diff --git a/src/backend/optimizer/path/indxpath.c b/src/backend/optimizer/path/indxpath.c
index b6efb0fb4cd74e3c1aa795a424fc7cdc40b3d550..750515fc34819a1175990091a07c813ac7424163 100644
--- a/src/backend/optimizer/path/indxpath.c
+++ b/src/backend/optimizer/path/indxpath.c
@@ -85,13 +85,23 @@ static void consider_index_join_clauses(PlannerInfo *root, RelOptInfo *rel,
IndexClauseSet *jclauseset,
IndexClauseSet *eclauseset,
List **bitindexpaths);
-static void expand_eclass_clause_combinations(PlannerInfo *root,
- RelOptInfo *rel,
- IndexOptInfo *index,
- int thiscol, int lastcol,
- IndexClauseSet *clauseset,
- IndexClauseSet *eclauseset,
- List **bitindexpaths);
+static void consider_index_join_outer_rels(PlannerInfo *root, RelOptInfo *rel,
+ IndexOptInfo *index,
+ IndexClauseSet *rclauseset,
+ IndexClauseSet *jclauseset,
+ IndexClauseSet *eclauseset,
+ List **bitindexpaths,
+ List *indexjoinclauses,
+ List **considered_relids);
+static void get_join_index_paths(PlannerInfo *root, RelOptInfo *rel,
+ IndexOptInfo *index,
+ IndexClauseSet *rclauseset,
+ IndexClauseSet *jclauseset,
+ IndexClauseSet *eclauseset,
+ List **bitindexpaths,
+ Relids relids,
+ List **considered_relids);
+static bool bms_equal_any(Relids relids, List *relids_list);
static void get_index_paths(PlannerInfo *root, RelOptInfo *rel,
IndexOptInfo *index, IndexClauseSet *clauses,
List **bitindexpaths);
@@ -247,7 +257,7 @@ create_index_paths(PlannerInfo *root, RelOptInfo *rel)
/*
* Identify the join clauses that can match the index. For the moment
* we keep them separate from the restriction clauses. Note that this
- * finds only "loose" join clauses that have not been merged into
+ * step finds only "loose" join clauses that have not been merged into
* EquivalenceClasses. Also, collect join OR clauses for later.
*/
MemSet(&jclauseset, 0, sizeof(jclauseset));
@@ -262,8 +272,8 @@ create_index_paths(PlannerInfo *root, RelOptInfo *rel)
match_eclass_clauses_to_index(root, index, &eclauseset);
/*
- * If we found any plain or eclass join clauses, decide what to do
- * with 'em.
+ * If we found any plain or eclass join clauses, build parameterized
+ * index paths using them.
*/
if (jclauseset.nonempty || eclauseset.nonempty)
consider_index_join_clauses(root, rel, index,
@@ -314,7 +324,9 @@ create_index_paths(PlannerInfo *root, RelOptInfo *rel)
* is to generate one such path for each distinct parameterization seen
* among the available bitmap index paths. This may look pretty
* expensive, but usually there won't be very many distinct
- * parameterizations.
+ * parameterizations. (This logic is quite similar to that in
+ * consider_index_join_clauses, but we're working with whole paths not
+ * individual clauses.)
*/
if (bitjoinpaths != NIL)
{
@@ -332,28 +344,11 @@ create_index_paths(PlannerInfo *root, RelOptInfo *rel)
{
Path *path = (Path *) lfirst(lc);
Relids required_outer;
- bool found = false;
- ListCell *lco;
required_outer = get_bitmap_tree_required_outer(path);
path_outer = lappend(path_outer, required_outer);
-
- /* Have we already seen this param set? */
- foreach(lco, all_path_outers)
- {
- Relids existing_outers = (Relids) lfirst(lco);
-
- if (bms_equal(existing_outers, required_outer))
- {
- found = true;
- break;
- }
- }
- if (!found)
- {
- /* No, so add it to all_path_outers */
+ if (!bms_equal_any(required_outer, all_path_outers))
all_path_outers = lappend(all_path_outers, required_outer);
- }
}
/* Now, for each distinct parameterization set ... */
@@ -412,9 +407,6 @@ create_index_paths(PlannerInfo *root, RelOptInfo *rel)
* 'jclauseset' is the collection of indexable simple join clauses
* 'eclauseset' is the collection of indexable clauses from EquivalenceClasses
* '*bitindexpaths' is the list to add bitmap paths to
- *
- * Note: this changes the clause lists contained in the passed clausesets,
- * but we don't care since the caller is done with them.
*/
static void
consider_index_join_clauses(PlannerInfo *root, RelOptInfo *rel,
@@ -424,156 +416,223 @@ consider_index_join_clauses(PlannerInfo *root, RelOptInfo *rel,
IndexClauseSet *eclauseset,
List **bitindexpaths)
{
- IndexClauseSet clauseset;
- int last_eclass_col;
+ List *considered_relids = NIL;
int indexcol;
/*
- * We can always include any restriction clauses in the index clauses.
- * However, it's not obvious which subsets of the join clauses are worth
- * generating paths from, and it's unlikely that considering every
- * possible subset is worth the cycles. Our current heuristic is based on
- * the index columns, with the idea that later index columns are less
- * useful than earlier ones; therefore it's unlikely to be worth trying
- * combinations that would remove a clause from an earlier index column
- * while adding one to a later column. Also, we know that all the eclass
- * clauses for a particular column are redundant, so we should use only
- * one of them. However, eclass clauses will always represent equality
- * which is the strongest type of index constraint, so those are
- * high-value and we should try every available combination when we have
- * eclass clauses for more than one column. Furthermore, it's unlikely to
- * be useful to combine an eclass clause with non-eclass clauses for the
- * same index column. These considerations lead to the following
- * heuristics:
- *
- * First, start with the restriction clauses, and add on all simple join
- * clauses for column 1. If there are any such join clauses, generate
- * paths with this collection of clauses. Then, if there are eclass
- * clauses for column 1, generate paths with each one of them replacing
- * any other clauses we have for column 1.
+ * The strategy here is to identify every potentially useful set of outer
+ * rels that can provide indexable join clauses. For each such set,
+ * select all the join clauses available from those outer rels, add on all
+ * the indexable restriction clauses, and generate plain and/or bitmap
+ * index paths for that set of clauses. This is based on the assumption
+ * that it's always better to apply a clause as an indexqual than as a
+ * filter (qpqual); which is where an available clause would end up being
+ * applied if we omit it from the indexquals.
*
- * Next, add on all simple join clauses for column 2. If there are any
- * such join clauses, generate paths with this collection. If there are
- * eclass clauses for columns 1 or 2, generate paths with each such clause
- * replacing other clauses for its index column, including cases where we
- * use restriction or simple join clauses for one column and an eclass
- * clause for the other.
+ * This looks expensive, but in practical cases there won't be very many
+ * distinct sets of outer rels to consider.
*
- * Repeat for each additional index column.
+ * For simplicity in selecting relevant clauses, we represent each set of
+ * outer rels as a maximum set of clause_relids --- that is, the indexed
+ * relation itself is also included in the relids set. considered_relids
+ * lists all relids sets we've already tried.
*/
+ for (indexcol = 0; indexcol < index->ncolumns; indexcol++)
+ {
+ /* Consider each applicable simple join clause */
+ consider_index_join_outer_rels(root, rel, index,
+ rclauseset, jclauseset, eclauseset,
+ bitindexpaths,
+ jclauseset->indexclauses[indexcol],
+ &considered_relids);
+ /* Consider each applicable eclass join clause */
+ consider_index_join_outer_rels(root, rel, index,
+ rclauseset, jclauseset, eclauseset,
+ bitindexpaths,
+ eclauseset->indexclauses[indexcol],
+ &considered_relids);
+ }
+}
- /* Set up working set with just the restriction clauses */
- memcpy(&clauseset, rclauseset, sizeof(clauseset));
- /* Even if it's empty right now, it won't be by the time we use it */
- clauseset.nonempty = true;
+/*
+ * consider_index_join_outer_rels
+ * Generate parameterized paths based on clause relids in the clause list.
+ *
+ * Workhorse for consider_index_join_clauses; see notes therein for rationale.
+ *
+ * 'rel', 'index', 'rclauseset', 'jclauseset', 'eclauseset', and
+ * 'bitindexpaths' as above
+ * 'indexjoinclauses' is a list of RestrictInfos for join clauses
+ * '*considered_relids' is a list of all relids sets already considered
+ */
+static void
+consider_index_join_outer_rels(PlannerInfo *root, RelOptInfo *rel,
+ IndexOptInfo *index,
+ IndexClauseSet *rclauseset,
+ IndexClauseSet *jclauseset,
+ IndexClauseSet *eclauseset,
+ List **bitindexpaths,
+ List *indexjoinclauses,
+ List **considered_relids)
+{
+ ListCell *lc;
- last_eclass_col = -1;
- for (indexcol = 0; indexcol < index->ncolumns; indexcol++)
+ /* Examine relids of each joinclause in the given list */
+ foreach(lc, indexjoinclauses)
{
- /*
- * If we don't have either simple join clauses or eclass clauses for
- * this column, no new paths can be created in this iteration.
- */
- if (jclauseset->indexclauses[indexcol] == NIL &&
- eclauseset->indexclauses[indexcol] == NIL)
+ RestrictInfo *rinfo = (RestrictInfo *) lfirst(lc);
+ Relids clause_relids = rinfo->clause_relids;
+ ListCell *lc2;
+
+ /* If we already tried its relids set, no need to do so again */
+ if (bms_equal_any(clause_relids, *considered_relids))
continue;
- /* Add any simple join clauses to the working set */
- clauseset.indexclauses[indexcol] =
- list_concat(clauseset.indexclauses[indexcol],
- jclauseset->indexclauses[indexcol]);
+ /*
+ * Generate the union of this clause's relids set with each
+ * previously-tried set. This ensures we try this clause along with
+ * every interesting subset of previous clauses.
+ *
+ * Note: get_join_index_paths adds entries to *considered_relids, but
+ * it prepends them to the list, so that we won't visit new entries
+ * during the inner foreach loop. No real harm would be done if we
+ * did, since the subset check would reject them; but it would waste
+ * some cycles.
+ */
+ foreach(lc2, *considered_relids)
+ {
+ Relids oldrelids = (Relids) lfirst(lc2);
- /* Set recursion depth to reach last col with eclass clauses */
- if (eclauseset->indexclauses[indexcol] != NIL)
- last_eclass_col = indexcol;
+ /*
+ * If either is a subset of the other, no new set is possible.
+ * This isn't a complete test for redundancy, but it's easy and
+ * cheap. get_join_index_paths will check more carefully if we
+ * already generated the same relids set.
+ */
+ if (bms_subset_compare(clause_relids, oldrelids) != BMS_DIFFERENT)
+ continue;
- /* Do we have eclass clauses for any column now under consideration? */
- if (last_eclass_col >= 0)
- {
- /* Yes, so recursively generate all eclass clause combinations */
- expand_eclass_clause_combinations(root, rel, index,
- 0, last_eclass_col,
- &clauseset, eclauseset,
- bitindexpaths);
- }
- else
- {
- /* No, consider the newly-enlarged set of simple join clauses */
- get_index_paths(root, rel, index, &clauseset, bitindexpaths);
+ /* OK, try the union set */
+ get_join_index_paths(root, rel, index,
+ rclauseset, jclauseset, eclauseset,
+ bitindexpaths,
+ bms_union(clause_relids, oldrelids),
+ considered_relids);
}
+
+ /* Also try this set of relids by itself */
+ get_join_index_paths(root, rel, index,
+ rclauseset, jclauseset, eclauseset,
+ bitindexpaths,
+ clause_relids,
+ considered_relids);
}
}
/*
- * expand_eclass_clause_combinations
- * Generate all combinations of eclass join clauses for first N columns,
- * and construct parameterized index paths for each combination.
+ * get_join_index_paths
+ * Generate index paths using clauses from the specified outer relations.
+ * In addition to generating paths, relids is added to *considered_relids
+ * if not already present.
*
* Workhorse for consider_index_join_clauses; see notes therein for rationale.
- * It's convenient to use recursion to implement the enumeration, since we
- * can have at most INDEX_MAX_KEYS recursion levels.
*
- * 'rel', 'index', 'eclauseset', 'bitindexpaths' as above
- * 'thiscol' is the current index column number/recursion level
- * 'lastcol' is the last index column we should consider eclass clauses for
- * 'clauseset' is the current collection of indexable clauses
+ * 'rel', 'index', 'rclauseset', 'jclauseset', 'eclauseset',
+ * 'bitindexpaths', 'considered_relids' as above
+ * 'relids' is the current set of relids to consider (the target rel plus
+ * one or more outer rels)
*/
static void
-expand_eclass_clause_combinations(PlannerInfo *root, RelOptInfo *rel,
- IndexOptInfo *index,
- int thiscol, int lastcol,
- IndexClauseSet *clauseset,
- IndexClauseSet *eclauseset,
- List **bitindexpaths)
+get_join_index_paths(PlannerInfo *root, RelOptInfo *rel,
+ IndexOptInfo *index,
+ IndexClauseSet *rclauseset,
+ IndexClauseSet *jclauseset,
+ IndexClauseSet *eclauseset,
+ List **bitindexpaths,
+ Relids relids,
+ List **considered_relids)
{
- List *save_clauses;
- ListCell *lc;
+ IndexClauseSet clauseset;
+ int indexcol;
- /* If past last eclass column, end the recursion and generate paths */
- if (thiscol > lastcol)
- {
- get_index_paths(root, rel, index, clauseset, bitindexpaths);
+ /* If we already considered this relids set, don't repeat the work */
+ if (bms_equal_any(relids, *considered_relids))
return;
- }
- /* If no eclass clauses to consider for this column, just recurse */
- if (eclauseset->indexclauses[thiscol] == NIL)
+ /* Identify indexclauses usable with this relids set */
+ MemSet(&clauseset, 0, sizeof(clauseset));
+
+ for (indexcol = 0; indexcol < index->ncolumns; indexcol++)
{
- Assert(thiscol < lastcol);
- expand_eclass_clause_combinations(root, rel, index,
- thiscol + 1, lastcol,
- clauseset, eclauseset,
- bitindexpaths);
- return;
- }
+ ListCell *lc;
- /* We'll momentarily save and restore the list of non-eclass clauses */
- save_clauses = clauseset->indexclauses[thiscol];
+ /* First find applicable simple join clauses */
+ foreach(lc, jclauseset->indexclauses[indexcol])
+ {
+ RestrictInfo *rinfo = (RestrictInfo *) lfirst(lc);
- /* If we have non-eclass clauses for this column, first try with those */
- if (save_clauses)
- expand_eclass_clause_combinations(root, rel, index,
- thiscol + 1, lastcol,
- clauseset, eclauseset,
- bitindexpaths);
+ if (bms_is_subset(rinfo->clause_relids, relids))
+ clauseset.indexclauses[indexcol] =
+ lappend(clauseset.indexclauses[indexcol], rinfo);
+ }
- /* For each eclass clause alternative ... */
- foreach(lc, eclauseset->indexclauses[thiscol])
- {
- RestrictInfo *rinfo = (RestrictInfo *) lfirst(lc);
+ /*
+ * Add applicable eclass join clauses. The clauses generated for each
+ * column are redundant (cf generate_implied_equalities_for_indexcol),
+ * so we need at most one. This is the only exception to the general
+ * rule of using all available index clauses.
+ */
+ foreach(lc, eclauseset->indexclauses[indexcol])
+ {
+ RestrictInfo *rinfo = (RestrictInfo *) lfirst(lc);
+
+ if (bms_is_subset(rinfo->clause_relids, relids))
+ {
+ clauseset.indexclauses[indexcol] =
+ lappend(clauseset.indexclauses[indexcol], rinfo);
+ break;
+ }
+ }
- /* Replace any existing clauses with the eclass clause */
- clauseset->indexclauses[thiscol] = list_make1(rinfo);
+ /* Add restriction clauses (this is nondestructive to rclauseset) */
+ clauseset.indexclauses[indexcol] =
+ list_concat(clauseset.indexclauses[indexcol],
+ rclauseset->indexclauses[indexcol]);
- /* Recurse to advance to next column */
- expand_eclass_clause_combinations(root, rel, index,
- thiscol + 1, lastcol,
- clauseset, eclauseset,
- bitindexpaths);
+ if (clauseset.indexclauses[indexcol] != NIL)
+ clauseset.nonempty = true;
}
- /* Restore previous list contents */
- clauseset->indexclauses[thiscol] = save_clauses;
+ /* We should have found something, else caller passed silly relids */
+ Assert(clauseset.nonempty);
+
+ /* Build index path(s) using the collected set of clauses */
+ get_index_paths(root, rel, index, &clauseset, bitindexpaths);
+
+ /*
+ * Remember we considered paths for this set of relids. We use lcons not
+ * lappend to avoid confusing the loop in consider_index_join_outer_rels.
+ */
+ *considered_relids = lcons(relids, *considered_relids);
+}
+
+/*
+ * bms_equal_any
+ * True if relids is bms_equal to any member of relids_list
+ *
+ * Perhaps this should be in bitmapset.c someday.
+ */
+static bool
+bms_equal_any(Relids relids, List *relids_list)
+{
+ ListCell *lc;
+
+ foreach(lc, relids_list)
+ {
+ if (bms_equal(relids, (Relids) lfirst(lc)))
+ return true;
+ }
+ return false;
}
diff --git a/src/test/regress/expected/join.out b/src/test/regress/expected/join.out
index 876b08a517c036243e6d527ab14846dfc9e7162f..624b7455f365fd1b49c582a368e692cc2f584f74 100644
--- a/src/test/regress/expected/join.out
+++ b/src/test/regress/expected/join.out
@@ -2804,17 +2804,17 @@ select b.unique1 from
Sort Key: b.unique1
-> Nested Loop Left Join
-> Seq Scan on int4_tbl i2
- -> Nested Loop
- -> Seq Scan on int4_tbl i1
- -> Nested Loop Left Join
- Join Filter: (b.unique1 = 42)
+ -> Nested Loop Left Join
+ Join Filter: (b.unique1 = 42)
+ -> Nested Loop
-> Nested Loop
+ -> Seq Scan on int4_tbl i1
-> Index Scan using tenk1_thous_tenthous on tenk1 b
Index Cond: ((thousand = i1.f1) AND (i2.f1 = tenthous))
- -> Index Scan using tenk1_unique1 on tenk1 a
- Index Cond: (unique1 = b.unique2)
- -> Index Only Scan using tenk1_thous_tenthous on tenk1 c
- Index Cond: (thousand = a.thousand)
+ -> Index Scan using tenk1_unique1 on tenk1 a
+ Index Cond: (unique1 = b.unique2)
+ -> Index Only Scan using tenk1_thous_tenthous on tenk1 c
+ Index Cond: (thousand = a.thousand)
(15 rows)
select b.unique1 from