- * enter the child nodes into base_rel_list. In most contexts, get_base_rel
- * should be called instead.
+ * Common code for build_base_rel and build_other_rel.
*/
-RelOptInfo *
+static RelOptInfo *
make_base_rel(Query *root, int relid)
{
RelOptInfo *rel = makeNode(RelOptInfo);
- Oid relationObjectId;
+ RangeTblEntry *rte = rt_fetch(relid, root->rtable);
- rel->relids = makeListi1(relid);
+ rel->reloptkind = RELOPT_BASEREL;
+ rel->relids = bms_make_singleton(relid);
rel->rows = 0;
rel->width = 0;
- rel->targetlist = NIL;
+ rel->reltargetlist = NIL;
rel->pathlist = NIL;
rel->cheapest_startup_path = NULL;
rel->cheapest_total_path = NULL;
- rel->pruneable = true;
- rel->issubquery = false;
- rel->indexed = false;
+ rel->cheapest_unique_path = NULL;
+ rel->relid = relid;
+ rel->rtekind = rte->rtekind;
+ /* min_attr, max_attr, attr_needed, attr_widths are set below */
+ rel->indexlist = NIL;
rel->pages = 0;
rel->tuples = 0;
rel->subplan = NULL;
rel->baserestrictinfo = NIL;
- rel->baserestrictcost = 0;
- rel->outerjoinset = NIL;
+ rel->baserestrictcost.startup = 0;
+ rel->baserestrictcost.per_tuple = 0;
+ rel->outerjoinset = NULL;
rel->joininfo = NIL;
- rel->innerjoin = NIL;
+ rel->index_outer_relids = NULL;
+ rel->index_inner_paths = NIL;
- /* Check rtable to see if it's a plain relation or a subquery */
- relationObjectId = getrelid(relid, root->rtable);
+ /* Check type of rtable entry */
+ switch (rte->rtekind)
+ {
+ case RTE_RELATION:
+ /* Table --- retrieve statistics from the system catalogs */
+ get_relation_info(rte->relid, rel);
+ break;
+ case RTE_SUBQUERY:
+ case RTE_FUNCTION:
+ /* Subquery or function --- need only set up attr range */
+ /* Note: 0 is included in range to support whole-row Vars */
+ rel->min_attr = 0;
+ rel->max_attr = list_length(rte->eref->colnames);
+ break;
+ default:
+ elog(ERROR, "unrecognized RTE kind: %d",
+ (int) rte->rtekind);
+ break;
+ }
- if (relationObjectId != InvalidOid)
+ Assert(rel->max_attr >= rel->min_attr);
+ rel->attr_needed = (Relids *)
+ palloc0((rel->max_attr - rel->min_attr + 1) * sizeof(Relids));
+ rel->attr_widths = (int32 *)
+ palloc0((rel->max_attr - rel->min_attr + 1) * sizeof(int32));
+
+ return rel;
+}
+
+/*
+ * find_base_rel
+ * Find a base or other relation entry, which must already exist
+ * (since we'd have no idea which list to add it to).
+ */
+RelOptInfo *
+find_base_rel(Query *root, int relid)
+{
+ ListCell *l;
+ RelOptInfo *rel;
+
+ foreach(l, root->base_rel_list)
{
- /* Plain relation --- retrieve statistics from the system catalogs */
- relation_info(relationObjectId,
- &rel->indexed, &rel->pages, &rel->tuples);
+ rel = (RelOptInfo *) lfirst(l);
+ if (relid == rel->relid)
+ return rel;
}
- else
+
+ foreach(l, root->other_rel_list)
{
- /* subquery --- mark it as such for later processing */
- rel->issubquery = true;
+ rel = (RelOptInfo *) lfirst(l);
+ if (relid == rel->relid)
+ return rel;
}
- return rel;
+ elog(ERROR, "no relation entry for relid %d", relid);
+
+ return NULL; /* keep compiler quiet */
}
/*
* find_join_rel
- * Returns relation entry corresponding to 'relids' (a list of RT indexes),
+ * Returns relation entry corresponding to 'relids' (a set of RT indexes),
* or NULL if none exists. This is for join relations.
- *
- * Note: there is probably no good reason for this to be called from
- * anywhere except get_join_rel, but keep it as a separate routine
- * just in case.
*/
-static RelOptInfo *
+RelOptInfo *
find_join_rel(Query *root, Relids relids)
{
- List *joinrels;
+ ListCell *l;
- foreach(joinrels, root->join_rel_list)
+ foreach(l, root->join_rel_list)
{
- RelOptInfo *rel = (RelOptInfo *) lfirst(joinrels);
+ RelOptInfo *rel = (RelOptInfo *) lfirst(l);
- if (sameseti(rel->relids, relids))
+ if (bms_equal(rel->relids, relids))
return rel;
}
}
/*
- * get_join_rel
+ * build_join_rel
* Returns relation entry corresponding to the union of two given rels,
* creating a new relation entry if none already exists.
*
+ * 'joinrelids' is the Relids set that uniquely identifies the join
* 'outer_rel' and 'inner_rel' are relation nodes for the relations to be
* joined
* 'jointype': type of join (inner/outer)
* duplicated calculation of the restrictlist...
*/
RelOptInfo *
-get_join_rel(Query *root,
- RelOptInfo *outer_rel,
- RelOptInfo *inner_rel,
- JoinType jointype,
- List **restrictlist_ptr)
+build_join_rel(Query *root,
+ Relids joinrelids,
+ RelOptInfo *outer_rel,
+ RelOptInfo *inner_rel,
+ JoinType jointype,
+ List **restrictlist_ptr)
{
- List *joinrelids;
RelOptInfo *joinrel;
List *restrictlist;
- List *new_outer_tlist;
- List *new_inner_tlist;
-
- /* We should never try to join two overlapping sets of rels. */
- Assert(nonoverlap_setsi(outer_rel->relids, inner_rel->relids));
/*
* See if we already have a joinrel for this set of base rels.
- *
- * nconc(listCopy(x), y) is an idiom for making a new list without
- * changing either input list.
*/
- joinrelids = nconc(listCopy(outer_rel->relids), inner_rel->relids);
joinrel = find_join_rel(root, joinrelids);
if (joinrel)
{
-
/*
* Yes, so we only need to figure the restrictlist for this
* particular pair of component relations.
*/
if (restrictlist_ptr)
- *restrictlist_ptr = build_joinrel_restrictlist(joinrel,
+ *restrictlist_ptr = build_joinrel_restrictlist(root,
+ joinrel,
outer_rel,
- inner_rel);
+ inner_rel,
+ jointype);
return joinrel;
}
* Nope, so make one.
*/
joinrel = makeNode(RelOptInfo);
- joinrel->relids = joinrelids;
+ joinrel->reloptkind = RELOPT_JOINREL;
+ joinrel->relids = bms_copy(joinrelids);
joinrel->rows = 0;
joinrel->width = 0;
- joinrel->targetlist = NIL;
+ joinrel->reltargetlist = NIL;
joinrel->pathlist = NIL;
joinrel->cheapest_startup_path = NULL;
joinrel->cheapest_total_path = NULL;
- joinrel->pruneable = true;
- joinrel->issubquery = false;
- joinrel->indexed = false;
+ joinrel->cheapest_unique_path = NULL;
+ joinrel->relid = 0; /* indicates not a baserel */
+ joinrel->rtekind = RTE_JOIN;
+ joinrel->min_attr = 0;
+ joinrel->max_attr = 0;
+ joinrel->attr_needed = NULL;
+ joinrel->attr_widths = NULL;
+ joinrel->indexlist = NIL;
joinrel->pages = 0;
joinrel->tuples = 0;
joinrel->subplan = NULL;
joinrel->baserestrictinfo = NIL;
- joinrel->baserestrictcost = 0;
- joinrel->outerjoinset = NIL;
+ joinrel->baserestrictcost.startup = 0;
+ joinrel->baserestrictcost.per_tuple = 0;
+ joinrel->outerjoinset = NULL;
joinrel->joininfo = NIL;
- joinrel->innerjoin = NIL;
+ joinrel->index_outer_relids = NULL;
+ joinrel->index_inner_paths = NIL;
/*
- * Create a new tlist by removing irrelevant elements from both tlists
- * of the outer and inner join relations and then merging the results
- * together.
- *
- * NOTE: the tlist order for a join rel will depend on which pair of
- * outer and inner rels we first try to build it from. But the
- * contents should be the same regardless.
- *
- * XXX someday: consider pruning vars from the join's targetlist if they
- * are needed only to evaluate restriction clauses of this join, and
- * will never be accessed at higher levels of the plantree.
+ * Create a new tlist containing just the vars that need to be output
+ * from this join (ie, are needed for higher joinclauses or final
+ * output).
*/
- new_outer_tlist = new_join_tlist(outer_rel->targetlist, 1);
- new_inner_tlist = new_join_tlist(inner_rel->targetlist,
- length(new_outer_tlist) + 1);
- joinrel->targetlist = nconc(new_outer_tlist, new_inner_tlist);
+ build_joinrel_tlist(root, joinrel);
/*
* Construct restrict and join clause lists for the new joinrel. (The
* caller might or might not need the restrictlist, but I need it
* anyway for set_joinrel_size_estimates().)
*/
- restrictlist = build_joinrel_restrictlist(joinrel, outer_rel, inner_rel);
+ restrictlist = build_joinrel_restrictlist(root,
+ joinrel,
+ outer_rel,
+ inner_rel,
+ jointype);
if (restrictlist_ptr)
*restrictlist_ptr = restrictlist;
build_joinrel_joinlist(joinrel, outer_rel, inner_rel);
}
/*
- * new_join_tlist
- * Builds a join relation's target list by keeping those elements that
- * will be in the final target list and any other elements that are still
- * needed for future joins. For a target list entry to still be needed
- * for future joins, its 'joinlist' field must not be empty after removal
- * of all relids in 'other_relids'.
+ * build_joinrel_tlist
+ * Builds a join relation's target list.
*
- * XXX the above comment refers to code that is long dead and gone;
- * we don't keep track of joinlists for individual targetlist entries
- * anymore. For now, all vars present in either input tlist will be
- * emitted in the join's tlist.
+ * The join's targetlist includes all Vars of its member relations that
+ * will still be needed above the join.
*
- * 'tlist' is the target list of one of the join relations
- * 'first_resdomno' is the resdom number to use for the first created
- * target list entry
+ * In a former lifetime, this just merged the tlists of the two member
+ * relations first presented. While we could still do that, working from
+ * lists of Vars would mean doing a find_base_rel lookup for each Var.
+ * It seems more efficient to scan the list of base rels and collect the
+ * needed vars directly from there.
*
- * Returns the new target list.
+ * We also compute the expected width of the join's output, making use
+ * of data that was cached at the baserel level by set_rel_width().
*/
-static List *
-new_join_tlist(List *tlist,
- int first_resdomno)
+static void
+build_joinrel_tlist(Query *root, RelOptInfo *joinrel)
{
- int resdomno = first_resdomno - 1;
- List *t_list = NIL;
- List *i;
+ Relids relids = joinrel->relids;
+ ListCell *rels;
+
+ joinrel->reltargetlist = NIL;
+ joinrel->width = 0;
- foreach(i, tlist)
+ foreach(rels, root->base_rel_list)
{
- TargetEntry *xtl = lfirst(i);
+ RelOptInfo *baserel = (RelOptInfo *) lfirst(rels);
+ ListCell *vars;
- resdomno += 1;
- t_list = lappend(t_list,
- create_tl_element(get_expr(xtl), resdomno));
- }
+ if (!bms_is_member(baserel->relid, relids))
+ continue;
- return t_list;
+ foreach(vars, baserel->reltargetlist)
+ {
+ Var *var = (Var *) lfirst(vars);
+ int ndx = var->varattno - baserel->min_attr;
+
+ if (bms_nonempty_difference(baserel->attr_needed[ndx], relids))
+ {
+ joinrel->reltargetlist = lappend(joinrel->reltargetlist, var);
+ Assert(baserel->attr_widths[ndx] > 0);
+ joinrel->width += baserel->attr_widths[ndx];
+ }
+ }
+ }
}
/*
* join paths made from this pair of sub-relations. (It will not need to
* be considered further up the join tree.)
*
+ * When building a restriction list, we eliminate redundant clauses.
+ * We don't try to do that for join clause lists, since the join clauses
+ * aren't really doing anything, just waiting to become part of higher
+ * levels' restriction lists.
+ *
* 'joinrel' is a join relation node
* 'outer_rel' and 'inner_rel' are a pair of relations that can be joined
* to form joinrel.
+ * 'jointype' is the type of join used.
*
* build_joinrel_restrictlist() returns a list of relevant restrictinfos,
* whereas build_joinrel_joinlist() stores its results in the joinrel's
* the original nodes in the lists made for the join relation.
*/
static List *
-build_joinrel_restrictlist(RelOptInfo *joinrel,
+build_joinrel_restrictlist(Query *root,
+ RelOptInfo *joinrel,
RelOptInfo *outer_rel,
- RelOptInfo *inner_rel)
+ RelOptInfo *inner_rel,
+ JoinType jointype)
{
+ List *result;
+ List *rlist;
+
+ /*
+ * Collect all the clauses that syntactically belong at this level.
+ */
+ rlist = list_concat(subbuild_joinrel_restrictlist(joinrel,
+ outer_rel->joininfo),
+ subbuild_joinrel_restrictlist(joinrel,
+ inner_rel->joininfo));
/*
- * We must eliminate duplicates, since we will see the same clauses
- * arriving from both input relations...
+ * Eliminate duplicate and redundant clauses.
+ *
+ * We must eliminate duplicates, since we will see many of the same
+ * clauses arriving from both input relations. Also, if a clause is a
+ * mergejoinable clause, it's possible that it is redundant with
+ * previous clauses (see optimizer/README for discussion). We detect
+ * that case and omit the redundant clause from the result list.
*/
- return set_union(subbuild_joinrel_restrictlist(joinrel,
- outer_rel->joininfo),
- subbuild_joinrel_restrictlist(joinrel,
- inner_rel->joininfo));
+ result = remove_redundant_join_clauses(root, rlist, jointype);
+
+ list_free(rlist);
+
+ return result;
}
static void
List *joininfo_list)
{
List *restrictlist = NIL;
- List *xjoininfo;
+ ListCell *xjoininfo;
foreach(xjoininfo, joininfo_list)
{
JoinInfo *joininfo = (JoinInfo *) lfirst(xjoininfo);
- if (is_subseti(joininfo->unjoined_relids, joinrel->relids))
+ if (bms_is_subset(joininfo->unjoined_relids, joinrel->relids))
{
-
/*
* Clauses in this JoinInfo list become restriction clauses
* for the joinrel, since they refer to no outside rels.
* We must copy the list to avoid disturbing the input relation,
* but we can use a shallow copy.
*/
- restrictlist = nconc(restrictlist,
- listCopy(joininfo->jinfo_restrictinfo));
+ restrictlist = list_concat(restrictlist,
+ list_copy(joininfo->jinfo_restrictinfo));
}
else
{
-
/*
* These clauses are still join clauses at this level, so we
* ignore them in this routine.
subbuild_joinrel_joinlist(RelOptInfo *joinrel,
List *joininfo_list)
{
- List *xjoininfo;
+ ListCell *xjoininfo;
foreach(xjoininfo, joininfo_list)
{
JoinInfo *joininfo = (JoinInfo *) lfirst(xjoininfo);
Relids new_unjoined_relids;
- new_unjoined_relids = set_differencei(joininfo->unjoined_relids,
- joinrel->relids);
- if (new_unjoined_relids == NIL)
+ new_unjoined_relids = bms_difference(joininfo->unjoined_relids,
+ joinrel->relids);
+ if (bms_is_empty(new_unjoined_relids))
{
-
/*
* Clauses in this JoinInfo list become restriction clauses
* for the joinrel, since they refer to no outside rels. So we
* can ignore them in this routine.
*/
+ bms_free(new_unjoined_relids);
}
else
{
-
/*
* These clauses are still join clauses at this level, so find
* or make the appropriate JoinInfo item for the joinrel, and
- * add the clauses to it (eliminating duplicates).
+ * add the clauses to it, eliminating duplicates. (Since
+ * RestrictInfo nodes are normally multiply-linked rather than
+ * copied, pointer equality should be a sufficient test. If
+ * two equal() nodes should happen to sneak in, no great harm
+ * is done --- they'll be detected by redundant-clause testing
+ * when they reach a restriction list.)
*/
JoinInfo *new_joininfo;
- new_joininfo = find_joininfo_node(joinrel, new_unjoined_relids);
+ new_joininfo = make_joininfo_node(joinrel, new_unjoined_relids);
new_joininfo->jinfo_restrictinfo =
- set_union(new_joininfo->jinfo_restrictinfo,
- joininfo->jinfo_restrictinfo);
+ list_union_ptr(new_joininfo->jinfo_restrictinfo,
+ joininfo->jinfo_restrictinfo);
}
}
}
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