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Diffstat (limited to 'src/backend/optimizer/plan/planner.c')
| -rw-r--r-- | src/backend/optimizer/plan/planner.c | 7492 |
1 files changed, 7492 insertions, 0 deletions
diff --git a/src/backend/optimizer/plan/planner.c b/src/backend/optimizer/plan/planner.c new file mode 100644 index 0000000..bd4e4ce --- /dev/null +++ b/src/backend/optimizer/plan/planner.c @@ -0,0 +1,7492 @@ +/*------------------------------------------------------------------------- + * + * planner.c + * The query optimizer external interface. + * + * Portions Copyright (c) 1996-2022, 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 <limits.h> +#include <math.h> + +#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 void create_partial_distinct_paths(PlannerInfo *root, + RelOptInfo *input_rel, + RelOptInfo *final_distinct_rel); +static RelOptInfo *create_final_distinct_paths(PlannerInfo *root, + RelOptInfo *input_rel, + RelOptInfo *distinct_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 this is safe only because + * the command is writing into a completely new table which workers won't + * be able to see. If the workers could see the table, the fact that + * group locking would cause them to ignore the leader's heavyweight + * GIN page locks would make this unsafe. We'll have to fix that somehow + * if we want to allow parallel inserts in general; updates and deletes + * have additional 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); + + /* + * Top plan must not have any initPlans, else it shouldn't have been + * marked parallel-safe. + */ + Assert(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 it's a MERGE command, transform the joinlist as appropriate. + */ + transform_MERGE_to_join(parse); + + /* + * 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); + wc->runCondition = (List *) preprocess_expression(root, + (Node *) wc->runCondition, + EXPRKIND_TARGET); + } + + 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 */ + } + + foreach(l, parse->mergeActionList) + { + MergeAction *action = (MergeAction *) lfirst(l); + + action->targetList = (List *) + preprocess_expression(root, + (Node *) action->targetList, + EXPRKIND_TARGET); + action->qual = + preprocess_expression(root, + (Node *) action->qual, + EXPRKIND_QUAL); + } + + 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_PARTIAL_DISTINCT] = sort_input_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/MERGE, add the ModifyTable node. + */ + if (parse->commandType != CMD_SELECT) + { + Index rootRelation; + List *resultRelations = NIL; + List *updateColnosLists = NIL; + List *withCheckOptionLists = NIL; + List *returningLists = NIL; + List *mergeActionLists = NIL; + List *rowMarks; + + if (bms_membership(root->all_result_relids) == BMS_MULTIPLE) + { + /* Inherited UPDATE/DELETE/MERGE */ + RelOptInfo *top_result_rel = find_base_rel(root, + parse->resultRelation); + int resultRelation = -1; + + /* Pass the root result rel forward to the executor. */ + rootRelation = parse->resultRelation; + + /* 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 (parse->mergeActionList) + { + ListCell *l; + List *mergeActionList = NIL; + + /* + * Copy MergeActions and translate stuff that + * references attribute numbers. + */ + foreach(l, parse->mergeActionList) + { + MergeAction *action = lfirst(l), + *leaf_action = copyObject(action); + + leaf_action->qual = + adjust_appendrel_attrs_multilevel(root, + (Node *) action->qual, + this_result_rel->relids, + top_result_rel->relids); + leaf_action->targetList = (List *) + adjust_appendrel_attrs_multilevel(root, + (Node *) action->targetList, + this_result_rel->relids, + top_result_rel->relids); + if (leaf_action->commandType == CMD_UPDATE) + leaf_action->updateColnos = + adjust_inherited_attnums_multilevel(root, + action->updateColnos, + this_result_rel->relid, + top_result_rel->relid); + mergeActionList = lappend(mergeActionList, + leaf_action); + } + + mergeActionLists = lappend(mergeActionLists, + mergeActionList); + } + } + + 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); + if (parse->mergeActionList) + mergeActionLists = list_make1(parse->mergeActionList); + } + } + else + { + /* Single-relation INSERT/UPDATE/DELETE/MERGE. */ + rootRelation = 0; /* there's no separate root rel */ + 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 (parse->mergeActionList) + mergeActionLists = list_make1(parse->mergeActionList); + } + + /* + * 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, + mergeActionLists, + 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, MERGE, or FOR [KEY] + * UPDATE/SHARE. + */ + if (parse->commandType != CMD_UPDATE && + parse->commandType != CMD_DELETE && + parse->commandType != CMD_MERGE) + 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; + List *topqual = NIL; + + /* + * 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; + bool topwindow; + + 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; + } + + /* mark the final item in the list as the top-level window */ + topwindow = foreach_current_index(l) == list_length(activeWindows) - 1; + + /* + * Accumulate all of the runConditions from each intermediate + * WindowClause. The top-level WindowAgg must pass these as a qual so + * that it filters out unwanted tuples correctly. + */ + if (!topwindow) + topqual = list_concat(topqual, wc->runCondition); + + path = (Path *) + create_windowagg_path(root, window_rel, path, window_target, + wflists->windowFuncs[wc->winref], + wc, topwindow ? topqual : NIL, topwindow); + } + + 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) +{ + RelOptInfo *distinct_rel; + + /* 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; + + /* build distinct paths based on input_rel's pathlist */ + create_final_distinct_paths(root, input_rel, distinct_rel); + + /* now build distinct paths based on input_rel's partial_pathlist */ + create_partial_distinct_paths(root, input_rel, distinct_rel); + + /* Give a helpful error if we failed to create any paths */ + 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_partial_distinct_paths + * + * Process 'input_rel' partial paths and add unique/aggregate paths to the + * UPPERREL_PARTIAL_DISTINCT rel. For paths created, add Gather/GatherMerge + * paths on top and add a final unique/aggregate path to remove any duplicate + * produced from combining rows from parallel workers. + */ +static void +create_partial_distinct_paths(PlannerInfo *root, RelOptInfo *input_rel, + RelOptInfo *final_distinct_rel) +{ + RelOptInfo *partial_distinct_rel; + Query *parse; + List *distinctExprs; + double numDistinctRows; + Path *cheapest_partial_path; + ListCell *lc; + + /* nothing to do when there are no partial paths in the input rel */ + if (!input_rel->consider_parallel || input_rel->partial_pathlist == NIL) + return; + + parse = root->parse; + + /* can't do parallel DISTINCT ON */ + if (parse->hasDistinctOn) + return; + + partial_distinct_rel = fetch_upper_rel(root, UPPERREL_PARTIAL_DISTINCT, + NULL); + partial_distinct_rel->reltarget = root->upper_targets[UPPERREL_PARTIAL_DISTINCT]; + partial_distinct_rel->consider_parallel = input_rel->consider_parallel; + + /* + * If input_rel belongs to a single FDW, so does the partial_distinct_rel. + */ + partial_distinct_rel->serverid = input_rel->serverid; + partial_distinct_rel->userid = input_rel->userid; + partial_distinct_rel->useridiscurrent = input_rel->useridiscurrent; + partial_distinct_rel->fdwroutine = input_rel->fdwroutine; + + cheapest_partial_path = linitial(input_rel->partial_pathlist); + + distinctExprs = get_sortgrouplist_exprs(parse->distinctClause, + parse->targetList); + + /* estimate how many distinct rows we'll get from each worker */ + numDistinctRows = estimate_num_groups(root, distinctExprs, + cheapest_partial_path->rows, + NULL, NULL); + + /* first try adding unique paths atop of sorted paths */ + if (grouping_is_sortable(parse->distinctClause)) + { + foreach(lc, input_rel->partial_pathlist) + { + Path *path = (Path *) lfirst(lc); + + if (pathkeys_contained_in(root->distinct_pathkeys, path->pathkeys)) + { + add_partial_path(partial_distinct_rel, (Path *) + create_upper_unique_path(root, + partial_distinct_rel, + path, + list_length(root->distinct_pathkeys), + numDistinctRows)); + } + } + } + + /* + * Now try hash aggregate paths, if enabled and hashing is possible. Since + * we're not on the hook to ensure we do our best to create at least one + * path here, we treat enable_hashagg as a hard off-switch rather than the + * slightly softer variant in create_final_distinct_paths. + */ + if (enable_hashagg && grouping_is_hashable(parse->distinctClause)) + { + add_partial_path(partial_distinct_rel, (Path *) + create_agg_path(root, + partial_distinct_rel, + cheapest_partial_path, + cheapest_partial_path->pathtarget, + AGG_HASHED, + AGGSPLIT_SIMPLE, + parse->distinctClause, + NIL, + NULL, + numDistinctRows)); + } + + /* + * If there is an FDW that's responsible for all baserels of the query, + * let it consider adding ForeignPaths. + */ + if (partial_distinct_rel->fdwroutine && + partial_distinct_rel->fdwroutine->GetForeignUpperPaths) + partial_distinct_rel->fdwroutine->GetForeignUpperPaths(root, + UPPERREL_PARTIAL_DISTINCT, + input_rel, + partial_distinct_rel, + NULL); + + /* Let extensions possibly add some more partial paths */ + if (create_upper_paths_hook) + (*create_upper_paths_hook) (root, UPPERREL_PARTIAL_DISTINCT, + input_rel, partial_distinct_rel, NULL); + + if (partial_distinct_rel->partial_pathlist != NIL) + { + generate_gather_paths(root, partial_distinct_rel, true); + set_cheapest(partial_distinct_rel); + + /* + * Finally, create paths to distinctify the final result. This step + * is needed to remove any duplicates due to combining rows from + * parallel workers. + */ + create_final_distinct_paths(root, partial_distinct_rel, + final_distinct_rel); + } +} + +/* + * create_final_distinct_paths + * Create distinct paths in 'distinct_rel' based on 'input_rel' pathlist + * + * input_rel: contains the source-data paths + * distinct_rel: destination relation for storing created paths + */ +static RelOptInfo * +create_final_distinct_paths(PlannerInfo *root, RelOptInfo *input_rel, + RelOptInfo *distinct_rel) +{ + Query *parse = root->parse; + Path *cheapest_input_path = input_rel->cheapest_total_path; + double numDistinctRows; + bool allow_hash; + Path *path; + ListCell *lc; + + /* 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)); + } + + 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 + * <window clause> 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 i; + + /* Adjust each partition. */ + i = -1; + while ((i = bms_next_member(rel->live_parts, i)) >= 0) + { + RelOptInfo *child_rel = rel->part_rels[i]; + AppendRelInfo **appinfos; + int nappinfos; + List *child_scanjoin_targets = NIL; + ListCell *lc; + + Assert(child_rel != NULL); + + /* Dummy children can be ignored. */ + if (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) +{ + List *grouped_live_children = NIL; + List *partially_grouped_live_children = NIL; + PathTarget *target = grouped_rel->reltarget; + bool partial_grouping_valid = true; + int i; + + Assert(patype != PARTITIONWISE_AGGREGATE_NONE); + Assert(patype != PARTITIONWISE_AGGREGATE_PARTIAL || + partially_grouped_rel != NULL); + + /* Add paths for partitionwise aggregation/grouping. */ + i = -1; + while ((i = bms_next_member(input_rel->live_parts, i)) >= 0) + { + RelOptInfo *child_input_rel = input_rel->part_rels[i]; + PathTarget *child_target; + AppendRelInfo **appinfos; + int nappinfos; + GroupPathExtraData child_extra; + RelOptInfo *child_grouped_rel; + RelOptInfo *child_partially_grouped_rel; + + Assert(child_input_rel != NULL); + + /* Dummy children can be ignored. */ + if (IS_DUMMY_REL(child_input_rel)) + continue; + + child_target = copy_pathtarget(target); + + /* + * 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; +} |