diff options
Diffstat (limited to 'src/backend/optimizer')
| -rw-r--r-- | src/backend/optimizer/path/joinrels.c | 40 | ||||
| -rw-r--r-- | src/backend/optimizer/plan/analyzejoins.c | 83 | ||||
| -rw-r--r-- | src/backend/optimizer/util/joininfo.c | 36 |
3 files changed, 129 insertions, 30 deletions
diff --git a/src/backend/optimizer/path/joinrels.c b/src/backend/optimizer/path/joinrels.c index e781ad5c1a8..3b65940c298 100644 --- a/src/backend/optimizer/path/joinrels.c +++ b/src/backend/optimizer/path/joinrels.c @@ -8,7 +8,7 @@ * * * IDENTIFICATION - * $PostgreSQL: pgsql/src/backend/optimizer/path/joinrels.c,v 1.105 2010/02/26 02:00:45 momjian Exp $ + * $PostgreSQL: pgsql/src/backend/optimizer/path/joinrels.c,v 1.105.4.1 2010/09/14 23:15:36 tgl Exp $ * *------------------------------------------------------------------------- */ @@ -29,7 +29,8 @@ static bool has_join_restriction(PlannerInfo *root, RelOptInfo *rel); static bool has_legal_joinclause(PlannerInfo *root, RelOptInfo *rel); static bool is_dummy_rel(RelOptInfo *rel); static void mark_dummy_rel(RelOptInfo *rel); -static bool restriction_is_constant_false(List *restrictlist); +static bool restriction_is_constant_false(List *restrictlist, + bool only_pushed_down); /* @@ -603,7 +604,10 @@ make_join_rel(PlannerInfo *root, RelOptInfo *rel1, RelOptInfo *rel2) * * Also, a provably constant-false join restriction typically means that * we can skip evaluating one or both sides of the join. We do this by - * marking the appropriate rel as dummy. + * marking the appropriate rel as dummy. For outer joins, a constant-false + * restriction that is pushed down still means the whole join is dummy, + * while a non-pushed-down one means that no inner rows will join so we + * can treat the inner rel as dummy. * * We need only consider the jointypes that appear in join_info_list, plus * JOIN_INNER. @@ -612,7 +616,7 @@ make_join_rel(PlannerInfo *root, RelOptInfo *rel1, RelOptInfo *rel2) { case JOIN_INNER: if (is_dummy_rel(rel1) || is_dummy_rel(rel2) || - restriction_is_constant_false(restrictlist)) + restriction_is_constant_false(restrictlist, false)) { mark_dummy_rel(joinrel); break; @@ -625,12 +629,13 @@ make_join_rel(PlannerInfo *root, RelOptInfo *rel1, RelOptInfo *rel2) restrictlist); break; case JOIN_LEFT: - if (is_dummy_rel(rel1)) + if (is_dummy_rel(rel1) || + restriction_is_constant_false(restrictlist, true)) { mark_dummy_rel(joinrel); break; } - if (restriction_is_constant_false(restrictlist) && + if (restriction_is_constant_false(restrictlist, false) && bms_is_subset(rel2->relids, sjinfo->syn_righthand)) mark_dummy_rel(rel2); add_paths_to_joinrel(root, joinrel, rel1, rel2, @@ -641,7 +646,8 @@ make_join_rel(PlannerInfo *root, RelOptInfo *rel1, RelOptInfo *rel2) restrictlist); break; case JOIN_FULL: - if (is_dummy_rel(rel1) && is_dummy_rel(rel2)) + if ((is_dummy_rel(rel1) && is_dummy_rel(rel2)) || + restriction_is_constant_false(restrictlist, true)) { mark_dummy_rel(joinrel); break; @@ -665,7 +671,7 @@ make_join_rel(PlannerInfo *root, RelOptInfo *rel1, RelOptInfo *rel2) bms_is_subset(sjinfo->min_righthand, rel2->relids)) { if (is_dummy_rel(rel1) || is_dummy_rel(rel2) || - restriction_is_constant_false(restrictlist)) + restriction_is_constant_false(restrictlist, false)) { mark_dummy_rel(joinrel); break; @@ -687,6 +693,12 @@ make_join_rel(PlannerInfo *root, RelOptInfo *rel1, RelOptInfo *rel2) create_unique_path(root, rel2, rel2->cheapest_total_path, sjinfo) != NULL) { + if (is_dummy_rel(rel1) || is_dummy_rel(rel2) || + restriction_is_constant_false(restrictlist, false)) + { + mark_dummy_rel(joinrel); + break; + } add_paths_to_joinrel(root, joinrel, rel1, rel2, JOIN_UNIQUE_INNER, sjinfo, restrictlist); @@ -696,12 +708,13 @@ make_join_rel(PlannerInfo *root, RelOptInfo *rel1, RelOptInfo *rel2) } break; case JOIN_ANTI: - if (is_dummy_rel(rel1)) + if (is_dummy_rel(rel1) || + restriction_is_constant_false(restrictlist, true)) { mark_dummy_rel(joinrel); break; } - if (restriction_is_constant_false(restrictlist) && + if (restriction_is_constant_false(restrictlist, false) && bms_is_subset(rel2->relids, sjinfo->syn_righthand)) mark_dummy_rel(rel2); add_paths_to_joinrel(root, joinrel, rel1, rel2, @@ -947,9 +960,11 @@ mark_dummy_rel(RelOptInfo *rel) * join situations this will leave us computing cartesian products only to * decide there's no match for an outer row, which is pretty stupid. So, * we need to detect the case. + * + * If only_pushed_down is TRUE, then consider only pushed-down quals. */ static bool -restriction_is_constant_false(List *restrictlist) +restriction_is_constant_false(List *restrictlist, bool only_pushed_down) { ListCell *lc; @@ -964,6 +979,9 @@ restriction_is_constant_false(List *restrictlist) RestrictInfo *rinfo = (RestrictInfo *) lfirst(lc); Assert(IsA(rinfo, RestrictInfo)); + if (only_pushed_down && !rinfo->is_pushed_down) + continue; + if (rinfo->clause && IsA(rinfo->clause, Const)) { Const *con = (Const *) rinfo->clause; diff --git a/src/backend/optimizer/plan/analyzejoins.c b/src/backend/optimizer/plan/analyzejoins.c index 0d90d072eaa..5fc056e2a57 100644 --- a/src/backend/optimizer/plan/analyzejoins.c +++ b/src/backend/optimizer/plan/analyzejoins.c @@ -16,19 +16,21 @@ * * * IDENTIFICATION - * $PostgreSQL: pgsql/src/backend/optimizer/plan/analyzejoins.c,v 1.3 2010/07/06 19:18:56 momjian Exp $ + * $PostgreSQL: pgsql/src/backend/optimizer/plan/analyzejoins.c,v 1.3.2.1 2010/09/14 23:15:36 tgl Exp $ * *------------------------------------------------------------------------- */ #include "postgres.h" +#include "optimizer/joininfo.h" #include "optimizer/pathnode.h" #include "optimizer/paths.h" #include "optimizer/planmain.h" /* local functions */ static bool join_is_removable(PlannerInfo *root, SpecialJoinInfo *sjinfo); -static void remove_rel_from_query(PlannerInfo *root, int relid); +static void remove_rel_from_query(PlannerInfo *root, int relid, + Relids joinrelids); static List *remove_rel_from_joinlist(List *joinlist, int relid, int *nremoved); @@ -67,7 +69,9 @@ restart: */ innerrelid = bms_singleton_member(sjinfo->min_righthand); - remove_rel_from_query(root, innerrelid); + remove_rel_from_query(root, innerrelid, + bms_union(sjinfo->min_lefthand, + sjinfo->min_righthand)); /* We verify that exactly one reference gets removed from joinlist */ nremoved = 0; @@ -216,19 +220,25 @@ join_is_removable(PlannerInfo *root, SpecialJoinInfo *sjinfo) { RestrictInfo *restrictinfo = (RestrictInfo *) lfirst(l); - /* Ignore clauses not pertinent to this join */ - if (!bms_is_subset(restrictinfo->required_relids, joinrelids)) - continue; - /* - * If we find a pushed-down clause, it must have come from above the - * outer join and it must contain references to the inner rel. (If it - * had only outer-rel variables, it'd have been pushed down into the - * outer rel.) Therefore, we can conclude that join removal is unsafe - * without any examination of the clause contents. + * If it's not a join clause for this outer join, we can't use it. + * Note that if the clause is pushed-down, then it is logically from + * above the outer join, even if it references no other rels (it might + * be from WHERE, for example). */ - if (restrictinfo->is_pushed_down) - return false; + if (restrictinfo->is_pushed_down || + !bms_equal(restrictinfo->required_relids, joinrelids)) + { + /* + * If such a clause actually references the inner rel then + * join removal has to be disallowed. We have to check this + * despite the previous attr_needed checks because of the + * possibility of pushed-down clauses referencing the rel. + */ + if (bms_is_member(innerrelid, restrictinfo->clause_relids)) + return false; + continue; /* else, ignore; not useful here */ + } /* Ignore if it's not a mergejoinable clause */ if (!restrictinfo->can_join || @@ -299,14 +309,14 @@ join_is_removable(PlannerInfo *root, SpecialJoinInfo *sjinfo) * We are not terribly thorough here. We must make sure that the rel is * no longer treated as a baserel, and that attributes of other baserels * are no longer marked as being needed at joins involving this rel. - * In particular, we don't bother removing join quals involving the rel from - * the joininfo lists; they'll just get ignored, since we will never form a - * join relation at which they could be evaluated. + * Also, join quals involving the rel have to be removed from the joininfo + * lists, but only if they belong to the outer join identified by joinrelids. */ static void -remove_rel_from_query(PlannerInfo *root, int relid) +remove_rel_from_query(PlannerInfo *root, int relid, Relids joinrelids) { RelOptInfo *rel = find_base_rel(root, relid); + List *joininfos; Index rti; ListCell *l; @@ -379,6 +389,43 @@ remove_rel_from_query(PlannerInfo *root, int relid) phinfo->ph_needed = bms_del_member(phinfo->ph_needed, relid); } + + /* + * Remove any joinquals referencing the rel from the joininfo lists. + * + * In some cases, a joinqual has to be put back after deleting its + * reference to the target rel. This can occur for pseudoconstant and + * outerjoin-delayed quals, which can get marked as requiring the rel in + * order to force them to be evaluated at or above the join. We can't + * just discard them, though. Only quals that logically belonged to the + * outer join being discarded should be removed from the query. + * + * We must make a copy of the rel's old joininfo list before starting the + * loop, because otherwise remove_join_clause_from_rels would destroy the + * list while we're scanning it. + */ + joininfos = list_copy(rel->joininfo); + foreach(l, joininfos) + { + RestrictInfo *rinfo = (RestrictInfo *) lfirst(l); + + remove_join_clause_from_rels(root, rinfo, rinfo->required_relids); + + if (rinfo->is_pushed_down || + !bms_equal(rinfo->required_relids, joinrelids)) + { + /* Recheck that qual doesn't actually reference the target rel */ + Assert(!bms_is_member(relid, rinfo->clause_relids)); + /* + * The required_relids probably aren't shared with anything else, + * but let's copy them just to be sure. + */ + rinfo->required_relids = bms_copy(rinfo->required_relids); + rinfo->required_relids = bms_del_member(rinfo->required_relids, + relid); + distribute_restrictinfo_to_rels(root, rinfo); + } + } } /* diff --git a/src/backend/optimizer/util/joininfo.c b/src/backend/optimizer/util/joininfo.c index b03045d657d..af1eccecb5d 100644 --- a/src/backend/optimizer/util/joininfo.c +++ b/src/backend/optimizer/util/joininfo.c @@ -8,7 +8,7 @@ * * * IDENTIFICATION - * $PostgreSQL: pgsql/src/backend/optimizer/util/joininfo.c,v 1.52 2010/01/02 16:57:48 momjian Exp $ + * $PostgreSQL: pgsql/src/backend/optimizer/util/joininfo.c,v 1.52.6.1 2010/09/14 23:15:36 tgl Exp $ * *------------------------------------------------------------------------- */ @@ -98,3 +98,37 @@ add_join_clause_to_rels(PlannerInfo *root, } bms_free(tmprelids); } + +/* + * remove_join_clause_from_rels + * Delete 'restrictinfo' from all the joininfo lists it is in + * + * This reverses the effect of add_join_clause_to_rels. It's used when we + * discover that a relation need not be joined at all. + * + * 'restrictinfo' describes the join clause + * 'join_relids' is the list of relations participating in the join clause + * (there must be more than one) + */ +void +remove_join_clause_from_rels(PlannerInfo *root, + RestrictInfo *restrictinfo, + Relids join_relids) +{ + Relids tmprelids; + int cur_relid; + + tmprelids = bms_copy(join_relids); + while ((cur_relid = bms_first_member(tmprelids)) >= 0) + { + RelOptInfo *rel = find_base_rel(root, cur_relid); + + /* + * Remove the restrictinfo from the list. Pointer comparison is + * sufficient. + */ + Assert(list_member_ptr(rel->joininfo, restrictinfo)); + rel->joininfo = list_delete_ptr(rel->joininfo, restrictinfo); + } + bms_free(tmprelids); +} |