/*------------------------------------------------------------------------- * * planner.c * The query optimizer external interface. * * Portions Copyright (c) 1996-2021, PostgreSQL Global Development Group * Portions Copyright (c) 1994, Regents of the University of California * * * IDENTIFICATION * src/backend/optimizer/plan/planner.c * *------------------------------------------------------------------------- */ #include "postgres.h" #include #include #include "access/genam.h" #include "access/htup_details.h" #include "access/parallel.h" #include "access/sysattr.h" #include "access/table.h" #include "access/xact.h" #include "catalog/pg_constraint.h" #include "catalog/pg_inherits.h" #include "catalog/pg_proc.h" #include "catalog/pg_type.h" #include "executor/executor.h" #include "executor/nodeAgg.h" #include "foreign/fdwapi.h" #include "jit/jit.h" #include "lib/bipartite_match.h" #include "lib/knapsack.h" #include "miscadmin.h" #include "nodes/makefuncs.h" #include "nodes/nodeFuncs.h" #ifdef OPTIMIZER_DEBUG #include "nodes/print.h" #endif #include "optimizer/appendinfo.h" #include "optimizer/clauses.h" #include "optimizer/cost.h" #include "optimizer/inherit.h" #include "optimizer/optimizer.h" #include "optimizer/paramassign.h" #include "optimizer/pathnode.h" #include "optimizer/paths.h" #include "optimizer/plancat.h" #include "optimizer/planmain.h" #include "optimizer/planner.h" #include "optimizer/prep.h" #include "optimizer/subselect.h" #include "optimizer/tlist.h" #include "parser/analyze.h" #include "parser/parse_agg.h" #include "parser/parsetree.h" #include "partitioning/partdesc.h" #include "rewrite/rewriteManip.h" #include "storage/dsm_impl.h" #include "utils/lsyscache.h" #include "utils/rel.h" #include "utils/selfuncs.h" #include "utils/syscache.h" /* GUC parameters */ double cursor_tuple_fraction = DEFAULT_CURSOR_TUPLE_FRACTION; int force_parallel_mode = FORCE_PARALLEL_OFF; bool parallel_leader_participation = true; /* Hook for plugins to get control in planner() */ planner_hook_type planner_hook = NULL; /* Hook for plugins to get control when grouping_planner() plans upper rels */ create_upper_paths_hook_type create_upper_paths_hook = NULL; /* Expression kind codes for preprocess_expression */ #define EXPRKIND_QUAL 0 #define EXPRKIND_TARGET 1 #define EXPRKIND_RTFUNC 2 #define EXPRKIND_RTFUNC_LATERAL 3 #define EXPRKIND_VALUES 4 #define EXPRKIND_VALUES_LATERAL 5 #define EXPRKIND_LIMIT 6 #define EXPRKIND_APPINFO 7 #define EXPRKIND_PHV 8 #define EXPRKIND_TABLESAMPLE 9 #define EXPRKIND_ARBITER_ELEM 10 #define EXPRKIND_TABLEFUNC 11 #define EXPRKIND_TABLEFUNC_LATERAL 12 /* Passthrough data for standard_qp_callback */ typedef struct { List *activeWindows; /* active windows, if any */ List *groupClause; /* overrides parse->groupClause */ } standard_qp_extra; /* * Data specific to grouping sets */ typedef struct { List *rollups; List *hash_sets_idx; double dNumHashGroups; bool any_hashable; Bitmapset *unsortable_refs; Bitmapset *unhashable_refs; List *unsortable_sets; int *tleref_to_colnum_map; } grouping_sets_data; /* * Temporary structure for use during WindowClause reordering in order to be * able to sort WindowClauses on partitioning/ordering prefix. */ typedef struct { WindowClause *wc; List *uniqueOrder; /* A List of unique ordering/partitioning * clauses per Window */ } WindowClauseSortData; /* Local functions */ static Node *preprocess_expression(PlannerInfo *root, Node *expr, int kind); static void preprocess_qual_conditions(PlannerInfo *root, Node *jtnode); static void grouping_planner(PlannerInfo *root, double tuple_fraction); static grouping_sets_data *preprocess_grouping_sets(PlannerInfo *root); static List *remap_to_groupclause_idx(List *groupClause, List *gsets, int *tleref_to_colnum_map); static void preprocess_rowmarks(PlannerInfo *root); static double preprocess_limit(PlannerInfo *root, double tuple_fraction, int64 *offset_est, int64 *count_est); static void remove_useless_groupby_columns(PlannerInfo *root); static List *preprocess_groupclause(PlannerInfo *root, List *force); static List *extract_rollup_sets(List *groupingSets); static List *reorder_grouping_sets(List *groupingSets, List *sortclause); static void standard_qp_callback(PlannerInfo *root, void *extra); static double get_number_of_groups(PlannerInfo *root, double path_rows, grouping_sets_data *gd, List *target_list); static RelOptInfo *create_grouping_paths(PlannerInfo *root, RelOptInfo *input_rel, PathTarget *target, bool target_parallel_safe, grouping_sets_data *gd); static bool is_degenerate_grouping(PlannerInfo *root); static void create_degenerate_grouping_paths(PlannerInfo *root, RelOptInfo *input_rel, RelOptInfo *grouped_rel); static RelOptInfo *make_grouping_rel(PlannerInfo *root, RelOptInfo *input_rel, PathTarget *target, bool target_parallel_safe, Node *havingQual); static void create_ordinary_grouping_paths(PlannerInfo *root, RelOptInfo *input_rel, RelOptInfo *grouped_rel, const AggClauseCosts *agg_costs, grouping_sets_data *gd, GroupPathExtraData *extra, RelOptInfo **partially_grouped_rel_p); static void consider_groupingsets_paths(PlannerInfo *root, RelOptInfo *grouped_rel, Path *path, bool is_sorted, bool can_hash, grouping_sets_data *gd, const AggClauseCosts *agg_costs, double dNumGroups); static RelOptInfo *create_window_paths(PlannerInfo *root, RelOptInfo *input_rel, PathTarget *input_target, PathTarget *output_target, bool output_target_parallel_safe, WindowFuncLists *wflists, List *activeWindows); static void create_one_window_path(PlannerInfo *root, RelOptInfo *window_rel, Path *path, PathTarget *input_target, PathTarget *output_target, WindowFuncLists *wflists, List *activeWindows); static RelOptInfo *create_distinct_paths(PlannerInfo *root, RelOptInfo *input_rel); static RelOptInfo *create_ordered_paths(PlannerInfo *root, RelOptInfo *input_rel, PathTarget *target, bool target_parallel_safe, double limit_tuples); static PathTarget *make_group_input_target(PlannerInfo *root, PathTarget *final_target); static PathTarget *make_partial_grouping_target(PlannerInfo *root, PathTarget *grouping_target, Node *havingQual); static List *postprocess_setop_tlist(List *new_tlist, List *orig_tlist); static List *select_active_windows(PlannerInfo *root, WindowFuncLists *wflists); static PathTarget *make_window_input_target(PlannerInfo *root, PathTarget *final_target, List *activeWindows); static List *make_pathkeys_for_window(PlannerInfo *root, WindowClause *wc, List *tlist); static PathTarget *make_sort_input_target(PlannerInfo *root, PathTarget *final_target, bool *have_postponed_srfs); static void adjust_paths_for_srfs(PlannerInfo *root, RelOptInfo *rel, List *targets, List *targets_contain_srfs); static void add_paths_to_grouping_rel(PlannerInfo *root, RelOptInfo *input_rel, RelOptInfo *grouped_rel, RelOptInfo *partially_grouped_rel, const AggClauseCosts *agg_costs, grouping_sets_data *gd, double dNumGroups, GroupPathExtraData *extra); static RelOptInfo *create_partial_grouping_paths(PlannerInfo *root, RelOptInfo *grouped_rel, RelOptInfo *input_rel, grouping_sets_data *gd, GroupPathExtraData *extra, bool force_rel_creation); static void gather_grouping_paths(PlannerInfo *root, RelOptInfo *rel); static bool can_partial_agg(PlannerInfo *root); static void apply_scanjoin_target_to_paths(PlannerInfo *root, RelOptInfo *rel, List *scanjoin_targets, List *scanjoin_targets_contain_srfs, bool scanjoin_target_parallel_safe, bool tlist_same_exprs); static void create_partitionwise_grouping_paths(PlannerInfo *root, RelOptInfo *input_rel, RelOptInfo *grouped_rel, RelOptInfo *partially_grouped_rel, const AggClauseCosts *agg_costs, grouping_sets_data *gd, PartitionwiseAggregateType patype, GroupPathExtraData *extra); static bool group_by_has_partkey(RelOptInfo *input_rel, List *targetList, List *groupClause); static int common_prefix_cmp(const void *a, const void *b); /***************************************************************************** * * Query optimizer entry point * * To support loadable plugins that monitor or modify planner behavior, * we provide a hook variable that lets a plugin get control before and * after the standard planning process. The plugin would normally call * standard_planner(). * * Note to plugin authors: standard_planner() scribbles on its Query input, * so you'd better copy that data structure if you want to plan more than once. * *****************************************************************************/ PlannedStmt * planner(Query *parse, const char *query_string, int cursorOptions, ParamListInfo boundParams) { PlannedStmt *result; if (planner_hook) result = (*planner_hook) (parse, query_string, cursorOptions, boundParams); else result = standard_planner(parse, query_string, cursorOptions, boundParams); return result; } PlannedStmt * standard_planner(Query *parse, const char *query_string, int cursorOptions, ParamListInfo boundParams) { PlannedStmt *result; PlannerGlobal *glob; double tuple_fraction; PlannerInfo *root; RelOptInfo *final_rel; Path *best_path; Plan *top_plan; ListCell *lp, *lr; /* * Set up global state for this planner invocation. This data is needed * across all levels of sub-Query that might exist in the given command, * so we keep it in a separate struct that's linked to by each per-Query * PlannerInfo. */ glob = makeNode(PlannerGlobal); glob->boundParams = boundParams; glob->subplans = NIL; glob->subroots = NIL; glob->rewindPlanIDs = NULL; glob->finalrtable = NIL; glob->finalrowmarks = NIL; glob->resultRelations = NIL; glob->appendRelations = NIL; glob->relationOids = NIL; glob->invalItems = NIL; glob->paramExecTypes = NIL; glob->lastPHId = 0; glob->lastRowMarkId = 0; glob->lastPlanNodeId = 0; glob->transientPlan = false; glob->dependsOnRole = false; /* * Assess whether it's feasible to use parallel mode for this query. We * can't do this in a standalone backend, or if the command will try to * modify any data, or if this is a cursor operation, or if GUCs are set * to values that don't permit parallelism, or if parallel-unsafe * functions are present in the query tree. * * (Note that we do allow CREATE TABLE AS, SELECT INTO, and CREATE * MATERIALIZED VIEW to use parallel plans, but as of now, only the leader * backend writes into a completely new table. In the future, we can * extend it to allow workers to write into the table. However, to allow * parallel updates and deletes, we have to solve other problems, * especially around combo CIDs.) * * For now, we don't try to use parallel mode if we're running inside a * parallel worker. We might eventually be able to relax this * restriction, but for now it seems best not to have parallel workers * trying to create their own parallel workers. */ if ((cursorOptions & CURSOR_OPT_PARALLEL_OK) != 0 && IsUnderPostmaster && parse->commandType == CMD_SELECT && !parse->hasModifyingCTE && max_parallel_workers_per_gather > 0 && !IsParallelWorker()) { /* all the cheap tests pass, so scan the query tree */ glob->maxParallelHazard = max_parallel_hazard(parse); glob->parallelModeOK = (glob->maxParallelHazard != PROPARALLEL_UNSAFE); } else { /* skip the query tree scan, just assume it's unsafe */ glob->maxParallelHazard = PROPARALLEL_UNSAFE; glob->parallelModeOK = false; } /* * glob->parallelModeNeeded is normally set to false here and changed to * true during plan creation if a Gather or Gather Merge plan is actually * created (cf. create_gather_plan, create_gather_merge_plan). * * However, if force_parallel_mode = on or force_parallel_mode = regress, * then we impose parallel mode whenever it's safe to do so, even if the * final plan doesn't use parallelism. It's not safe to do so if the * query contains anything parallel-unsafe; parallelModeOK will be false * in that case. Note that parallelModeOK can't change after this point. * Otherwise, everything in the query is either parallel-safe or * parallel-restricted, and in either case it should be OK to impose * parallel-mode restrictions. If that ends up breaking something, then * either some function the user included in the query is incorrectly * labeled as parallel-safe or parallel-restricted when in reality it's * parallel-unsafe, or else the query planner itself has a bug. */ glob->parallelModeNeeded = glob->parallelModeOK && (force_parallel_mode != FORCE_PARALLEL_OFF); /* Determine what fraction of the plan is likely to be scanned */ if (cursorOptions & CURSOR_OPT_FAST_PLAN) { /* * We have no real idea how many tuples the user will ultimately FETCH * from a cursor, but it is often the case that he doesn't want 'em * all, or would prefer a fast-start plan anyway so that he can * process some of the tuples sooner. Use a GUC parameter to decide * what fraction to optimize for. */ tuple_fraction = cursor_tuple_fraction; /* * We document cursor_tuple_fraction as simply being a fraction, which * means the edge cases 0 and 1 have to be treated specially here. We * convert 1 to 0 ("all the tuples") and 0 to a very small fraction. */ if (tuple_fraction >= 1.0) tuple_fraction = 0.0; else if (tuple_fraction <= 0.0) tuple_fraction = 1e-10; } else { /* Default assumption is we need all the tuples */ tuple_fraction = 0.0; } /* primary planning entry point (may recurse for subqueries) */ root = subquery_planner(glob, parse, NULL, false, tuple_fraction); /* Select best Path and turn it into a Plan */ final_rel = fetch_upper_rel(root, UPPERREL_FINAL, NULL); best_path = get_cheapest_fractional_path(final_rel, tuple_fraction); top_plan = create_plan(root, best_path); /* * If creating a plan for a scrollable cursor, make sure it can run * backwards on demand. Add a Material node at the top at need. */ if (cursorOptions & CURSOR_OPT_SCROLL) { if (!ExecSupportsBackwardScan(top_plan)) top_plan = materialize_finished_plan(top_plan); } /* * Optionally add a Gather node for testing purposes, provided this is * actually a safe thing to do. */ if (force_parallel_mode != FORCE_PARALLEL_OFF && top_plan->parallel_safe) { Gather *gather = makeNode(Gather); /* * If there are any initPlans attached to the formerly-top plan node, * move them up to the Gather node; same as we do for Material node in * materialize_finished_plan. */ gather->plan.initPlan = top_plan->initPlan; top_plan->initPlan = NIL; gather->plan.targetlist = top_plan->targetlist; gather->plan.qual = NIL; gather->plan.lefttree = top_plan; gather->plan.righttree = NULL; gather->num_workers = 1; gather->single_copy = true; gather->invisible = (force_parallel_mode == FORCE_PARALLEL_REGRESS); /* * Since this Gather has no parallel-aware descendants to signal to, * we don't need a rescan Param. */ gather->rescan_param = -1; /* * Ideally we'd use cost_gather here, but setting up dummy path data * to satisfy it doesn't seem much cleaner than knowing what it does. */ gather->plan.startup_cost = top_plan->startup_cost + parallel_setup_cost; gather->plan.total_cost = top_plan->total_cost + parallel_setup_cost + parallel_tuple_cost * top_plan->plan_rows; gather->plan.plan_rows = top_plan->plan_rows; gather->plan.plan_width = top_plan->plan_width; gather->plan.parallel_aware = false; gather->plan.parallel_safe = false; /* use parallel mode for parallel plans. */ root->glob->parallelModeNeeded = true; top_plan = &gather->plan; } /* * If any Params were generated, run through the plan tree and compute * each plan node's extParam/allParam sets. Ideally we'd merge this into * set_plan_references' tree traversal, but for now it has to be separate * because we need to visit subplans before not after main plan. */ if (glob->paramExecTypes != NIL) { Assert(list_length(glob->subplans) == list_length(glob->subroots)); forboth(lp, glob->subplans, lr, glob->subroots) { Plan *subplan = (Plan *) lfirst(lp); PlannerInfo *subroot = lfirst_node(PlannerInfo, lr); SS_finalize_plan(subroot, subplan); } SS_finalize_plan(root, top_plan); } /* final cleanup of the plan */ Assert(glob->finalrtable == NIL); Assert(glob->finalrowmarks == NIL); Assert(glob->resultRelations == NIL); Assert(glob->appendRelations == NIL); top_plan = set_plan_references(root, top_plan); /* ... and the subplans (both regular subplans and initplans) */ Assert(list_length(glob->subplans) == list_length(glob->subroots)); forboth(lp, glob->subplans, lr, glob->subroots) { Plan *subplan = (Plan *) lfirst(lp); PlannerInfo *subroot = lfirst_node(PlannerInfo, lr); lfirst(lp) = set_plan_references(subroot, subplan); } /* build the PlannedStmt result */ result = makeNode(PlannedStmt); result->commandType = parse->commandType; result->queryId = parse->queryId; result->hasReturning = (parse->returningList != NIL); result->hasModifyingCTE = parse->hasModifyingCTE; result->canSetTag = parse->canSetTag; result->transientPlan = glob->transientPlan; result->dependsOnRole = glob->dependsOnRole; result->parallelModeNeeded = glob->parallelModeNeeded; result->planTree = top_plan; result->rtable = glob->finalrtable; result->resultRelations = glob->resultRelations; result->appendRelations = glob->appendRelations; result->subplans = glob->subplans; result->rewindPlanIDs = glob->rewindPlanIDs; result->rowMarks = glob->finalrowmarks; result->relationOids = glob->relationOids; result->invalItems = glob->invalItems; result->paramExecTypes = glob->paramExecTypes; /* utilityStmt should be null, but we might as well copy it */ result->utilityStmt = parse->utilityStmt; result->stmt_location = parse->stmt_location; result->stmt_len = parse->stmt_len; result->jitFlags = PGJIT_NONE; if (jit_enabled && jit_above_cost >= 0 && top_plan->total_cost > jit_above_cost) { result->jitFlags |= PGJIT_PERFORM; /* * Decide how much effort should be put into generating better code. */ if (jit_optimize_above_cost >= 0 && top_plan->total_cost > jit_optimize_above_cost) result->jitFlags |= PGJIT_OPT3; if (jit_inline_above_cost >= 0 && top_plan->total_cost > jit_inline_above_cost) result->jitFlags |= PGJIT_INLINE; /* * Decide which operations should be JITed. */ if (jit_expressions) result->jitFlags |= PGJIT_EXPR; if (jit_tuple_deforming) result->jitFlags |= PGJIT_DEFORM; } if (glob->partition_directory != NULL) DestroyPartitionDirectory(glob->partition_directory); return result; } /*-------------------- * subquery_planner * Invokes the planner on a subquery. We recurse to here for each * sub-SELECT found in the query tree. * * glob is the global state for the current planner run. * parse is the querytree produced by the parser & rewriter. * parent_root is the immediate parent Query's info (NULL at the top level). * hasRecursion is true if this is a recursive WITH query. * tuple_fraction is the fraction of tuples we expect will be retrieved. * tuple_fraction is interpreted as explained for grouping_planner, below. * * Basically, this routine does the stuff that should only be done once * per Query object. It then calls grouping_planner. At one time, * grouping_planner could be invoked recursively on the same Query object; * that's not currently true, but we keep the separation between the two * routines anyway, in case we need it again someday. * * subquery_planner will be called recursively to handle sub-Query nodes * found within the query's expressions and rangetable. * * Returns the PlannerInfo struct ("root") that contains all data generated * while planning the subquery. In particular, the Path(s) attached to * the (UPPERREL_FINAL, NULL) upperrel represent our conclusions about the * cheapest way(s) to implement the query. The top level will select the * best Path and pass it through createplan.c to produce a finished Plan. *-------------------- */ PlannerInfo * subquery_planner(PlannerGlobal *glob, Query *parse, PlannerInfo *parent_root, bool hasRecursion, double tuple_fraction) { PlannerInfo *root; List *newWithCheckOptions; List *newHaving; bool hasOuterJoins; bool hasResultRTEs; RelOptInfo *final_rel; ListCell *l; /* Create a PlannerInfo data structure for this subquery */ root = makeNode(PlannerInfo); root->parse = parse; root->glob = glob; root->query_level = parent_root ? parent_root->query_level + 1 : 1; root->parent_root = parent_root; root->plan_params = NIL; root->outer_params = NULL; root->planner_cxt = CurrentMemoryContext; root->init_plans = NIL; root->cte_plan_ids = NIL; root->multiexpr_params = NIL; root->eq_classes = NIL; root->ec_merging_done = false; root->all_result_relids = parse->resultRelation ? bms_make_singleton(parse->resultRelation) : NULL; root->leaf_result_relids = NULL; /* we'll find out leaf-ness later */ root->append_rel_list = NIL; root->row_identity_vars = NIL; root->rowMarks = NIL; memset(root->upper_rels, 0, sizeof(root->upper_rels)); memset(root->upper_targets, 0, sizeof(root->upper_targets)); root->processed_tlist = NIL; root->update_colnos = NIL; root->grouping_map = NULL; root->minmax_aggs = NIL; root->qual_security_level = 0; root->hasPseudoConstantQuals = false; root->hasAlternativeSubPlans = false; root->hasRecursion = hasRecursion; if (hasRecursion) root->wt_param_id = assign_special_exec_param(root); else root->wt_param_id = -1; root->non_recursive_path = NULL; root->partColsUpdated = false; /* * If there is a WITH list, process each WITH query and either convert it * to RTE_SUBQUERY RTE(s) or build an initplan SubPlan structure for it. */ if (parse->cteList) SS_process_ctes(root); /* * If the FROM clause is empty, replace it with a dummy RTE_RESULT RTE, so * that we don't need so many special cases to deal with that situation. */ replace_empty_jointree(parse); /* * Look for ANY and EXISTS SubLinks in WHERE and JOIN/ON clauses, and try * to transform them into joins. Note that this step does not descend * into subqueries; if we pull up any subqueries below, their SubLinks are * processed just before pulling them up. */ if (parse->hasSubLinks) pull_up_sublinks(root); /* * Scan the rangetable for function RTEs, do const-simplification on them, * and then inline them if possible (producing subqueries that might get * pulled up next). Recursion issues here are handled in the same way as * for SubLinks. */ preprocess_function_rtes(root); /* * Check to see if any subqueries in the jointree can be merged into this * query. */ pull_up_subqueries(root); /* * If this is a simple UNION ALL query, flatten it into an appendrel. We * do this now because it requires applying pull_up_subqueries to the leaf * queries of the UNION ALL, which weren't touched above because they * weren't referenced by the jointree (they will be after we do this). */ if (parse->setOperations) flatten_simple_union_all(root); /* * Survey the rangetable to see what kinds of entries are present. We can * skip some later processing if relevant SQL features are not used; for * example if there are no JOIN RTEs we can avoid the expense of doing * flatten_join_alias_vars(). This must be done after we have finished * adding rangetable entries, of course. (Note: actually, processing of * inherited or partitioned rels can cause RTEs for their child tables to * get added later; but those must all be RTE_RELATION entries, so they * don't invalidate the conclusions drawn here.) */ root->hasJoinRTEs = false; root->hasLateralRTEs = false; hasOuterJoins = false; hasResultRTEs = false; foreach(l, parse->rtable) { RangeTblEntry *rte = lfirst_node(RangeTblEntry, l); switch (rte->rtekind) { case RTE_RELATION: if (rte->inh) { /* * Check to see if the relation actually has any children; * if not, clear the inh flag so we can treat it as a * plain base relation. * * Note: this could give a false-positive result, if the * rel once had children but no longer does. We used to * be able to clear rte->inh later on when we discovered * that, but no more; we have to handle such cases as * full-fledged inheritance. */ rte->inh = has_subclass(rte->relid); } break; case RTE_JOIN: root->hasJoinRTEs = true; if (IS_OUTER_JOIN(rte->jointype)) hasOuterJoins = true; break; case RTE_RESULT: hasResultRTEs = true; break; default: /* No work here for other RTE types */ break; } if (rte->lateral) root->hasLateralRTEs = true; /* * We can also determine the maximum security level required for any * securityQuals now. Addition of inheritance-child RTEs won't affect * this, because child tables don't have their own securityQuals; see * expand_single_inheritance_child(). */ if (rte->securityQuals) root->qual_security_level = Max(root->qual_security_level, list_length(rte->securityQuals)); } /* * If we have now verified that the query target relation is * non-inheriting, mark it as a leaf target. */ if (parse->resultRelation) { RangeTblEntry *rte = rt_fetch(parse->resultRelation, parse->rtable); if (!rte->inh) root->leaf_result_relids = bms_make_singleton(parse->resultRelation); } /* * Preprocess RowMark information. We need to do this after subquery * pullup, so that all base relations are present. */ preprocess_rowmarks(root); /* * Set hasHavingQual to remember if HAVING clause is present. Needed * because preprocess_expression will reduce a constant-true condition to * an empty qual list ... but "HAVING TRUE" is not a semantic no-op. */ root->hasHavingQual = (parse->havingQual != NULL); /* * Do expression preprocessing on targetlist and quals, as well as other * random expressions in the querytree. Note that we do not need to * handle sort/group expressions explicitly, because they are actually * part of the targetlist. */ parse->targetList = (List *) preprocess_expression(root, (Node *) parse->targetList, EXPRKIND_TARGET); /* Constant-folding might have removed all set-returning functions */ if (parse->hasTargetSRFs) parse->hasTargetSRFs = expression_returns_set((Node *) parse->targetList); newWithCheckOptions = NIL; foreach(l, parse->withCheckOptions) { WithCheckOption *wco = lfirst_node(WithCheckOption, l); wco->qual = preprocess_expression(root, wco->qual, EXPRKIND_QUAL); if (wco->qual != NULL) newWithCheckOptions = lappend(newWithCheckOptions, wco); } parse->withCheckOptions = newWithCheckOptions; parse->returningList = (List *) preprocess_expression(root, (Node *) parse->returningList, EXPRKIND_TARGET); preprocess_qual_conditions(root, (Node *) parse->jointree); parse->havingQual = preprocess_expression(root, parse->havingQual, EXPRKIND_QUAL); foreach(l, parse->windowClause) { WindowClause *wc = lfirst_node(WindowClause, l); /* partitionClause/orderClause are sort/group expressions */ wc->startOffset = preprocess_expression(root, wc->startOffset, EXPRKIND_LIMIT); wc->endOffset = preprocess_expression(root, wc->endOffset, EXPRKIND_LIMIT); } parse->limitOffset = preprocess_expression(root, parse->limitOffset, EXPRKIND_LIMIT); parse->limitCount = preprocess_expression(root, parse->limitCount, EXPRKIND_LIMIT); if (parse->onConflict) { parse->onConflict->arbiterElems = (List *) preprocess_expression(root, (Node *) parse->onConflict->arbiterElems, EXPRKIND_ARBITER_ELEM); parse->onConflict->arbiterWhere = preprocess_expression(root, parse->onConflict->arbiterWhere, EXPRKIND_QUAL); parse->onConflict->onConflictSet = (List *) preprocess_expression(root, (Node *) parse->onConflict->onConflictSet, EXPRKIND_TARGET); parse->onConflict->onConflictWhere = preprocess_expression(root, parse->onConflict->onConflictWhere, EXPRKIND_QUAL); /* exclRelTlist contains only Vars, so no preprocessing needed */ } root->append_rel_list = (List *) preprocess_expression(root, (Node *) root->append_rel_list, EXPRKIND_APPINFO); /* Also need to preprocess expressions within RTEs */ foreach(l, parse->rtable) { RangeTblEntry *rte = lfirst_node(RangeTblEntry, l); int kind; ListCell *lcsq; if (rte->rtekind == RTE_RELATION) { if (rte->tablesample) rte->tablesample = (TableSampleClause *) preprocess_expression(root, (Node *) rte->tablesample, EXPRKIND_TABLESAMPLE); } else if (rte->rtekind == RTE_SUBQUERY) { /* * We don't want to do all preprocessing yet on the subquery's * expressions, since that will happen when we plan it. But if it * contains any join aliases of our level, those have to get * expanded now, because planning of the subquery won't do it. * That's only possible if the subquery is LATERAL. */ if (rte->lateral && root->hasJoinRTEs) rte->subquery = (Query *) flatten_join_alias_vars(root->parse, (Node *) rte->subquery); } else if (rte->rtekind == RTE_FUNCTION) { /* Preprocess the function expression(s) fully */ kind = rte->lateral ? EXPRKIND_RTFUNC_LATERAL : EXPRKIND_RTFUNC; rte->functions = (List *) preprocess_expression(root, (Node *) rte->functions, kind); } else if (rte->rtekind == RTE_TABLEFUNC) { /* Preprocess the function expression(s) fully */ kind = rte->lateral ? EXPRKIND_TABLEFUNC_LATERAL : EXPRKIND_TABLEFUNC; rte->tablefunc = (TableFunc *) preprocess_expression(root, (Node *) rte->tablefunc, kind); } else if (rte->rtekind == RTE_VALUES) { /* Preprocess the values lists fully */ kind = rte->lateral ? EXPRKIND_VALUES_LATERAL : EXPRKIND_VALUES; rte->values_lists = (List *) preprocess_expression(root, (Node *) rte->values_lists, kind); } /* * Process each element of the securityQuals list as if it were a * separate qual expression (as indeed it is). We need to do it this * way to get proper canonicalization of AND/OR structure. Note that * this converts each element into an implicit-AND sublist. */ foreach(lcsq, rte->securityQuals) { lfirst(lcsq) = preprocess_expression(root, (Node *) lfirst(lcsq), EXPRKIND_QUAL); } } /* * Now that we are done preprocessing expressions, and in particular done * flattening join alias variables, get rid of the joinaliasvars lists. * They no longer match what expressions in the rest of the tree look * like, because we have not preprocessed expressions in those lists (and * do not want to; for example, expanding a SubLink there would result in * a useless unreferenced subplan). Leaving them in place simply creates * a hazard for later scans of the tree. We could try to prevent that by * using QTW_IGNORE_JOINALIASES in every tree scan done after this point, * but that doesn't sound very reliable. */ if (root->hasJoinRTEs) { foreach(l, parse->rtable) { RangeTblEntry *rte = lfirst_node(RangeTblEntry, l); rte->joinaliasvars = NIL; } } /* * In some cases we may want to transfer a HAVING clause into WHERE. We * cannot do so if the HAVING clause contains aggregates (obviously) or * volatile functions (since a HAVING clause is supposed to be executed * only once per group). We also can't do this if there are any nonempty * grouping sets; moving such a clause into WHERE would potentially change * the results, if any referenced column isn't present in all the grouping * sets. (If there are only empty grouping sets, then the HAVING clause * must be degenerate as discussed below.) * * Also, it may be that the clause is so expensive to execute that we're * better off doing it only once per group, despite the loss of * selectivity. This is hard to estimate short of doing the entire * planning process twice, so we use a heuristic: clauses containing * subplans are left in HAVING. Otherwise, we move or copy the HAVING * clause into WHERE, in hopes of eliminating tuples before aggregation * instead of after. * * If the query has explicit grouping then we can simply move such a * clause into WHERE; any group that fails the clause will not be in the * output because none of its tuples will reach the grouping or * aggregation stage. Otherwise we must have a degenerate (variable-free) * HAVING clause, which we put in WHERE so that query_planner() can use it * in a gating Result node, but also keep in HAVING to ensure that we * don't emit a bogus aggregated row. (This could be done better, but it * seems not worth optimizing.) * * Note that both havingQual and parse->jointree->quals are in * implicitly-ANDed-list form at this point, even though they are declared * as Node *. */ newHaving = NIL; foreach(l, (List *) parse->havingQual) { Node *havingclause = (Node *) lfirst(l); if ((parse->groupClause && parse->groupingSets) || contain_agg_clause(havingclause) || contain_volatile_functions(havingclause) || contain_subplans(havingclause)) { /* keep it in HAVING */ newHaving = lappend(newHaving, havingclause); } else if (parse->groupClause && !parse->groupingSets) { /* move it to WHERE */ parse->jointree->quals = (Node *) lappend((List *) parse->jointree->quals, havingclause); } else { /* put a copy in WHERE, keep it in HAVING */ parse->jointree->quals = (Node *) lappend((List *) parse->jointree->quals, copyObject(havingclause)); newHaving = lappend(newHaving, havingclause); } } parse->havingQual = (Node *) newHaving; /* Remove any redundant GROUP BY columns */ remove_useless_groupby_columns(root); /* * If we have any outer joins, try to reduce them to plain inner joins. * This step is most easily done after we've done expression * preprocessing. */ if (hasOuterJoins) reduce_outer_joins(root); /* * If we have any RTE_RESULT relations, see if they can be deleted from * the jointree. This step is most effectively done after we've done * expression preprocessing and outer join reduction. */ if (hasResultRTEs) remove_useless_result_rtes(root); /* * Do the main planning. */ grouping_planner(root, tuple_fraction); /* * Capture the set of outer-level param IDs we have access to, for use in * extParam/allParam calculations later. */ SS_identify_outer_params(root); /* * If any initPlans were created in this query level, adjust the surviving * Paths' costs and parallel-safety flags to account for them. The * initPlans won't actually get attached to the plan tree till * create_plan() runs, but we must include their effects now. */ final_rel = fetch_upper_rel(root, UPPERREL_FINAL, NULL); SS_charge_for_initplans(root, final_rel); /* * Make sure we've identified the cheapest Path for the final rel. (By * doing this here not in grouping_planner, we include initPlan costs in * the decision, though it's unlikely that will change anything.) */ set_cheapest(final_rel); return root; } /* * preprocess_expression * Do subquery_planner's preprocessing work for an expression, * which can be a targetlist, a WHERE clause (including JOIN/ON * conditions), a HAVING clause, or a few other things. */ static Node * preprocess_expression(PlannerInfo *root, Node *expr, int kind) { /* * Fall out quickly if expression is empty. This occurs often enough to * be worth checking. Note that null->null is the correct conversion for * implicit-AND result format, too. */ if (expr == NULL) return NULL; /* * If the query has any join RTEs, replace join alias variables with * base-relation variables. We must do this first, since any expressions * we may extract from the joinaliasvars lists have not been preprocessed. * For example, if we did this after sublink processing, sublinks expanded * out from join aliases would not get processed. But we can skip this in * non-lateral RTE functions, VALUES lists, and TABLESAMPLE clauses, since * they can't contain any Vars of the current query level. */ if (root->hasJoinRTEs && !(kind == EXPRKIND_RTFUNC || kind == EXPRKIND_VALUES || kind == EXPRKIND_TABLESAMPLE || kind == EXPRKIND_TABLEFUNC)) expr = flatten_join_alias_vars(root->parse, expr); /* * Simplify constant expressions. For function RTEs, this was already * done by preprocess_function_rtes. (But note we must do it again for * EXPRKIND_RTFUNC_LATERAL, because those might by now contain * un-simplified subexpressions inserted by flattening of subqueries or * join alias variables.) * * Note: an essential effect of this is to convert named-argument function * calls to positional notation and insert the current actual values of * any default arguments for functions. To ensure that happens, we *must* * process all expressions here. Previous PG versions sometimes skipped * const-simplification if it didn't seem worth the trouble, but we can't * do that anymore. * * Note: this also flattens nested AND and OR expressions into N-argument * form. All processing of a qual expression after this point must be * careful to maintain AND/OR flatness --- that is, do not generate a tree * with AND directly under AND, nor OR directly under OR. */ if (kind != EXPRKIND_RTFUNC) expr = eval_const_expressions(root, expr); /* * If it's a qual or havingQual, canonicalize it. */ if (kind == EXPRKIND_QUAL) { expr = (Node *) canonicalize_qual((Expr *) expr, false); #ifdef OPTIMIZER_DEBUG printf("After canonicalize_qual()\n"); pprint(expr); #endif } /* * Check for ANY ScalarArrayOpExpr with Const arrays and set the * hashfuncid of any that might execute more quickly by using hash lookups * instead of a linear search. */ if (kind == EXPRKIND_QUAL || kind == EXPRKIND_TARGET) { convert_saop_to_hashed_saop(expr); } /* Expand SubLinks to SubPlans */ if (root->parse->hasSubLinks) expr = SS_process_sublinks(root, expr, (kind == EXPRKIND_QUAL)); /* * XXX do not insert anything here unless you have grokked the comments in * SS_replace_correlation_vars ... */ /* Replace uplevel vars with Param nodes (this IS possible in VALUES) */ if (root->query_level > 1) expr = SS_replace_correlation_vars(root, expr); /* * If it's a qual or havingQual, convert it to implicit-AND format. (We * don't want to do this before eval_const_expressions, since the latter * would be unable to simplify a top-level AND correctly. Also, * SS_process_sublinks expects explicit-AND format.) */ if (kind == EXPRKIND_QUAL) expr = (Node *) make_ands_implicit((Expr *) expr); return expr; } /* * preprocess_qual_conditions * Recursively scan the query's jointree and do subquery_planner's * preprocessing work on each qual condition found therein. */ static void preprocess_qual_conditions(PlannerInfo *root, Node *jtnode) { if (jtnode == NULL) return; if (IsA(jtnode, RangeTblRef)) { /* nothing to do here */ } else if (IsA(jtnode, FromExpr)) { FromExpr *f = (FromExpr *) jtnode; ListCell *l; foreach(l, f->fromlist) preprocess_qual_conditions(root, lfirst(l)); f->quals = preprocess_expression(root, f->quals, EXPRKIND_QUAL); } else if (IsA(jtnode, JoinExpr)) { JoinExpr *j = (JoinExpr *) jtnode; preprocess_qual_conditions(root, j->larg); preprocess_qual_conditions(root, j->rarg); j->quals = preprocess_expression(root, j->quals, EXPRKIND_QUAL); } else elog(ERROR, "unrecognized node type: %d", (int) nodeTag(jtnode)); } /* * preprocess_phv_expression * Do preprocessing on a PlaceHolderVar expression that's been pulled up. * * If a LATERAL subquery references an output of another subquery, and that * output must be wrapped in a PlaceHolderVar because of an intermediate outer * join, then we'll push the PlaceHolderVar expression down into the subquery * and later pull it back up during find_lateral_references, which runs after * subquery_planner has preprocessed all the expressions that were in the * current query level to start with. So we need to preprocess it then. */ Expr * preprocess_phv_expression(PlannerInfo *root, Expr *expr) { return (Expr *) preprocess_expression(root, (Node *) expr, EXPRKIND_PHV); } /*-------------------- * grouping_planner * Perform planning steps related to grouping, aggregation, etc. * * This function adds all required top-level processing to the scan/join * Path(s) produced by query_planner. * * tuple_fraction is the fraction of tuples we expect will be retrieved. * tuple_fraction is interpreted as follows: * 0: expect all tuples to be retrieved (normal case) * 0 < tuple_fraction < 1: expect the given fraction of tuples available * from the plan to be retrieved * tuple_fraction >= 1: tuple_fraction is the absolute number of tuples * expected to be retrieved (ie, a LIMIT specification) * * Returns nothing; the useful output is in the Paths we attach to the * (UPPERREL_FINAL, NULL) upperrel in *root. In addition, * root->processed_tlist contains the final processed targetlist. * * Note that we have not done set_cheapest() on the final rel; it's convenient * to leave this to the caller. *-------------------- */ static void grouping_planner(PlannerInfo *root, double tuple_fraction) { Query *parse = root->parse; int64 offset_est = 0; int64 count_est = 0; double limit_tuples = -1.0; bool have_postponed_srfs = false; PathTarget *final_target; List *final_targets; List *final_targets_contain_srfs; bool final_target_parallel_safe; RelOptInfo *current_rel; RelOptInfo *final_rel; FinalPathExtraData extra; ListCell *lc; /* Tweak caller-supplied tuple_fraction if have LIMIT/OFFSET */ if (parse->limitCount || parse->limitOffset) { tuple_fraction = preprocess_limit(root, tuple_fraction, &offset_est, &count_est); /* * If we have a known LIMIT, and don't have an unknown OFFSET, we can * estimate the effects of using a bounded sort. */ if (count_est > 0 && offset_est >= 0) limit_tuples = (double) count_est + (double) offset_est; } /* Make tuple_fraction accessible to lower-level routines */ root->tuple_fraction = tuple_fraction; if (parse->setOperations) { /* * If there's a top-level ORDER BY, assume we have to fetch all the * tuples. This might be too simplistic given all the hackery below * to possibly avoid the sort; but the odds of accurate estimates here * are pretty low anyway. XXX try to get rid of this in favor of * letting plan_set_operations generate both fast-start and * cheapest-total paths. */ if (parse->sortClause) root->tuple_fraction = 0.0; /* * Construct Paths for set operations. The results will not need any * work except perhaps a top-level sort and/or LIMIT. Note that any * special work for recursive unions is the responsibility of * plan_set_operations. */ current_rel = plan_set_operations(root); /* * We should not need to call preprocess_targetlist, since we must be * in a SELECT query node. Instead, use the processed_tlist returned * by plan_set_operations (since this tells whether it returned any * resjunk columns!), and transfer any sort key information from the * original tlist. */ Assert(parse->commandType == CMD_SELECT); /* for safety, copy processed_tlist instead of modifying in-place */ root->processed_tlist = postprocess_setop_tlist(copyObject(root->processed_tlist), parse->targetList); /* Also extract the PathTarget form of the setop result tlist */ final_target = current_rel->cheapest_total_path->pathtarget; /* And check whether it's parallel safe */ final_target_parallel_safe = is_parallel_safe(root, (Node *) final_target->exprs); /* The setop result tlist couldn't contain any SRFs */ Assert(!parse->hasTargetSRFs); final_targets = final_targets_contain_srfs = NIL; /* * Can't handle FOR [KEY] UPDATE/SHARE here (parser should have * checked already, but let's make sure). */ if (parse->rowMarks) ereport(ERROR, (errcode(ERRCODE_FEATURE_NOT_SUPPORTED), /*------ translator: %s is a SQL row locking clause such as FOR UPDATE */ errmsg("%s is not allowed with UNION/INTERSECT/EXCEPT", LCS_asString(linitial_node(RowMarkClause, parse->rowMarks)->strength)))); /* * Calculate pathkeys that represent result ordering requirements */ Assert(parse->distinctClause == NIL); root->sort_pathkeys = make_pathkeys_for_sortclauses(root, parse->sortClause, root->processed_tlist); } else { /* No set operations, do regular planning */ PathTarget *sort_input_target; List *sort_input_targets; List *sort_input_targets_contain_srfs; bool sort_input_target_parallel_safe; PathTarget *grouping_target; List *grouping_targets; List *grouping_targets_contain_srfs; bool grouping_target_parallel_safe; PathTarget *scanjoin_target; List *scanjoin_targets; List *scanjoin_targets_contain_srfs; bool scanjoin_target_parallel_safe; bool scanjoin_target_same_exprs; bool have_grouping; WindowFuncLists *wflists = NULL; List *activeWindows = NIL; grouping_sets_data *gset_data = NULL; standard_qp_extra qp_extra; /* A recursive query should always have setOperations */ Assert(!root->hasRecursion); /* Preprocess grouping sets and GROUP BY clause, if any */ if (parse->groupingSets) { gset_data = preprocess_grouping_sets(root); } else { /* Preprocess regular GROUP BY clause, if any */ if (parse->groupClause) parse->groupClause = preprocess_groupclause(root, NIL); } /* * Preprocess targetlist. Note that much of the remaining planning * work will be done with the PathTarget representation of tlists, but * we must also maintain the full representation of the final tlist so * that we can transfer its decoration (resnames etc) to the topmost * tlist of the finished Plan. This is kept in processed_tlist. */ preprocess_targetlist(root); /* * Mark all the aggregates with resolved aggtranstypes, and detect * aggregates that are duplicates or can share transition state. We * must do this before slicing and dicing the tlist into various * pathtargets, else some copies of the Aggref nodes might escape * being marked. */ if (parse->hasAggs) { preprocess_aggrefs(root, (Node *) root->processed_tlist); preprocess_aggrefs(root, (Node *) parse->havingQual); } /* * Locate any window functions in the tlist. (We don't need to look * anywhere else, since expressions used in ORDER BY will be in there * too.) Note that they could all have been eliminated by constant * folding, in which case we don't need to do any more work. */ if (parse->hasWindowFuncs) { wflists = find_window_functions((Node *) root->processed_tlist, list_length(parse->windowClause)); if (wflists->numWindowFuncs > 0) activeWindows = select_active_windows(root, wflists); else parse->hasWindowFuncs = false; } /* * Preprocess MIN/MAX aggregates, if any. Note: be careful about * adding logic between here and the query_planner() call. Anything * that is needed in MIN/MAX-optimizable cases will have to be * duplicated in planagg.c. */ if (parse->hasAggs) preprocess_minmax_aggregates(root); /* * Figure out whether there's a hard limit on the number of rows that * query_planner's result subplan needs to return. Even if we know a * hard limit overall, it doesn't apply if the query has any * grouping/aggregation operations, or SRFs in the tlist. */ if (parse->groupClause || parse->groupingSets || parse->distinctClause || parse->hasAggs || parse->hasWindowFuncs || parse->hasTargetSRFs || root->hasHavingQual) root->limit_tuples = -1.0; else root->limit_tuples = limit_tuples; /* Set up data needed by standard_qp_callback */ qp_extra.activeWindows = activeWindows; qp_extra.groupClause = (gset_data ? (gset_data->rollups ? linitial_node(RollupData, gset_data->rollups)->groupClause : NIL) : parse->groupClause); /* * Generate the best unsorted and presorted paths for the scan/join * portion of this Query, ie the processing represented by the * FROM/WHERE clauses. (Note there may not be any presorted paths.) * We also generate (in standard_qp_callback) pathkey representations * of the query's sort clause, distinct clause, etc. */ current_rel = query_planner(root, standard_qp_callback, &qp_extra); /* * Convert the query's result tlist into PathTarget format. * * Note: this cannot be done before query_planner() has performed * appendrel expansion, because that might add resjunk entries to * root->processed_tlist. Waiting till afterwards is also helpful * because the target width estimates can use per-Var width numbers * that were obtained within query_planner(). */ final_target = create_pathtarget(root, root->processed_tlist); final_target_parallel_safe = is_parallel_safe(root, (Node *) final_target->exprs); /* * If ORDER BY was given, consider whether we should use a post-sort * projection, and compute the adjusted target for preceding steps if * so. */ if (parse->sortClause) { sort_input_target = make_sort_input_target(root, final_target, &have_postponed_srfs); sort_input_target_parallel_safe = is_parallel_safe(root, (Node *) sort_input_target->exprs); } else { sort_input_target = final_target; sort_input_target_parallel_safe = final_target_parallel_safe; } /* * If we have window functions to deal with, the output from any * grouping step needs to be what the window functions want; * otherwise, it should be sort_input_target. */ if (activeWindows) { grouping_target = make_window_input_target(root, final_target, activeWindows); grouping_target_parallel_safe = is_parallel_safe(root, (Node *) grouping_target->exprs); } else { grouping_target = sort_input_target; grouping_target_parallel_safe = sort_input_target_parallel_safe; } /* * If we have grouping or aggregation to do, the topmost scan/join * plan node must emit what the grouping step wants; otherwise, it * should emit grouping_target. */ have_grouping = (parse->groupClause || parse->groupingSets || parse->hasAggs || root->hasHavingQual); if (have_grouping) { scanjoin_target = make_group_input_target(root, final_target); scanjoin_target_parallel_safe = is_parallel_safe(root, (Node *) scanjoin_target->exprs); } else { scanjoin_target = grouping_target; scanjoin_target_parallel_safe = grouping_target_parallel_safe; } /* * If there are any SRFs in the targetlist, we must separate each of * these PathTargets into SRF-computing and SRF-free targets. Replace * each of the named targets with a SRF-free version, and remember the * list of additional projection steps we need to add afterwards. */ if (parse->hasTargetSRFs) { /* final_target doesn't recompute any SRFs in sort_input_target */ split_pathtarget_at_srfs(root, final_target, sort_input_target, &final_targets, &final_targets_contain_srfs); final_target = linitial_node(PathTarget, final_targets); Assert(!linitial_int(final_targets_contain_srfs)); /* likewise for sort_input_target vs. grouping_target */ split_pathtarget_at_srfs(root, sort_input_target, grouping_target, &sort_input_targets, &sort_input_targets_contain_srfs); sort_input_target = linitial_node(PathTarget, sort_input_targets); Assert(!linitial_int(sort_input_targets_contain_srfs)); /* likewise for grouping_target vs. scanjoin_target */ split_pathtarget_at_srfs(root, grouping_target, scanjoin_target, &grouping_targets, &grouping_targets_contain_srfs); grouping_target = linitial_node(PathTarget, grouping_targets); Assert(!linitial_int(grouping_targets_contain_srfs)); /* scanjoin_target will not have any SRFs precomputed for it */ split_pathtarget_at_srfs(root, scanjoin_target, NULL, &scanjoin_targets, &scanjoin_targets_contain_srfs); scanjoin_target = linitial_node(PathTarget, scanjoin_targets); Assert(!linitial_int(scanjoin_targets_contain_srfs)); } else { /* initialize lists; for most of these, dummy values are OK */ final_targets = final_targets_contain_srfs = NIL; sort_input_targets = sort_input_targets_contain_srfs = NIL; grouping_targets = grouping_targets_contain_srfs = NIL; scanjoin_targets = list_make1(scanjoin_target); scanjoin_targets_contain_srfs = NIL; } /* Apply scan/join target. */ scanjoin_target_same_exprs = list_length(scanjoin_targets) == 1 && equal(scanjoin_target->exprs, current_rel->reltarget->exprs); apply_scanjoin_target_to_paths(root, current_rel, scanjoin_targets, scanjoin_targets_contain_srfs, scanjoin_target_parallel_safe, scanjoin_target_same_exprs); /* * Save the various upper-rel PathTargets we just computed into * root->upper_targets[]. The core code doesn't use this, but it * provides a convenient place for extensions to get at the info. For * consistency, we save all the intermediate targets, even though some * of the corresponding upperrels might not be needed for this query. */ root->upper_targets[UPPERREL_FINAL] = final_target; root->upper_targets[UPPERREL_ORDERED] = final_target; root->upper_targets[UPPERREL_DISTINCT] = sort_input_target; root->upper_targets[UPPERREL_WINDOW] = sort_input_target; root->upper_targets[UPPERREL_GROUP_AGG] = grouping_target; /* * If we have grouping and/or aggregation, consider ways to implement * that. We build a new upperrel representing the output of this * phase. */ if (have_grouping) { current_rel = create_grouping_paths(root, current_rel, grouping_target, grouping_target_parallel_safe, gset_data); /* Fix things up if grouping_target contains SRFs */ if (parse->hasTargetSRFs) adjust_paths_for_srfs(root, current_rel, grouping_targets, grouping_targets_contain_srfs); } /* * If we have window functions, consider ways to implement those. We * build a new upperrel representing the output of this phase. */ if (activeWindows) { current_rel = create_window_paths(root, current_rel, grouping_target, sort_input_target, sort_input_target_parallel_safe, wflists, activeWindows); /* Fix things up if sort_input_target contains SRFs */ if (parse->hasTargetSRFs) adjust_paths_for_srfs(root, current_rel, sort_input_targets, sort_input_targets_contain_srfs); } /* * If there is a DISTINCT clause, consider ways to implement that. We * build a new upperrel representing the output of this phase. */ if (parse->distinctClause) { current_rel = create_distinct_paths(root, current_rel); } } /* end of if (setOperations) */ /* * If ORDER BY was given, consider ways to implement that, and generate a * new upperrel containing only paths that emit the correct ordering and * project the correct final_target. We can apply the original * limit_tuples limit in sort costing here, but only if there are no * postponed SRFs. */ if (parse->sortClause) { current_rel = create_ordered_paths(root, current_rel, final_target, final_target_parallel_safe, have_postponed_srfs ? -1.0 : limit_tuples); /* Fix things up if final_target contains SRFs */ if (parse->hasTargetSRFs) adjust_paths_for_srfs(root, current_rel, final_targets, final_targets_contain_srfs); } /* * Now we are prepared to build the final-output upperrel. */ final_rel = fetch_upper_rel(root, UPPERREL_FINAL, NULL); /* * If the input rel is marked consider_parallel and there's nothing that's * not parallel-safe in the LIMIT clause, then the final_rel can be marked * consider_parallel as well. Note that if the query has rowMarks or is * not a SELECT, consider_parallel will be false for every relation in the * query. */ if (current_rel->consider_parallel && is_parallel_safe(root, parse->limitOffset) && is_parallel_safe(root, parse->limitCount)) final_rel->consider_parallel = true; /* * If the current_rel belongs to a single FDW, so does the final_rel. */ final_rel->serverid = current_rel->serverid; final_rel->userid = current_rel->userid; final_rel->useridiscurrent = current_rel->useridiscurrent; final_rel->fdwroutine = current_rel->fdwroutine; /* * Generate paths for the final_rel. Insert all surviving paths, with * LockRows, Limit, and/or ModifyTable steps added if needed. */ foreach(lc, current_rel->pathlist) { Path *path = (Path *) lfirst(lc); /* * If there is a FOR [KEY] UPDATE/SHARE clause, add the LockRows node. * (Note: we intentionally test parse->rowMarks not root->rowMarks * here. If there are only non-locking rowmarks, they should be * handled by the ModifyTable node instead. However, root->rowMarks * is what goes into the LockRows node.) */ if (parse->rowMarks) { path = (Path *) create_lockrows_path(root, final_rel, path, root->rowMarks, assign_special_exec_param(root)); } /* * If there is a LIMIT/OFFSET clause, add the LIMIT node. */ if (limit_needed(parse)) { path = (Path *) create_limit_path(root, final_rel, path, parse->limitOffset, parse->limitCount, parse->limitOption, offset_est, count_est); } /* * If this is an INSERT/UPDATE/DELETE, add the ModifyTable node. */ if (parse->commandType != CMD_SELECT) { Index rootRelation; List *resultRelations = NIL; List *updateColnosLists = NIL; List *withCheckOptionLists = NIL; List *returningLists = NIL; List *rowMarks; if (bms_membership(root->all_result_relids) == BMS_MULTIPLE) { /* Inherited UPDATE/DELETE */ RelOptInfo *top_result_rel = find_base_rel(root, parse->resultRelation); int resultRelation = -1; /* Add only leaf children to ModifyTable. */ while ((resultRelation = bms_next_member(root->leaf_result_relids, resultRelation)) >= 0) { RelOptInfo *this_result_rel = find_base_rel(root, resultRelation); /* * Also exclude any leaf rels that have turned dummy since * being added to the list, for example, by being excluded * by constraint exclusion. */ if (IS_DUMMY_REL(this_result_rel)) continue; /* Build per-target-rel lists needed by ModifyTable */ resultRelations = lappend_int(resultRelations, resultRelation); if (parse->commandType == CMD_UPDATE) { List *update_colnos = root->update_colnos; if (this_result_rel != top_result_rel) update_colnos = adjust_inherited_attnums_multilevel(root, update_colnos, this_result_rel->relid, top_result_rel->relid); updateColnosLists = lappend(updateColnosLists, update_colnos); } if (parse->withCheckOptions) { List *withCheckOptions = parse->withCheckOptions; if (this_result_rel != top_result_rel) withCheckOptions = (List *) adjust_appendrel_attrs_multilevel(root, (Node *) withCheckOptions, this_result_rel->relids, top_result_rel->relids); withCheckOptionLists = lappend(withCheckOptionLists, withCheckOptions); } if (parse->returningList) { List *returningList = parse->returningList; if (this_result_rel != top_result_rel) returningList = (List *) adjust_appendrel_attrs_multilevel(root, (Node *) returningList, this_result_rel->relids, top_result_rel->relids); returningLists = lappend(returningLists, returningList); } } if (resultRelations == NIL) { /* * We managed to exclude every child rel, so generate a * dummy one-relation plan using info for the top target * rel (even though that may not be a leaf target). * Although it's clear that no data will be updated or * deleted, we still need to have a ModifyTable node so * that any statement triggers will be executed. (This * could be cleaner if we fixed nodeModifyTable.c to allow * zero target relations, but that probably wouldn't be a * net win.) */ resultRelations = list_make1_int(parse->resultRelation); if (parse->commandType == CMD_UPDATE) updateColnosLists = list_make1(root->update_colnos); if (parse->withCheckOptions) withCheckOptionLists = list_make1(parse->withCheckOptions); if (parse->returningList) returningLists = list_make1(parse->returningList); } } else { /* Single-relation INSERT/UPDATE/DELETE. */ resultRelations = list_make1_int(parse->resultRelation); if (parse->commandType == CMD_UPDATE) updateColnosLists = list_make1(root->update_colnos); if (parse->withCheckOptions) withCheckOptionLists = list_make1(parse->withCheckOptions); if (parse->returningList) returningLists = list_make1(parse->returningList); } /* * If target is a partition root table, we need to mark the * ModifyTable node appropriately for that. */ if (rt_fetch(parse->resultRelation, parse->rtable)->relkind == RELKIND_PARTITIONED_TABLE) rootRelation = parse->resultRelation; else rootRelation = 0; /* * If there was a FOR [KEY] UPDATE/SHARE clause, the LockRows node * will have dealt with fetching non-locked marked rows, else we * need to have ModifyTable do that. */ if (parse->rowMarks) rowMarks = NIL; else rowMarks = root->rowMarks; path = (Path *) create_modifytable_path(root, final_rel, path, parse->commandType, parse->canSetTag, parse->resultRelation, rootRelation, root->partColsUpdated, resultRelations, updateColnosLists, withCheckOptionLists, returningLists, rowMarks, parse->onConflict, assign_special_exec_param(root)); } /* And shove it into final_rel */ add_path(final_rel, path); } /* * Generate partial paths for final_rel, too, if outer query levels might * be able to make use of them. */ if (final_rel->consider_parallel && root->query_level > 1 && !limit_needed(parse)) { Assert(!parse->rowMarks && parse->commandType == CMD_SELECT); foreach(lc, current_rel->partial_pathlist) { Path *partial_path = (Path *) lfirst(lc); add_partial_path(final_rel, partial_path); } } extra.limit_needed = limit_needed(parse); extra.limit_tuples = limit_tuples; extra.count_est = count_est; extra.offset_est = offset_est; /* * If there is an FDW that's responsible for all baserels of the query, * let it consider adding ForeignPaths. */ if (final_rel->fdwroutine && final_rel->fdwroutine->GetForeignUpperPaths) final_rel->fdwroutine->GetForeignUpperPaths(root, UPPERREL_FINAL, current_rel, final_rel, &extra); /* Let extensions possibly add some more paths */ if (create_upper_paths_hook) (*create_upper_paths_hook) (root, UPPERREL_FINAL, current_rel, final_rel, &extra); /* Note: currently, we leave it to callers to do set_cheapest() */ } /* * Do preprocessing for groupingSets clause and related data. This handles the * preliminary steps of expanding the grouping sets, organizing them into lists * of rollups, and preparing annotations which will later be filled in with * size estimates. */ static grouping_sets_data * preprocess_grouping_sets(PlannerInfo *root) { Query *parse = root->parse; List *sets; int maxref = 0; ListCell *lc; ListCell *lc_set; grouping_sets_data *gd = palloc0(sizeof(grouping_sets_data)); parse->groupingSets = expand_grouping_sets(parse->groupingSets, parse->groupDistinct, -1); gd->any_hashable = false; gd->unhashable_refs = NULL; gd->unsortable_refs = NULL; gd->unsortable_sets = NIL; if (parse->groupClause) { ListCell *lc; foreach(lc, parse->groupClause) { SortGroupClause *gc = lfirst_node(SortGroupClause, lc); Index ref = gc->tleSortGroupRef; if (ref > maxref) maxref = ref; if (!gc->hashable) gd->unhashable_refs = bms_add_member(gd->unhashable_refs, ref); if (!OidIsValid(gc->sortop)) gd->unsortable_refs = bms_add_member(gd->unsortable_refs, ref); } } /* Allocate workspace array for remapping */ gd->tleref_to_colnum_map = (int *) palloc((maxref + 1) * sizeof(int)); /* * If we have any unsortable sets, we must extract them before trying to * prepare rollups. Unsortable sets don't go through * reorder_grouping_sets, so we must apply the GroupingSetData annotation * here. */ if (!bms_is_empty(gd->unsortable_refs)) { List *sortable_sets = NIL; foreach(lc, parse->groupingSets) { List *gset = (List *) lfirst(lc); if (bms_overlap_list(gd->unsortable_refs, gset)) { GroupingSetData *gs = makeNode(GroupingSetData); gs->set = gset; gd->unsortable_sets = lappend(gd->unsortable_sets, gs); /* * We must enforce here that an unsortable set is hashable; * later code assumes this. Parse analysis only checks that * every individual column is either hashable or sortable. * * Note that passing this test doesn't guarantee we can * generate a plan; there might be other showstoppers. */ if (bms_overlap_list(gd->unhashable_refs, gset)) ereport(ERROR, (errcode(ERRCODE_FEATURE_NOT_SUPPORTED), errmsg("could not implement GROUP BY"), errdetail("Some of the datatypes only support hashing, while others only support sorting."))); } else sortable_sets = lappend(sortable_sets, gset); } if (sortable_sets) sets = extract_rollup_sets(sortable_sets); else sets = NIL; } else sets = extract_rollup_sets(parse->groupingSets); foreach(lc_set, sets) { List *current_sets = (List *) lfirst(lc_set); RollupData *rollup = makeNode(RollupData); GroupingSetData *gs; /* * Reorder the current list of grouping sets into correct prefix * order. If only one aggregation pass is needed, try to make the * list match the ORDER BY clause; if more than one pass is needed, we * don't bother with that. * * Note that this reorders the sets from smallest-member-first to * largest-member-first, and applies the GroupingSetData annotations, * though the data will be filled in later. */ current_sets = reorder_grouping_sets(current_sets, (list_length(sets) == 1 ? parse->sortClause : NIL)); /* * Get the initial (and therefore largest) grouping set. */ gs = linitial_node(GroupingSetData, current_sets); /* * Order the groupClause appropriately. If the first grouping set is * empty, then the groupClause must also be empty; otherwise we have * to force the groupClause to match that grouping set's order. * * (The first grouping set can be empty even though parse->groupClause * is not empty only if all non-empty grouping sets are unsortable. * The groupClauses for hashed grouping sets are built later on.) */ if (gs->set) rollup->groupClause = preprocess_groupclause(root, gs->set); else rollup->groupClause = NIL; /* * Is it hashable? We pretend empty sets are hashable even though we * actually force them not to be hashed later. But don't bother if * there's nothing but empty sets (since in that case we can't hash * anything). */ if (gs->set && !bms_overlap_list(gd->unhashable_refs, gs->set)) { rollup->hashable = true; gd->any_hashable = true; } /* * Now that we've pinned down an order for the groupClause for this * list of grouping sets, we need to remap the entries in the grouping * sets from sortgrouprefs to plain indices (0-based) into the * groupClause for this collection of grouping sets. We keep the * original form for later use, though. */ rollup->gsets = remap_to_groupclause_idx(rollup->groupClause, current_sets, gd->tleref_to_colnum_map); rollup->gsets_data = current_sets; gd->rollups = lappend(gd->rollups, rollup); } if (gd->unsortable_sets) { /* * We have not yet pinned down a groupclause for this, but we will * need index-based lists for estimation purposes. Construct * hash_sets_idx based on the entire original groupclause for now. */ gd->hash_sets_idx = remap_to_groupclause_idx(parse->groupClause, gd->unsortable_sets, gd->tleref_to_colnum_map); gd->any_hashable = true; } return gd; } /* * Given a groupclause and a list of GroupingSetData, return equivalent sets * (without annotation) mapped to indexes into the given groupclause. */ static List * remap_to_groupclause_idx(List *groupClause, List *gsets, int *tleref_to_colnum_map) { int ref = 0; List *result = NIL; ListCell *lc; foreach(lc, groupClause) { SortGroupClause *gc = lfirst_node(SortGroupClause, lc); tleref_to_colnum_map[gc->tleSortGroupRef] = ref++; } foreach(lc, gsets) { List *set = NIL; ListCell *lc2; GroupingSetData *gs = lfirst_node(GroupingSetData, lc); foreach(lc2, gs->set) { set = lappend_int(set, tleref_to_colnum_map[lfirst_int(lc2)]); } result = lappend(result, set); } return result; } /* * preprocess_rowmarks - set up PlanRowMarks if needed */ static void preprocess_rowmarks(PlannerInfo *root) { Query *parse = root->parse; Bitmapset *rels; List *prowmarks; ListCell *l; int i; if (parse->rowMarks) { /* * We've got trouble if FOR [KEY] UPDATE/SHARE appears inside * grouping, since grouping renders a reference to individual tuple * CTIDs invalid. This is also checked at parse time, but that's * insufficient because of rule substitution, query pullup, etc. */ CheckSelectLocking(parse, linitial_node(RowMarkClause, parse->rowMarks)->strength); } else { /* * We only need rowmarks for UPDATE, DELETE, or FOR [KEY] * UPDATE/SHARE. */ if (parse->commandType != CMD_UPDATE && parse->commandType != CMD_DELETE) return; } /* * We need to have rowmarks for all base relations except the target. We * make a bitmapset of all base rels and then remove the items we don't * need or have FOR [KEY] UPDATE/SHARE marks for. */ rels = get_relids_in_jointree((Node *) parse->jointree, false); if (parse->resultRelation) rels = bms_del_member(rels, parse->resultRelation); /* * Convert RowMarkClauses to PlanRowMark representation. */ prowmarks = NIL; foreach(l, parse->rowMarks) { RowMarkClause *rc = lfirst_node(RowMarkClause, l); RangeTblEntry *rte = rt_fetch(rc->rti, parse->rtable); PlanRowMark *newrc; /* * Currently, it is syntactically impossible to have FOR UPDATE et al * applied to an update/delete target rel. If that ever becomes * possible, we should drop the target from the PlanRowMark list. */ Assert(rc->rti != parse->resultRelation); /* * Ignore RowMarkClauses for subqueries; they aren't real tables and * can't support true locking. Subqueries that got flattened into the * main query should be ignored completely. Any that didn't will get * ROW_MARK_COPY items in the next loop. */ if (rte->rtekind != RTE_RELATION) continue; rels = bms_del_member(rels, rc->rti); newrc = makeNode(PlanRowMark); newrc->rti = newrc->prti = rc->rti; newrc->rowmarkId = ++(root->glob->lastRowMarkId); newrc->markType = select_rowmark_type(rte, rc->strength); newrc->allMarkTypes = (1 << newrc->markType); newrc->strength = rc->strength; newrc->waitPolicy = rc->waitPolicy; newrc->isParent = false; prowmarks = lappend(prowmarks, newrc); } /* * Now, add rowmarks for any non-target, non-locked base relations. */ i = 0; foreach(l, parse->rtable) { RangeTblEntry *rte = lfirst_node(RangeTblEntry, l); PlanRowMark *newrc; i++; if (!bms_is_member(i, rels)) continue; newrc = makeNode(PlanRowMark); newrc->rti = newrc->prti = i; newrc->rowmarkId = ++(root->glob->lastRowMarkId); newrc->markType = select_rowmark_type(rte, LCS_NONE); newrc->allMarkTypes = (1 << newrc->markType); newrc->strength = LCS_NONE; newrc->waitPolicy = LockWaitBlock; /* doesn't matter */ newrc->isParent = false; prowmarks = lappend(prowmarks, newrc); } root->rowMarks = prowmarks; } /* * Select RowMarkType to use for a given table */ RowMarkType select_rowmark_type(RangeTblEntry *rte, LockClauseStrength strength) { if (rte->rtekind != RTE_RELATION) { /* If it's not a table at all, use ROW_MARK_COPY */ return ROW_MARK_COPY; } else if (rte->relkind == RELKIND_FOREIGN_TABLE) { /* Let the FDW select the rowmark type, if it wants to */ FdwRoutine *fdwroutine = GetFdwRoutineByRelId(rte->relid); if (fdwroutine->GetForeignRowMarkType != NULL) return fdwroutine->GetForeignRowMarkType(rte, strength); /* Otherwise, use ROW_MARK_COPY by default */ return ROW_MARK_COPY; } else { /* Regular table, apply the appropriate lock type */ switch (strength) { case LCS_NONE: /* * We don't need a tuple lock, only the ability to re-fetch * the row. */ return ROW_MARK_REFERENCE; break; case LCS_FORKEYSHARE: return ROW_MARK_KEYSHARE; break; case LCS_FORSHARE: return ROW_MARK_SHARE; break; case LCS_FORNOKEYUPDATE: return ROW_MARK_NOKEYEXCLUSIVE; break; case LCS_FORUPDATE: return ROW_MARK_EXCLUSIVE; break; } elog(ERROR, "unrecognized LockClauseStrength %d", (int) strength); return ROW_MARK_EXCLUSIVE; /* keep compiler quiet */ } } /* * preprocess_limit - do pre-estimation for LIMIT and/or OFFSET clauses * * We try to estimate the values of the LIMIT/OFFSET clauses, and pass the * results back in *count_est and *offset_est. These variables are set to * 0 if the corresponding clause is not present, and -1 if it's present * but we couldn't estimate the value for it. (The "0" convention is OK * for OFFSET but a little bit bogus for LIMIT: effectively we estimate * LIMIT 0 as though it were LIMIT 1. But this is in line with the planner's * usual practice of never estimating less than one row.) These values will * be passed to create_limit_path, which see if you change this code. * * The return value is the suitably adjusted tuple_fraction to use for * planning the query. This adjustment is not overridable, since it reflects * plan actions that grouping_planner() will certainly take, not assumptions * about context. */ static double preprocess_limit(PlannerInfo *root, double tuple_fraction, int64 *offset_est, int64 *count_est) { Query *parse = root->parse; Node *est; double limit_fraction; /* Should not be called unless LIMIT or OFFSET */ Assert(parse->limitCount || parse->limitOffset); /* * Try to obtain the clause values. We use estimate_expression_value * primarily because it can sometimes do something useful with Params. */ if (parse->limitCount) { est = estimate_expression_value(root, parse->limitCount); if (est && IsA(est, Const)) { if (((Const *) est)->constisnull) { /* NULL indicates LIMIT ALL, ie, no limit */ *count_est = 0; /* treat as not present */ } else { *count_est = DatumGetInt64(((Const *) est)->constvalue); if (*count_est <= 0) *count_est = 1; /* force to at least 1 */ } } else *count_est = -1; /* can't estimate */ } else *count_est = 0; /* not present */ if (parse->limitOffset) { est = estimate_expression_value(root, parse->limitOffset); if (est && IsA(est, Const)) { if (((Const *) est)->constisnull) { /* Treat NULL as no offset; the executor will too */ *offset_est = 0; /* treat as not present */ } else { *offset_est = DatumGetInt64(((Const *) est)->constvalue); if (*offset_est < 0) *offset_est = 0; /* treat as not present */ } } else *offset_est = -1; /* can't estimate */ } else *offset_est = 0; /* not present */ if (*count_est != 0) { /* * A LIMIT clause limits the absolute number of tuples returned. * However, if it's not a constant LIMIT then we have to guess; for * lack of a better idea, assume 10% of the plan's result is wanted. */ if (*count_est < 0 || *offset_est < 0) { /* LIMIT or OFFSET is an expression ... punt ... */ limit_fraction = 0.10; } else { /* LIMIT (plus OFFSET, if any) is max number of tuples needed */ limit_fraction = (double) *count_est + (double) *offset_est; } /* * If we have absolute limits from both caller and LIMIT, use the * smaller value; likewise if they are both fractional. If one is * fractional and the other absolute, we can't easily determine which * is smaller, but we use the heuristic that the absolute will usually * be smaller. */ if (tuple_fraction >= 1.0) { if (limit_fraction >= 1.0) { /* both absolute */ tuple_fraction = Min(tuple_fraction, limit_fraction); } else { /* caller absolute, limit fractional; use caller's value */ } } else if (tuple_fraction > 0.0) { if (limit_fraction >= 1.0) { /* caller fractional, limit absolute; use limit */ tuple_fraction = limit_fraction; } else { /* both fractional */ tuple_fraction = Min(tuple_fraction, limit_fraction); } } else { /* no info from caller, just use limit */ tuple_fraction = limit_fraction; } } else if (*offset_est != 0 && tuple_fraction > 0.0) { /* * We have an OFFSET but no LIMIT. This acts entirely differently * from the LIMIT case: here, we need to increase rather than decrease * the caller's tuple_fraction, because the OFFSET acts to cause more * tuples to be fetched instead of fewer. This only matters if we got * a tuple_fraction > 0, however. * * As above, use 10% if OFFSET is present but unestimatable. */ if (*offset_est < 0) limit_fraction = 0.10; else limit_fraction = (double) *offset_est; /* * If we have absolute counts from both caller and OFFSET, add them * together; likewise if they are both fractional. If one is * fractional and the other absolute, we want to take the larger, and * we heuristically assume that's the fractional one. */ if (tuple_fraction >= 1.0) { if (limit_fraction >= 1.0) { /* both absolute, so add them together */ tuple_fraction += limit_fraction; } else { /* caller absolute, limit fractional; use limit */ tuple_fraction = limit_fraction; } } else { if (limit_fraction >= 1.0) { /* caller fractional, limit absolute; use caller's value */ } else { /* both fractional, so add them together */ tuple_fraction += limit_fraction; if (tuple_fraction >= 1.0) tuple_fraction = 0.0; /* assume fetch all */ } } } return tuple_fraction; } /* * limit_needed - do we actually need a Limit plan node? * * If we have constant-zero OFFSET and constant-null LIMIT, we can skip adding * a Limit node. This is worth checking for because "OFFSET 0" is a common * locution for an optimization fence. (Because other places in the planner * merely check whether parse->limitOffset isn't NULL, it will still work as * an optimization fence --- we're just suppressing unnecessary run-time * overhead.) * * This might look like it could be merged into preprocess_limit, but there's * a key distinction: here we need hard constants in OFFSET/LIMIT, whereas * in preprocess_limit it's good enough to consider estimated values. */ bool limit_needed(Query *parse) { Node *node; node = parse->limitCount; if (node) { if (IsA(node, Const)) { /* NULL indicates LIMIT ALL, ie, no limit */ if (!((Const *) node)->constisnull) return true; /* LIMIT with a constant value */ } else return true; /* non-constant LIMIT */ } node = parse->limitOffset; if (node) { if (IsA(node, Const)) { /* Treat NULL as no offset; the executor would too */ if (!((Const *) node)->constisnull) { int64 offset = DatumGetInt64(((Const *) node)->constvalue); if (offset != 0) return true; /* OFFSET with a nonzero value */ } } else return true; /* non-constant OFFSET */ } return false; /* don't need a Limit plan node */ } /* * remove_useless_groupby_columns * Remove any columns in the GROUP BY clause that are redundant due to * being functionally dependent on other GROUP BY columns. * * Since some other DBMSes do not allow references to ungrouped columns, it's * not unusual to find all columns listed in GROUP BY even though listing the * primary-key columns would be sufficient. Deleting such excess columns * avoids redundant sorting work, so it's worth doing. * * Relcache invalidations will ensure that cached plans become invalidated * when the underlying index of the pkey constraint is dropped. * * Currently, we only make use of pkey constraints for this, however, we may * wish to take this further in the future and also use unique constraints * which have NOT NULL columns. In that case, plan invalidation will still * work since relations will receive a relcache invalidation when a NOT NULL * constraint is dropped. */ static void remove_useless_groupby_columns(PlannerInfo *root) { Query *parse = root->parse; Bitmapset **groupbyattnos; Bitmapset **surplusvars; ListCell *lc; int relid; /* No chance to do anything if there are less than two GROUP BY items */ if (list_length(parse->groupClause) < 2) return; /* Don't fiddle with the GROUP BY clause if the query has grouping sets */ if (parse->groupingSets) return; /* * Scan the GROUP BY clause to find GROUP BY items that are simple Vars. * Fill groupbyattnos[k] with a bitmapset of the column attnos of RTE k * that are GROUP BY items. */ groupbyattnos = (Bitmapset **) palloc0(sizeof(Bitmapset *) * (list_length(parse->rtable) + 1)); foreach(lc, parse->groupClause) { SortGroupClause *sgc = lfirst_node(SortGroupClause, lc); TargetEntry *tle = get_sortgroupclause_tle(sgc, parse->targetList); Var *var = (Var *) tle->expr; /* * Ignore non-Vars and Vars from other query levels. * * XXX in principle, stable expressions containing Vars could also be * removed, if all the Vars are functionally dependent on other GROUP * BY items. But it's not clear that such cases occur often enough to * be worth troubling over. */ if (!IsA(var, Var) || var->varlevelsup > 0) continue; /* OK, remember we have this Var */ relid = var->varno; Assert(relid <= list_length(parse->rtable)); groupbyattnos[relid] = bms_add_member(groupbyattnos[relid], var->varattno - FirstLowInvalidHeapAttributeNumber); } /* * Consider each relation and see if it is possible to remove some of its * Vars from GROUP BY. For simplicity and speed, we do the actual removal * in a separate pass. Here, we just fill surplusvars[k] with a bitmapset * of the column attnos of RTE k that are removable GROUP BY items. */ surplusvars = NULL; /* don't allocate array unless required */ relid = 0; foreach(lc, parse->rtable) { RangeTblEntry *rte = lfirst_node(RangeTblEntry, lc); Bitmapset *relattnos; Bitmapset *pkattnos; Oid constraintOid; relid++; /* Only plain relations could have primary-key constraints */ if (rte->rtekind != RTE_RELATION) continue; /* * We must skip inheritance parent tables as some of the child rels * may cause duplicate rows. This cannot happen with partitioned * tables, however. */ if (rte->inh && rte->relkind != RELKIND_PARTITIONED_TABLE) continue; /* Nothing to do unless this rel has multiple Vars in GROUP BY */ relattnos = groupbyattnos[relid]; if (bms_membership(relattnos) != BMS_MULTIPLE) continue; /* * Can't remove any columns for this rel if there is no suitable * (i.e., nondeferrable) primary key constraint. */ pkattnos = get_primary_key_attnos(rte->relid, false, &constraintOid); if (pkattnos == NULL) continue; /* * If the primary key is a proper subset of relattnos then we have * some items in the GROUP BY that can be removed. */ if (bms_subset_compare(pkattnos, relattnos) == BMS_SUBSET1) { /* * To easily remember whether we've found anything to do, we don't * allocate the surplusvars[] array until we find something. */ if (surplusvars == NULL) surplusvars = (Bitmapset **) palloc0(sizeof(Bitmapset *) * (list_length(parse->rtable) + 1)); /* Remember the attnos of the removable columns */ surplusvars[relid] = bms_difference(relattnos, pkattnos); } } /* * If we found any surplus Vars, build a new GROUP BY clause without them. * (Note: this may leave some TLEs with unreferenced ressortgroupref * markings, but that's harmless.) */ if (surplusvars != NULL) { List *new_groupby = NIL; foreach(lc, parse->groupClause) { SortGroupClause *sgc = lfirst_node(SortGroupClause, lc); TargetEntry *tle = get_sortgroupclause_tle(sgc, parse->targetList); Var *var = (Var *) tle->expr; /* * New list must include non-Vars, outer Vars, and anything not * marked as surplus. */ if (!IsA(var, Var) || var->varlevelsup > 0 || !bms_is_member(var->varattno - FirstLowInvalidHeapAttributeNumber, surplusvars[var->varno])) new_groupby = lappend(new_groupby, sgc); } parse->groupClause = new_groupby; } } /* * preprocess_groupclause - do preparatory work on GROUP BY clause * * The idea here is to adjust the ordering of the GROUP BY elements * (which in itself is semantically insignificant) to match ORDER BY, * thereby allowing a single sort operation to both implement the ORDER BY * requirement and set up for a Unique step that implements GROUP BY. * * In principle it might be interesting to consider other orderings of the * GROUP BY elements, which could match the sort ordering of other * possible plans (eg an indexscan) and thereby reduce cost. We don't * bother with that, though. Hashed grouping will frequently win anyway. * * Note: we need no comparable processing of the distinctClause because * the parser already enforced that that matches ORDER BY. * * For grouping sets, the order of items is instead forced to agree with that * of the grouping set (and items not in the grouping set are skipped). The * work of sorting the order of grouping set elements to match the ORDER BY if * possible is done elsewhere. */ static List * preprocess_groupclause(PlannerInfo *root, List *force) { Query *parse = root->parse; List *new_groupclause = NIL; bool partial_match; ListCell *sl; ListCell *gl; /* For grouping sets, we need to force the ordering */ if (force) { foreach(sl, force) { Index ref = lfirst_int(sl); SortGroupClause *cl = get_sortgroupref_clause(ref, parse->groupClause); new_groupclause = lappend(new_groupclause, cl); } return new_groupclause; } /* If no ORDER BY, nothing useful to do here */ if (parse->sortClause == NIL) return parse->groupClause; /* * Scan the ORDER BY clause and construct a list of matching GROUP BY * items, but only as far as we can make a matching prefix. * * This code assumes that the sortClause contains no duplicate items. */ foreach(sl, parse->sortClause) { SortGroupClause *sc = lfirst_node(SortGroupClause, sl); foreach(gl, parse->groupClause) { SortGroupClause *gc = lfirst_node(SortGroupClause, gl); if (equal(gc, sc)) { new_groupclause = lappend(new_groupclause, gc); break; } } if (gl == NULL) break; /* no match, so stop scanning */ } /* Did we match all of the ORDER BY list, or just some of it? */ partial_match = (sl != NULL); /* If no match at all, no point in reordering GROUP BY */ if (new_groupclause == NIL) return parse->groupClause; /* * Add any remaining GROUP BY items to the new list, but only if we were * able to make a complete match. In other words, we only rearrange the * GROUP BY list if the result is that one list is a prefix of the other * --- otherwise there's no possibility of a common sort. Also, give up * if there are any non-sortable GROUP BY items, since then there's no * hope anyway. */ foreach(gl, parse->groupClause) { SortGroupClause *gc = lfirst_node(SortGroupClause, gl); if (list_member_ptr(new_groupclause, gc)) continue; /* it matched an ORDER BY item */ if (partial_match) return parse->groupClause; /* give up, no common sort possible */ if (!OidIsValid(gc->sortop)) return parse->groupClause; /* give up, GROUP BY can't be sorted */ new_groupclause = lappend(new_groupclause, gc); } /* Success --- install the rearranged GROUP BY list */ Assert(list_length(parse->groupClause) == list_length(new_groupclause)); return new_groupclause; } /* * Extract lists of grouping sets that can be implemented using a single * rollup-type aggregate pass each. Returns a list of lists of grouping sets. * * Input must be sorted with smallest sets first. Result has each sublist * sorted with smallest sets first. * * We want to produce the absolute minimum possible number of lists here to * avoid excess sorts. Fortunately, there is an algorithm for this; the problem * of finding the minimal partition of a partially-ordered set into chains * (which is what we need, taking the list of grouping sets as a poset ordered * by set inclusion) can be mapped to the problem of finding the maximum * cardinality matching on a bipartite graph, which is solvable in polynomial * time with a worst case of no worse than O(n^2.5) and usually much * better. Since our N is at most 4096, we don't need to consider fallbacks to * heuristic or approximate methods. (Planning time for a 12-d cube is under * half a second on my modest system even with optimization off and assertions * on.) */ static List * extract_rollup_sets(List *groupingSets) { int num_sets_raw = list_length(groupingSets); int num_empty = 0; int num_sets = 0; /* distinct sets */ int num_chains = 0; List *result = NIL; List **results; List **orig_sets; Bitmapset **set_masks; int *chains; short **adjacency; short *adjacency_buf; BipartiteMatchState *state; int i; int j; int j_size; ListCell *lc1 = list_head(groupingSets); ListCell *lc; /* * Start by stripping out empty sets. The algorithm doesn't require this, * but the planner currently needs all empty sets to be returned in the * first list, so we strip them here and add them back after. */ while (lc1 && lfirst(lc1) == NIL) { ++num_empty; lc1 = lnext(groupingSets, lc1); } /* bail out now if it turns out that all we had were empty sets. */ if (!lc1) return list_make1(groupingSets); /*---------- * We don't strictly need to remove duplicate sets here, but if we don't, * they tend to become scattered through the result, which is a bit * confusing (and irritating if we ever decide to optimize them out). * So we remove them here and add them back after. * * For each non-duplicate set, we fill in the following: * * orig_sets[i] = list of the original set lists * set_masks[i] = bitmapset for testing inclusion * adjacency[i] = array [n, v1, v2, ... vn] of adjacency indices * * chains[i] will be the result group this set is assigned to. * * We index all of these from 1 rather than 0 because it is convenient * to leave 0 free for the NIL node in the graph algorithm. *---------- */ orig_sets = palloc0((num_sets_raw + 1) * sizeof(List *)); set_masks = palloc0((num_sets_raw + 1) * sizeof(Bitmapset *)); adjacency = palloc0((num_sets_raw + 1) * sizeof(short *)); adjacency_buf = palloc((num_sets_raw + 1) * sizeof(short)); j_size = 0; j = 0; i = 1; for_each_cell(lc, groupingSets, lc1) { List *candidate = (List *) lfirst(lc); Bitmapset *candidate_set = NULL; ListCell *lc2; int dup_of = 0; foreach(lc2, candidate) { candidate_set = bms_add_member(candidate_set, lfirst_int(lc2)); } /* we can only be a dup if we're the same length as a previous set */ if (j_size == list_length(candidate)) { int k; for (k = j; k < i; ++k) { if (bms_equal(set_masks[k], candidate_set)) { dup_of = k; break; } } } else if (j_size < list_length(candidate)) { j_size = list_length(candidate); j = i; } if (dup_of > 0) { orig_sets[dup_of] = lappend(orig_sets[dup_of], candidate); bms_free(candidate_set); } else { int k; int n_adj = 0; orig_sets[i] = list_make1(candidate); set_masks[i] = candidate_set; /* fill in adjacency list; no need to compare equal-size sets */ for (k = j - 1; k > 0; --k) { if (bms_is_subset(set_masks[k], candidate_set)) adjacency_buf[++n_adj] = k; } if (n_adj > 0) { adjacency_buf[0] = n_adj; adjacency[i] = palloc((n_adj + 1) * sizeof(short)); memcpy(adjacency[i], adjacency_buf, (n_adj + 1) * sizeof(short)); } else adjacency[i] = NULL; ++i; } } num_sets = i - 1; /* * Apply the graph matching algorithm to do the work. */ state = BipartiteMatch(num_sets, num_sets, adjacency); /* * Now, the state->pair* fields have the info we need to assign sets to * chains. Two sets (u,v) belong to the same chain if pair_uv[u] = v or * pair_vu[v] = u (both will be true, but we check both so that we can do * it in one pass) */ chains = palloc0((num_sets + 1) * sizeof(int)); for (i = 1; i <= num_sets; ++i) { int u = state->pair_vu[i]; int v = state->pair_uv[i]; if (u > 0 && u < i) chains[i] = chains[u]; else if (v > 0 && v < i) chains[i] = chains[v]; else chains[i] = ++num_chains; } /* build result lists. */ results = palloc0((num_chains + 1) * sizeof(List *)); for (i = 1; i <= num_sets; ++i) { int c = chains[i]; Assert(c > 0); results[c] = list_concat(results[c], orig_sets[i]); } /* push any empty sets back on the first list. */ while (num_empty-- > 0) results[1] = lcons(NIL, results[1]); /* make result list */ for (i = 1; i <= num_chains; ++i) result = lappend(result, results[i]); /* * Free all the things. * * (This is over-fussy for small sets but for large sets we could have * tied up a nontrivial amount of memory.) */ BipartiteMatchFree(state); pfree(results); pfree(chains); for (i = 1; i <= num_sets; ++i) if (adjacency[i]) pfree(adjacency[i]); pfree(adjacency); pfree(adjacency_buf); pfree(orig_sets); for (i = 1; i <= num_sets; ++i) bms_free(set_masks[i]); pfree(set_masks); return result; } /* * Reorder the elements of a list of grouping sets such that they have correct * prefix relationships. Also inserts the GroupingSetData annotations. * * The input must be ordered with smallest sets first; the result is returned * with largest sets first. Note that the result shares no list substructure * with the input, so it's safe for the caller to modify it later. * * If we're passed in a sortclause, we follow its order of columns to the * extent possible, to minimize the chance that we add unnecessary sorts. * (We're trying here to ensure that GROUPING SETS ((a,b,c),(c)) ORDER BY c,b,a * gets implemented in one pass.) */ static List * reorder_grouping_sets(List *groupingsets, List *sortclause) { ListCell *lc; List *previous = NIL; List *result = NIL; foreach(lc, groupingsets) { List *candidate = (List *) lfirst(lc); List *new_elems = list_difference_int(candidate, previous); GroupingSetData *gs = makeNode(GroupingSetData); while (list_length(sortclause) > list_length(previous) && list_length(new_elems) > 0) { SortGroupClause *sc = list_nth(sortclause, list_length(previous)); int ref = sc->tleSortGroupRef; if (list_member_int(new_elems, ref)) { previous = lappend_int(previous, ref); new_elems = list_delete_int(new_elems, ref); } else { /* diverged from the sortclause; give up on it */ sortclause = NIL; break; } } previous = list_concat(previous, new_elems); gs->set = list_copy(previous); result = lcons(gs, result); } list_free(previous); return result; } /* * Compute query_pathkeys and other pathkeys during plan generation */ static void standard_qp_callback(PlannerInfo *root, void *extra) { Query *parse = root->parse; standard_qp_extra *qp_extra = (standard_qp_extra *) extra; List *tlist = root->processed_tlist; List *activeWindows = qp_extra->activeWindows; /* * Calculate pathkeys that represent grouping/ordering requirements. The * sortClause is certainly sort-able, but GROUP BY and DISTINCT might not * be, in which case we just leave their pathkeys empty. */ if (qp_extra->groupClause && grouping_is_sortable(qp_extra->groupClause)) root->group_pathkeys = make_pathkeys_for_sortclauses(root, qp_extra->groupClause, tlist); else root->group_pathkeys = NIL; /* We consider only the first (bottom) window in pathkeys logic */ if (activeWindows != NIL) { WindowClause *wc = linitial_node(WindowClause, activeWindows); root->window_pathkeys = make_pathkeys_for_window(root, wc, tlist); } else root->window_pathkeys = NIL; if (parse->distinctClause && grouping_is_sortable(parse->distinctClause)) root->distinct_pathkeys = make_pathkeys_for_sortclauses(root, parse->distinctClause, tlist); else root->distinct_pathkeys = NIL; root->sort_pathkeys = make_pathkeys_for_sortclauses(root, parse->sortClause, tlist); /* * Figure out whether we want a sorted result from query_planner. * * If we have a sortable GROUP BY clause, then we want a result sorted * properly for grouping. Otherwise, if we have window functions to * evaluate, we try to sort for the first window. Otherwise, if there's a * sortable DISTINCT clause that's more rigorous than the ORDER BY clause, * we try to produce output that's sufficiently well sorted for the * DISTINCT. Otherwise, if there is an ORDER BY clause, we want to sort * by the ORDER BY clause. * * Note: if we have both ORDER BY and GROUP BY, and ORDER BY is a superset * of GROUP BY, it would be tempting to request sort by ORDER BY --- but * that might just leave us failing to exploit an available sort order at * all. Needs more thought. The choice for DISTINCT versus ORDER BY is * much easier, since we know that the parser ensured that one is a * superset of the other. */ if (root->group_pathkeys) root->query_pathkeys = root->group_pathkeys; else if (root->window_pathkeys) root->query_pathkeys = root->window_pathkeys; else if (list_length(root->distinct_pathkeys) > list_length(root->sort_pathkeys)) root->query_pathkeys = root->distinct_pathkeys; else if (root->sort_pathkeys) root->query_pathkeys = root->sort_pathkeys; else root->query_pathkeys = NIL; } /* * Estimate number of groups produced by grouping clauses (1 if not grouping) * * path_rows: number of output rows from scan/join step * gd: grouping sets data including list of grouping sets and their clauses * target_list: target list containing group clause references * * If doing grouping sets, we also annotate the gsets data with the estimates * for each set and each individual rollup list, with a view to later * determining whether some combination of them could be hashed instead. */ static double get_number_of_groups(PlannerInfo *root, double path_rows, grouping_sets_data *gd, List *target_list) { Query *parse = root->parse; double dNumGroups; if (parse->groupClause) { List *groupExprs; if (parse->groupingSets) { /* Add up the estimates for each grouping set */ ListCell *lc; ListCell *lc2; Assert(gd); /* keep Coverity happy */ dNumGroups = 0; foreach(lc, gd->rollups) { RollupData *rollup = lfirst_node(RollupData, lc); ListCell *lc; groupExprs = get_sortgrouplist_exprs(rollup->groupClause, target_list); rollup->numGroups = 0.0; forboth(lc, rollup->gsets, lc2, rollup->gsets_data) { List *gset = (List *) lfirst(lc); GroupingSetData *gs = lfirst_node(GroupingSetData, lc2); double numGroups = estimate_num_groups(root, groupExprs, path_rows, &gset, NULL); gs->numGroups = numGroups; rollup->numGroups += numGroups; } dNumGroups += rollup->numGroups; } if (gd->hash_sets_idx) { ListCell *lc; gd->dNumHashGroups = 0; groupExprs = get_sortgrouplist_exprs(parse->groupClause, target_list); forboth(lc, gd->hash_sets_idx, lc2, gd->unsortable_sets) { List *gset = (List *) lfirst(lc); GroupingSetData *gs = lfirst_node(GroupingSetData, lc2); double numGroups = estimate_num_groups(root, groupExprs, path_rows, &gset, NULL); gs->numGroups = numGroups; gd->dNumHashGroups += numGroups; } dNumGroups += gd->dNumHashGroups; } } else { /* Plain GROUP BY */ groupExprs = get_sortgrouplist_exprs(parse->groupClause, target_list); dNumGroups = estimate_num_groups(root, groupExprs, path_rows, NULL, NULL); } } else if (parse->groupingSets) { /* Empty grouping sets ... one result row for each one */ dNumGroups = list_length(parse->groupingSets); } else if (parse->hasAggs || root->hasHavingQual) { /* Plain aggregation, one result row */ dNumGroups = 1; } else { /* Not grouping */ dNumGroups = 1; } return dNumGroups; } /* * create_grouping_paths * * Build a new upperrel containing Paths for grouping and/or aggregation. * Along the way, we also build an upperrel for Paths which are partially * grouped and/or aggregated. A partially grouped and/or aggregated path * needs a FinalizeAggregate node to complete the aggregation. Currently, * the only partially grouped paths we build are also partial paths; that * is, they need a Gather and then a FinalizeAggregate. * * input_rel: contains the source-data Paths * target: the pathtarget for the result Paths to compute * gd: grouping sets data including list of grouping sets and their clauses * * Note: all Paths in input_rel are expected to return the target computed * by make_group_input_target. */ static RelOptInfo * create_grouping_paths(PlannerInfo *root, RelOptInfo *input_rel, PathTarget *target, bool target_parallel_safe, grouping_sets_data *gd) { Query *parse = root->parse; RelOptInfo *grouped_rel; RelOptInfo *partially_grouped_rel; AggClauseCosts agg_costs; MemSet(&agg_costs, 0, sizeof(AggClauseCosts)); get_agg_clause_costs(root, AGGSPLIT_SIMPLE, &agg_costs); /* * Create grouping relation to hold fully aggregated grouping and/or * aggregation paths. */ grouped_rel = make_grouping_rel(root, input_rel, target, target_parallel_safe, parse->havingQual); /* * Create either paths for a degenerate grouping or paths for ordinary * grouping, as appropriate. */ if (is_degenerate_grouping(root)) create_degenerate_grouping_paths(root, input_rel, grouped_rel); else { int flags = 0; GroupPathExtraData extra; /* * Determine whether it's possible to perform sort-based * implementations of grouping. (Note that if groupClause is empty, * grouping_is_sortable() is trivially true, and all the * pathkeys_contained_in() tests will succeed too, so that we'll * consider every surviving input path.) * * If we have grouping sets, we might be able to sort some but not all * of them; in this case, we need can_sort to be true as long as we * must consider any sorted-input plan. */ if ((gd && gd->rollups != NIL) || grouping_is_sortable(parse->groupClause)) flags |= GROUPING_CAN_USE_SORT; /* * Determine whether we should consider hash-based implementations of * grouping. * * Hashed aggregation only applies if we're grouping. If we have * grouping sets, some groups might be hashable but others not; in * this case we set can_hash true as long as there is nothing globally * preventing us from hashing (and we should therefore consider plans * with hashes). * * Executor doesn't support hashed aggregation with DISTINCT or ORDER * BY aggregates. (Doing so would imply storing *all* the input * values in the hash table, and/or running many sorts in parallel, * either of which seems like a certain loser.) We similarly don't * support ordered-set aggregates in hashed aggregation, but that case * is also included in the numOrderedAggs count. * * Note: grouping_is_hashable() is much more expensive to check than * the other gating conditions, so we want to do it last. */ if ((parse->groupClause != NIL && root->numOrderedAggs == 0 && (gd ? gd->any_hashable : grouping_is_hashable(parse->groupClause)))) flags |= GROUPING_CAN_USE_HASH; /* * Determine whether partial aggregation is possible. */ if (can_partial_agg(root)) flags |= GROUPING_CAN_PARTIAL_AGG; extra.flags = flags; extra.target_parallel_safe = target_parallel_safe; extra.havingQual = parse->havingQual; extra.targetList = parse->targetList; extra.partial_costs_set = false; /* * Determine whether partitionwise aggregation is in theory possible. * It can be disabled by the user, and for now, we don't try to * support grouping sets. create_ordinary_grouping_paths() will check * additional conditions, such as whether input_rel is partitioned. */ if (enable_partitionwise_aggregate && !parse->groupingSets) extra.patype = PARTITIONWISE_AGGREGATE_FULL; else extra.patype = PARTITIONWISE_AGGREGATE_NONE; create_ordinary_grouping_paths(root, input_rel, grouped_rel, &agg_costs, gd, &extra, &partially_grouped_rel); } set_cheapest(grouped_rel); return grouped_rel; } /* * make_grouping_rel * * Create a new grouping rel and set basic properties. * * input_rel represents the underlying scan/join relation. * target is the output expected from the grouping relation. */ static RelOptInfo * make_grouping_rel(PlannerInfo *root, RelOptInfo *input_rel, PathTarget *target, bool target_parallel_safe, Node *havingQual) { RelOptInfo *grouped_rel; if (IS_OTHER_REL(input_rel)) { grouped_rel = fetch_upper_rel(root, UPPERREL_GROUP_AGG, input_rel->relids); grouped_rel->reloptkind = RELOPT_OTHER_UPPER_REL; } else { /* * By tradition, the relids set for the main grouping relation is * NULL. (This could be changed, but might require adjustments * elsewhere.) */ grouped_rel = fetch_upper_rel(root, UPPERREL_GROUP_AGG, NULL); } /* Set target. */ grouped_rel->reltarget = target; /* * If the input relation is not parallel-safe, then the grouped relation * can't be parallel-safe, either. Otherwise, it's parallel-safe if the * target list and HAVING quals are parallel-safe. */ if (input_rel->consider_parallel && target_parallel_safe && is_parallel_safe(root, (Node *) havingQual)) grouped_rel->consider_parallel = true; /* * If the input rel belongs to a single FDW, so does the grouped rel. */ grouped_rel->serverid = input_rel->serverid; grouped_rel->userid = input_rel->userid; grouped_rel->useridiscurrent = input_rel->useridiscurrent; grouped_rel->fdwroutine = input_rel->fdwroutine; return grouped_rel; } /* * is_degenerate_grouping * * A degenerate grouping is one in which the query has a HAVING qual and/or * grouping sets, but no aggregates and no GROUP BY (which implies that the * grouping sets are all empty). */ static bool is_degenerate_grouping(PlannerInfo *root) { Query *parse = root->parse; return (root->hasHavingQual || parse->groupingSets) && !parse->hasAggs && parse->groupClause == NIL; } /* * create_degenerate_grouping_paths * * When the grouping is degenerate (see is_degenerate_grouping), we are * supposed to emit either zero or one row for each grouping set depending on * whether HAVING succeeds. Furthermore, there cannot be any variables in * either HAVING or the targetlist, so we actually do not need the FROM table * at all! We can just throw away the plan-so-far and generate a Result node. * This is a sufficiently unusual corner case that it's not worth contorting * the structure of this module to avoid having to generate the earlier paths * in the first place. */ static void create_degenerate_grouping_paths(PlannerInfo *root, RelOptInfo *input_rel, RelOptInfo *grouped_rel) { Query *parse = root->parse; int nrows; Path *path; nrows = list_length(parse->groupingSets); if (nrows > 1) { /* * Doesn't seem worthwhile writing code to cons up a generate_series * or a values scan to emit multiple rows. Instead just make N clones * and append them. (With a volatile HAVING clause, this means you * might get between 0 and N output rows. Offhand I think that's * desired.) */ List *paths = NIL; while (--nrows >= 0) { path = (Path *) create_group_result_path(root, grouped_rel, grouped_rel->reltarget, (List *) parse->havingQual); paths = lappend(paths, path); } path = (Path *) create_append_path(root, grouped_rel, paths, NIL, NIL, NULL, 0, false, -1); } else { /* No grouping sets, or just one, so one output row */ path = (Path *) create_group_result_path(root, grouped_rel, grouped_rel->reltarget, (List *) parse->havingQual); } add_path(grouped_rel, path); } /* * create_ordinary_grouping_paths * * Create grouping paths for the ordinary (that is, non-degenerate) case. * * We need to consider sorted and hashed aggregation in the same function, * because otherwise (1) it would be harder to throw an appropriate error * message if neither way works, and (2) we should not allow hashtable size * considerations to dissuade us from using hashing if sorting is not possible. * * *partially_grouped_rel_p will be set to the partially grouped rel which this * function creates, or to NULL if it doesn't create one. */ static void create_ordinary_grouping_paths(PlannerInfo *root, RelOptInfo *input_rel, RelOptInfo *grouped_rel, const AggClauseCosts *agg_costs, grouping_sets_data *gd, GroupPathExtraData *extra, RelOptInfo **partially_grouped_rel_p) { Path *cheapest_path = input_rel->cheapest_total_path; RelOptInfo *partially_grouped_rel = NULL; double dNumGroups; PartitionwiseAggregateType patype = PARTITIONWISE_AGGREGATE_NONE; /* * 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. */ if (extra->patype != PARTITIONWISE_AGGREGATE_NONE && IS_PARTITIONED_REL(input_rel)) { /* * If this is the topmost relation or if the parent relation is doing * full partitionwise aggregation, then we can do full partitionwise * aggregation provided that the GROUP BY clause contains all of the * partitioning columns at this level. Otherwise, we can do at most * partial partitionwise aggregation. But if partial aggregation is * not supported in general then we can't use it for partitionwise * aggregation either. */ if (extra->patype == PARTITIONWISE_AGGREGATE_FULL && group_by_has_partkey(input_rel, extra->targetList, root->parse->groupClause)) patype = PARTITIONWISE_AGGREGATE_FULL; else if ((extra->flags & GROUPING_CAN_PARTIAL_AGG) != 0) patype = PARTITIONWISE_AGGREGATE_PARTIAL; else patype = PARTITIONWISE_AGGREGATE_NONE; } /* * Before generating paths for grouped_rel, we first generate any possible * partially grouped paths; that way, later code can easily consider both * parallel and non-parallel approaches to grouping. */ if ((extra->flags & GROUPING_CAN_PARTIAL_AGG) != 0) { bool force_rel_creation; /* * If we're doing partitionwise aggregation at this level, force * creation of a partially_grouped_rel so we can add partitionwise * paths to it. */ force_rel_creation = (patype == PARTITIONWISE_AGGREGATE_PARTIAL); partially_grouped_rel = create_partial_grouping_paths(root, grouped_rel, input_rel, gd, extra, force_rel_creation); } /* Set out parameter. */ *partially_grouped_rel_p = partially_grouped_rel; /* Apply partitionwise aggregation technique, if possible. */ if (patype != PARTITIONWISE_AGGREGATE_NONE) create_partitionwise_grouping_paths(root, input_rel, grouped_rel, partially_grouped_rel, agg_costs, gd, patype, extra); /* If we are doing partial aggregation only, return. */ if (extra->patype == PARTITIONWISE_AGGREGATE_PARTIAL) { Assert(partially_grouped_rel); if (partially_grouped_rel->pathlist) set_cheapest(partially_grouped_rel); return; } /* Gather any partially grouped partial paths. */ if (partially_grouped_rel && partially_grouped_rel->partial_pathlist) { gather_grouping_paths(root, partially_grouped_rel); set_cheapest(partially_grouped_rel); } /* * Estimate number of groups. */ dNumGroups = get_number_of_groups(root, cheapest_path->rows, gd, extra->targetList); /* Build final grouping paths */ add_paths_to_grouping_rel(root, input_rel, grouped_rel, partially_grouped_rel, agg_costs, gd, dNumGroups, extra); /* Give a helpful error if we failed to find any implementation */ if (grouped_rel->pathlist == NIL) ereport(ERROR, (errcode(ERRCODE_FEATURE_NOT_SUPPORTED), errmsg("could not implement GROUP BY"), errdetail("Some of the datatypes only support hashing, while others only support sorting."))); /* * If there is an FDW that's responsible for all baserels of the query, * let it consider adding ForeignPaths. */ if (grouped_rel->fdwroutine && grouped_rel->fdwroutine->GetForeignUpperPaths) grouped_rel->fdwroutine->GetForeignUpperPaths(root, UPPERREL_GROUP_AGG, input_rel, grouped_rel, extra); /* Let extensions possibly add some more paths */ if (create_upper_paths_hook) (*create_upper_paths_hook) (root, UPPERREL_GROUP_AGG, input_rel, grouped_rel, extra); } /* * For a given input path, consider the possible ways of doing grouping sets on * it, by combinations of hashing and sorting. This can be called multiple * times, so it's important that it not scribble on input. No result is * returned, but any generated paths are added to grouped_rel. */ static void consider_groupingsets_paths(PlannerInfo *root, RelOptInfo *grouped_rel, Path *path, bool is_sorted, bool can_hash, grouping_sets_data *gd, const AggClauseCosts *agg_costs, double dNumGroups) { Query *parse = root->parse; Size hash_mem_limit = get_hash_memory_limit(); /* * If we're not being offered sorted input, then only consider plans that * can be done entirely by hashing. * * We can hash everything if it looks like it'll fit in hash_mem. But if * the input is actually sorted despite not being advertised as such, we * prefer to make use of that in order to use less memory. * * If none of the grouping sets are sortable, then ignore the hash_mem * limit and generate a path anyway, since otherwise we'll just fail. */ if (!is_sorted) { List *new_rollups = NIL; RollupData *unhashed_rollup = NULL; List *sets_data; List *empty_sets_data = NIL; List *empty_sets = NIL; ListCell *lc; ListCell *l_start = list_head(gd->rollups); AggStrategy strat = AGG_HASHED; double hashsize; double exclude_groups = 0.0; Assert(can_hash); /* * If the input is coincidentally sorted usefully (which can happen * even if is_sorted is false, since that only means that our caller * has set up the sorting for us), then save some hashtable space by * making use of that. But we need to watch out for degenerate cases: * * 1) If there are any empty grouping sets, then group_pathkeys might * be NIL if all non-empty grouping sets are unsortable. In this case, * there will be a rollup containing only empty groups, and the * pathkeys_contained_in test is vacuously true; this is ok. * * XXX: the above relies on the fact that group_pathkeys is generated * from the first rollup. If we add the ability to consider multiple * sort orders for grouping input, this assumption might fail. * * 2) If there are no empty sets and only unsortable sets, then the * rollups list will be empty (and thus l_start == NULL), and * group_pathkeys will be NIL; we must ensure that the vacuously-true * pathkeys_contained_in test doesn't cause us to crash. */ if (l_start != NULL && pathkeys_contained_in(root->group_pathkeys, path->pathkeys)) { unhashed_rollup = lfirst_node(RollupData, l_start); exclude_groups = unhashed_rollup->numGroups; l_start = lnext(gd->rollups, l_start); } hashsize = estimate_hashagg_tablesize(root, path, agg_costs, dNumGroups - exclude_groups); /* * gd->rollups is empty if we have only unsortable columns to work * with. Override hash_mem in that case; otherwise, we'll rely on the * sorted-input case to generate usable mixed paths. */ if (hashsize > hash_mem_limit && gd->rollups) return; /* nope, won't fit */ /* * We need to burst the existing rollups list into individual grouping * sets and recompute a groupClause for each set. */ sets_data = list_copy(gd->unsortable_sets); for_each_cell(lc, gd->rollups, l_start) { RollupData *rollup = lfirst_node(RollupData, lc); /* * If we find an unhashable rollup that's not been skipped by the * "actually sorted" check above, we can't cope; we'd need sorted * input (with a different sort order) but we can't get that here. * So bail out; we'll get a valid path from the is_sorted case * instead. * * The mere presence of empty grouping sets doesn't make a rollup * unhashable (see preprocess_grouping_sets), we handle those * specially below. */ if (!rollup->hashable) return; sets_data = list_concat(sets_data, rollup->gsets_data); } foreach(lc, sets_data) { GroupingSetData *gs = lfirst_node(GroupingSetData, lc); List *gset = gs->set; RollupData *rollup; if (gset == NIL) { /* Empty grouping sets can't be hashed. */ empty_sets_data = lappend(empty_sets_data, gs); empty_sets = lappend(empty_sets, NIL); } else { rollup = makeNode(RollupData); rollup->groupClause = preprocess_groupclause(root, gset); rollup->gsets_data = list_make1(gs); rollup->gsets = remap_to_groupclause_idx(rollup->groupClause, rollup->gsets_data, gd->tleref_to_colnum_map); rollup->numGroups = gs->numGroups; rollup->hashable = true; rollup->is_hashed = true; new_rollups = lappend(new_rollups, rollup); } } /* * If we didn't find anything nonempty to hash, then bail. We'll * generate a path from the is_sorted case. */ if (new_rollups == NIL) return; /* * If there were empty grouping sets they should have been in the * first rollup. */ Assert(!unhashed_rollup || !empty_sets); if (unhashed_rollup) { new_rollups = lappend(new_rollups, unhashed_rollup); strat = AGG_MIXED; } else if (empty_sets) { RollupData *rollup = makeNode(RollupData); rollup->groupClause = NIL; rollup->gsets_data = empty_sets_data; rollup->gsets = empty_sets; rollup->numGroups = list_length(empty_sets); rollup->hashable = false; rollup->is_hashed = false; new_rollups = lappend(new_rollups, rollup); strat = AGG_MIXED; } add_path(grouped_rel, (Path *) create_groupingsets_path(root, grouped_rel, path, (List *) parse->havingQual, strat, new_rollups, agg_costs, dNumGroups)); return; } /* * If we have sorted input but nothing we can do with it, bail. */ if (list_length(gd->rollups) == 0) return; /* * Given sorted input, we try and make two paths: one sorted and one mixed * sort/hash. (We need to try both because hashagg might be disabled, or * some columns might not be sortable.) * * can_hash is passed in as false if some obstacle elsewhere (such as * ordered aggs) means that we shouldn't consider hashing at all. */ if (can_hash && gd->any_hashable) { List *rollups = NIL; List *hash_sets = list_copy(gd->unsortable_sets); double availspace = hash_mem_limit; ListCell *lc; /* * Account first for space needed for groups we can't sort at all. */ availspace -= estimate_hashagg_tablesize(root, path, agg_costs, gd->dNumHashGroups); if (availspace > 0 && list_length(gd->rollups) > 1) { double scale; int num_rollups = list_length(gd->rollups); int k_capacity; int *k_weights = palloc(num_rollups * sizeof(int)); Bitmapset *hash_items = NULL; int i; /* * We treat this as a knapsack problem: the knapsack capacity * represents hash_mem, the item weights are the estimated memory * usage of the hashtables needed to implement a single rollup, * and we really ought to use the cost saving as the item value; * however, currently the costs assigned to sort nodes don't * reflect the comparison costs well, and so we treat all items as * of equal value (each rollup we hash instead saves us one sort). * * To use the discrete knapsack, we need to scale the values to a * reasonably small bounded range. We choose to allow a 5% error * margin; we have no more than 4096 rollups in the worst possible * case, which with a 5% error margin will require a bit over 42MB * of workspace. (Anyone wanting to plan queries that complex had * better have the memory for it. In more reasonable cases, with * no more than a couple of dozen rollups, the memory usage will * be negligible.) * * k_capacity is naturally bounded, but we clamp the values for * scale and weight (below) to avoid overflows or underflows (or * uselessly trying to use a scale factor less than 1 byte). */ scale = Max(availspace / (20.0 * num_rollups), 1.0); k_capacity = (int) floor(availspace / scale); /* * We leave the first rollup out of consideration since it's the * one that matches the input sort order. We assign indexes "i" * to only those entries considered for hashing; the second loop, * below, must use the same condition. */ i = 0; for_each_from(lc, gd->rollups, 1) { RollupData *rollup = lfirst_node(RollupData, lc); if (rollup->hashable) { double sz = estimate_hashagg_tablesize(root, path, agg_costs, rollup->numGroups); /* * If sz is enormous, but hash_mem (and hence scale) is * small, avoid integer overflow here. */ k_weights[i] = (int) Min(floor(sz / scale), k_capacity + 1.0); ++i; } } /* * Apply knapsack algorithm; compute the set of items which * maximizes the value stored (in this case the number of sorts * saved) while keeping the total size (approximately) within * capacity. */ if (i > 0) hash_items = DiscreteKnapsack(k_capacity, i, k_weights, NULL); if (!bms_is_empty(hash_items)) { rollups = list_make1(linitial(gd->rollups)); i = 0; for_each_from(lc, gd->rollups, 1) { RollupData *rollup = lfirst_node(RollupData, lc); if (rollup->hashable) { if (bms_is_member(i, hash_items)) hash_sets = list_concat(hash_sets, rollup->gsets_data); else rollups = lappend(rollups, rollup); ++i; } else rollups = lappend(rollups, rollup); } } } if (!rollups && hash_sets) rollups = list_copy(gd->rollups); foreach(lc, hash_sets) { GroupingSetData *gs = lfirst_node(GroupingSetData, lc); RollupData *rollup = makeNode(RollupData); Assert(gs->set != NIL); rollup->groupClause = preprocess_groupclause(root, gs->set); rollup->gsets_data = list_make1(gs); rollup->gsets = remap_to_groupclause_idx(rollup->groupClause, rollup->gsets_data, gd->tleref_to_colnum_map); rollup->numGroups = gs->numGroups; rollup->hashable = true; rollup->is_hashed = true; rollups = lcons(rollup, rollups); } if (rollups) { add_path(grouped_rel, (Path *) create_groupingsets_path(root, grouped_rel, path, (List *) parse->havingQual, AGG_MIXED, rollups, agg_costs, dNumGroups)); } } /* * Now try the simple sorted case. */ if (!gd->unsortable_sets) add_path(grouped_rel, (Path *) create_groupingsets_path(root, grouped_rel, path, (List *) parse->havingQual, AGG_SORTED, gd->rollups, agg_costs, dNumGroups)); } /* * create_window_paths * * Build a new upperrel containing Paths for window-function evaluation. * * input_rel: contains the source-data Paths * input_target: result of make_window_input_target * output_target: what the topmost WindowAggPath should return * wflists: result of find_window_functions * activeWindows: result of select_active_windows * * Note: all Paths in input_rel are expected to return input_target. */ static RelOptInfo * create_window_paths(PlannerInfo *root, RelOptInfo *input_rel, PathTarget *input_target, PathTarget *output_target, bool output_target_parallel_safe, WindowFuncLists *wflists, List *activeWindows) { RelOptInfo *window_rel; ListCell *lc; /* For now, do all work in the (WINDOW, NULL) upperrel */ window_rel = fetch_upper_rel(root, UPPERREL_WINDOW, NULL); /* * If the input relation is not parallel-safe, then the window relation * can't be parallel-safe, either. Otherwise, we need to examine the * target list and active windows for non-parallel-safe constructs. */ if (input_rel->consider_parallel && output_target_parallel_safe && is_parallel_safe(root, (Node *) activeWindows)) window_rel->consider_parallel = true; /* * If the input rel belongs to a single FDW, so does the window rel. */ window_rel->serverid = input_rel->serverid; window_rel->userid = input_rel->userid; window_rel->useridiscurrent = input_rel->useridiscurrent; window_rel->fdwroutine = input_rel->fdwroutine; /* * Consider computing window functions starting from the existing * cheapest-total path (which will likely require a sort) as well as any * existing paths that satisfy or partially satisfy root->window_pathkeys. */ foreach(lc, input_rel->pathlist) { Path *path = (Path *) lfirst(lc); int presorted_keys; if (path == input_rel->cheapest_total_path || pathkeys_count_contained_in(root->window_pathkeys, path->pathkeys, &presorted_keys) || presorted_keys > 0) create_one_window_path(root, window_rel, path, input_target, output_target, wflists, activeWindows); } /* * If there is an FDW that's responsible for all baserels of the query, * let it consider adding ForeignPaths. */ if (window_rel->fdwroutine && window_rel->fdwroutine->GetForeignUpperPaths) window_rel->fdwroutine->GetForeignUpperPaths(root, UPPERREL_WINDOW, input_rel, window_rel, NULL); /* Let extensions possibly add some more paths */ if (create_upper_paths_hook) (*create_upper_paths_hook) (root, UPPERREL_WINDOW, input_rel, window_rel, NULL); /* Now choose the best path(s) */ set_cheapest(window_rel); return window_rel; } /* * Stack window-function implementation steps atop the given Path, and * add the result to window_rel. * * window_rel: upperrel to contain result * path: input Path to use (must return input_target) * input_target: result of make_window_input_target * output_target: what the topmost WindowAggPath should return * wflists: result of find_window_functions * activeWindows: result of select_active_windows */ static void create_one_window_path(PlannerInfo *root, RelOptInfo *window_rel, Path *path, PathTarget *input_target, PathTarget *output_target, WindowFuncLists *wflists, List *activeWindows) { PathTarget *window_target; ListCell *l; /* * Since each window clause could require a different sort order, we stack * up a WindowAgg node for each clause, with sort steps between them as * needed. (We assume that select_active_windows chose a good order for * executing the clauses in.) * * input_target should contain all Vars and Aggs needed for the result. * (In some cases we wouldn't need to propagate all of these all the way * to the top, since they might only be needed as inputs to WindowFuncs. * It's probably not worth trying to optimize that though.) It must also * contain all window partitioning and sorting expressions, to ensure * they're computed only once at the bottom of the stack (that's critical * for volatile functions). As we climb up the stack, we'll add outputs * for the WindowFuncs computed at each level. */ window_target = input_target; foreach(l, activeWindows) { WindowClause *wc = lfirst_node(WindowClause, l); List *window_pathkeys; int presorted_keys; bool is_sorted; window_pathkeys = make_pathkeys_for_window(root, wc, root->processed_tlist); is_sorted = pathkeys_count_contained_in(window_pathkeys, path->pathkeys, &presorted_keys); /* Sort if necessary */ if (!is_sorted) { /* * No presorted keys or incremental sort disabled, just perform a * complete sort. */ if (presorted_keys == 0 || !enable_incremental_sort) path = (Path *) create_sort_path(root, window_rel, path, window_pathkeys, -1.0); else { /* * Since we have presorted keys and incremental sort is * enabled, just use incremental sort. */ path = (Path *) create_incremental_sort_path(root, window_rel, path, window_pathkeys, presorted_keys, -1.0); } } if (lnext(activeWindows, l)) { /* * Add the current WindowFuncs to the output target for this * intermediate WindowAggPath. We must copy window_target to * avoid changing the previous path's target. * * Note: a WindowFunc adds nothing to the target's eval costs; but * we do need to account for the increase in tlist width. */ ListCell *lc2; window_target = copy_pathtarget(window_target); foreach(lc2, wflists->windowFuncs[wc->winref]) { WindowFunc *wfunc = lfirst_node(WindowFunc, lc2); add_column_to_pathtarget(window_target, (Expr *) wfunc, 0); window_target->width += get_typavgwidth(wfunc->wintype, -1); } } else { /* Install the goal target in the topmost WindowAgg */ window_target = output_target; } path = (Path *) create_windowagg_path(root, window_rel, path, window_target, wflists->windowFuncs[wc->winref], wc); } add_path(window_rel, path); } /* * create_distinct_paths * * Build a new upperrel containing Paths for SELECT DISTINCT evaluation. * * input_rel: contains the source-data Paths * * Note: input paths should already compute the desired pathtarget, since * Sort/Unique won't project anything. */ static RelOptInfo * create_distinct_paths(PlannerInfo *root, RelOptInfo *input_rel) { Query *parse = root->parse; Path *cheapest_input_path = input_rel->cheapest_total_path; RelOptInfo *distinct_rel; double numDistinctRows; bool allow_hash; Path *path; ListCell *lc; /* For now, do all work in the (DISTINCT, NULL) upperrel */ distinct_rel = fetch_upper_rel(root, UPPERREL_DISTINCT, NULL); /* * We don't compute anything at this level, so distinct_rel will be * parallel-safe if the input rel is parallel-safe. In particular, if * there is a DISTINCT ON (...) clause, any path for the input_rel will * output those expressions, and will not be parallel-safe unless those * expressions are parallel-safe. */ distinct_rel->consider_parallel = input_rel->consider_parallel; /* * If the input rel belongs to a single FDW, so does the distinct_rel. */ distinct_rel->serverid = input_rel->serverid; distinct_rel->userid = input_rel->userid; distinct_rel->useridiscurrent = input_rel->useridiscurrent; distinct_rel->fdwroutine = input_rel->fdwroutine; /* Estimate number of distinct rows there will be */ if (parse->groupClause || parse->groupingSets || parse->hasAggs || root->hasHavingQual) { /* * If there was grouping or aggregation, use the number of input rows * as the estimated number of DISTINCT rows (ie, assume the input is * already mostly unique). */ numDistinctRows = cheapest_input_path->rows; } else { /* * Otherwise, the UNIQUE filter has effects comparable to GROUP BY. */ List *distinctExprs; distinctExprs = get_sortgrouplist_exprs(parse->distinctClause, parse->targetList); numDistinctRows = estimate_num_groups(root, distinctExprs, cheapest_input_path->rows, NULL, NULL); } /* * Consider sort-based implementations of DISTINCT, if possible. */ if (grouping_is_sortable(parse->distinctClause)) { /* * First, if we have any adequately-presorted paths, just stick a * Unique node on those. Then consider doing an explicit sort of the * cheapest input path and Unique'ing that. * * When we have DISTINCT ON, we must sort by the more rigorous of * DISTINCT and ORDER BY, else it won't have the desired behavior. * Also, if we do have to do an explicit sort, we might as well use * the more rigorous ordering to avoid a second sort later. (Note * that the parser will have ensured that one clause is a prefix of * the other.) */ List *needed_pathkeys; if (parse->hasDistinctOn && list_length(root->distinct_pathkeys) < list_length(root->sort_pathkeys)) needed_pathkeys = root->sort_pathkeys; else needed_pathkeys = root->distinct_pathkeys; foreach(lc, input_rel->pathlist) { Path *path = (Path *) lfirst(lc); if (pathkeys_contained_in(needed_pathkeys, path->pathkeys)) { add_path(distinct_rel, (Path *) create_upper_unique_path(root, distinct_rel, path, list_length(root->distinct_pathkeys), numDistinctRows)); } } /* For explicit-sort case, always use the more rigorous clause */ if (list_length(root->distinct_pathkeys) < list_length(root->sort_pathkeys)) { needed_pathkeys = root->sort_pathkeys; /* Assert checks that parser didn't mess up... */ Assert(pathkeys_contained_in(root->distinct_pathkeys, needed_pathkeys)); } else needed_pathkeys = root->distinct_pathkeys; path = cheapest_input_path; if (!pathkeys_contained_in(needed_pathkeys, path->pathkeys)) path = (Path *) create_sort_path(root, distinct_rel, path, needed_pathkeys, -1.0); add_path(distinct_rel, (Path *) create_upper_unique_path(root, distinct_rel, path, list_length(root->distinct_pathkeys), numDistinctRows)); } /* * Consider hash-based implementations of DISTINCT, if possible. * * If we were not able to make any other types of path, we *must* hash or * die trying. If we do have other choices, there are two things that * should prevent selection of hashing: if the query uses DISTINCT ON * (because it won't really have the expected behavior if we hash), or if * enable_hashagg is off. * * Note: grouping_is_hashable() is much more expensive to check than the * other gating conditions, so we want to do it last. */ if (distinct_rel->pathlist == NIL) allow_hash = true; /* we have no alternatives */ else if (parse->hasDistinctOn || !enable_hashagg) allow_hash = false; /* policy-based decision not to hash */ else allow_hash = true; /* default */ if (allow_hash && grouping_is_hashable(parse->distinctClause)) { /* Generate hashed aggregate path --- no sort needed */ add_path(distinct_rel, (Path *) create_agg_path(root, distinct_rel, cheapest_input_path, cheapest_input_path->pathtarget, AGG_HASHED, AGGSPLIT_SIMPLE, parse->distinctClause, NIL, NULL, numDistinctRows)); } /* Give a helpful error if we failed to find any implementation */ if (distinct_rel->pathlist == NIL) ereport(ERROR, (errcode(ERRCODE_FEATURE_NOT_SUPPORTED), errmsg("could not implement DISTINCT"), errdetail("Some of the datatypes only support hashing, while others only support sorting."))); /* * If there is an FDW that's responsible for all baserels of the query, * let it consider adding ForeignPaths. */ if (distinct_rel->fdwroutine && distinct_rel->fdwroutine->GetForeignUpperPaths) distinct_rel->fdwroutine->GetForeignUpperPaths(root, UPPERREL_DISTINCT, input_rel, distinct_rel, NULL); /* Let extensions possibly add some more paths */ if (create_upper_paths_hook) (*create_upper_paths_hook) (root, UPPERREL_DISTINCT, input_rel, distinct_rel, NULL); /* Now choose the best path(s) */ set_cheapest(distinct_rel); return distinct_rel; } /* * create_ordered_paths * * Build a new upperrel containing Paths for ORDER BY evaluation. * * All paths in the result must satisfy the ORDER BY ordering. * The only new paths we need consider are an explicit full sort * and incremental sort on the cheapest-total existing path. * * input_rel: contains the source-data Paths * target: the output tlist the result Paths must emit * limit_tuples: estimated bound on the number of output tuples, * or -1 if no LIMIT or couldn't estimate * * XXX This only looks at sort_pathkeys. I wonder if it needs to look at the * other pathkeys (grouping, ...) like generate_useful_gather_paths. */ static RelOptInfo * create_ordered_paths(PlannerInfo *root, RelOptInfo *input_rel, PathTarget *target, bool target_parallel_safe, double limit_tuples) { Path *cheapest_input_path = input_rel->cheapest_total_path; RelOptInfo *ordered_rel; ListCell *lc; /* For now, do all work in the (ORDERED, NULL) upperrel */ ordered_rel = fetch_upper_rel(root, UPPERREL_ORDERED, NULL); /* * If the input relation is not parallel-safe, then the ordered relation * can't be parallel-safe, either. Otherwise, it's parallel-safe if the * target list is parallel-safe. */ if (input_rel->consider_parallel && target_parallel_safe) ordered_rel->consider_parallel = true; /* * If the input rel belongs to a single FDW, so does the ordered_rel. */ ordered_rel->serverid = input_rel->serverid; ordered_rel->userid = input_rel->userid; ordered_rel->useridiscurrent = input_rel->useridiscurrent; ordered_rel->fdwroutine = input_rel->fdwroutine; foreach(lc, input_rel->pathlist) { Path *input_path = (Path *) lfirst(lc); Path *sorted_path = input_path; bool is_sorted; int presorted_keys; is_sorted = pathkeys_count_contained_in(root->sort_pathkeys, input_path->pathkeys, &presorted_keys); if (is_sorted) { /* Use the input path as is, but add a projection step if needed */ if (sorted_path->pathtarget != target) sorted_path = apply_projection_to_path(root, ordered_rel, sorted_path, target); add_path(ordered_rel, sorted_path); } else { /* * Try adding an explicit sort, but only to the cheapest total * path since a full sort should generally add the same cost to * all paths. */ if (input_path == cheapest_input_path) { /* * Sort the cheapest input path. An explicit sort here can * take advantage of LIMIT. */ sorted_path = (Path *) create_sort_path(root, ordered_rel, input_path, root->sort_pathkeys, limit_tuples); /* Add projection step if needed */ if (sorted_path->pathtarget != target) sorted_path = apply_projection_to_path(root, ordered_rel, sorted_path, target); add_path(ordered_rel, sorted_path); } /* * If incremental sort is enabled, then try it as well. Unlike * with regular sorts, we can't just look at the cheapest path, * because the cost of incremental sort depends on how well * presorted the path is. Additionally incremental sort may enable * a cheaper startup path to win out despite higher total cost. */ if (!enable_incremental_sort) continue; /* Likewise, if the path can't be used for incremental sort. */ if (!presorted_keys) continue; /* Also consider incremental sort. */ sorted_path = (Path *) create_incremental_sort_path(root, ordered_rel, input_path, root->sort_pathkeys, presorted_keys, limit_tuples); /* Add projection step if needed */ if (sorted_path->pathtarget != target) sorted_path = apply_projection_to_path(root, ordered_rel, sorted_path, target); add_path(ordered_rel, sorted_path); } } /* * generate_gather_paths() will have already generated a simple Gather * path for the best parallel path, if any, and the loop above will have * considered sorting it. Similarly, generate_gather_paths() will also * have generated order-preserving Gather Merge plans which can be used * without sorting if they happen to match the sort_pathkeys, and the loop * above will have handled those as well. However, there's one more * possibility: it may make sense to sort the cheapest partial path * according to the required output order and then use Gather Merge. */ if (ordered_rel->consider_parallel && root->sort_pathkeys != NIL && input_rel->partial_pathlist != NIL) { Path *cheapest_partial_path; cheapest_partial_path = linitial(input_rel->partial_pathlist); /* * If cheapest partial path doesn't need a sort, this is redundant * with what's already been tried. */ if (!pathkeys_contained_in(root->sort_pathkeys, cheapest_partial_path->pathkeys)) { Path *path; double total_groups; path = (Path *) create_sort_path(root, ordered_rel, cheapest_partial_path, root->sort_pathkeys, limit_tuples); total_groups = cheapest_partial_path->rows * cheapest_partial_path->parallel_workers; path = (Path *) create_gather_merge_path(root, ordered_rel, path, path->pathtarget, root->sort_pathkeys, NULL, &total_groups); /* Add projection step if needed */ if (path->pathtarget != target) path = apply_projection_to_path(root, ordered_rel, path, target); add_path(ordered_rel, path); } /* * Consider incremental sort with a gather merge on partial paths. * * We can also skip the entire loop when we only have a single-item * sort_pathkeys because then we can't possibly have a presorted * prefix of the list without having the list be fully sorted. */ if (enable_incremental_sort && list_length(root->sort_pathkeys) > 1) { ListCell *lc; foreach(lc, input_rel->partial_pathlist) { Path *input_path = (Path *) lfirst(lc); Path *sorted_path; bool is_sorted; int presorted_keys; double total_groups; /* * We don't care if this is the cheapest partial path - we * can't simply skip it, because it may be partially sorted in * which case we want to consider adding incremental sort * (instead of full sort, which is what happens above). */ is_sorted = pathkeys_count_contained_in(root->sort_pathkeys, input_path->pathkeys, &presorted_keys); /* No point in adding incremental sort on fully sorted paths. */ if (is_sorted) continue; if (presorted_keys == 0) continue; /* Since we have presorted keys, consider incremental sort. */ sorted_path = (Path *) create_incremental_sort_path(root, ordered_rel, input_path, root->sort_pathkeys, presorted_keys, limit_tuples); total_groups = input_path->rows * input_path->parallel_workers; sorted_path = (Path *) create_gather_merge_path(root, ordered_rel, sorted_path, sorted_path->pathtarget, root->sort_pathkeys, NULL, &total_groups); /* Add projection step if needed */ if (sorted_path->pathtarget != target) sorted_path = apply_projection_to_path(root, ordered_rel, sorted_path, target); add_path(ordered_rel, sorted_path); } } } /* * If there is an FDW that's responsible for all baserels of the query, * let it consider adding ForeignPaths. */ if (ordered_rel->fdwroutine && ordered_rel->fdwroutine->GetForeignUpperPaths) ordered_rel->fdwroutine->GetForeignUpperPaths(root, UPPERREL_ORDERED, input_rel, ordered_rel, NULL); /* Let extensions possibly add some more paths */ if (create_upper_paths_hook) (*create_upper_paths_hook) (root, UPPERREL_ORDERED, input_rel, ordered_rel, NULL); /* * No need to bother with set_cheapest here; grouping_planner does not * need us to do it. */ Assert(ordered_rel->pathlist != NIL); return ordered_rel; } /* * make_group_input_target * Generate appropriate PathTarget for initial input to grouping nodes. * * If there is grouping or aggregation, the scan/join subplan cannot emit * the query's final targetlist; for example, it certainly can't emit any * aggregate function calls. This routine generates the correct target * for the scan/join subplan. * * The query target list passed from the parser already contains entries * for all ORDER BY and GROUP BY expressions, but it will not have entries * for variables used only in HAVING clauses; so we need to add those * variables to the subplan target list. Also, we flatten all expressions * except GROUP BY items into their component variables; other expressions * will be computed by the upper plan nodes rather than by the subplan. * For example, given a query like * SELECT a+b,SUM(c+d) FROM table GROUP BY a+b; * we want to pass this targetlist to the subplan: * a+b,c,d * where the a+b target will be used by the Sort/Group steps, and the * other targets will be used for computing the final results. * * 'final_target' is the query's final target list (in PathTarget form) * * The result is the PathTarget to be computed by the Paths returned from * query_planner(). */ static PathTarget * make_group_input_target(PlannerInfo *root, PathTarget *final_target) { Query *parse = root->parse; PathTarget *input_target; List *non_group_cols; List *non_group_vars; int i; ListCell *lc; /* * We must build a target containing all grouping columns, plus any other * Vars mentioned in the query's targetlist and HAVING qual. */ input_target = create_empty_pathtarget(); non_group_cols = NIL; i = 0; foreach(lc, final_target->exprs) { Expr *expr = (Expr *) lfirst(lc); Index sgref = get_pathtarget_sortgroupref(final_target, i); if (sgref && parse->groupClause && get_sortgroupref_clause_noerr(sgref, parse->groupClause) != NULL) { /* * It's a grouping column, so add it to the input target as-is. */ add_column_to_pathtarget(input_target, expr, sgref); } else { /* * Non-grouping column, so just remember the expression for later * call to pull_var_clause. */ non_group_cols = lappend(non_group_cols, expr); } i++; } /* * If there's a HAVING clause, we'll need the Vars it uses, too. */ if (parse->havingQual) non_group_cols = lappend(non_group_cols, parse->havingQual); /* * Pull out all the Vars mentioned in non-group cols (plus HAVING), and * add them to the input target if not already present. (A Var used * directly as a GROUP BY item will be present already.) Note this * includes Vars used in resjunk items, so we are covering the needs of * ORDER BY and window specifications. Vars used within Aggrefs and * WindowFuncs will be pulled out here, too. */ non_group_vars = pull_var_clause((Node *) non_group_cols, PVC_RECURSE_AGGREGATES | PVC_RECURSE_WINDOWFUNCS | PVC_INCLUDE_PLACEHOLDERS); add_new_columns_to_pathtarget(input_target, non_group_vars); /* clean up cruft */ list_free(non_group_vars); list_free(non_group_cols); /* XXX this causes some redundant cost calculation ... */ return set_pathtarget_cost_width(root, input_target); } /* * make_partial_grouping_target * Generate appropriate PathTarget for output of partial aggregate * (or partial grouping, if there are no aggregates) nodes. * * A partial aggregation node needs to emit all the same aggregates that * a regular aggregation node would, plus any aggregates used in HAVING; * except that the Aggref nodes should be marked as partial aggregates. * * In addition, we'd better emit any Vars and PlaceHolderVars that are * used outside of Aggrefs in the aggregation tlist and HAVING. (Presumably, * these would be Vars that are grouped by or used in grouping expressions.) * * grouping_target is the tlist to be emitted by the topmost aggregation step. * havingQual represents the HAVING clause. */ static PathTarget * make_partial_grouping_target(PlannerInfo *root, PathTarget *grouping_target, Node *havingQual) { Query *parse = root->parse; PathTarget *partial_target; List *non_group_cols; List *non_group_exprs; int i; ListCell *lc; partial_target = create_empty_pathtarget(); non_group_cols = NIL; i = 0; foreach(lc, grouping_target->exprs) { Expr *expr = (Expr *) lfirst(lc); Index sgref = get_pathtarget_sortgroupref(grouping_target, i); if (sgref && parse->groupClause && get_sortgroupref_clause_noerr(sgref, parse->groupClause) != NULL) { /* * It's a grouping column, so add it to the partial_target as-is. * (This allows the upper agg step to repeat the grouping calcs.) */ add_column_to_pathtarget(partial_target, expr, sgref); } else { /* * Non-grouping column, so just remember the expression for later * call to pull_var_clause. */ non_group_cols = lappend(non_group_cols, expr); } i++; } /* * If there's a HAVING clause, we'll need the Vars/Aggrefs it uses, too. */ if (havingQual) non_group_cols = lappend(non_group_cols, havingQual); /* * Pull out all the Vars, PlaceHolderVars, and Aggrefs mentioned in * non-group cols (plus HAVING), and add them to the partial_target if not * already present. (An expression used directly as a GROUP BY item will * be present already.) Note this includes Vars used in resjunk items, so * we are covering the needs of ORDER BY and window specifications. */ non_group_exprs = pull_var_clause((Node *) non_group_cols, PVC_INCLUDE_AGGREGATES | PVC_RECURSE_WINDOWFUNCS | PVC_INCLUDE_PLACEHOLDERS); add_new_columns_to_pathtarget(partial_target, non_group_exprs); /* * Adjust Aggrefs to put them in partial mode. At this point all Aggrefs * are at the top level of the target list, so we can just scan the list * rather than recursing through the expression trees. */ foreach(lc, partial_target->exprs) { Aggref *aggref = (Aggref *) lfirst(lc); if (IsA(aggref, Aggref)) { Aggref *newaggref; /* * We shouldn't need to copy the substructure of the Aggref node, * but flat-copy the node itself to avoid damaging other trees. */ newaggref = makeNode(Aggref); memcpy(newaggref, aggref, sizeof(Aggref)); /* For now, assume serialization is required */ mark_partial_aggref(newaggref, AGGSPLIT_INITIAL_SERIAL); lfirst(lc) = newaggref; } } /* clean up cruft */ list_free(non_group_exprs); list_free(non_group_cols); /* XXX this causes some redundant cost calculation ... */ return set_pathtarget_cost_width(root, partial_target); } /* * mark_partial_aggref * Adjust an Aggref to make it represent a partial-aggregation step. * * The Aggref node is modified in-place; caller must do any copying required. */ void mark_partial_aggref(Aggref *agg, AggSplit aggsplit) { /* aggtranstype should be computed by this point */ Assert(OidIsValid(agg->aggtranstype)); /* ... but aggsplit should still be as the parser left it */ Assert(agg->aggsplit == AGGSPLIT_SIMPLE); /* Mark the Aggref with the intended partial-aggregation mode */ agg->aggsplit = aggsplit; /* * Adjust result type if needed. Normally, a partial aggregate returns * the aggregate's transition type; but if that's INTERNAL and we're * serializing, it returns BYTEA instead. */ if (DO_AGGSPLIT_SKIPFINAL(aggsplit)) { if (agg->aggtranstype == INTERNALOID && DO_AGGSPLIT_SERIALIZE(aggsplit)) agg->aggtype = BYTEAOID; else agg->aggtype = agg->aggtranstype; } } /* * postprocess_setop_tlist * Fix up targetlist returned by plan_set_operations(). * * We need to transpose sort key info from the orig_tlist into new_tlist. * NOTE: this would not be good enough if we supported resjunk sort keys * for results of set operations --- then, we'd need to project a whole * new tlist to evaluate the resjunk columns. For now, just ereport if we * find any resjunk columns in orig_tlist. */ static List * postprocess_setop_tlist(List *new_tlist, List *orig_tlist) { ListCell *l; ListCell *orig_tlist_item = list_head(orig_tlist); foreach(l, new_tlist) { TargetEntry *new_tle = lfirst_node(TargetEntry, l); TargetEntry *orig_tle; /* ignore resjunk columns in setop result */ if (new_tle->resjunk) continue; Assert(orig_tlist_item != NULL); orig_tle = lfirst_node(TargetEntry, orig_tlist_item); orig_tlist_item = lnext(orig_tlist, orig_tlist_item); if (orig_tle->resjunk) /* should not happen */ elog(ERROR, "resjunk output columns are not implemented"); Assert(new_tle->resno == orig_tle->resno); new_tle->ressortgroupref = orig_tle->ressortgroupref; } if (orig_tlist_item != NULL) elog(ERROR, "resjunk output columns are not implemented"); return new_tlist; } /* * select_active_windows * Create a list of the "active" window clauses (ie, those referenced * by non-deleted WindowFuncs) in the order they are to be executed. */ static List * select_active_windows(PlannerInfo *root, WindowFuncLists *wflists) { List *windowClause = root->parse->windowClause; List *result = NIL; ListCell *lc; int nActive = 0; WindowClauseSortData *actives = palloc(sizeof(WindowClauseSortData) * list_length(windowClause)); /* First, construct an array of the active windows */ foreach(lc, windowClause) { WindowClause *wc = lfirst_node(WindowClause, lc); /* It's only active if wflists shows some related WindowFuncs */ Assert(wc->winref <= wflists->maxWinRef); if (wflists->windowFuncs[wc->winref] == NIL) continue; actives[nActive].wc = wc; /* original clause */ /* * For sorting, we want the list of partition keys followed by the * list of sort keys. But pathkeys construction will remove duplicates * between the two, so we can as well (even though we can't detect all * of the duplicates, since some may come from ECs - that might mean * we miss optimization chances here). We must, however, ensure that * the order of entries is preserved with respect to the ones we do * keep. * * partitionClause and orderClause had their own duplicates removed in * parse analysis, so we're only concerned here with removing * orderClause entries that also appear in partitionClause. */ actives[nActive].uniqueOrder = list_concat_unique(list_copy(wc->partitionClause), wc->orderClause); nActive++; } /* * Sort active windows by their partitioning/ordering clauses, ignoring * any framing clauses, so that the windows that need the same sorting are * adjacent in the list. When we come to generate paths, this will avoid * inserting additional Sort nodes. * * This is how we implement a specific requirement from the SQL standard, * which says that when two or more windows are order-equivalent (i.e. * have matching partition and order clauses, even if their names or * framing clauses differ), then all peer rows must be presented in the * same order in all of them. If we allowed multiple sort nodes for such * cases, we'd risk having the peer rows end up in different orders in * equivalent windows due to sort instability. (See General Rule 4 of * in SQL2008 - SQL2016.) * * Additionally, if the entire list of clauses of one window is a prefix * of another, put first the window with stronger sorting requirements. * This way we will first sort for stronger window, and won't have to sort * again for the weaker one. */ qsort(actives, nActive, sizeof(WindowClauseSortData), common_prefix_cmp); /* build ordered list of the original WindowClause nodes */ for (int i = 0; i < nActive; i++) result = lappend(result, actives[i].wc); pfree(actives); return result; } /* * common_prefix_cmp * QSort comparison function for WindowClauseSortData * * Sort the windows by the required sorting clauses. First, compare the sort * clauses themselves. Second, if one window's clauses are a prefix of another * one's clauses, put the window with more sort clauses first. */ static int common_prefix_cmp(const void *a, const void *b) { const WindowClauseSortData *wcsa = a; const WindowClauseSortData *wcsb = b; ListCell *item_a; ListCell *item_b; forboth(item_a, wcsa->uniqueOrder, item_b, wcsb->uniqueOrder) { SortGroupClause *sca = lfirst_node(SortGroupClause, item_a); SortGroupClause *scb = lfirst_node(SortGroupClause, item_b); if (sca->tleSortGroupRef > scb->tleSortGroupRef) return -1; else if (sca->tleSortGroupRef < scb->tleSortGroupRef) return 1; else if (sca->sortop > scb->sortop) return -1; else if (sca->sortop < scb->sortop) return 1; else if (sca->nulls_first && !scb->nulls_first) return -1; else if (!sca->nulls_first && scb->nulls_first) return 1; /* no need to compare eqop, since it is fully determined by sortop */ } if (list_length(wcsa->uniqueOrder) > list_length(wcsb->uniqueOrder)) return -1; else if (list_length(wcsa->uniqueOrder) < list_length(wcsb->uniqueOrder)) return 1; return 0; } /* * make_window_input_target * Generate appropriate PathTarget for initial input to WindowAgg nodes. * * When the query has window functions, this function computes the desired * target to be computed by the node just below the first WindowAgg. * This tlist must contain all values needed to evaluate the window functions, * compute the final target list, and perform any required final sort step. * If multiple WindowAggs are needed, each intermediate one adds its window * function results onto this base tlist; only the topmost WindowAgg computes * the actual desired target list. * * This function is much like make_group_input_target, though not quite enough * like it to share code. As in that function, we flatten most expressions * into their component variables. But we do not want to flatten window * PARTITION BY/ORDER BY clauses, since that might result in multiple * evaluations of them, which would be bad (possibly even resulting in * inconsistent answers, if they contain volatile functions). * Also, we must not flatten GROUP BY clauses that were left unflattened by * make_group_input_target, because we may no longer have access to the * individual Vars in them. * * Another key difference from make_group_input_target is that we don't * flatten Aggref expressions, since those are to be computed below the * window functions and just referenced like Vars above that. * * 'final_target' is the query's final target list (in PathTarget form) * 'activeWindows' is the list of active windows previously identified by * select_active_windows. * * The result is the PathTarget to be computed by the plan node immediately * below the first WindowAgg node. */ static PathTarget * make_window_input_target(PlannerInfo *root, PathTarget *final_target, List *activeWindows) { Query *parse = root->parse; PathTarget *input_target; Bitmapset *sgrefs; List *flattenable_cols; List *flattenable_vars; int i; ListCell *lc; Assert(parse->hasWindowFuncs); /* * Collect the sortgroupref numbers of window PARTITION/ORDER BY clauses * into a bitmapset for convenient reference below. */ sgrefs = NULL; foreach(lc, activeWindows) { WindowClause *wc = lfirst_node(WindowClause, lc); ListCell *lc2; foreach(lc2, wc->partitionClause) { SortGroupClause *sortcl = lfirst_node(SortGroupClause, lc2); sgrefs = bms_add_member(sgrefs, sortcl->tleSortGroupRef); } foreach(lc2, wc->orderClause) { SortGroupClause *sortcl = lfirst_node(SortGroupClause, lc2); sgrefs = bms_add_member(sgrefs, sortcl->tleSortGroupRef); } } /* Add in sortgroupref numbers of GROUP BY clauses, too */ foreach(lc, parse->groupClause) { SortGroupClause *grpcl = lfirst_node(SortGroupClause, lc); sgrefs = bms_add_member(sgrefs, grpcl->tleSortGroupRef); } /* * Construct a target containing all the non-flattenable targetlist items, * and save aside the others for a moment. */ input_target = create_empty_pathtarget(); flattenable_cols = NIL; i = 0; foreach(lc, final_target->exprs) { Expr *expr = (Expr *) lfirst(lc); Index sgref = get_pathtarget_sortgroupref(final_target, i); /* * Don't want to deconstruct window clauses or GROUP BY items. (Note * that such items can't contain window functions, so it's okay to * compute them below the WindowAgg nodes.) */ if (sgref != 0 && bms_is_member(sgref, sgrefs)) { /* * Don't want to deconstruct this value, so add it to the input * target as-is. */ add_column_to_pathtarget(input_target, expr, sgref); } else { /* * Column is to be flattened, so just remember the expression for * later call to pull_var_clause. */ flattenable_cols = lappend(flattenable_cols, expr); } i++; } /* * Pull out all the Vars and Aggrefs mentioned in flattenable columns, and * add them to the input target if not already present. (Some might be * there already because they're used directly as window/group clauses.) * * Note: it's essential to use PVC_INCLUDE_AGGREGATES here, so that any * Aggrefs are placed in the Agg node's tlist and not left to be computed * at higher levels. On the other hand, we should recurse into * WindowFuncs to make sure their input expressions are available. */ flattenable_vars = pull_var_clause((Node *) flattenable_cols, PVC_INCLUDE_AGGREGATES | PVC_RECURSE_WINDOWFUNCS | PVC_INCLUDE_PLACEHOLDERS); add_new_columns_to_pathtarget(input_target, flattenable_vars); /* clean up cruft */ list_free(flattenable_vars); list_free(flattenable_cols); /* XXX this causes some redundant cost calculation ... */ return set_pathtarget_cost_width(root, input_target); } /* * make_pathkeys_for_window * Create a pathkeys list describing the required input ordering * for the given WindowClause. * * The required ordering is first the PARTITION keys, then the ORDER keys. * In the future we might try to implement windowing using hashing, in which * case the ordering could be relaxed, but for now we always sort. */ static List * make_pathkeys_for_window(PlannerInfo *root, WindowClause *wc, List *tlist) { List *window_pathkeys; List *window_sortclauses; /* Throw error if can't sort */ if (!grouping_is_sortable(wc->partitionClause)) ereport(ERROR, (errcode(ERRCODE_FEATURE_NOT_SUPPORTED), errmsg("could not implement window PARTITION BY"), errdetail("Window partitioning columns must be of sortable datatypes."))); if (!grouping_is_sortable(wc->orderClause)) ereport(ERROR, (errcode(ERRCODE_FEATURE_NOT_SUPPORTED), errmsg("could not implement window ORDER BY"), errdetail("Window ordering columns must be of sortable datatypes."))); /* Okay, make the combined pathkeys */ window_sortclauses = list_concat_copy(wc->partitionClause, wc->orderClause); window_pathkeys = make_pathkeys_for_sortclauses(root, window_sortclauses, tlist); list_free(window_sortclauses); return window_pathkeys; } /* * make_sort_input_target * Generate appropriate PathTarget for initial input to Sort step. * * If the query has ORDER BY, this function chooses the target to be computed * by the node just below the Sort (and DISTINCT, if any, since Unique can't * project) steps. This might or might not be identical to the query's final * output target. * * The main argument for keeping the sort-input tlist the same as the final * is that we avoid a separate projection node (which will be needed if * they're different, because Sort can't project). However, there are also * advantages to postponing tlist evaluation till after the Sort: it ensures * a consistent order of evaluation for any volatile functions in the tlist, * and if there's also a LIMIT, we can stop the query without ever computing * tlist functions for later rows, which is beneficial for both volatile and * expensive functions. * * Our current policy is to postpone volatile expressions till after the sort * unconditionally (assuming that that's possible, ie they are in plain tlist * columns and not ORDER BY/GROUP BY/DISTINCT columns). We also prefer to * postpone set-returning expressions, because running them beforehand would * bloat the sort dataset, and because it might cause unexpected output order * if the sort isn't stable. However there's a constraint on that: all SRFs * in the tlist should be evaluated at the same plan step, so that they can * run in sync in nodeProjectSet. So if any SRFs are in sort columns, we * mustn't postpone any SRFs. (Note that in principle that policy should * probably get applied to the group/window input targetlists too, but we * have not done that historically.) Lastly, expensive expressions are * postponed if there is a LIMIT, or if root->tuple_fraction shows that * partial evaluation of the query is possible (if neither is true, we expect * to have to evaluate the expressions for every row anyway), or if there are * any volatile or set-returning expressions (since once we've put in a * projection at all, it won't cost any more to postpone more stuff). * * Another issue that could potentially be considered here is that * evaluating tlist expressions could result in data that's either wider * or narrower than the input Vars, thus changing the volume of data that * has to go through the Sort. However, we usually have only a very bad * idea of the output width of any expression more complex than a Var, * so for now it seems too risky to try to optimize on that basis. * * Note that if we do produce a modified sort-input target, and then the * query ends up not using an explicit Sort, no particular harm is done: * we'll initially use the modified target for the preceding path nodes, * but then change them to the final target with apply_projection_to_path. * Moreover, in such a case the guarantees about evaluation order of * volatile functions still hold, since the rows are sorted already. * * This function has some things in common with make_group_input_target and * make_window_input_target, though the detailed rules for what to do are * different. We never flatten/postpone any grouping or ordering columns; * those are needed before the sort. If we do flatten a particular * expression, we leave Aggref and WindowFunc nodes alone, since those were * computed earlier. * * 'final_target' is the query's final target list (in PathTarget form) * 'have_postponed_srfs' is an output argument, see below * * The result is the PathTarget to be computed by the plan node immediately * below the Sort step (and the Distinct step, if any). This will be * exactly final_target if we decide a projection step wouldn't be helpful. * * In addition, *have_postponed_srfs is set to true if we choose to postpone * any set-returning functions to after the Sort. */ static PathTarget * make_sort_input_target(PlannerInfo *root, PathTarget *final_target, bool *have_postponed_srfs) { Query *parse = root->parse; PathTarget *input_target; int ncols; bool *col_is_srf; bool *postpone_col; bool have_srf; bool have_volatile; bool have_expensive; bool have_srf_sortcols; bool postpone_srfs; List *postponable_cols; List *postponable_vars; int i; ListCell *lc; /* Shouldn't get here unless query has ORDER BY */ Assert(parse->sortClause); *have_postponed_srfs = false; /* default result */ /* Inspect tlist and collect per-column information */ ncols = list_length(final_target->exprs); col_is_srf = (bool *) palloc0(ncols * sizeof(bool)); postpone_col = (bool *) palloc0(ncols * sizeof(bool)); have_srf = have_volatile = have_expensive = have_srf_sortcols = false; i = 0; foreach(lc, final_target->exprs) { Expr *expr = (Expr *) lfirst(lc); /* * If the column has a sortgroupref, assume it has to be evaluated * before sorting. Generally such columns would be ORDER BY, GROUP * BY, etc targets. One exception is columns that were removed from * GROUP BY by remove_useless_groupby_columns() ... but those would * only be Vars anyway. There don't seem to be any cases where it * would be worth the trouble to double-check. */ if (get_pathtarget_sortgroupref(final_target, i) == 0) { /* * Check for SRF or volatile functions. Check the SRF case first * because we must know whether we have any postponed SRFs. */ if (parse->hasTargetSRFs && expression_returns_set((Node *) expr)) { /* We'll decide below whether these are postponable */ col_is_srf[i] = true; have_srf = true; } else if (contain_volatile_functions((Node *) expr)) { /* Unconditionally postpone */ postpone_col[i] = true; have_volatile = true; } else { /* * Else check the cost. XXX it's annoying to have to do this * when set_pathtarget_cost_width() just did it. Refactor to * allow sharing the work? */ QualCost cost; cost_qual_eval_node(&cost, (Node *) expr, root); /* * We arbitrarily define "expensive" as "more than 10X * cpu_operator_cost". Note this will take in any PL function * with default cost. */ if (cost.per_tuple > 10 * cpu_operator_cost) { postpone_col[i] = true; have_expensive = true; } } } else { /* For sortgroupref cols, just check if any contain SRFs */ if (!have_srf_sortcols && parse->hasTargetSRFs && expression_returns_set((Node *) expr)) have_srf_sortcols = true; } i++; } /* * We can postpone SRFs if we have some but none are in sortgroupref cols. */ postpone_srfs = (have_srf && !have_srf_sortcols); /* * If we don't need a post-sort projection, just return final_target. */ if (!(postpone_srfs || have_volatile || (have_expensive && (parse->limitCount || root->tuple_fraction > 0)))) return final_target; /* * Report whether the post-sort projection will contain set-returning * functions. This is important because it affects whether the Sort can * rely on the query's LIMIT (if any) to bound the number of rows it needs * to return. */ *have_postponed_srfs = postpone_srfs; /* * Construct the sort-input target, taking all non-postponable columns and * then adding Vars, PlaceHolderVars, Aggrefs, and WindowFuncs found in * the postponable ones. */ input_target = create_empty_pathtarget(); postponable_cols = NIL; i = 0; foreach(lc, final_target->exprs) { Expr *expr = (Expr *) lfirst(lc); if (postpone_col[i] || (postpone_srfs && col_is_srf[i])) postponable_cols = lappend(postponable_cols, expr); else add_column_to_pathtarget(input_target, expr, get_pathtarget_sortgroupref(final_target, i)); i++; } /* * Pull out all the Vars, Aggrefs, and WindowFuncs mentioned in * postponable columns, and add them to the sort-input target if not * already present. (Some might be there already.) We mustn't * deconstruct Aggrefs or WindowFuncs here, since the projection node * would be unable to recompute them. */ postponable_vars = pull_var_clause((Node *) postponable_cols, PVC_INCLUDE_AGGREGATES | PVC_INCLUDE_WINDOWFUNCS | PVC_INCLUDE_PLACEHOLDERS); add_new_columns_to_pathtarget(input_target, postponable_vars); /* clean up cruft */ list_free(postponable_vars); list_free(postponable_cols); /* XXX this represents even more redundant cost calculation ... */ return set_pathtarget_cost_width(root, input_target); } /* * get_cheapest_fractional_path * Find the cheapest path for retrieving a specified fraction of all * the tuples expected to be returned by the given relation. * * We interpret tuple_fraction the same way as grouping_planner. * * We assume set_cheapest() has been run on the given rel. */ Path * get_cheapest_fractional_path(RelOptInfo *rel, double tuple_fraction) { Path *best_path = rel->cheapest_total_path; ListCell *l; /* If all tuples will be retrieved, just return the cheapest-total path */ if (tuple_fraction <= 0.0) return best_path; /* Convert absolute # of tuples to a fraction; no need to clamp to 0..1 */ if (tuple_fraction >= 1.0 && best_path->rows > 0) tuple_fraction /= best_path->rows; foreach(l, rel->pathlist) { Path *path = (Path *) lfirst(l); if (path == rel->cheapest_total_path || compare_fractional_path_costs(best_path, path, tuple_fraction) <= 0) continue; best_path = path; } return best_path; } /* * adjust_paths_for_srfs * Fix up the Paths of the given upperrel to handle tSRFs properly. * * The executor can only handle set-returning functions that appear at the * top level of the targetlist of a ProjectSet plan node. If we have any SRFs * that are not at top level, we need to split up the evaluation into multiple * plan levels in which each level satisfies this constraint. This function * modifies each Path of an upperrel that (might) compute any SRFs in its * output tlist to insert appropriate projection steps. * * The given targets and targets_contain_srfs lists are from * split_pathtarget_at_srfs(). We assume the existing Paths emit the first * target in targets. */ static void adjust_paths_for_srfs(PlannerInfo *root, RelOptInfo *rel, List *targets, List *targets_contain_srfs) { ListCell *lc; Assert(list_length(targets) == list_length(targets_contain_srfs)); Assert(!linitial_int(targets_contain_srfs)); /* If no SRFs appear at this plan level, nothing to do */ if (list_length(targets) == 1) return; /* * Stack SRF-evaluation nodes atop each path for the rel. * * In principle we should re-run set_cheapest() here to identify the * cheapest path, but it seems unlikely that adding the same tlist eval * costs to all the paths would change that, so we don't bother. Instead, * just assume that the cheapest-startup and cheapest-total paths remain * so. (There should be no parameterized paths anymore, so we needn't * worry about updating cheapest_parameterized_paths.) */ foreach(lc, rel->pathlist) { Path *subpath = (Path *) lfirst(lc); Path *newpath = subpath; ListCell *lc1, *lc2; Assert(subpath->param_info == NULL); forboth(lc1, targets, lc2, targets_contain_srfs) { PathTarget *thistarget = lfirst_node(PathTarget, lc1); bool contains_srfs = (bool) lfirst_int(lc2); /* If this level doesn't contain SRFs, do regular projection */ if (contains_srfs) newpath = (Path *) create_set_projection_path(root, rel, newpath, thistarget); else newpath = (Path *) apply_projection_to_path(root, rel, newpath, thistarget); } lfirst(lc) = newpath; if (subpath == rel->cheapest_startup_path) rel->cheapest_startup_path = newpath; if (subpath == rel->cheapest_total_path) rel->cheapest_total_path = newpath; } /* Likewise for partial paths, if any */ foreach(lc, rel->partial_pathlist) { Path *subpath = (Path *) lfirst(lc); Path *newpath = subpath; ListCell *lc1, *lc2; Assert(subpath->param_info == NULL); forboth(lc1, targets, lc2, targets_contain_srfs) { PathTarget *thistarget = lfirst_node(PathTarget, lc1); bool contains_srfs = (bool) lfirst_int(lc2); /* If this level doesn't contain SRFs, do regular projection */ if (contains_srfs) newpath = (Path *) create_set_projection_path(root, rel, newpath, thistarget); else { /* avoid apply_projection_to_path, in case of multiple refs */ newpath = (Path *) create_projection_path(root, rel, newpath, thistarget); } } lfirst(lc) = newpath; } } /* * expression_planner * Perform planner's transformations on a standalone expression. * * Various utility commands need to evaluate expressions that are not part * of a plannable query. They can do so using the executor's regular * expression-execution machinery, but first the expression has to be fed * through here to transform it from parser output to something executable. * * Currently, we disallow sublinks in standalone expressions, so there's no * real "planning" involved here. (That might not always be true though.) * What we must do is run eval_const_expressions to ensure that any function * calls are converted to positional notation and function default arguments * get inserted. The fact that constant subexpressions get simplified is a * side-effect that is useful when the expression will get evaluated more than * once. Also, we must fix operator function IDs. * * This does not return any information about dependencies of the expression. * Hence callers should use the results only for the duration of the current * query. Callers that would like to cache the results for longer should use * expression_planner_with_deps, probably via the plancache. * * Note: this must not make any damaging changes to the passed-in expression * tree. (It would actually be okay to apply fix_opfuncids to it, but since * we first do an expression_tree_mutator-based walk, what is returned will * be a new node tree.) The result is constructed in the current memory * context; beware that this can leak a lot of additional stuff there, too. */ Expr * expression_planner(Expr *expr) { Node *result; /* * Convert named-argument function calls, insert default arguments and * simplify constant subexprs */ result = eval_const_expressions(NULL, (Node *) expr); /* Fill in opfuncid values if missing */ fix_opfuncids(result); return (Expr *) result; } /* * expression_planner_with_deps * Perform planner's transformations on a standalone expression, * returning expression dependency information along with the result. * * This is identical to expression_planner() except that it also returns * information about possible dependencies of the expression, ie identities of * objects whose definitions affect the result. As in a PlannedStmt, these * are expressed as a list of relation Oids and a list of PlanInvalItems. */ Expr * expression_planner_with_deps(Expr *expr, List **relationOids, List **invalItems) { Node *result; PlannerGlobal glob; PlannerInfo root; /* Make up dummy planner state so we can use setrefs machinery */ MemSet(&glob, 0, sizeof(glob)); glob.type = T_PlannerGlobal; glob.relationOids = NIL; glob.invalItems = NIL; MemSet(&root, 0, sizeof(root)); root.type = T_PlannerInfo; root.glob = &glob; /* * Convert named-argument function calls, insert default arguments and * simplify constant subexprs. Collect identities of inlined functions * and elided domains, too. */ result = eval_const_expressions(&root, (Node *) expr); /* Fill in opfuncid values if missing */ fix_opfuncids(result); /* * Now walk the finished expression to find anything else we ought to * record as an expression dependency. */ (void) extract_query_dependencies_walker(result, &root); *relationOids = glob.relationOids; *invalItems = glob.invalItems; return (Expr *) result; } /* * plan_cluster_use_sort * Use the planner to decide how CLUSTER should implement sorting * * tableOid is the OID of a table to be clustered on its index indexOid * (which is already known to be a btree index). Decide whether it's * cheaper to do an indexscan or a seqscan-plus-sort to execute the CLUSTER. * Return true to use sorting, false to use an indexscan. * * Note: caller had better already hold some type of lock on the table. */ bool plan_cluster_use_sort(Oid tableOid, Oid indexOid) { PlannerInfo *root; Query *query; PlannerGlobal *glob; RangeTblEntry *rte; RelOptInfo *rel; IndexOptInfo *indexInfo; QualCost indexExprCost; Cost comparisonCost; Path *seqScanPath; Path seqScanAndSortPath; IndexPath *indexScanPath; ListCell *lc; /* We can short-circuit the cost comparison if indexscans are disabled */ if (!enable_indexscan) return true; /* use sort */ /* Set up mostly-dummy planner state */ query = makeNode(Query); query->commandType = CMD_SELECT; glob = makeNode(PlannerGlobal); root = makeNode(PlannerInfo); root->parse = query; root->glob = glob; root->query_level = 1; root->planner_cxt = CurrentMemoryContext; root->wt_param_id = -1; /* Build a minimal RTE for the rel */ rte = makeNode(RangeTblEntry); rte->rtekind = RTE_RELATION; rte->relid = tableOid; rte->relkind = RELKIND_RELATION; /* Don't be too picky. */ rte->rellockmode = AccessShareLock; rte->lateral = false; rte->inh = false; rte->inFromCl = true; query->rtable = list_make1(rte); /* Set up RTE/RelOptInfo arrays */ setup_simple_rel_arrays(root); /* Build RelOptInfo */ rel = build_simple_rel(root, 1, NULL); /* Locate IndexOptInfo for the target index */ indexInfo = NULL; foreach(lc, rel->indexlist) { indexInfo = lfirst_node(IndexOptInfo, lc); if (indexInfo->indexoid == indexOid) break; } /* * It's possible that get_relation_info did not generate an IndexOptInfo * for the desired index; this could happen if it's not yet reached its * indcheckxmin usability horizon, or if it's a system index and we're * ignoring system indexes. In such cases we should tell CLUSTER to not * trust the index contents but use seqscan-and-sort. */ if (lc == NULL) /* not in the list? */ return true; /* use sort */ /* * Rather than doing all the pushups that would be needed to use * set_baserel_size_estimates, just do a quick hack for rows and width. */ rel->rows = rel->tuples; rel->reltarget->width = get_relation_data_width(tableOid, NULL); root->total_table_pages = rel->pages; /* * Determine eval cost of the index expressions, if any. We need to * charge twice that amount for each tuple comparison that happens during * the sort, since tuplesort.c will have to re-evaluate the index * expressions each time. (XXX that's pretty inefficient...) */ cost_qual_eval(&indexExprCost, indexInfo->indexprs, root); comparisonCost = 2.0 * (indexExprCost.startup + indexExprCost.per_tuple); /* Estimate the cost of seq scan + sort */ seqScanPath = create_seqscan_path(root, rel, NULL, 0); cost_sort(&seqScanAndSortPath, root, NIL, seqScanPath->total_cost, rel->tuples, rel->reltarget->width, comparisonCost, maintenance_work_mem, -1.0); /* Estimate the cost of index scan */ indexScanPath = create_index_path(root, indexInfo, NIL, NIL, NIL, NIL, ForwardScanDirection, false, NULL, 1.0, false); return (seqScanAndSortPath.total_cost < indexScanPath->path.total_cost); } /* * plan_create_index_workers * Use the planner to decide how many parallel worker processes * CREATE INDEX should request for use * * tableOid is the table on which the index is to be built. indexOid is the * OID of an index to be created or reindexed (which must be a btree index). * * Return value is the number of parallel worker processes to request. It * may be unsafe to proceed if this is 0. Note that this does not include the * leader participating as a worker (value is always a number of parallel * worker processes). * * Note: caller had better already hold some type of lock on the table and * index. */ int plan_create_index_workers(Oid tableOid, Oid indexOid) { PlannerInfo *root; Query *query; PlannerGlobal *glob; RangeTblEntry *rte; Relation heap; Relation index; RelOptInfo *rel; int parallel_workers; BlockNumber heap_blocks; double reltuples; double allvisfrac; /* * We don't allow performing parallel operation in standalone backend or * when parallelism is disabled. */ if (!IsUnderPostmaster || max_parallel_maintenance_workers == 0) return 0; /* Set up largely-dummy planner state */ query = makeNode(Query); query->commandType = CMD_SELECT; glob = makeNode(PlannerGlobal); root = makeNode(PlannerInfo); root->parse = query; root->glob = glob; root->query_level = 1; root->planner_cxt = CurrentMemoryContext; root->wt_param_id = -1; /* * Build a minimal RTE. * * Mark the RTE with inh = true. This is a kludge to prevent * get_relation_info() from fetching index info, which is necessary * because it does not expect that any IndexOptInfo is currently * undergoing REINDEX. */ rte = makeNode(RangeTblEntry); rte->rtekind = RTE_RELATION; rte->relid = tableOid; rte->relkind = RELKIND_RELATION; /* Don't be too picky. */ rte->rellockmode = AccessShareLock; rte->lateral = false; rte->inh = true; rte->inFromCl = true; query->rtable = list_make1(rte); /* Set up RTE/RelOptInfo arrays */ setup_simple_rel_arrays(root); /* Build RelOptInfo */ rel = build_simple_rel(root, 1, NULL); /* Rels are assumed already locked by the caller */ heap = table_open(tableOid, NoLock); index = index_open(indexOid, NoLock); /* * Determine if it's safe to proceed. * * Currently, parallel workers can't access the leader's temporary tables. * Furthermore, any index predicate or index expressions must be parallel * safe. */ if (heap->rd_rel->relpersistence == RELPERSISTENCE_TEMP || !is_parallel_safe(root, (Node *) RelationGetIndexExpressions(index)) || !is_parallel_safe(root, (Node *) RelationGetIndexPredicate(index))) { parallel_workers = 0; goto done; } /* * If parallel_workers storage parameter is set for the table, accept that * as the number of parallel worker processes to launch (though still cap * at max_parallel_maintenance_workers). Note that we deliberately do not * consider any other factor when parallel_workers is set. (e.g., memory * use by workers.) */ if (rel->rel_parallel_workers != -1) { parallel_workers = Min(rel->rel_parallel_workers, max_parallel_maintenance_workers); goto done; } /* * Estimate heap relation size ourselves, since rel->pages cannot be * trusted (heap RTE was marked as inheritance parent) */ estimate_rel_size(heap, NULL, &heap_blocks, &reltuples, &allvisfrac); /* * Determine number of workers to scan the heap relation using generic * model */ parallel_workers = compute_parallel_worker(rel, heap_blocks, -1, max_parallel_maintenance_workers); /* * Cap workers based on available maintenance_work_mem as needed. * * Note that each tuplesort participant receives an even share of the * total maintenance_work_mem budget. Aim to leave participants * (including the leader as a participant) with no less than 32MB of * memory. This leaves cases where maintenance_work_mem is set to 64MB * immediately past the threshold of being capable of launching a single * parallel worker to sort. */ while (parallel_workers > 0 && maintenance_work_mem / (parallel_workers + 1) < 32768L) parallel_workers--; done: index_close(index, NoLock); table_close(heap, NoLock); return parallel_workers; } /* * add_paths_to_grouping_rel * * Add non-partial paths to grouping relation. */ static void add_paths_to_grouping_rel(PlannerInfo *root, RelOptInfo *input_rel, RelOptInfo *grouped_rel, RelOptInfo *partially_grouped_rel, const AggClauseCosts *agg_costs, grouping_sets_data *gd, double dNumGroups, GroupPathExtraData *extra) { Query *parse = root->parse; Path *cheapest_path = input_rel->cheapest_total_path; ListCell *lc; bool can_hash = (extra->flags & GROUPING_CAN_USE_HASH) != 0; bool can_sort = (extra->flags & GROUPING_CAN_USE_SORT) != 0; List *havingQual = (List *) extra->havingQual; AggClauseCosts *agg_final_costs = &extra->agg_final_costs; if (can_sort) { /* * Use any available suitably-sorted path as input, and also consider * sorting the cheapest-total path. */ foreach(lc, input_rel->pathlist) { Path *path = (Path *) lfirst(lc); Path *path_original = path; bool is_sorted; int presorted_keys; is_sorted = pathkeys_count_contained_in(root->group_pathkeys, path->pathkeys, &presorted_keys); if (path == cheapest_path || is_sorted) { /* Sort the cheapest-total path if it isn't already sorted */ if (!is_sorted) path = (Path *) create_sort_path(root, grouped_rel, path, root->group_pathkeys, -1.0); /* Now decide what to stick atop it */ if (parse->groupingSets) { consider_groupingsets_paths(root, grouped_rel, path, true, can_hash, gd, agg_costs, dNumGroups); } else if (parse->hasAggs) { /* * We have aggregation, possibly with plain GROUP BY. Make * an AggPath. */ add_path(grouped_rel, (Path *) create_agg_path(root, grouped_rel, path, grouped_rel->reltarget, parse->groupClause ? AGG_SORTED : AGG_PLAIN, AGGSPLIT_SIMPLE, parse->groupClause, havingQual, agg_costs, dNumGroups)); } else if (parse->groupClause) { /* * We have GROUP BY without aggregation or grouping sets. * Make a GroupPath. */ add_path(grouped_rel, (Path *) create_group_path(root, grouped_rel, path, parse->groupClause, havingQual, dNumGroups)); } else { /* Other cases should have been handled above */ Assert(false); } } /* * Now we may consider incremental sort on this path, but only * when the path is not already sorted and when incremental sort * is enabled. */ if (is_sorted || !enable_incremental_sort) continue; /* Restore the input path (we might have added Sort on top). */ path = path_original; /* no shared prefix, no point in building incremental sort */ if (presorted_keys == 0) continue; /* * We should have already excluded pathkeys of length 1 because * then presorted_keys > 0 would imply is_sorted was true. */ Assert(list_length(root->group_pathkeys) != 1); path = (Path *) create_incremental_sort_path(root, grouped_rel, path, root->group_pathkeys, presorted_keys, -1.0); /* Now decide what to stick atop it */ if (parse->groupingSets) { consider_groupingsets_paths(root, grouped_rel, path, true, can_hash, gd, agg_costs, dNumGroups); } else if (parse->hasAggs) { /* * We have aggregation, possibly with plain GROUP BY. Make an * AggPath. */ add_path(grouped_rel, (Path *) create_agg_path(root, grouped_rel, path, grouped_rel->reltarget, parse->groupClause ? AGG_SORTED : AGG_PLAIN, AGGSPLIT_SIMPLE, parse->groupClause, havingQual, agg_costs, dNumGroups)); } else if (parse->groupClause) { /* * We have GROUP BY without aggregation or grouping sets. Make * a GroupPath. */ add_path(grouped_rel, (Path *) create_group_path(root, grouped_rel, path, parse->groupClause, havingQual, dNumGroups)); } else { /* Other cases should have been handled above */ Assert(false); } } /* * Instead of operating directly on the input relation, we can * consider finalizing a partially aggregated path. */ if (partially_grouped_rel != NULL) { foreach(lc, partially_grouped_rel->pathlist) { Path *path = (Path *) lfirst(lc); Path *path_original = path; bool is_sorted; int presorted_keys; is_sorted = pathkeys_count_contained_in(root->group_pathkeys, path->pathkeys, &presorted_keys); /* * Insert a Sort node, if required. But there's no point in * sorting anything but the cheapest path. */ if (!is_sorted) { if (path != partially_grouped_rel->cheapest_total_path) continue; path = (Path *) create_sort_path(root, grouped_rel, path, root->group_pathkeys, -1.0); } if (parse->hasAggs) add_path(grouped_rel, (Path *) create_agg_path(root, grouped_rel, path, grouped_rel->reltarget, parse->groupClause ? AGG_SORTED : AGG_PLAIN, AGGSPLIT_FINAL_DESERIAL, parse->groupClause, havingQual, agg_final_costs, dNumGroups)); else add_path(grouped_rel, (Path *) create_group_path(root, grouped_rel, path, parse->groupClause, havingQual, dNumGroups)); /* * Now we may consider incremental sort on this path, but only * when the path is not already sorted and when incremental * sort is enabled. */ if (is_sorted || !enable_incremental_sort) continue; /* Restore the input path (we might have added Sort on top). */ path = path_original; /* no shared prefix, not point in building incremental sort */ if (presorted_keys == 0) continue; /* * We should have already excluded pathkeys of length 1 * because then presorted_keys > 0 would imply is_sorted was * true. */ Assert(list_length(root->group_pathkeys) != 1); path = (Path *) create_incremental_sort_path(root, grouped_rel, path, root->group_pathkeys, presorted_keys, -1.0); if (parse->hasAggs) add_path(grouped_rel, (Path *) create_agg_path(root, grouped_rel, path, grouped_rel->reltarget, parse->groupClause ? AGG_SORTED : AGG_PLAIN, AGGSPLIT_FINAL_DESERIAL, parse->groupClause, havingQual, agg_final_costs, dNumGroups)); else add_path(grouped_rel, (Path *) create_group_path(root, grouped_rel, path, parse->groupClause, havingQual, dNumGroups)); } } } if (can_hash) { if (parse->groupingSets) { /* * Try for a hash-only groupingsets path over unsorted input. */ consider_groupingsets_paths(root, grouped_rel, cheapest_path, false, true, gd, agg_costs, dNumGroups); } else { /* * Generate a HashAgg Path. We just need an Agg over the * cheapest-total input path, since input order won't matter. */ add_path(grouped_rel, (Path *) create_agg_path(root, grouped_rel, cheapest_path, grouped_rel->reltarget, AGG_HASHED, AGGSPLIT_SIMPLE, parse->groupClause, havingQual, agg_costs, dNumGroups)); } /* * Generate a Finalize HashAgg Path atop of the cheapest partially * grouped path, assuming there is one */ if (partially_grouped_rel && partially_grouped_rel->pathlist) { Path *path = partially_grouped_rel->cheapest_total_path; add_path(grouped_rel, (Path *) create_agg_path(root, grouped_rel, path, grouped_rel->reltarget, AGG_HASHED, AGGSPLIT_FINAL_DESERIAL, parse->groupClause, havingQual, agg_final_costs, dNumGroups)); } } /* * When partitionwise aggregate is used, we might have fully aggregated * paths in the partial pathlist, because add_paths_to_append_rel() will * consider a path for grouped_rel consisting of a Parallel Append of * non-partial paths from each child. */ if (grouped_rel->partial_pathlist != NIL) gather_grouping_paths(root, grouped_rel); } /* * create_partial_grouping_paths * * Create a new upper relation representing the result of partial aggregation * and populate it with appropriate paths. Note that we don't finalize the * lists of paths here, so the caller can add additional partial or non-partial * paths and must afterward call gather_grouping_paths and set_cheapest on * the returned upper relation. * * All paths for this new upper relation -- both partial and non-partial -- * have been partially aggregated but require a subsequent FinalizeAggregate * step. * * NB: This function is allowed to return NULL if it determines that there is * no real need to create a new RelOptInfo. */ static RelOptInfo * create_partial_grouping_paths(PlannerInfo *root, RelOptInfo *grouped_rel, RelOptInfo *input_rel, grouping_sets_data *gd, GroupPathExtraData *extra, bool force_rel_creation) { Query *parse = root->parse; RelOptInfo *partially_grouped_rel; AggClauseCosts *agg_partial_costs = &extra->agg_partial_costs; AggClauseCosts *agg_final_costs = &extra->agg_final_costs; Path *cheapest_partial_path = NULL; Path *cheapest_total_path = NULL; double dNumPartialGroups = 0; double dNumPartialPartialGroups = 0; ListCell *lc; bool can_hash = (extra->flags & GROUPING_CAN_USE_HASH) != 0; bool can_sort = (extra->flags & GROUPING_CAN_USE_SORT) != 0; /* * Consider whether we should generate partially aggregated non-partial * paths. We can only do this if we have a non-partial path, and only if * the parent of the input rel is performing partial partitionwise * aggregation. (Note that extra->patype is the type of partitionwise * aggregation being used at the parent level, not this level.) */ if (input_rel->pathlist != NIL && extra->patype == PARTITIONWISE_AGGREGATE_PARTIAL) cheapest_total_path = input_rel->cheapest_total_path; /* * If parallelism is possible for grouped_rel, then we should consider * generating partially-grouped partial paths. However, if the input rel * has no partial paths, then we can't. */ if (grouped_rel->consider_parallel && input_rel->partial_pathlist != NIL) cheapest_partial_path = linitial(input_rel->partial_pathlist); /* * If we can't partially aggregate partial paths, and we can't partially * aggregate non-partial paths, then don't bother creating the new * RelOptInfo at all, unless the caller specified force_rel_creation. */ if (cheapest_total_path == NULL && cheapest_partial_path == NULL && !force_rel_creation) return NULL; /* * Build a new upper relation to represent the result of partially * aggregating the rows from the input relation. */ partially_grouped_rel = fetch_upper_rel(root, UPPERREL_PARTIAL_GROUP_AGG, grouped_rel->relids); partially_grouped_rel->consider_parallel = grouped_rel->consider_parallel; partially_grouped_rel->reloptkind = grouped_rel->reloptkind; partially_grouped_rel->serverid = grouped_rel->serverid; partially_grouped_rel->userid = grouped_rel->userid; partially_grouped_rel->useridiscurrent = grouped_rel->useridiscurrent; partially_grouped_rel->fdwroutine = grouped_rel->fdwroutine; /* * Build target list for partial aggregate paths. These paths cannot just * emit the same tlist as regular aggregate paths, because (1) we must * include Vars and Aggrefs needed in HAVING, which might not appear in * the result tlist, and (2) the Aggrefs must be set in partial mode. */ partially_grouped_rel->reltarget = make_partial_grouping_target(root, grouped_rel->reltarget, extra->havingQual); if (!extra->partial_costs_set) { /* * Collect statistics about aggregates for estimating costs of * performing aggregation in parallel. */ MemSet(agg_partial_costs, 0, sizeof(AggClauseCosts)); MemSet(agg_final_costs, 0, sizeof(AggClauseCosts)); if (parse->hasAggs) { /* partial phase */ get_agg_clause_costs(root, AGGSPLIT_INITIAL_SERIAL, agg_partial_costs); /* final phase */ get_agg_clause_costs(root, AGGSPLIT_FINAL_DESERIAL, agg_final_costs); } extra->partial_costs_set = true; } /* Estimate number of partial groups. */ if (cheapest_total_path != NULL) dNumPartialGroups = get_number_of_groups(root, cheapest_total_path->rows, gd, extra->targetList); if (cheapest_partial_path != NULL) dNumPartialPartialGroups = get_number_of_groups(root, cheapest_partial_path->rows, gd, extra->targetList); if (can_sort && cheapest_total_path != NULL) { /* This should have been checked previously */ Assert(parse->hasAggs || parse->groupClause); /* * Use any available suitably-sorted path as input, and also consider * sorting the cheapest partial path. */ foreach(lc, input_rel->pathlist) { Path *path = (Path *) lfirst(lc); bool is_sorted; is_sorted = pathkeys_contained_in(root->group_pathkeys, path->pathkeys); if (path == cheapest_total_path || is_sorted) { /* Sort the cheapest partial path, if it isn't already */ if (!is_sorted) path = (Path *) create_sort_path(root, partially_grouped_rel, path, root->group_pathkeys, -1.0); if (parse->hasAggs) add_path(partially_grouped_rel, (Path *) create_agg_path(root, partially_grouped_rel, path, partially_grouped_rel->reltarget, parse->groupClause ? AGG_SORTED : AGG_PLAIN, AGGSPLIT_INITIAL_SERIAL, parse->groupClause, NIL, agg_partial_costs, dNumPartialGroups)); else add_path(partially_grouped_rel, (Path *) create_group_path(root, partially_grouped_rel, path, parse->groupClause, NIL, dNumPartialGroups)); } } /* * Consider incremental sort on all partial paths, if enabled. * * We can also skip the entire loop when we only have a single-item * group_pathkeys because then we can't possibly have a presorted * prefix of the list without having the list be fully sorted. */ if (enable_incremental_sort && list_length(root->group_pathkeys) > 1) { foreach(lc, input_rel->pathlist) { Path *path = (Path *) lfirst(lc); bool is_sorted; int presorted_keys; is_sorted = pathkeys_count_contained_in(root->group_pathkeys, path->pathkeys, &presorted_keys); /* Ignore already sorted paths */ if (is_sorted) continue; if (presorted_keys == 0) continue; /* Since we have presorted keys, consider incremental sort. */ path = (Path *) create_incremental_sort_path(root, partially_grouped_rel, path, root->group_pathkeys, presorted_keys, -1.0); if (parse->hasAggs) add_path(partially_grouped_rel, (Path *) create_agg_path(root, partially_grouped_rel, path, partially_grouped_rel->reltarget, parse->groupClause ? AGG_SORTED : AGG_PLAIN, AGGSPLIT_INITIAL_SERIAL, parse->groupClause, NIL, agg_partial_costs, dNumPartialGroups)); else add_path(partially_grouped_rel, (Path *) create_group_path(root, partially_grouped_rel, path, parse->groupClause, NIL, dNumPartialGroups)); } } } if (can_sort && cheapest_partial_path != NULL) { /* Similar to above logic, but for partial paths. */ foreach(lc, input_rel->partial_pathlist) { Path *path = (Path *) lfirst(lc); Path *path_original = path; bool is_sorted; int presorted_keys; is_sorted = pathkeys_count_contained_in(root->group_pathkeys, path->pathkeys, &presorted_keys); if (path == cheapest_partial_path || is_sorted) { /* Sort the cheapest partial path, if it isn't already */ if (!is_sorted) path = (Path *) create_sort_path(root, partially_grouped_rel, path, root->group_pathkeys, -1.0); if (parse->hasAggs) add_partial_path(partially_grouped_rel, (Path *) create_agg_path(root, partially_grouped_rel, path, partially_grouped_rel->reltarget, parse->groupClause ? AGG_SORTED : AGG_PLAIN, AGGSPLIT_INITIAL_SERIAL, parse->groupClause, NIL, agg_partial_costs, dNumPartialPartialGroups)); else add_partial_path(partially_grouped_rel, (Path *) create_group_path(root, partially_grouped_rel, path, parse->groupClause, NIL, dNumPartialPartialGroups)); } /* * Now we may consider incremental sort on this path, but only * when the path is not already sorted and when incremental sort * is enabled. */ if (is_sorted || !enable_incremental_sort) continue; /* Restore the input path (we might have added Sort on top). */ path = path_original; /* no shared prefix, not point in building incremental sort */ if (presorted_keys == 0) continue; /* * We should have already excluded pathkeys of length 1 because * then presorted_keys > 0 would imply is_sorted was true. */ Assert(list_length(root->group_pathkeys) != 1); path = (Path *) create_incremental_sort_path(root, partially_grouped_rel, path, root->group_pathkeys, presorted_keys, -1.0); if (parse->hasAggs) add_partial_path(partially_grouped_rel, (Path *) create_agg_path(root, partially_grouped_rel, path, partially_grouped_rel->reltarget, parse->groupClause ? AGG_SORTED : AGG_PLAIN, AGGSPLIT_INITIAL_SERIAL, parse->groupClause, NIL, agg_partial_costs, dNumPartialPartialGroups)); else add_partial_path(partially_grouped_rel, (Path *) create_group_path(root, partially_grouped_rel, path, parse->groupClause, NIL, dNumPartialPartialGroups)); } } /* * Add a partially-grouped HashAgg Path where possible */ if (can_hash && cheapest_total_path != NULL) { /* Checked above */ Assert(parse->hasAggs || parse->groupClause); add_path(partially_grouped_rel, (Path *) create_agg_path(root, partially_grouped_rel, cheapest_total_path, partially_grouped_rel->reltarget, AGG_HASHED, AGGSPLIT_INITIAL_SERIAL, parse->groupClause, NIL, agg_partial_costs, dNumPartialGroups)); } /* * Now add a partially-grouped HashAgg partial Path where possible */ if (can_hash && cheapest_partial_path != NULL) { add_partial_path(partially_grouped_rel, (Path *) create_agg_path(root, partially_grouped_rel, cheapest_partial_path, partially_grouped_rel->reltarget, AGG_HASHED, AGGSPLIT_INITIAL_SERIAL, parse->groupClause, NIL, agg_partial_costs, dNumPartialPartialGroups)); } /* * If there is an FDW that's responsible for all baserels of the query, * let it consider adding partially grouped ForeignPaths. */ if (partially_grouped_rel->fdwroutine && partially_grouped_rel->fdwroutine->GetForeignUpperPaths) { FdwRoutine *fdwroutine = partially_grouped_rel->fdwroutine; fdwroutine->GetForeignUpperPaths(root, UPPERREL_PARTIAL_GROUP_AGG, input_rel, partially_grouped_rel, extra); } return partially_grouped_rel; } /* * Generate Gather and Gather Merge paths for a grouping relation or partial * grouping relation. * * generate_useful_gather_paths does most of the work, but we also consider a * special case: we could try sorting the data by the group_pathkeys and then * applying Gather Merge. * * NB: This function shouldn't be used for anything other than a grouped or * partially grouped relation not only because of the fact that it explicitly * references group_pathkeys but we pass "true" as the third argument to * generate_useful_gather_paths(). */ static void gather_grouping_paths(PlannerInfo *root, RelOptInfo *rel) { ListCell *lc; Path *cheapest_partial_path; /* Try Gather for unordered paths and Gather Merge for ordered ones. */ generate_useful_gather_paths(root, rel, true); /* Try cheapest partial path + explicit Sort + Gather Merge. */ cheapest_partial_path = linitial(rel->partial_pathlist); if (!pathkeys_contained_in(root->group_pathkeys, cheapest_partial_path->pathkeys)) { Path *path; double total_groups; total_groups = cheapest_partial_path->rows * cheapest_partial_path->parallel_workers; path = (Path *) create_sort_path(root, rel, cheapest_partial_path, root->group_pathkeys, -1.0); path = (Path *) create_gather_merge_path(root, rel, path, rel->reltarget, root->group_pathkeys, NULL, &total_groups); add_path(rel, path); } /* * Consider incremental sort on all partial paths, if enabled. * * We can also skip the entire loop when we only have a single-item * group_pathkeys because then we can't possibly have a presorted prefix * of the list without having the list be fully sorted. */ if (!enable_incremental_sort || list_length(root->group_pathkeys) == 1) return; /* also consider incremental sort on partial paths, if enabled */ foreach(lc, rel->partial_pathlist) { Path *path = (Path *) lfirst(lc); bool is_sorted; int presorted_keys; double total_groups; is_sorted = pathkeys_count_contained_in(root->group_pathkeys, path->pathkeys, &presorted_keys); if (is_sorted) continue; if (presorted_keys == 0) continue; path = (Path *) create_incremental_sort_path(root, rel, path, root->group_pathkeys, presorted_keys, -1.0); path = (Path *) create_gather_merge_path(root, rel, path, rel->reltarget, root->group_pathkeys, NULL, &total_groups); add_path(rel, path); } } /* * can_partial_agg * * Determines whether or not partial grouping and/or aggregation is possible. * Returns true when possible, false otherwise. */ static bool can_partial_agg(PlannerInfo *root) { Query *parse = root->parse; if (!parse->hasAggs && parse->groupClause == NIL) { /* * We don't know how to do parallel aggregation unless we have either * some aggregates or a grouping clause. */ return false; } else if (parse->groupingSets) { /* We don't know how to do grouping sets in parallel. */ return false; } else if (root->hasNonPartialAggs || root->hasNonSerialAggs) { /* Insufficient support for partial mode. */ return false; } /* Everything looks good. */ return true; } /* * apply_scanjoin_target_to_paths * * Adjust the final scan/join relation, and recursively all of its children, * to generate the final scan/join target. It would be more correct to model * this as a separate planning step with a new RelOptInfo at the toplevel and * for each child relation, but doing it this way is noticeably cheaper. * Maybe that problem can be solved at some point, but for now we do this. * * If tlist_same_exprs is true, then the scan/join target to be applied has * the same expressions as the existing reltarget, so we need only insert the * appropriate sortgroupref information. By avoiding the creation of * projection paths we save effort both immediately and at plan creation time. */ static void apply_scanjoin_target_to_paths(PlannerInfo *root, RelOptInfo *rel, List *scanjoin_targets, List *scanjoin_targets_contain_srfs, bool scanjoin_target_parallel_safe, bool tlist_same_exprs) { bool rel_is_partitioned = IS_PARTITIONED_REL(rel); PathTarget *scanjoin_target; 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_useful_gather_paths to see the old partial paths in the next * stanza. Hence, zap the main pathlist here, then allow * generate_useful_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 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_useful_gather_paths(root, rel, false); /* Can't use parallel query above this level. */ rel->partial_pathlist = NIL; rel->consider_parallel = false; } /* Finish dropping old paths for a partitioned rel, per comment above */ if (rel_is_partitioned) rel->partial_pathlist = NIL; /* Extract SRF-free scan/join target. */ scanjoin_target = linitial_node(PathTarget, scanjoin_targets); /* * 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); /* Shouldn't have any parameterized paths anymore */ Assert(subpath->param_info == NULL); if (tlist_same_exprs) subpath->pathtarget->sortgrouprefs = scanjoin_target->sortgrouprefs; else { Path *newpath; newpath = (Path *) create_projection_path(root, rel, subpath, scanjoin_target); lfirst(lc) = newpath; } } /* Likewise adjust the targets for any partial paths. */ foreach(lc, rel->partial_pathlist) { Path *subpath = (Path *) lfirst(lc); /* Shouldn't have any parameterized paths anymore */ Assert(subpath->param_info == NULL); if (tlist_same_exprs) subpath->pathtarget->sortgrouprefs = scanjoin_target->sortgrouprefs; else { Path *newpath; newpath = (Path *) create_projection_path(root, rel, subpath, scanjoin_target); lfirst(lc) = newpath; } } /* * 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); /* * 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). * * Note that this is also necessary if GetForeignUpperPaths() gets called * on the final scan/join relation or on any of its children, since the * FDW might look at the rel's target to create ForeignPaths. */ 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) { 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]; AppendRelInfo **appinfos; int nappinfos; List *child_scanjoin_targets = NIL; ListCell *lc; /* Pruned or dummy children can be ignored. */ if (child_rel == NULL || IS_DUMMY_REL(child_rel)) continue; /* Translate scan/join targets for this child. */ appinfos = find_appinfos_by_relids(root, child_rel->relids, &nappinfos); foreach(lc, scanjoin_targets) { PathTarget *target = lfirst_node(PathTarget, lc); target = copy_pathtarget(target); target->exprs = (List *) adjust_appendrel_attrs(root, (Node *) target->exprs, nappinfos, appinfos); child_scanjoin_targets = lappend(child_scanjoin_targets, target); } pfree(appinfos); /* Recursion does the real work. */ apply_scanjoin_target_to_paths(root, child_rel, child_scanjoin_targets, scanjoin_targets_contain_srfs, scanjoin_target_parallel_safe, tlist_same_exprs); /* Save non-dummy children for Append paths. */ if (!IS_DUMMY_REL(child_rel)) live_children = lappend(live_children, child_rel); } /* Build new paths for this relation by appending child paths. */ add_paths_to_append_rel(root, rel, live_children); } /* * Consider generating Gather or Gather Merge paths. We must only do this * if the relation is parallel safe, and we don't do it for child rels to * avoid creating multiple Gather nodes within the same plan. We must do * this after all paths have been generated and before set_cheapest, since * one of the generated paths may turn out to be the cheapest one. */ if (rel->consider_parallel && !IS_OTHER_REL(rel)) generate_useful_gather_paths(root, rel, false); /* * Reassess which paths are the cheapest, now that we've potentially added * new Gather (or Gather Merge) and/or Append (or MergeAppend) paths to * this relation. */ set_cheapest(rel); } /* * create_partitionwise_grouping_paths * * If the partition keys of input relation are part of the GROUP BY clause, all * the rows belonging to a given group come from a single partition. This * allows aggregation/grouping over a partitioned relation to be broken down * into aggregation/grouping on each partition. This should be no worse, and * often better, than the normal approach. * * However, if the GROUP BY clause does not contain all the partition keys, * rows from a given group may be spread across multiple partitions. In that * case, we perform partial aggregation for each group, append the results, * and then finalize aggregation. This is less certain to win than the * previous case. It may win if the PartialAggregate stage greatly reduces * the number of groups, because fewer rows will pass through the Append node. * It may lose if we have lots of small groups. */ static void create_partitionwise_grouping_paths(PlannerInfo *root, RelOptInfo *input_rel, RelOptInfo *grouped_rel, RelOptInfo *partially_grouped_rel, const AggClauseCosts *agg_costs, grouping_sets_data *gd, PartitionwiseAggregateType patype, GroupPathExtraData *extra) { int nparts = input_rel->nparts; int cnt_parts; List *grouped_live_children = NIL; List *partially_grouped_live_children = NIL; PathTarget *target = grouped_rel->reltarget; bool partial_grouping_valid = true; Assert(patype != PARTITIONWISE_AGGREGATE_NONE); Assert(patype != PARTITIONWISE_AGGREGATE_PARTIAL || partially_grouped_rel != NULL); /* Add paths for partitionwise aggregation/grouping. */ for (cnt_parts = 0; cnt_parts < nparts; cnt_parts++) { RelOptInfo *child_input_rel = input_rel->part_rels[cnt_parts]; PathTarget *child_target = copy_pathtarget(target); AppendRelInfo **appinfos; int nappinfos; GroupPathExtraData child_extra; RelOptInfo *child_grouped_rel; RelOptInfo *child_partially_grouped_rel; /* Pruned or dummy children can be ignored. */ if (child_input_rel == NULL || IS_DUMMY_REL(child_input_rel)) continue; /* * Copy the given "extra" structure as is and then override the * members specific to this child. */ memcpy(&child_extra, extra, sizeof(child_extra)); appinfos = find_appinfos_by_relids(root, child_input_rel->relids, &nappinfos); child_target->exprs = (List *) adjust_appendrel_attrs(root, (Node *) target->exprs, nappinfos, appinfos); /* Translate havingQual and targetList. */ child_extra.havingQual = (Node *) adjust_appendrel_attrs(root, extra->havingQual, nappinfos, appinfos); child_extra.targetList = (List *) adjust_appendrel_attrs(root, (Node *) extra->targetList, nappinfos, appinfos); /* * extra->patype was the value computed for our parent rel; patype is * the value for this relation. For the child, our value is its * parent rel's value. */ child_extra.patype = patype; /* * Create grouping relation to hold fully aggregated grouping and/or * aggregation paths for the child. */ child_grouped_rel = make_grouping_rel(root, child_input_rel, child_target, extra->target_parallel_safe, child_extra.havingQual); /* Create grouping paths for this child relation. */ create_ordinary_grouping_paths(root, child_input_rel, child_grouped_rel, agg_costs, gd, &child_extra, &child_partially_grouped_rel); if (child_partially_grouped_rel) { partially_grouped_live_children = lappend(partially_grouped_live_children, child_partially_grouped_rel); } else partial_grouping_valid = false; if (patype == PARTITIONWISE_AGGREGATE_FULL) { set_cheapest(child_grouped_rel); grouped_live_children = lappend(grouped_live_children, child_grouped_rel); } pfree(appinfos); } /* * Try to create append paths for partially grouped children. For full * partitionwise aggregation, we might have paths in the partial_pathlist * if parallel aggregation is possible. For partial partitionwise * aggregation, we may have paths in both pathlist and partial_pathlist. * * NB: We must have a partially grouped path for every child in order to * generate a partially grouped path for this relation. */ if (partially_grouped_rel && partial_grouping_valid) { Assert(partially_grouped_live_children != NIL); add_paths_to_append_rel(root, partially_grouped_rel, partially_grouped_live_children); /* * We need call set_cheapest, since the finalization step will use the * cheapest path from the rel. */ if (partially_grouped_rel->pathlist) set_cheapest(partially_grouped_rel); } /* If possible, create append paths for fully grouped children. */ if (patype == PARTITIONWISE_AGGREGATE_FULL) { Assert(grouped_live_children != NIL); add_paths_to_append_rel(root, grouped_rel, grouped_live_children); } } /* * group_by_has_partkey * * Returns true, if all the partition keys of the given relation are part of * the GROUP BY clauses, false otherwise. */ static bool group_by_has_partkey(RelOptInfo *input_rel, List *targetList, List *groupClause) { List *groupexprs = get_sortgrouplist_exprs(groupClause, targetList); int cnt = 0; int partnatts; /* Input relation should be partitioned. */ Assert(input_rel->part_scheme); /* Rule out early, if there are no partition keys present. */ if (!input_rel->partexprs) return false; partnatts = input_rel->part_scheme->partnatts; for (cnt = 0; cnt < partnatts; cnt++) { List *partexprs = input_rel->partexprs[cnt]; ListCell *lc; bool found = false; foreach(lc, partexprs) { Expr *partexpr = lfirst(lc); if (list_member(groupexprs, partexpr)) { found = true; break; } } /* * If none of the partition key expressions match with any of the * GROUP BY expression, return false. */ if (!found) return false; } return true; }