diff options
Diffstat (limited to 'src/backend/optimizer/plan/createplan.c')
| -rw-r--r-- | src/backend/optimizer/plan/createplan.c | 205 |
1 files changed, 187 insertions, 18 deletions
diff --git a/src/backend/optimizer/plan/createplan.c b/src/backend/optimizer/plan/createplan.c index 2c398d2eed9..52dd27b1583 100644 --- a/src/backend/optimizer/plan/createplan.c +++ b/src/backend/optimizer/plan/createplan.c @@ -25,6 +25,7 @@ #include "nodes/nodeFuncs.h" #include "optimizer/clauses.h" #include "optimizer/cost.h" +#include "optimizer/paths.h" #include "optimizer/plancat.h" #include "optimizer/planmain.h" #include "optimizer/predtest.h" @@ -45,6 +46,7 @@ static void disuse_physical_tlist(Plan *plan, Path *path); static Plan *create_gating_plan(PlannerInfo *root, Plan *plan, List *quals); static Plan *create_join_plan(PlannerInfo *root, JoinPath *best_path); static Plan *create_append_plan(PlannerInfo *root, AppendPath *best_path); +static Plan *create_merge_append_plan(PlannerInfo *root, MergeAppendPath *best_path); static Result *create_result_plan(PlannerInfo *root, ResultPath *best_path); static Material *create_material_plan(PlannerInfo *root, MaterialPath *best_path); static Plan *create_unique_plan(PlannerInfo *root, UniquePath *best_path); @@ -134,6 +136,13 @@ static MergeJoin *make_mergejoin(List *tlist, static Sort *make_sort(PlannerInfo *root, Plan *lefttree, int numCols, AttrNumber *sortColIdx, Oid *sortOperators, bool *nullsFirst, double limit_tuples); +static Plan *prepare_sort_from_pathkeys(PlannerInfo *root, + Plan *lefttree, List *pathkeys, + bool adjust_tlist_in_place, + int *p_numsortkeys, + AttrNumber **p_sortColIdx, + Oid **p_sortOperators, + bool **p_nullsFirst); static Material *make_material(Plan *lefttree); @@ -203,6 +212,10 @@ create_plan_recurse(PlannerInfo *root, Path *best_path) plan = create_append_plan(root, (AppendPath *) best_path); break; + case T_MergeAppend: + plan = create_merge_append_plan(root, + (MergeAppendPath *) best_path); + break; case T_Result: plan = (Plan *) create_result_plan(root, (ResultPath *) best_path); @@ -620,6 +633,97 @@ create_append_plan(PlannerInfo *root, AppendPath *best_path) } /* + * create_merge_append_plan + * Create a MergeAppend plan for 'best_path' and (recursively) plans + * for its subpaths. + * + * Returns a Plan node. + */ +static Plan * +create_merge_append_plan(PlannerInfo *root, MergeAppendPath *best_path) +{ + MergeAppend *node = makeNode(MergeAppend); + Plan *plan = &node->plan; + List *tlist = build_relation_tlist(best_path->path.parent); + List *pathkeys = best_path->path.pathkeys; + List *subplans = NIL; + ListCell *subpaths; + + /* + * We don't have the actual creation of the MergeAppend node split out + * into a separate make_xxx function. This is because we want to run + * prepare_sort_from_pathkeys on it before we do so on the individual + * child plans, to make cross-checking the sort info easier. + */ + copy_path_costsize(plan, (Path *) best_path); + plan->targetlist = tlist; + plan->qual = NIL; + plan->lefttree = NULL; + plan->righttree = NULL; + + /* Compute sort column info, and adjust MergeAppend's tlist as needed */ + (void) prepare_sort_from_pathkeys(root, plan, pathkeys, + true, + &node->numCols, + &node->sortColIdx, + &node->sortOperators, + &node->nullsFirst); + + /* + * Now prepare the child plans. We must apply prepare_sort_from_pathkeys + * even to subplans that don't need an explicit sort, to make sure they + * are returning the same sort key columns the MergeAppend expects. + */ + foreach(subpaths, best_path->subpaths) + { + Path *subpath = (Path *) lfirst(subpaths); + Plan *subplan; + int numsortkeys; + AttrNumber *sortColIdx; + Oid *sortOperators; + bool *nullsFirst; + + /* Build the child plan */ + subplan = create_plan_recurse(root, subpath); + + /* Compute sort column info, and adjust subplan's tlist as needed */ + subplan = prepare_sort_from_pathkeys(root, subplan, pathkeys, + false, + &numsortkeys, + &sortColIdx, + &sortOperators, + &nullsFirst); + + /* + * Check that we got the same sort key information. We just Assert + * that the sortops match, since those depend only on the pathkeys; + * but it seems like a good idea to check the sort column numbers + * explicitly, to ensure the tlists really do match up. + */ + Assert(numsortkeys == node->numCols); + if (memcmp(sortColIdx, node->sortColIdx, + numsortkeys * sizeof(AttrNumber)) != 0) + elog(ERROR, "MergeAppend child's targetlist doesn't match MergeAppend"); + Assert(memcmp(sortOperators, node->sortOperators, + numsortkeys * sizeof(Oid)) == 0); + Assert(memcmp(nullsFirst, node->nullsFirst, + numsortkeys * sizeof(bool)) == 0); + + /* Now, insert a Sort node if subplan isn't sufficiently ordered */ + if (!pathkeys_contained_in(pathkeys, subpath->pathkeys)) + subplan = (Plan *) make_sort(root, subplan, numsortkeys, + sortColIdx, sortOperators, nullsFirst, + -1.0); + + subplans = lappend(subplans, subplan); + } + + node->mergeplans = subplans; + + return (Plan *) node; +} + +/* * create_result_plan * Create a Result plan for 'best_path'. * This is only used for the case of a query with an empty jointree. @@ -2502,7 +2606,7 @@ order_qual_clauses(PlannerInfo *root, List *clauses) /* * Copy cost and size info from a Path node to the Plan node created from it. - * The executor won't use this info, but it's needed by EXPLAIN. + * The executor usually won't use this info, but it's needed by EXPLAIN. */ static void copy_path_costsize(Plan *dest, Path *src) @@ -2525,9 +2629,7 @@ copy_path_costsize(Plan *dest, Path *src) /* * Copy cost and size info from a lower plan node to an inserted node. - * This is not critical, since the decisions have already been made, - * but it helps produce more reasonable-looking EXPLAIN output. - * (Some callers alter the info after copying it.) + * (Most callers alter the info after copying it.) */ static void copy_plan_costsize(Plan *dest, Plan *src) @@ -2796,6 +2898,12 @@ make_append(List *appendplans, List *tlist) * Compute cost as sum of subplan costs. We charge nothing extra for the * Append itself, which perhaps is too optimistic, but since it doesn't do * any selection or projection, it is a pretty cheap node. + * + * If you change this, see also create_append_path(). Also, the size + * calculations should match set_append_rel_pathlist(). It'd be better + * not to duplicate all this logic, but some callers of this function + * aren't working from an appendrel or AppendPath, so there's noplace + * to copy the data from. */ plan->startup_cost = 0; plan->total_cost = 0; @@ -3102,26 +3210,41 @@ add_sort_column(AttrNumber colIdx, Oid sortOp, bool nulls_first, } /* - * make_sort_from_pathkeys - * Create sort plan to sort according to given pathkeys + * prepare_sort_from_pathkeys + * Prepare to sort according to given pathkeys + * + * This is used to set up for both Sort and MergeAppend nodes. It calculates + * the executor's representation of the sort key information, and adjusts the + * plan targetlist if needed to add resjunk sort columns. * + * Input parameters: * 'lefttree' is the node which yields input tuples * 'pathkeys' is the list of pathkeys by which the result is to be sorted - * 'limit_tuples' is the bound on the number of output tuples; - * -1 if no bound + * 'adjust_tlist_in_place' is TRUE if lefttree must be modified in-place * * We must convert the pathkey information into arrays of sort key column - * numbers and sort operator OIDs. + * numbers and sort operator OIDs, which is the representation the executor + * wants. These are returned into the output parameters *p_numsortkeys etc. * * If the pathkeys include expressions that aren't simple Vars, we will * usually need to add resjunk items to the input plan's targetlist to - * compute these expressions (since the Sort node itself won't do it). - * If the input plan type isn't one that can do projections, this means - * adding a Result node just to do the projection. + * compute these expressions, since the Sort/MergeAppend node itself won't + * do any such calculations. If the input plan type isn't one that can do + * projections, this means adding a Result node just to do the projection. + * However, the caller can pass adjust_tlist_in_place = TRUE to force the + * lefttree tlist to be modified in-place regardless of whether the node type + * can project --- we use this for fixing the tlist of MergeAppend itself. + * + * Returns the node which is to be the input to the Sort (either lefttree, + * or a Result stacked atop lefttree). */ -Sort * -make_sort_from_pathkeys(PlannerInfo *root, Plan *lefttree, List *pathkeys, - double limit_tuples) +static Plan * +prepare_sort_from_pathkeys(PlannerInfo *root, Plan *lefttree, List *pathkeys, + bool adjust_tlist_in_place, + int *p_numsortkeys, + AttrNumber **p_sortColIdx, + Oid **p_sortOperators, + bool **p_nullsFirst) { List *tlist = lefttree->targetlist; ListCell *i; @@ -3185,7 +3308,12 @@ make_sort_from_pathkeys(PlannerInfo *root, Plan *lefttree, List *pathkeys, { EquivalenceMember *em = (EquivalenceMember *) lfirst(j); - if (em->em_is_const || em->em_is_child) + /* + * We shouldn't be trying to sort by an equivalence class that + * contains a constant, so no need to consider such cases any + * further. + */ + if (em->em_is_const) continue; tle = tlist_member((Node *) em->em_expr, tlist); @@ -3221,7 +3349,7 @@ make_sort_from_pathkeys(PlannerInfo *root, Plan *lefttree, List *pathkeys, List *exprvars; ListCell *k; - if (em->em_is_const || em->em_is_child) + if (em->em_is_const) continue; sortexpr = em->em_expr; exprvars = pull_var_clause((Node *) sortexpr, @@ -3244,7 +3372,8 @@ make_sort_from_pathkeys(PlannerInfo *root, Plan *lefttree, List *pathkeys, /* * Do we need to insert a Result node? */ - if (!is_projection_capable_plan(lefttree)) + if (!adjust_tlist_in_place && + !is_projection_capable_plan(lefttree)) { /* copy needed so we don't modify input's tlist below */ tlist = copyObject(tlist); @@ -3252,6 +3381,9 @@ make_sort_from_pathkeys(PlannerInfo *root, Plan *lefttree, List *pathkeys, lefttree); } + /* Don't bother testing is_projection_capable_plan again */ + adjust_tlist_in_place = true; + /* * Add resjunk entry to input's tlist */ @@ -3292,6 +3424,42 @@ make_sort_from_pathkeys(PlannerInfo *root, Plan *lefttree, List *pathkeys, Assert(numsortkeys > 0); + /* Return results */ + *p_numsortkeys = numsortkeys; + *p_sortColIdx = sortColIdx; + *p_sortOperators = sortOperators; + *p_nullsFirst = nullsFirst; + + return lefttree; +} + +/* + * make_sort_from_pathkeys + * Create sort plan to sort according to given pathkeys + * + * 'lefttree' is the node which yields input tuples + * 'pathkeys' is the list of pathkeys by which the result is to be sorted + * 'limit_tuples' is the bound on the number of output tuples; + * -1 if no bound + */ +Sort * +make_sort_from_pathkeys(PlannerInfo *root, Plan *lefttree, List *pathkeys, + double limit_tuples) +{ + int numsortkeys; + AttrNumber *sortColIdx; + Oid *sortOperators; + bool *nullsFirst; + + /* Compute sort column info, and adjust lefttree as needed */ + lefttree = prepare_sort_from_pathkeys(root, lefttree, pathkeys, + false, + &numsortkeys, + &sortColIdx, + &sortOperators, + &nullsFirst); + + /* Now build the Sort node */ return make_sort(root, lefttree, numsortkeys, sortColIdx, sortOperators, nullsFirst, limit_tuples); } @@ -3998,6 +4166,7 @@ is_projection_capable_plan(Plan *plan) case T_Limit: case T_ModifyTable: case T_Append: + case T_MergeAppend: case T_RecursiveUnion: return false; default: |