* planner.c
* The query optimizer external interface.
*
- * Portions Copyright (c) 1996-2006, PostgreSQL Global Development Group
+ * Portions Copyright (c) 1996-2009, PostgreSQL Global Development Group
* Portions Copyright (c) 1994, Regents of the University of California
*
*
* IDENTIFICATION
- * $PostgreSQL: pgsql/src/backend/optimizer/plan/planner.c,v 1.203 2006/07/14 14:52:20 momjian Exp $
+ * $PostgreSQL: pgsql/src/backend/optimizer/plan/planner.c,v 1.250 2009/01/01 17:23:44 momjian Exp $
*
*-------------------------------------------------------------------------
*/
#include "parser/parse_expr.h"
#include "parser/parse_oper.h"
#include "parser/parsetree.h"
+#include "utils/lsyscache.h"
#include "utils/syscache.h"
-ParamListInfo PlannerBoundParamList = NULL; /* current boundParams */
+/* GUC parameter */
+double cursor_tuple_fraction = DEFAULT_CURSOR_TUPLE_FRACTION;
+
+/* Hook for plugins to get control in planner() */
+planner_hook_type planner_hook = NULL;
/* Expression kind codes for preprocess_expression */
#define EXPRKIND_QUAL 0
#define EXPRKIND_TARGET 1
#define EXPRKIND_RTFUNC 2
-#define EXPRKIND_LIMIT 3
-#define EXPRKIND_ININFO 4
+#define EXPRKIND_VALUES 3
+#define EXPRKIND_LIMIT 4
#define EXPRKIND_APPINFO 5
static void preprocess_qual_conditions(PlannerInfo *root, Node *jtnode);
static Plan *inheritance_planner(PlannerInfo *root);
static Plan *grouping_planner(PlannerInfo *root, double tuple_fraction);
+static bool is_dummy_plan(Plan *plan);
static double preprocess_limit(PlannerInfo *root,
double tuple_fraction,
- int *offset_est, int *count_est);
-static bool choose_hashed_grouping(PlannerInfo *root, double tuple_fraction,
+ int64 *offset_est, int64 *count_est);
+static void preprocess_groupclause(PlannerInfo *root);
+static bool choose_hashed_grouping(PlannerInfo *root,
+ double tuple_fraction, double limit_tuples,
Path *cheapest_path, Path *sorted_path,
double dNumGroups, AggClauseCounts *agg_counts);
-static bool hash_safe_grouping(PlannerInfo *root);
+static bool choose_hashed_distinct(PlannerInfo *root,
+ Plan *input_plan, List *input_pathkeys,
+ double tuple_fraction, double limit_tuples,
+ double dNumDistinctRows);
static List *make_subplanTargetList(PlannerInfo *root, List *tlist,
AttrNumber **groupColIdx, bool *need_tlist_eval);
static void locate_grouping_columns(PlannerInfo *root,
List *sub_tlist,
AttrNumber *groupColIdx);
static List *postprocess_setop_tlist(List *new_tlist, List *orig_tlist);
+static List *select_active_windows(PlannerInfo *root, WindowFuncLists *wflists);
+static List *make_pathkeys_for_window(PlannerInfo *root, WindowClause *wc,
+ List *tlist, bool canonicalize);
+static void get_column_info_for_window(PlannerInfo *root, WindowClause *wc,
+ List *tlist,
+ int numSortCols, AttrNumber *sortColIdx,
+ int *partNumCols,
+ AttrNumber **partColIdx,
+ Oid **partOperators,
+ int *ordNumCols,
+ AttrNumber **ordColIdx,
+ Oid **ordOperators);
/*****************************************************************************
*
* 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.
+ *
*****************************************************************************/
-Plan *
-planner(Query *parse, bool isCursor, int cursorOptions,
- ParamListInfo boundParams)
+PlannedStmt *
+planner(Query *parse, int cursorOptions, ParamListInfo boundParams)
+{
+ PlannedStmt *result;
+
+ if (planner_hook)
+ result = (*planner_hook) (parse, cursorOptions, boundParams);
+ else
+ result = standard_planner(parse, cursorOptions, boundParams);
+ return result;
+}
+
+PlannedStmt *
+standard_planner(Query *parse, int cursorOptions, ParamListInfo boundParams)
{
+ PlannedStmt *result;
+ PlannerGlobal *glob;
double tuple_fraction;
- Plan *result_plan;
- Index save_PlannerQueryLevel;
- List *save_PlannerParamList;
- ParamListInfo save_PlannerBoundParamList;
+ PlannerInfo *root;
+ Plan *top_plan;
+ ListCell *lp,
+ *lr;
+
+ /* Cursor options may come from caller or from DECLARE CURSOR stmt */
+ if (parse->utilityStmt &&
+ IsA(parse->utilityStmt, DeclareCursorStmt))
+ cursorOptions |= ((DeclareCursorStmt *) parse->utilityStmt)->options;
/*
- * The planner can be called recursively (an example is when
- * eval_const_expressions tries to pre-evaluate an SQL function). So,
- * these global state variables must be saved and restored.
- *
- * Query level and the param list cannot be moved into the per-query
- * PlannerInfo structure since their whole purpose is communication across
- * multiple sub-queries. Also, boundParams is explicitly info from outside
- * the query, and so is likewise better handled as a global variable.
- *
- * Note we do NOT save and restore PlannerPlanId: it exists to assign
- * unique IDs to SubPlan nodes, and we want those IDs to be unique for the
- * life of a backend. Also, PlannerInitPlan is saved/restored in
- * subquery_planner, not here.
+ * 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.
*/
- save_PlannerQueryLevel = PlannerQueryLevel;
- save_PlannerParamList = PlannerParamList;
- save_PlannerBoundParamList = PlannerBoundParamList;
-
- /* Initialize state for handling outer-level references and params */
- PlannerQueryLevel = 0; /* will be 1 in top-level subquery_planner */
- PlannerParamList = NIL;
- PlannerBoundParamList = boundParams;
+ glob = makeNode(PlannerGlobal);
+
+ glob->boundParams = boundParams;
+ glob->paramlist = NIL;
+ glob->subplans = NIL;
+ glob->subrtables = NIL;
+ glob->rewindPlanIDs = NULL;
+ glob->finalrtable = NIL;
+ glob->relationOids = NIL;
+ glob->invalItems = NIL;
+ glob->lastPHId = 0;
+ glob->transientPlan = false;
/* Determine what fraction of the plan is likely to be scanned */
- if (isCursor)
+ if (cursorOptions & CURSOR_OPT_FAST_PLAN)
{
/*
* We have no real idea how many tuples the user will ultimately FETCH
- * from a cursor, but it seems a good bet that he doesn't want 'em
- * all. Optimize for 10% retrieval (you gotta better number? Should
- * this be a SETtable parameter?)
+ * 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.
*/
- tuple_fraction = 0.10;
+ if (tuple_fraction >= 1.0)
+ tuple_fraction = 0.0;
+ else if (tuple_fraction <= 0.0)
+ tuple_fraction = 1e-10;
}
else
{
}
/* primary planning entry point (may recurse for subqueries) */
- result_plan = subquery_planner(parse, tuple_fraction, NULL);
-
- /* check we popped out the right number of levels */
- Assert(PlannerQueryLevel == 0);
+ top_plan = subquery_planner(glob, parse, NULL,
+ false, tuple_fraction, &root);
/*
* 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 (isCursor && (cursorOptions & CURSOR_OPT_SCROLL))
+ if (cursorOptions & CURSOR_OPT_SCROLL)
{
- if (!ExecSupportsBackwardScan(result_plan))
- result_plan = materialize_finished_plan(result_plan);
+ if (!ExecSupportsBackwardScan(top_plan))
+ top_plan = materialize_finished_plan(top_plan);
}
/* final cleanup of the plan */
- result_plan = set_plan_references(result_plan, parse->rtable);
-
- /* executor wants to know total number of Params used overall */
- result_plan->nParamExec = list_length(PlannerParamList);
+ Assert(glob->finalrtable == NIL);
+ top_plan = set_plan_references(glob, top_plan, root->parse->rtable);
+ /* ... and the subplans (both regular subplans and initplans) */
+ Assert(list_length(glob->subplans) == list_length(glob->subrtables));
+ forboth(lp, glob->subplans, lr, glob->subrtables)
+ {
+ Plan *subplan = (Plan *) lfirst(lp);
+ List *subrtable = (List *) lfirst(lr);
- /* restore state for outer planner, if any */
- PlannerQueryLevel = save_PlannerQueryLevel;
- PlannerParamList = save_PlannerParamList;
- PlannerBoundParamList = save_PlannerBoundParamList;
+ lfirst(lp) = set_plan_references(glob, subplan, subrtable);
+ }
- return result_plan;
+ /* build the PlannedStmt result */
+ result = makeNode(PlannedStmt);
+
+ result->commandType = parse->commandType;
+ result->canSetTag = parse->canSetTag;
+ result->transientPlan = glob->transientPlan;
+ result->planTree = top_plan;
+ result->rtable = glob->finalrtable;
+ result->resultRelations = root->resultRelations;
+ result->utilityStmt = parse->utilityStmt;
+ result->intoClause = parse->intoClause;
+ result->subplans = glob->subplans;
+ result->rewindPlanIDs = glob->rewindPlanIDs;
+ result->returningLists = root->returningLists;
+ result->rowMarks = parse->rowMarks;
+ result->relationOids = glob->relationOids;
+ result->invalItems = glob->invalItems;
+ result->nParamExec = list_length(glob->paramlist);
+
+ return result;
}
* 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.
*
- * If subquery_pathkeys isn't NULL, it receives a list of pathkeys indicating
- * the output sort ordering of the completed plan.
+ * If subroot isn't NULL, we pass back the query's final PlannerInfo struct;
+ * among other things this tells the output sort ordering of the plan.
*
* Basically, this routine does the stuff that should only be done once
* per Query object. It then calls grouping_planner. At one time,
*--------------------
*/
Plan *
-subquery_planner(Query *parse, double tuple_fraction,
- List **subquery_pathkeys)
+subquery_planner(PlannerGlobal *glob, Query *parse,
+ PlannerInfo *parent_root,
+ bool hasRecursion, double tuple_fraction,
+ PlannerInfo **subroot)
{
- List *saved_initplan = PlannerInitPlan;
- int saved_planid = PlannerPlanId;
+ int num_old_subplans = list_length(glob->subplans);
PlannerInfo *root;
Plan *plan;
List *newHaving;
+ bool hasOuterJoins;
ListCell *l;
- /* Set up for a new level of subquery */
- PlannerQueryLevel++;
- PlannerInitPlan = NIL;
-
/* Create a PlannerInfo data structure for this subquery */
root = makeNode(PlannerInfo);
root->parse = parse;
- root->in_info_list = NIL;
+ root->glob = glob;
+ root->query_level = parent_root ? parent_root->query_level + 1 : 1;
+ root->parent_root = parent_root;
+ root->planner_cxt = CurrentMemoryContext;
+ root->init_plans = NIL;
+ root->cte_plan_ids = NIL;
+ root->eq_classes = NIL;
root->append_rel_list = NIL;
+ root->hasRecursion = hasRecursion;
+ if (hasRecursion)
+ root->wt_param_id = SS_assign_worktable_param(root);
+ else
+ root->wt_param_id = -1;
+ root->non_recursive_plan = NULL;
+
+ /*
+ * If there is a WITH list, process each WITH query and build an
+ * initplan SubPlan structure for it.
+ */
+ if (parse->cteList)
+ SS_process_ctes(root);
+
/*
- * Look for IN clauses at the top level of WHERE, and transform them into
- * joins. Note that this step only handles IN clauses originally at top
- * level of WHERE; if we pull up any subqueries in the next step, their
- * INs are processed just before pulling them up.
+ * 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)
- parse->jointree->quals = pull_up_IN_clauses(root,
- parse->jointree->quals);
+ pull_up_sublinks(root);
+
+ /*
+ * Scan the rangetable for set-returning functions, and inline them
+ * if possible (producing subqueries that might get pulled up next).
+ * Recursion issues here are handled in the same way as for SubLinks.
+ */
+ inline_set_returning_functions(root);
/*
* Check to see if any subqueries in the rangetable can be merged into
/*
* Detect whether any rangetable entries are RTE_JOIN kind; if not, we can
* avoid the expense of doing flatten_join_alias_vars(). Also check for
- * outer joins --- if none, we can skip reduce_outer_joins() and some
- * other processing. This must be done after we have done
- * pull_up_subqueries, of course.
- *
- * Note: if reduce_outer_joins manages to eliminate all outer joins,
- * root->hasOuterJoins is not reset currently. This is OK since its
- * purpose is merely to suppress unnecessary processing in simple cases.
+ * outer joins --- if none, we can skip reduce_outer_joins().
+ * This must be done after we have done pull_up_subqueries, of course.
*/
root->hasJoinRTEs = false;
- root->hasOuterJoins = false;
+ hasOuterJoins = false;
foreach(l, parse->rtable)
{
RangeTblEntry *rte = (RangeTblEntry *) lfirst(l);
root->hasJoinRTEs = true;
if (IS_OUTER_JOIN(rte->jointype))
{
- root->hasOuterJoins = true;
+ hasOuterJoins = true;
/* Can quit scanning once we find an outer join */
break;
}
preprocess_expression(root, (Node *) parse->targetList,
EXPRKIND_TARGET);
+ 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,
parse->limitCount = preprocess_expression(root, parse->limitCount,
EXPRKIND_LIMIT);
- root->in_info_list = (List *)
- preprocess_expression(root, (Node *) root->in_info_list,
- EXPRKIND_ININFO);
root->append_rel_list = (List *)
preprocess_expression(root, (Node *) root->append_rel_list,
EXPRKIND_APPINFO);
- /* Also need to preprocess expressions for function RTEs */
+ /* Also need to preprocess expressions for function and values RTEs */
foreach(l, parse->rtable)
{
RangeTblEntry *rte = (RangeTblEntry *) lfirst(l);
if (rte->rtekind == RTE_FUNCTION)
rte->funcexpr = preprocess_expression(root, rte->funcexpr,
EXPRKIND_RTFUNC);
+ else if (rte->rtekind == RTE_VALUES)
+ rte->values_lists = (List *)
+ preprocess_expression(root, (Node *) rte->values_lists,
+ EXPRKIND_VALUES);
}
/*
* This step is most easily done after we've done expression
* preprocessing.
*/
- if (root->hasOuterJoins)
+ if (hasOuterJoins)
reduce_outer_joins(root);
/*
* initPlan list and extParam/allParam sets for plan nodes, and attach the
* initPlans to the top plan node.
*/
- if (PlannerPlanId != saved_planid || PlannerQueryLevel > 1)
- SS_finalize_plan(plan, parse->rtable);
-
- /* Return sort ordering info if caller wants it */
- if (subquery_pathkeys)
- *subquery_pathkeys = root->query_pathkeys;
+ if (list_length(glob->subplans) != num_old_subplans ||
+ root->query_level > 1)
+ SS_finalize_plan(root, plan, true);
- /* Return to outer subquery context */
- PlannerQueryLevel--;
- PlannerInitPlan = saved_initplan;
- /* we do NOT restore PlannerPlanId; that's not an oversight! */
+ /* Return internal info if caller wants it */
+ if (subroot)
+ *subroot = root;
return plan;
}
/*
* If the query has any join RTEs, replace join alias variables with
* base-relation variables. We must do this before sublink processing,
- * else sublinks expanded out from join aliases wouldn't get processed.
+ * else sublinks expanded out from join aliases wouldn't get processed. We
+ * can skip it in VALUES lists, however, since they can't contain any Vars
+ * at all.
*/
- if (root->hasJoinRTEs)
+ if (root->hasJoinRTEs && kind != EXPRKIND_VALUES)
expr = flatten_join_alias_vars(root, expr);
/*
* Simplify constant expressions.
*
+ * Note: one essential effect here is to 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.
- *
- * Because this is a relatively expensive process, we skip it when the
- * query is trivial, such as "SELECT 2+2;" or "INSERT ... VALUES()". The
- * expression will only be evaluated once anyway, so no point in
- * pre-simplifying; we can't execute it any faster than the executor can,
- * and we will waste cycles copying the tree. Notice however that we
- * still must do it for quals (to get AND/OR flatness); and if we are in a
- * subquery we should not assume it will be done only once.
*/
- if (root->parse->jointree->fromlist != NIL ||
- kind == EXPRKIND_QUAL ||
- PlannerQueryLevel > 1)
- expr = eval_const_expressions(expr);
+ expr = eval_const_expressions(root, expr);
/*
* If it's a qual or havingQual, canonicalize it.
/* Expand SubLinks to SubPlans */
if (root->parse->hasSubLinks)
- expr = SS_process_sublinks(expr, (kind == EXPRKIND_QUAL));
+ 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 */
- if (PlannerQueryLevel > 1)
- expr = SS_replace_correlation_vars(expr);
+ /* 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
Query *parse = root->parse;
int parentRTindex = parse->resultRelation;
List *subplans = NIL;
+ List *resultRelations = NIL;
+ List *returningLists = NIL;
+ List *rtable = NIL;
List *tlist = NIL;
PlannerInfo subroot;
ListCell *l;
- subroot.parse = NULL; /* catch it if no matches in loop */
-
- parse->resultRelations = NIL;
-
foreach(l, root->append_rel_list)
{
AppendRelInfo *appinfo = (AppendRelInfo *) lfirst(l);
if (appinfo->parent_relid != parentRTindex)
continue;
- /* Build target-relations list for the executor */
- parse->resultRelations = lappend_int(parse->resultRelations,
- appinfo->child_relid);
-
/*
- * Generate modified query with this rel as target. We have to be
- * prepared to translate varnos in in_info_list as well as in the
- * Query proper.
+ * Generate modified query with this rel as target.
*/
memcpy(&subroot, root, sizeof(PlannerInfo));
subroot.parse = (Query *)
adjust_appendrel_attrs((Node *) parse,
appinfo);
- subroot.in_info_list = (List *)
- adjust_appendrel_attrs((Node *) root->in_info_list,
- appinfo);
+ subroot.returningLists = NIL;
+ subroot.init_plans = NIL;
+ /* We needn't modify the child's append_rel_list */
/* There shouldn't be any OJ info to translate, as yet */
- Assert(subroot.oj_info_list == NIL);
+ Assert(subroot.join_info_list == NIL);
+ /* and we haven't created PlaceHolderInfos, either */
+ Assert(subroot.placeholder_list == NIL);
/* Generate plan */
subplan = grouping_planner(&subroot, 0.0 /* retrieve all tuples */ );
- subplans = lappend(subplans, subplan);
+ /*
+ * If this child rel was excluded by constraint exclusion, exclude it
+ * from the plan.
+ */
+ if (is_dummy_plan(subplan))
+ continue;
- /* Save preprocessed tlist from first rel for use in Append */
- if (tlist == NIL)
+ /* Save rtable and tlist from first rel for use below */
+ if (subplans == NIL)
+ {
+ rtable = subroot.parse->rtable;
tlist = subplan->targetlist;
+ }
+
+ subplans = lappend(subplans, subplan);
+
+ /* Make sure any initplans from this rel get into the outer list */
+ root->init_plans = list_concat(root->init_plans, subroot.init_plans);
+
+ /* Build target-relations list for the executor */
+ resultRelations = lappend_int(resultRelations, appinfo->child_relid);
+
+ /* Build list of per-relation RETURNING targetlists */
+ if (parse->returningList)
+ {
+ Assert(list_length(subroot.returningLists) == 1);
+ returningLists = list_concat(returningLists,
+ subroot.returningLists);
+ }
+ }
+
+ root->resultRelations = resultRelations;
+ root->returningLists = returningLists;
+
+ /* Mark result as unordered (probably unnecessary) */
+ root->query_pathkeys = NIL;
+
+ /*
+ * If we managed to exclude every child rel, return a dummy plan
+ */
+ if (subplans == NIL)
+ {
+ root->resultRelations = list_make1_int(parentRTindex);
+ /* although dummy, it must have a valid tlist for executor */
+ tlist = preprocess_targetlist(root, parse->targetList);
+ return (Plan *) make_result(root,
+ tlist,
+ (Node *) list_make1(makeBoolConst(false,
+ false)),
+ NULL);
}
/*
*
* XXX should clean this up someday
*/
- parse->rtable = subroot.parse->rtable;
+ parse->rtable = rtable;
- /* Mark result as unordered (probably unnecessary) */
- root->query_pathkeys = NIL;
+ /* Suppress Append if there's only one surviving child rel */
+ if (list_length(subplans) == 1)
+ return (Plan *) linitial(subplans);
return (Plan *) make_append(subplans, true, tlist);
}
{
Query *parse = root->parse;
List *tlist = parse->targetList;
- int offset_est = 0;
- int count_est = 0;
+ int64 offset_est = 0;
+ int64 count_est = 0;
+ double limit_tuples = -1.0;
Plan *result_plan;
List *current_pathkeys;
- List *sort_pathkeys;
double dNumGroups = 0;
/* 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;
+ }
+
if (parse->setOperations)
{
List *set_sortclauses;
/*
* If there's a top-level ORDER BY, assume we have to fetch all the
- * tuples. This might seem too simplistic given all the hackery below
- * to possibly avoid the sort ... but a nonzero tuple_fraction is only
- * of use to plan_set_operations() when the setop is UNION ALL, and
- * the result of UNION ALL is always unsorted.
+ * 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.
*/
if (parse->sortClause)
tuple_fraction = 0.0;
/*
* Construct the plan for set operations. The result will not need
- * any work except perhaps a top-level sort and/or LIMIT.
+ * 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.
*/
result_plan = plan_set_operations(root, tuple_fraction,
&set_sortclauses);
* operation's result. We have to do this before overwriting the sort
* key information...
*/
- current_pathkeys = make_pathkeys_for_sortclauses(set_sortclauses,
- result_plan->targetlist);
- current_pathkeys = canonicalize_pathkeys(root, current_pathkeys);
+ current_pathkeys = make_pathkeys_for_sortclauses(root,
+ set_sortclauses,
+ result_plan->targetlist,
+ true);
/*
* We should not need to call preprocess_targetlist, since we must be
*/
Assert(parse->commandType == CMD_SELECT);
- tlist = postprocess_setop_tlist(result_plan->targetlist, tlist);
+ tlist = postprocess_setop_tlist(copyObject(result_plan->targetlist),
+ tlist);
/*
* Can't handle FOR UPDATE/SHARE here (parser should have checked
/*
* Calculate pathkeys that represent result ordering requirements
*/
- sort_pathkeys = make_pathkeys_for_sortclauses(parse->sortClause,
- tlist);
- sort_pathkeys = canonicalize_pathkeys(root, sort_pathkeys);
+ Assert(parse->distinctClause == NIL);
+ root->sort_pathkeys = make_pathkeys_for_sortclauses(root,
+ parse->sortClause,
+ tlist,
+ true);
}
else
{
/* No set operations, do regular planning */
List *sub_tlist;
- List *group_pathkeys;
AttrNumber *groupColIdx = NULL;
bool need_tlist_eval = true;
QualCost tlist_cost;
Path *best_path;
long numGroups = 0;
AggClauseCounts agg_counts;
- int numGroupCols = list_length(parse->groupClause);
+ int numGroupCols;
bool use_hashed_grouping = false;
+ WindowFuncLists *wflists = NULL;
+ List *activeWindows = NIL;
MemSet(&agg_counts, 0, sizeof(AggClauseCounts));
+ /* A recursive query should always have setOperations */
+ Assert(!root->hasRecursion);
+
+ /* Preprocess GROUP BY clause, if any */
+ if (parse->groupClause)
+ preprocess_groupclause(root);
+ numGroupCols = list_length(parse->groupClause);
+
/* Preprocess targetlist */
tlist = preprocess_targetlist(root, tlist);
+ /*
+ * 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 *) tlist,
+ list_length(parse->windowClause));
+ if (wflists->numWindowFuncs > 0)
+ activeWindows = select_active_windows(root, wflists);
+ else
+ parse->hasWindowFuncs = false;
+ }
+
/*
* Generate appropriate target list for subplan; may be different from
* tlist if grouping or aggregation is needed.
/*
* Calculate pathkeys that represent grouping/ordering requirements.
* Stash them in PlannerInfo so that query_planner can canonicalize
- * them.
+ * them after EquivalenceClasses have been formed. The sortClause
+ * is certainly sort-able, but GROUP BY and DISTINCT might not be,
+ * in which case we just leave their pathkeys empty.
*/
- root->group_pathkeys =
- make_pathkeys_for_sortclauses(parse->groupClause, tlist);
+ if (parse->groupClause &&
+ grouping_is_sortable(parse->groupClause))
+ root->group_pathkeys =
+ make_pathkeys_for_sortclauses(root,
+ parse->groupClause,
+ tlist,
+ false);
+ else
+ root->group_pathkeys = NIL;
+
+ /* We consider only the first (bottom) window in pathkeys logic */
+ if (activeWindows != NIL)
+ {
+ WindowClause *wc = (WindowClause *) linitial(activeWindows);
+
+ root->window_pathkeys = make_pathkeys_for_window(root,
+ wc,
+ tlist,
+ false);
+ }
+ else
+ root->window_pathkeys = NIL;
+
+ if (parse->distinctClause &&
+ grouping_is_sortable(parse->distinctClause))
+ root->distinct_pathkeys =
+ make_pathkeys_for_sortclauses(root,
+ parse->distinctClause,
+ tlist,
+ false);
+ else
+ root->distinct_pathkeys = NIL;
+
root->sort_pathkeys =
- make_pathkeys_for_sortclauses(parse->sortClause, tlist);
+ make_pathkeys_for_sortclauses(root,
+ parse->sortClause,
+ tlist,
+ false);
/*
* Will need actual number of aggregates for estimating costs.
}
/*
- * Figure out whether we need a sorted result from query_planner.
+ * Figure out whether we want a sorted result from query_planner.
*
- * If we have a GROUP BY clause, then we want a result sorted properly
- * for grouping. Otherwise, if there is an ORDER BY clause, we want
- * to sort by the ORDER BY clause. (Note: if we have both, 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...)
+ * 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 (parse->groupClause)
+ if (root->group_pathkeys)
root->query_pathkeys = root->group_pathkeys;
- else if (parse->sortClause)
+ 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 the number of groups in the query, and canonicalize all
* the pathkeys.
*/
- query_planner(root, sub_tlist, tuple_fraction,
+ query_planner(root, sub_tlist, tuple_fraction, limit_tuples,
&cheapest_path, &sorted_path, &dNumGroups);
- group_pathkeys = root->group_pathkeys;
- sort_pathkeys = root->sort_pathkeys;
-
/*
- * If grouping, decide whether we want to use hashed grouping.
+ * If grouping, decide whether to use sorted or hashed grouping.
*/
if (parse->groupClause)
{
- use_hashed_grouping =
- choose_hashed_grouping(root, tuple_fraction,
- cheapest_path, sorted_path,
- dNumGroups, &agg_counts);
+ bool can_hash;
+ bool can_sort;
+
+ /*
+ * Executor doesn't support hashed aggregation with DISTINCT
+ * aggregates. (Doing so would imply storing *all* the input
+ * values in the hash table, which seems like a certain loser.)
+ */
+ can_hash = (agg_counts.numDistinctAggs == 0 &&
+ grouping_is_hashable(parse->groupClause));
+ can_sort = grouping_is_sortable(parse->groupClause);
+ if (can_hash && can_sort)
+ {
+ /* we have a meaningful choice to make ... */
+ use_hashed_grouping =
+ choose_hashed_grouping(root,
+ tuple_fraction, limit_tuples,
+ cheapest_path, sorted_path,
+ dNumGroups, &agg_counts);
+ }
+ else if (can_hash)
+ use_hashed_grouping = true;
+ else if (can_sort)
+ use_hashed_grouping = false;
+ else
+ 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.")));
/* Also convert # groups to long int --- but 'ware overflow! */
numGroups = (long) Min(dNumGroups, (double) LONG_MAX);
* Normal case --- create a plan according to query_planner's
* results.
*/
+ bool need_sort_for_grouping = false;
+
result_plan = create_plan(root, best_path);
current_pathkeys = best_path->pathkeys;
+ /* Detect if we'll need an explicit sort for grouping */
+ if (parse->groupClause && !use_hashed_grouping &&
+ !pathkeys_contained_in(root->group_pathkeys, current_pathkeys))
+ {
+ need_sort_for_grouping = true;
+ /*
+ * Always override query_planner's tlist, so that we don't
+ * sort useless data from a "physical" tlist.
+ */
+ need_tlist_eval = true;
+ }
+
/*
* create_plan() returns a plan with just a "flat" tlist of
* required Vars. Usually we need to insert the sub_tlist as the
*/
if (!is_projection_capable_plan(result_plan))
{
- result_plan = (Plan *) make_result(sub_tlist, NULL,
+ result_plan = (Plan *) make_result(root,
+ sub_tlist,
+ NULL,
result_plan);
}
else
*
* Below this point, any tlist eval cost for added-on nodes
* should be accounted for as we create those nodes.
- * Presently, of the node types we can add on, only Agg and
- * Group project new tlists (the rest just copy their input
- * tuples) --- so make_agg() and make_group() are responsible
- * for computing the added cost.
+ * Presently, of the node types we can add on, only Agg,
+ * WindowAgg, and Group project new tlists (the rest just copy
+ * their input tuples) --- so make_agg(), make_windowagg() and
+ * make_group() are responsible for computing the added cost.
*/
- cost_qual_eval(&tlist_cost, sub_tlist);
+ cost_qual_eval(&tlist_cost, sub_tlist, root);
result_plan->startup_cost += tlist_cost.startup;
result_plan->total_cost += tlist_cost.startup +
tlist_cost.per_tuple * result_plan->plan_rows;
AGG_HASHED,
numGroupCols,
groupColIdx,
+ extract_grouping_ops(parse->groupClause),
numGroups,
agg_counts.numAggs,
result_plan);
if (parse->groupClause)
{
- if (!pathkeys_contained_in(group_pathkeys,
- current_pathkeys))
+ if (need_sort_for_grouping)
{
result_plan = (Plan *)
make_sort_from_groupcols(root,
parse->groupClause,
groupColIdx,
result_plan);
- current_pathkeys = group_pathkeys;
+ current_pathkeys = root->group_pathkeys;
}
aggstrategy = AGG_SORTED;
aggstrategy,
numGroupCols,
groupColIdx,
+ extract_grouping_ops(parse->groupClause),
numGroups,
agg_counts.numAggs,
result_plan);
* Add an explicit sort if we couldn't make the path come out
* the way the GROUP node needs it.
*/
- if (!pathkeys_contained_in(group_pathkeys, current_pathkeys))
+ if (need_sort_for_grouping)
{
result_plan = (Plan *)
make_sort_from_groupcols(root,
parse->groupClause,
groupColIdx,
result_plan);
- current_pathkeys = group_pathkeys;
+ current_pathkeys = root->group_pathkeys;
}
result_plan = (Plan *) make_group(root,
(List *) parse->havingQual,
numGroupCols,
groupColIdx,
+ extract_grouping_ops(parse->groupClause),
dNumGroups,
result_plan);
/* The Group node won't change sort ordering */
* this routine to avoid having to generate the plan in the
* first place.
*/
- result_plan = (Plan *) make_result(tlist,
+ result_plan = (Plan *) make_result(root,
+ tlist,
parse->havingQual,
NULL);
}
} /* end of non-minmax-aggregate case */
+
+ /*
+ * Since each window function could require a different sort order,
+ * we stack up a WindowAgg node for each window, with sort steps
+ * between them as needed.
+ */
+ if (activeWindows)
+ {
+ List *window_tlist;
+ ListCell *l;
+
+ /*
+ * If the top-level plan node is one that cannot do expression
+ * evaluation, we must insert a Result node to project the
+ * desired tlist. (In some cases this might not really be
+ * required, but it's not worth trying to avoid it.) Note that
+ * on second and subsequent passes through the following loop,
+ * the top-level node will be a WindowAgg which we know can
+ * project; so we only need to check once.
+ */
+ if (!is_projection_capable_plan(result_plan))
+ {
+ result_plan = (Plan *) make_result(root,
+ NIL,
+ NULL,
+ result_plan);
+ }
+
+ /*
+ * The "base" targetlist for all steps of the windowing process
+ * is a flat tlist of all Vars and Aggs needed in 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.) As we climb up the stack, we add
+ * outputs for the WindowFuncs computed at each level. Also,
+ * each input tlist has to present all the columns needed to
+ * sort the data for the next WindowAgg step. That's handled
+ * internally by make_sort_from_pathkeys, but we need the
+ * copyObject steps here to ensure that each plan node has
+ * a separately modifiable tlist.
+ */
+ window_tlist = flatten_tlist(tlist);
+ if (parse->hasAggs)
+ window_tlist = add_to_flat_tlist(window_tlist,
+ pull_agg_clause((Node *) tlist));
+ result_plan->targetlist = (List *) copyObject(window_tlist);
+
+ foreach(l, activeWindows)
+ {
+ WindowClause *wc = (WindowClause *) lfirst(l);
+ List *window_pathkeys;
+ int partNumCols;
+ AttrNumber *partColIdx;
+ Oid *partOperators;
+ int ordNumCols;
+ AttrNumber *ordColIdx;
+ Oid *ordOperators;
+
+ window_pathkeys = make_pathkeys_for_window(root,
+ wc,
+ tlist,
+ true);
+
+ /*
+ * This is a bit tricky: we build a sort node even if we don't
+ * really have to sort. Even when no explicit sort is needed,
+ * we need to have suitable resjunk items added to the input
+ * plan's tlist for any partitioning or ordering columns that
+ * aren't plain Vars. Furthermore, this way we can use
+ * existing infrastructure to identify which input columns are
+ * the interesting ones.
+ */
+ if (window_pathkeys)
+ {
+ Sort *sort_plan;
+
+ sort_plan = make_sort_from_pathkeys(root,
+ result_plan,
+ window_pathkeys,
+ -1.0);
+ if (!pathkeys_contained_in(window_pathkeys,
+ current_pathkeys))
+ {
+ /* we do indeed need to sort */
+ result_plan = (Plan *) sort_plan;
+ current_pathkeys = window_pathkeys;
+ }
+ /* In either case, extract the per-column information */
+ get_column_info_for_window(root, wc, tlist,
+ sort_plan->numCols,
+ sort_plan->sortColIdx,
+ &partNumCols,
+ &partColIdx,
+ &partOperators,
+ &ordNumCols,
+ &ordColIdx,
+ &ordOperators);
+ }
+ else
+ {
+ /* empty window specification, nothing to sort */
+ partNumCols = 0;
+ partColIdx = NULL;
+ partOperators = NULL;
+ ordNumCols = 0;
+ ordColIdx = NULL;
+ ordOperators = NULL;
+ }
+
+ if (lnext(l))
+ {
+ /* Add the current WindowFuncs to the running tlist */
+ window_tlist = add_to_flat_tlist(window_tlist,
+ wflists->windowFuncs[wc->winref]);
+ }
+ else
+ {
+ /* Install the original tlist in the topmost WindowAgg */
+ window_tlist = tlist;
+ }
+
+ /* ... and make the WindowAgg plan node */
+ result_plan = (Plan *)
+ make_windowagg(root,
+ (List *) copyObject(window_tlist),
+ list_length(wflists->windowFuncs[wc->winref]),
+ wc->winref,
+ partNumCols,
+ partColIdx,
+ partOperators,
+ ordNumCols,
+ ordColIdx,
+ ordOperators,
+ wc->frameOptions,
+ result_plan);
+ }
+ }
} /* end of if (setOperations) */
/*
- * If we were not able to make the plan come out in the right order, add
- * an explicit sort step.
+ * If there is a DISTINCT clause, add the necessary node(s).
*/
- if (parse->sortClause)
+ if (parse->distinctClause)
{
- if (!pathkeys_contained_in(sort_pathkeys, current_pathkeys))
+ double dNumDistinctRows;
+ long numDistinctRows;
+ bool use_hashed_distinct;
+ bool can_sort;
+ bool can_hash;
+
+ /*
+ * If there was grouping or aggregation, use the current number of
+ * rows as the estimated number of DISTINCT rows (ie, assume the
+ * result was already mostly unique). If not, use the number of
+ * distinct-groups calculated by query_planner.
+ */
+ if (parse->groupClause || root->hasHavingQual || parse->hasAggs)
+ dNumDistinctRows = result_plan->plan_rows;
+ else
+ dNumDistinctRows = dNumGroups;
+
+ /* Also convert to long int --- but 'ware overflow! */
+ numDistinctRows = (long) Min(dNumDistinctRows, (double) LONG_MAX);
+
+ /*
+ * If we have a sortable DISTINCT ON clause, we always use sorting.
+ * This enforces the expected behavior of DISTINCT ON.
+ */
+ can_sort = grouping_is_sortable(parse->distinctClause);
+ if (can_sort && parse->hasDistinctOn)
+ use_hashed_distinct = false;
+ else
+ {
+ can_hash = grouping_is_hashable(parse->distinctClause);
+ if (can_hash && can_sort)
+ {
+ /* we have a meaningful choice to make ... */
+ use_hashed_distinct =
+ choose_hashed_distinct(root,
+ result_plan, current_pathkeys,
+ tuple_fraction, limit_tuples,
+ dNumDistinctRows);
+ }
+ else if (can_hash)
+ use_hashed_distinct = true;
+ else if (can_sort)
+ use_hashed_distinct = false;
+ else
+ {
+ 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.")));
+ use_hashed_distinct = false; /* keep compiler quiet */
+ }
+ }
+
+ if (use_hashed_distinct)
{
- result_plan = (Plan *)
- make_sort_from_sortclauses(root,
- parse->sortClause,
- result_plan);
- current_pathkeys = sort_pathkeys;
+ /* Hashed aggregate plan --- no sort needed */
+ result_plan = (Plan *) make_agg(root,
+ result_plan->targetlist,
+ NIL,
+ AGG_HASHED,
+ list_length(parse->distinctClause),
+ extract_grouping_cols(parse->distinctClause,
+ result_plan->targetlist),
+ extract_grouping_ops(parse->distinctClause),
+ numDistinctRows,
+ 0,
+ result_plan);
+ /* Hashed aggregation produces randomly-ordered results */
+ current_pathkeys = NIL;
+ }
+ else
+ {
+ /*
+ * Use a Unique node to implement DISTINCT. Add an explicit sort
+ * if we couldn't make the path come out the way the Unique node
+ * needs it. If we do have to sort, always sort by the more
+ * rigorous of DISTINCT and ORDER BY, to avoid a second sort
+ * below. However, for regular DISTINCT, don't sort now if we
+ * don't have to --- sorting afterwards will likely be cheaper,
+ * and also has the possibility of optimizing via LIMIT. But
+ * for DISTINCT ON, we *must* force the final sort now, else
+ * it won't have the desired behavior.
+ */
+ 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;
+
+ if (!pathkeys_contained_in(needed_pathkeys, current_pathkeys))
+ {
+ if (list_length(root->distinct_pathkeys) >=
+ list_length(root->sort_pathkeys))
+ current_pathkeys = root->distinct_pathkeys;
+ else
+ {
+ current_pathkeys = root->sort_pathkeys;
+ /* Assert checks that parser didn't mess up... */
+ Assert(pathkeys_contained_in(root->distinct_pathkeys,
+ current_pathkeys));
+ }
+
+ result_plan = (Plan *) make_sort_from_pathkeys(root,
+ result_plan,
+ current_pathkeys,
+ -1.0);
+ }
+
+ result_plan = (Plan *) make_unique(result_plan,
+ parse->distinctClause);
+ result_plan->plan_rows = dNumDistinctRows;
+ /* The Unique node won't change sort ordering */
}
}
/*
- * If there is a DISTINCT clause, add the UNIQUE node.
+ * If ORDER BY was given and we were not able to make the plan come out in
+ * the right order, add an explicit sort step.
*/
- if (parse->distinctClause)
+ if (parse->sortClause)
{
- result_plan = (Plan *) make_unique(result_plan, parse->distinctClause);
-
- /*
- * If there was grouping or aggregation, leave plan_rows as-is (ie,
- * assume the result was already mostly unique). If not, use the
- * number of distinct-groups calculated by query_planner.
- */
- if (!parse->groupClause && !root->hasHavingQual && !parse->hasAggs)
- result_plan->plan_rows = dNumGroups;
+ if (!pathkeys_contained_in(root->sort_pathkeys, current_pathkeys))
+ {
+ result_plan = (Plan *) make_sort_from_pathkeys(root,
+ result_plan,
+ root->sort_pathkeys,
+ limit_tuples);
+ current_pathkeys = root->sort_pathkeys;
+ }
}
/*
count_est);
}
+ /*
+ * Deal with the RETURNING clause if any. It's convenient to pass the
+ * returningList through setrefs.c now rather than at top level (if we
+ * waited, handling inherited UPDATE/DELETE would be much harder).
+ */
+ if (parse->returningList)
+ {
+ List *rlist;
+
+ Assert(parse->resultRelation);
+ rlist = set_returning_clause_references(root->glob,
+ parse->returningList,
+ result_plan,
+ parse->resultRelation);
+ root->returningLists = list_make1(rlist);
+ }
+ else
+ root->returningLists = NIL;
+
+ /* Compute result-relations list if needed */
+ if (parse->resultRelation)
+ root->resultRelations = list_make1_int(parse->resultRelation);
+ else
+ root->resultRelations = NIL;
+
/*
* Return the actual output ordering in query_pathkeys for possible use by
* an outer query level.
return result_plan;
}
+/*
+ * Detect whether a plan node is a "dummy" plan created when a relation
+ * is deemed not to need scanning due to constraint exclusion.
+ *
+ * Currently, such dummy plans are Result nodes with constant FALSE
+ * filter quals.
+ */
+static bool
+is_dummy_plan(Plan *plan)
+{
+ if (IsA(plan, Result))
+ {
+ List *rcqual = (List *) ((Result *) plan)->resconstantqual;
+
+ if (list_length(rcqual) == 1)
+ {
+ Const *constqual = (Const *) linitial(rcqual);
+
+ if (constqual && IsA(constqual, Const))
+ {
+ if (!constqual->constisnull &&
+ !DatumGetBool(constqual->constvalue))
+ return true;
+ }
+ }
+ }
+ return false;
+}
+
/*
* preprocess_limit - do pre-estimation for LIMIT and/or OFFSET clauses
*
*/
static double
preprocess_limit(PlannerInfo *root, double tuple_fraction,
- int *offset_est, int *count_est)
+ int64 *offset_est, int64 *count_est)
{
Query *parse = root->parse;
Node *est;
*/
if (parse->limitCount)
{
- est = estimate_expression_value(parse->limitCount);
+ est = estimate_expression_value(root, parse->limitCount);
if (est && IsA(est, Const))
{
if (((Const *) est)->constisnull)
}
else
{
- *count_est = DatumGetInt32(((Const *) est)->constvalue);
+ *count_est = DatumGetInt64(((Const *) est)->constvalue);
if (*count_est <= 0)
*count_est = 1; /* force to at least 1 */
}
if (parse->limitOffset)
{
- est = estimate_expression_value(parse->limitOffset);
+ est = estimate_expression_value(root, parse->limitOffset);
if (est && IsA(est, Const))
{
if (((Const *) est)->constisnull)
}
else
{
- *offset_est = DatumGetInt32(((Const *) est)->constvalue);
+ *offset_est = DatumGetInt64(((Const *) est)->constvalue);
if (*offset_est < 0)
*offset_est = 0; /* less than 0 is same as 0 */
}
return tuple_fraction;
}
+
+/*
+ * 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.
+ */
+static void
+preprocess_groupclause(PlannerInfo *root)
+{
+ Query *parse = root->parse;
+ List *new_groupclause;
+ bool partial_match;
+ ListCell *sl;
+ ListCell *gl;
+
+ /* If no ORDER BY, nothing useful to do here */
+ if (parse->sortClause == NIL)
+ return;
+
+ /*
+ * 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.
+ */
+ new_groupclause = NIL;
+ foreach(sl, parse->sortClause)
+ {
+ SortGroupClause *sc = (SortGroupClause *) lfirst(sl);
+
+ foreach(gl, parse->groupClause)
+ {
+ SortGroupClause *gc = (SortGroupClause *) lfirst(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;
+
+ /*
+ * 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 = (SortGroupClause *) lfirst(gl);
+
+ if (list_member_ptr(new_groupclause, gc))
+ continue; /* it matched an ORDER BY item */
+ if (partial_match)
+ return; /* give up, no common sort possible */
+ if (!OidIsValid(gc->sortop))
+ return; /* 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));
+ parse->groupClause = new_groupclause;
+}
+
/*
* choose_hashed_grouping - should we use hashed grouping?
+ *
+ * Note: this is only applied when both alternatives are actually feasible.
*/
static bool
-choose_hashed_grouping(PlannerInfo *root, double tuple_fraction,
+choose_hashed_grouping(PlannerInfo *root,
+ double tuple_fraction, double limit_tuples,
Path *cheapest_path, Path *sorted_path,
double dNumGroups, AggClauseCounts *agg_counts)
{
double cheapest_path_rows;
int cheapest_path_width;
Size hashentrysize;
+ List *target_pathkeys;
List *current_pathkeys;
Path hashed_p;
Path sorted_p;
- /*
- * Check can't-do-it conditions, including whether the grouping operators
- * are hashjoinable.
- *
- * Executor doesn't support hashed aggregation with DISTINCT aggregates.
- * (Doing so would imply storing *all* the input values in the hash table,
- * which seems like a certain loser.)
- */
+ /* Prefer sorting when enable_hashagg is off */
if (!enable_hashagg)
return false;
- if (agg_counts->numDistinctAggs != 0)
- return false;
- if (!hash_safe_grouping(root))
- return false;
/*
* Don't do it if it doesn't look like the hashtable will fit into
if (hashentrysize * dNumGroups > work_mem * 1024L)
return false;
+ /*
+ * When we have both GROUP BY and DISTINCT, use the more-rigorous of
+ * DISTINCT and ORDER BY as the assumed required output sort order.
+ * This is an oversimplification because the DISTINCT might get
+ * implemented via hashing, but it's not clear that the case is common
+ * enough (or that our estimates are good enough) to justify trying to
+ * solve it exactly.
+ */
+ if (list_length(root->distinct_pathkeys) >
+ list_length(root->sort_pathkeys))
+ target_pathkeys = root->distinct_pathkeys;
+ else
+ target_pathkeys = root->sort_pathkeys;
+
/*
* See if the estimated cost is no more than doing it the other way. While
* avoiding the need for sorted input is usually a win, the fact that the
cheapest_path->startup_cost, cheapest_path->total_cost,
cheapest_path_rows);
/* Result of hashed agg is always unsorted */
- if (root->sort_pathkeys)
- cost_sort(&hashed_p, root, root->sort_pathkeys, hashed_p.total_cost,
- dNumGroups, cheapest_path_width);
+ if (target_pathkeys)
+ cost_sort(&hashed_p, root, target_pathkeys, hashed_p.total_cost,
+ dNumGroups, cheapest_path_width, limit_tuples);
if (sorted_path)
{
if (!pathkeys_contained_in(root->group_pathkeys, current_pathkeys))
{
cost_sort(&sorted_p, root, root->group_pathkeys, sorted_p.total_cost,
- cheapest_path_rows, cheapest_path_width);
+ cheapest_path_rows, cheapest_path_width, -1.0);
current_pathkeys = root->group_pathkeys;
}
sorted_p.startup_cost, sorted_p.total_cost,
cheapest_path_rows);
/* The Agg or Group node will preserve ordering */
- if (root->sort_pathkeys &&
- !pathkeys_contained_in(root->sort_pathkeys, current_pathkeys))
- cost_sort(&sorted_p, root, root->sort_pathkeys, sorted_p.total_cost,
- dNumGroups, cheapest_path_width);
+ if (target_pathkeys &&
+ !pathkeys_contained_in(target_pathkeys, current_pathkeys))
+ cost_sort(&sorted_p, root, target_pathkeys, sorted_p.total_cost,
+ dNumGroups, cheapest_path_width, limit_tuples);
/*
* Now make the decision using the top-level tuple fraction. First we
}
/*
- * hash_safe_grouping - are grouping operators hashable?
+ * choose_hashed_distinct - should we use hashing for DISTINCT?
*
- * We assume hashed aggregation will work if the datatype's equality operator
- * is marked hashjoinable.
+ * This is fairly similar to choose_hashed_grouping, but there are enough
+ * differences that it doesn't seem worth trying to unify the two functions.
+ *
+ * But note that making the two choices independently is a bit bogus in
+ * itself. If the two could be combined into a single choice operation
+ * it'd probably be better, but that seems far too unwieldy to be practical,
+ * especially considering that the combination of GROUP BY and DISTINCT
+ * isn't very common in real queries. By separating them, we are giving
+ * extra preference to using a sorting implementation when a common sort key
+ * is available ... and that's not necessarily wrong anyway.
+ *
+ * Note: this is only applied when both alternatives are actually feasible.
*/
static bool
-hash_safe_grouping(PlannerInfo *root)
+choose_hashed_distinct(PlannerInfo *root,
+ Plan *input_plan, List *input_pathkeys,
+ double tuple_fraction, double limit_tuples,
+ double dNumDistinctRows)
{
- ListCell *gl;
+ int numDistinctCols = list_length(root->parse->distinctClause);
+ Size hashentrysize;
+ List *current_pathkeys;
+ List *needed_pathkeys;
+ Path hashed_p;
+ Path sorted_p;
- foreach(gl, root->parse->groupClause)
+ /* Prefer sorting when enable_hashagg is off */
+ if (!enable_hashagg)
+ return false;
+
+ /*
+ * Don't do it if it doesn't look like the hashtable will fit into
+ * work_mem.
+ */
+ hashentrysize = MAXALIGN(input_plan->plan_width) + MAXALIGN(sizeof(MinimalTupleData));
+
+ if (hashentrysize * dNumDistinctRows > work_mem * 1024L)
+ return false;
+
+ /*
+ * See if the estimated cost is no more than doing it the other way. While
+ * avoiding the need for sorted input is usually a win, the fact that the
+ * output won't be sorted may be a loss; so we need to do an actual cost
+ * comparison.
+ *
+ * We need to consider input_plan + hashagg [+ final sort] versus
+ * input_plan [+ sort] + group [+ final sort] where brackets indicate
+ * a step that may not be needed.
+ *
+ * These path variables are dummies that just hold cost fields; we don't
+ * make actual Paths for these steps.
+ */
+ cost_agg(&hashed_p, root, AGG_HASHED, 0,
+ numDistinctCols, dNumDistinctRows,
+ input_plan->startup_cost, input_plan->total_cost,
+ input_plan->plan_rows);
+ /*
+ * Result of hashed agg is always unsorted, so if ORDER BY is present
+ * we need to charge for the final sort.
+ */
+ if (root->parse->sortClause)
+ cost_sort(&hashed_p, root, root->sort_pathkeys, hashed_p.total_cost,
+ dNumDistinctRows, input_plan->plan_width, limit_tuples);
+
+ /*
+ * Now for the GROUP case. See comments in grouping_planner about the
+ * sorting choices here --- this code should match that code.
+ */
+ sorted_p.startup_cost = input_plan->startup_cost;
+ sorted_p.total_cost = input_plan->total_cost;
+ current_pathkeys = input_pathkeys;
+ if (root->parse->hasDistinctOn &&
+ list_length(root->distinct_pathkeys) <
+ list_length(root->sort_pathkeys))
+ needed_pathkeys = root->sort_pathkeys;
+ else
+ needed_pathkeys = root->distinct_pathkeys;
+ if (!pathkeys_contained_in(needed_pathkeys, current_pathkeys))
{
- GroupClause *grpcl = (GroupClause *) lfirst(gl);
- TargetEntry *tle = get_sortgroupclause_tle(grpcl,
- root->parse->targetList);
- Operator optup;
- bool oprcanhash;
-
- optup = equality_oper(exprType((Node *) tle->expr), true);
- if (!optup)
- return false;
- oprcanhash = ((Form_pg_operator) GETSTRUCT(optup))->oprcanhash;
- ReleaseSysCache(optup);
- if (!oprcanhash)
- return false;
+ if (list_length(root->distinct_pathkeys) >=
+ list_length(root->sort_pathkeys))
+ current_pathkeys = root->distinct_pathkeys;
+ else
+ current_pathkeys = root->sort_pathkeys;
+ cost_sort(&sorted_p, root, current_pathkeys, sorted_p.total_cost,
+ input_plan->plan_rows, input_plan->plan_width, -1.0);
}
- return true;
+ cost_group(&sorted_p, root, numDistinctCols, dNumDistinctRows,
+ sorted_p.startup_cost, sorted_p.total_cost,
+ input_plan->plan_rows);
+ if (root->parse->sortClause &&
+ !pathkeys_contained_in(root->sort_pathkeys, current_pathkeys))
+ cost_sort(&sorted_p, root, root->sort_pathkeys, sorted_p.total_cost,
+ dNumDistinctRows, input_plan->plan_width, limit_tuples);
+
+ /*
+ * Now make the decision using the top-level tuple fraction. First we
+ * have to convert an absolute count (LIMIT) into fractional form.
+ */
+ if (tuple_fraction >= 1.0)
+ tuple_fraction /= dNumDistinctRows;
+
+ if (compare_fractional_path_costs(&hashed_p, &sorted_p,
+ tuple_fraction) < 0)
+ {
+ /* Hashed is cheaper, so use it */
+ return true;
+ }
+ return false;
}
/*---------------
* pass down only c,d,a+b, but it's not really worth the trouble to
* eliminate simple var references from the subplan. We will avoid doing
* the extra computation to recompute a+b at the outer level; see
- * replace_vars_with_subplan_refs() in setrefs.c.)
+ * fix_upper_expr() in setrefs.c.)
*
* If we are grouping or aggregating, *and* there are no non-Var grouping
* expressions, then the returned tlist is effectively dummy; we do not
* If we're not grouping or aggregating, there's nothing to do here;
* query_planner should receive the unmodified target list.
*/
- if (!parse->hasAggs && !parse->groupClause && !root->hasHavingQual)
+ if (!parse->hasAggs && !parse->groupClause && !root->hasHavingQual &&
+ !parse->hasWindowFuncs)
{
*need_tlist_eval = true;
return tlist;
/*
* Otherwise, start with a "flattened" tlist (having just the vars
- * mentioned in the targetlist and HAVING qual --- but not upper- level
- * Vars; they will be replaced by Params later on).
+ * mentioned in the targetlist and HAVING qual --- but not upper-level
+ * Vars; they will be replaced by Params later on). Note this includes
+ * vars used in resjunk items, so we are covering the needs of ORDER BY
+ * and window specifications.
*/
sub_tlist = flatten_tlist(tlist);
- extravars = pull_var_clause(parse->havingQual, false);
+ extravars = pull_var_clause(parse->havingQual, true);
sub_tlist = add_to_flat_tlist(sub_tlist, extravars);
list_free(extravars);
*need_tlist_eval = false; /* only eval if not flat tlist */
foreach(gl, parse->groupClause)
{
- GroupClause *grpcl = (GroupClause *) lfirst(gl);
+ SortGroupClause *grpcl = (SortGroupClause *) lfirst(gl);
Node *groupexpr = get_sortgroupclause_expr(grpcl, tlist);
- TargetEntry *te = NULL;
- ListCell *sl;
+ TargetEntry *te;
- /* Find or make a matching sub_tlist entry */
- foreach(sl, sub_tlist)
- {
- te = (TargetEntry *) lfirst(sl);
- if (equal(groupexpr, te->expr))
- break;
- }
- if (!sl)
+ /*
+ * Find or make a matching sub_tlist entry. If the groupexpr
+ * isn't a Var, no point in searching. (Note that the parser
+ * won't make multiple groupClause entries for the same TLE.)
+ */
+ if (groupexpr && IsA(groupexpr, Var))
+ te = tlist_member(groupexpr, sub_tlist);
+ else
+ te = NULL;
+
+ if (!te)
{
te = makeTargetEntry((Expr *) groupexpr,
list_length(sub_tlist) + 1,
*
* This is only needed if we don't use the sub_tlist chosen by
* make_subplanTargetList. We have to forget the column indexes found
- * by that routine and re-locate the grouping vars in the real sub_tlist.
+ * by that routine and re-locate the grouping exprs in the real sub_tlist.
*/
static void
locate_grouping_columns(PlannerInfo *root,
foreach(gl, root->parse->groupClause)
{
- GroupClause *grpcl = (GroupClause *) lfirst(gl);
+ SortGroupClause *grpcl = (SortGroupClause *) lfirst(gl);
Node *groupexpr = get_sortgroupclause_expr(grpcl, tlist);
- TargetEntry *te = NULL;
- ListCell *sl;
+ TargetEntry *te = tlist_member(groupexpr, sub_tlist);
- foreach(sl, sub_tlist)
- {
- te = (TargetEntry *) lfirst(sl);
- if (equal(groupexpr, te->expr))
- break;
- }
- if (!sl)
+ if (!te)
elog(ERROR, "failed to locate grouping columns");
-
groupColIdx[keyno++] = te->resno;
}
}
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 *result;
+ List *actives;
+ ListCell *lc;
+
+ /* First, make a list of the active windows */
+ actives = NIL;
+ foreach(lc, root->parse->windowClause)
+ {
+ WindowClause *wc = (WindowClause *) lfirst(lc);
+
+ /* It's only active if wflists shows some related WindowFuncs */
+ Assert(wc->winref <= wflists->maxWinRef);
+ if (wflists->windowFuncs[wc->winref] != NIL)
+ actives = lappend(actives, wc);
+ }
+
+ /*
+ * Now, ensure that windows with identical partitioning/ordering clauses
+ * are adjacent in the list. This is required by the SQL standard, which
+ * says that only one sort is to be used for such windows, even if they
+ * are otherwise distinct (eg, different names or framing clauses).
+ *
+ * There is room to be much smarter here, for example detecting whether
+ * one window's sort keys are a prefix of another's (so that sorting
+ * for the latter would do for the former), or putting windows first
+ * that match a sort order available for the underlying query. For the
+ * moment we are content with meeting the spec.
+ */
+ result = NIL;
+ while (actives != NIL)
+ {
+ WindowClause *wc = (WindowClause *) linitial(actives);
+ ListCell *prev;
+ ListCell *next;
+
+ /* Move wc from actives to result */
+ actives = list_delete_first(actives);
+ result = lappend(result, wc);
+
+ /* Now move any matching windows from actives to result */
+ prev = NULL;
+ for (lc = list_head(actives); lc; lc = next)
+ {
+ WindowClause *wc2 = (WindowClause *) lfirst(lc);
+
+ next = lnext(lc);
+ /* framing options are NOT to be compared here! */
+ if (equal(wc->partitionClause, wc2->partitionClause) &&
+ equal(wc->orderClause, wc2->orderClause))
+ {
+ actives = list_delete_cell(actives, lc, prev);
+ result = lappend(result, wc2);
+ }
+ else
+ prev = lc;
+ }
+ }
+
+ return result;
+}
+
+/*
+ * 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, bool canonicalize)
+{
+ 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(list_copy(wc->partitionClause),
+ list_copy(wc->orderClause));
+ window_pathkeys = make_pathkeys_for_sortclauses(root,
+ window_sortclauses,
+ tlist,
+ canonicalize);
+ list_free(window_sortclauses);
+ return window_pathkeys;
+}
+
+/*----------
+ * get_column_info_for_window
+ * Get the partitioning/ordering column numbers and equality operators
+ * for a WindowAgg node.
+ *
+ * This depends on the behavior of make_pathkeys_for_window()!
+ *
+ * We are given the target WindowClause and an array of the input column
+ * numbers associated with the resulting pathkeys. In the easy case, there
+ * are the same number of pathkey columns as partitioning + ordering columns
+ * and we just have to copy some data around. However, it's possible that
+ * some of the original partitioning + ordering columns were eliminated as
+ * redundant during the transformation to pathkeys. (This can happen even
+ * though the parser gets rid of obvious duplicates. A typical scenario is a
+ * window specification "PARTITION BY x ORDER BY y" coupled with a clause
+ * "WHERE x = y" that causes the two sort columns to be recognized as
+ * redundant.) In that unusual case, we have to work a lot harder to
+ * determine which keys are significant.
+ *
+ * The method used here is a bit brute-force: add the sort columns to a list
+ * one at a time and note when the resulting pathkey list gets longer. But
+ * it's a sufficiently uncommon case that a faster way doesn't seem worth
+ * the amount of code refactoring that'd be needed.
+ *----------
+ */
+static void
+get_column_info_for_window(PlannerInfo *root, WindowClause *wc, List *tlist,
+ int numSortCols, AttrNumber *sortColIdx,
+ int *partNumCols,
+ AttrNumber **partColIdx,
+ Oid **partOperators,
+ int *ordNumCols,
+ AttrNumber **ordColIdx,
+ Oid **ordOperators)
+{
+ int numPart = list_length(wc->partitionClause);
+ int numOrder = list_length(wc->orderClause);
+
+ if (numSortCols == numPart + numOrder)
+ {
+ /* easy case */
+ *partNumCols = numPart;
+ *partColIdx = sortColIdx;
+ *partOperators = extract_grouping_ops(wc->partitionClause);
+ *ordNumCols = numOrder;
+ *ordColIdx = sortColIdx + numPart;
+ *ordOperators = extract_grouping_ops(wc->orderClause);
+ }
+ else
+ {
+ List *sortclauses;
+ List *pathkeys;
+ int scidx;
+ ListCell *lc;
+
+ /* first, allocate what's certainly enough space for the arrays */
+ *partNumCols = 0;
+ *partColIdx = (AttrNumber *) palloc(numPart * sizeof(AttrNumber));
+ *partOperators = (Oid *) palloc(numPart * sizeof(Oid));
+ *ordNumCols = 0;
+ *ordColIdx = (AttrNumber *) palloc(numOrder * sizeof(AttrNumber));
+ *ordOperators = (Oid *) palloc(numOrder * sizeof(Oid));
+ sortclauses = NIL;
+ pathkeys = NIL;
+ scidx = 0;
+ foreach(lc, wc->partitionClause)
+ {
+ SortGroupClause *sgc = (SortGroupClause *) lfirst(lc);
+ List *new_pathkeys;
+
+ sortclauses = lappend(sortclauses, sgc);
+ new_pathkeys = make_pathkeys_for_sortclauses(root,
+ sortclauses,
+ tlist,
+ true);
+ if (list_length(new_pathkeys) > list_length(pathkeys))
+ {
+ /* this sort clause is actually significant */
+ *partColIdx[*partNumCols] = sortColIdx[scidx++];
+ *partOperators[*partNumCols] = sgc->eqop;
+ (*partNumCols)++;
+ pathkeys = new_pathkeys;
+ }
+ }
+ foreach(lc, wc->orderClause)
+ {
+ SortGroupClause *sgc = (SortGroupClause *) lfirst(lc);
+ List *new_pathkeys;
+
+ sortclauses = lappend(sortclauses, sgc);
+ new_pathkeys = make_pathkeys_for_sortclauses(root,
+ sortclauses,
+ tlist,
+ true);
+ if (list_length(new_pathkeys) > list_length(pathkeys))
+ {
+ /* this sort clause is actually significant */
+ *ordColIdx[*ordNumCols] = sortColIdx[scidx++];
+ *ordOperators[*ordNumCols] = sgc->eqop;
+ (*ordNumCols)++;
+ pathkeys = new_pathkeys;
+ }
+ }
+ /* complain if we didn't eat exactly the right number of sort cols */
+ if (scidx != numSortCols)
+ elog(ERROR, "failed to deconstruct sort operators into partitioning/ordering operators");
+ }
+}
projects / postgresql / blobdiff