diff options
Diffstat (limited to 'src/backend/optimizer')
| -rw-r--r-- | src/backend/optimizer/path/allpaths.c | 21 | ||||
| -rw-r--r-- | src/backend/optimizer/path/joinrels.c | 33 | ||||
| -rw-r--r-- | src/backend/optimizer/plan/createplan.c | 11 | ||||
| -rw-r--r-- | src/backend/optimizer/plan/planner.c | 148 |
4 files changed, 121 insertions, 92 deletions
diff --git a/src/backend/optimizer/path/allpaths.c b/src/backend/optimizer/path/allpaths.c index f8f4e0b68f3..2091f715d32 100644 --- a/src/backend/optimizer/path/allpaths.c +++ b/src/backend/optimizer/path/allpaths.c @@ -1607,7 +1607,7 @@ add_paths_to_append_rel(PlannerInfo *root, RelOptInfo *rel, * Consider an append of unordered, unparameterized partial paths. Make * it parallel-aware if possible. */ - if (partial_subpaths_valid) + if (partial_subpaths_valid && partial_subpaths != NIL) { AppendPath *appendpath; ListCell *lc; @@ -2004,9 +2004,11 @@ accumulate_append_subpath(Path *path, List **subpaths, List **special_subpaths) * Build a dummy path for a relation that's been excluded by constraints * * Rather than inventing a special "dummy" path type, we represent this as an - * AppendPath with no members (see also IS_DUMMY_PATH/IS_DUMMY_REL macros). + * AppendPath with no members (see also IS_DUMMY_APPEND/IS_DUMMY_REL macros). * - * This is exported because inheritance_planner() has need for it. + * (See also mark_dummy_rel, which does basically the same thing, but is + * typically used to change a rel into dummy state after we already made + * paths for it.) */ void set_dummy_rel_pathlist(RelOptInfo *rel) @@ -2019,14 +2021,15 @@ set_dummy_rel_pathlist(RelOptInfo *rel) rel->pathlist = NIL; rel->partial_pathlist = NIL; + /* Set up the dummy path */ add_path(rel, (Path *) create_append_path(NULL, rel, NIL, NIL, NULL, 0, false, NIL, -1)); /* - * We set the cheapest path immediately, to ensure that IS_DUMMY_REL() - * will recognize the relation as dummy if anyone asks. This is redundant - * when we're called from set_rel_size(), but not when called from - * elsewhere, and doing it twice is harmless anyway. + * We set the cheapest-path fields immediately, just in case they were + * pointing at some discarded path. This is redundant when we're called + * from set_rel_size(), but not when called from elsewhere, and doing it + * twice is harmless anyway. */ set_cheapest(rel); } @@ -3552,12 +3555,12 @@ generate_partitionwise_join_paths(PlannerInfo *root, RelOptInfo *rel) /* Add partitionwise join paths for partitioned child-joins. */ generate_partitionwise_join_paths(root, child_rel); + set_cheapest(child_rel); + /* Dummy children will not be scanned, so ignore those. */ if (IS_DUMMY_REL(child_rel)) continue; - set_cheapest(child_rel); - #ifdef OPTIMIZER_DEBUG debug_print_rel(root, child_rel); #endif diff --git a/src/backend/optimizer/path/joinrels.c b/src/backend/optimizer/path/joinrels.c index 6ddf8461257..50fc0c500d0 100644 --- a/src/backend/optimizer/path/joinrels.c +++ b/src/backend/optimizer/path/joinrels.c @@ -33,7 +33,6 @@ static void make_rels_by_clauseless_joins(PlannerInfo *root, ListCell *other_rels); 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 bool restriction_is_constant_false(List *restrictlist, RelOptInfo *joinrel, bool only_pushed_down); @@ -1192,10 +1191,38 @@ have_dangerous_phv(PlannerInfo *root, /* * is_dummy_rel --- has relation been proven empty? */ -static bool +bool is_dummy_rel(RelOptInfo *rel) { - return IS_DUMMY_REL(rel); + Path *path; + + /* + * A rel that is known dummy will have just one path that is a childless + * Append. (Even if somehow it has more paths, a childless Append will + * have cost zero and hence should be at the front of the pathlist.) + */ + if (rel->pathlist == NIL) + return false; + path = (Path *) linitial(rel->pathlist); + + /* + * Initially, a dummy path will just be a childless Append. But in later + * planning stages we might stick a ProjectSetPath and/or ProjectionPath + * on top, since Append can't project. Rather than make assumptions about + * which combinations can occur, just descend through whatever we find. + */ + for (;;) + { + if (IsA(path, ProjectionPath)) + path = ((ProjectionPath *) path)->subpath; + else if (IsA(path, ProjectSetPath)) + path = ((ProjectSetPath *) path)->subpath; + else + break; + } + if (IS_DUMMY_APPEND(path)) + return true; + return false; } /* diff --git a/src/backend/optimizer/plan/createplan.c b/src/backend/optimizer/plan/createplan.c index c225e61be96..ae51c0e0b0c 100644 --- a/src/backend/optimizer/plan/createplan.c +++ b/src/backend/optimizer/plan/createplan.c @@ -1038,7 +1038,7 @@ create_append_plan(PlannerInfo *root, AppendPath *best_path) * * Note that an AppendPath with no members is also generated in certain * cases where there was no appending construct at all, but we know the - * relation is empty (see set_dummy_rel_pathlist). + * relation is empty (see set_dummy_rel_pathlist and mark_dummy_rel). */ if (best_path->subpaths == NIL) { @@ -6506,12 +6506,11 @@ is_projection_capable_path(Path *path) case T_Append: /* - * Append can't project, but if it's being used to represent a - * dummy path, claim that it can project. This prevents us from - * converting a rel from dummy to non-dummy status by applying a - * projection to its dummy path. + * Append can't project, but if an AppendPath is being used to + * represent a dummy path, what will actually be generated is a + * Result which can project. */ - return IS_DUMMY_PATH(path); + return IS_DUMMY_APPEND(path); case T_ProjectSet: /* diff --git a/src/backend/optimizer/plan/planner.c b/src/backend/optimizer/plan/planner.c index bbf355dbf2c..680085096ae 100644 --- a/src/backend/optimizer/plan/planner.c +++ b/src/backend/optimizer/plan/planner.c @@ -1495,7 +1495,7 @@ inheritance_planner(PlannerInfo *root) * If this child rel was excluded by constraint exclusion, exclude it * from the result plan. */ - if (IS_DUMMY_PATH(subpath)) + if (IS_DUMMY_REL(sub_final_rel)) continue; /* @@ -3987,12 +3987,10 @@ create_ordinary_grouping_paths(PlannerInfo *root, RelOptInfo *input_rel, * If this is the topmost grouping relation or if the parent relation is * doing some form of partitionwise aggregation, then we may be able to do * it at this level also. However, if the input relation is not - * partitioned, partitionwise aggregate is impossible, and if it is dummy, - * partitionwise aggregate is pointless. + * partitioned, partitionwise aggregate is impossible. */ if (extra->patype != PARTITIONWISE_AGGREGATE_NONE && - input_rel->part_scheme && input_rel->part_rels && - !IS_DUMMY_REL(input_rel)) + IS_PARTITIONED_REL(input_rel)) { /* * If this is the topmost relation or if the parent relation is doing @@ -6817,27 +6815,48 @@ apply_scanjoin_target_to_paths(PlannerInfo *root, bool scanjoin_target_parallel_safe, bool tlist_same_exprs) { - ListCell *lc; + bool rel_is_partitioned = IS_PARTITIONED_REL(rel); PathTarget *scanjoin_target; - bool is_dummy_rel = IS_DUMMY_REL(rel); + ListCell *lc; + /* This recurses, so be paranoid. */ check_stack_depth(); /* + * If the rel is partitioned, we want to drop its existing paths and + * generate new ones. This function would still be correct if we kept the + * existing paths: we'd modify them to generate the correct target above + * the partitioning Append, and then they'd compete on cost with paths + * generating the target below the Append. However, in our current cost + * model the latter way is always the same or cheaper cost, so modifying + * the existing paths would just be useless work. Moreover, when the cost + * is the same, varying roundoff errors might sometimes allow an existing + * path to be picked, resulting in undesirable cross-platform plan + * variations. So we drop old paths and thereby force the work to be done + * below the Append, except in the case of a non-parallel-safe target. + * + * Some care is needed, because we have to allow generate_gather_paths to + * see the old partial paths in the next stanza. Hence, zap the main + * pathlist here, then allow generate_gather_paths to add path(s) to the + * main list, and finally zap the partial pathlist. + */ + if (rel_is_partitioned) + rel->pathlist = NIL; + + /* * If the scan/join target is not parallel-safe, partial paths cannot * generate it. */ if (!scanjoin_target_parallel_safe) { /* - * Since we can't generate the final scan/join target, this is our - * last opportunity to use any partial paths that exist. We don't do - * this if the case where the target is parallel-safe, since we will - * be able to generate superior paths by doing it after the final - * scan/join target has been applied. - * - * Note that this may invalidate rel->cheapest_total_path, so we must - * not rely on it after this point without first calling set_cheapest. + * Since we can't generate the final scan/join target in parallel + * workers, this is our last opportunity to use any partial paths that + * exist; so build Gather path(s) that use them and emit whatever the + * current reltarget is. We don't do this in the case where the + * target is parallel-safe, since we will be able to generate superior + * paths by doing it after the final scan/join target has been + * applied. */ generate_gather_paths(root, rel, false); @@ -6846,61 +6865,27 @@ apply_scanjoin_target_to_paths(PlannerInfo *root, rel->consider_parallel = false; } - /* - * Update the reltarget. This may not be strictly necessary in all cases, - * but it is at least necessary when create_append_path() gets called - * below directly or indirectly, since that function uses the reltarget as - * the pathtarget for the resulting path. It seems like a good idea to do - * it unconditionally. - */ - rel->reltarget = llast_node(PathTarget, scanjoin_targets); - - /* Special case: handle dummy relations separately. */ - if (is_dummy_rel) - { - /* - * Since this is a dummy rel, it's got a single Append path with no - * child paths. Replace it with a new path having the final scan/join - * target. (Note that since Append is not projection-capable, it - * would be bad to handle this using the general purpose code below; - * we'd end up putting a ProjectionPath on top of the existing Append - * node, which would cause this relation to stop appearing to be a - * dummy rel.) - */ - rel->pathlist = list_make1(create_append_path(root, rel, NIL, NIL, - NULL, 0, false, NIL, - -1)); + /* Finish dropping old paths for a partitioned rel, per comment above */ + if (rel_is_partitioned) rel->partial_pathlist = NIL; - set_cheapest(rel); - Assert(IS_DUMMY_REL(rel)); - - /* - * Forget about any child relations. There's no point in adjusting - * them and no point in using them for later planning stages (in - * particular, partitionwise aggregate). - */ - rel->nparts = 0; - rel->part_rels = NULL; - rel->boundinfo = NULL; - - return; - } /* Extract SRF-free scan/join target. */ scanjoin_target = linitial_node(PathTarget, scanjoin_targets); /* - * Adjust each input path. If the tlist exprs are the same, we can just - * inject the sortgroupref information into the existing pathtarget. - * Otherwise, replace each path with a projection path that generates the - * SRF-free scan/join target. This can't change the ordering of paths - * within rel->pathlist, so we just modify the list in place. + * Apply the SRF-free scan/join target to each existing path. + * + * If the tlist exprs are the same, we can just inject the sortgroupref + * information into the existing pathtargets. Otherwise, replace each + * path with a projection path that generates the SRF-free scan/join + * target. This can't change the ordering of paths within rel->pathlist, + * so we just modify the list in place. */ foreach(lc, rel->pathlist) { Path *subpath = (Path *) lfirst(lc); - Path *newpath; + /* Shouldn't have any parameterized paths anymore */ Assert(subpath->param_info == NULL); if (tlist_same_exprs) @@ -6908,17 +6893,18 @@ apply_scanjoin_target_to_paths(PlannerInfo *root, scanjoin_target->sortgrouprefs; else { + Path *newpath; + newpath = (Path *) create_projection_path(root, rel, subpath, scanjoin_target); lfirst(lc) = newpath; } } - /* Same for partial paths. */ + /* Likewise adjust the targets for any partial paths. */ foreach(lc, rel->partial_pathlist) { Path *subpath = (Path *) lfirst(lc); - Path *newpath; /* Shouldn't have any parameterized paths anymore */ Assert(subpath->param_info == NULL); @@ -6928,39 +6914,54 @@ apply_scanjoin_target_to_paths(PlannerInfo *root, scanjoin_target->sortgrouprefs; else { - newpath = (Path *) create_projection_path(root, - rel, - subpath, + Path *newpath; + + newpath = (Path *) create_projection_path(root, rel, subpath, scanjoin_target); lfirst(lc) = newpath; } } - /* Now fix things up if scan/join target contains SRFs */ + /* + * Now, if final scan/join target contains SRFs, insert ProjectSetPath(s) + * atop each existing path. (Note that this function doesn't look at the + * cheapest-path fields, which is a good thing because they're bogus right + * now.) + */ if (root->parse->hasTargetSRFs) adjust_paths_for_srfs(root, rel, scanjoin_targets, scanjoin_targets_contain_srfs); /* - * If the relation is partitioned, recursively apply the same changes to - * all partitions and generate new Append paths. Since Append is not - * projection-capable, that might save a separate Result node, and it also - * is important for partitionwise aggregate. + * Update the rel's target to be the final (with SRFs) scan/join target. + * This now matches the actual output of all the paths, and we might get + * confused in createplan.c if they don't agree. We must do this now so + * that any append paths made in the next part will use the correct + * pathtarget (cf. create_append_path). */ - if (rel->part_scheme && rel->part_rels) + rel->reltarget = llast_node(PathTarget, scanjoin_targets); + + /* + * If the relation is partitioned, recursively apply the scan/join target + * to all partitions, and generate brand-new Append paths in which the + * scan/join target is computed below the Append rather than above it. + * Since Append is not projection-capable, that might save a separate + * Result node, and it also is important for partitionwise aggregate. + */ + if (rel_is_partitioned) { - int partition_idx; List *live_children = NIL; + int partition_idx; /* Adjust each partition. */ for (partition_idx = 0; partition_idx < rel->nparts; partition_idx++) { RelOptInfo *child_rel = rel->part_rels[partition_idx]; - ListCell *lc; AppendRelInfo **appinfos; int nappinfos; List *child_scanjoin_targets = NIL; + ListCell *lc; /* Translate scan/join targets for this child. */ appinfos = find_appinfos_by_relids(root, child_rel->relids, @@ -6992,8 +6993,7 @@ apply_scanjoin_target_to_paths(PlannerInfo *root, } /* Build new paths for this relation by appending child paths. */ - if (live_children != NIL) - add_paths_to_append_rel(root, rel, live_children); + add_paths_to_append_rel(root, rel, live_children); } /* |