* planner.c
* The query optimizer external interface.
*
- * Portions Copyright (c) 1996-2003, PostgreSQL Global Development Group
+ * Portions Copyright (c) 1996-2005, PostgreSQL Global Development Group
* Portions Copyright (c) 1994, Regents of the University of California
*
*
* IDENTIFICATION
- * $PostgreSQL: pgsql/src/backend/optimizer/plan/planner.c,v 1.166 2004/02/03 17:34:03 tgl Exp $
+ * $PostgreSQL: pgsql/src/backend/optimizer/plan/planner.c,v 1.190 2005/07/02 23:00:41 tgl Exp $
*
*-------------------------------------------------------------------------
*/
#include "catalog/pg_operator.h"
#include "catalog/pg_type.h"
#include "executor/executor.h"
+#include "executor/nodeAgg.h"
#include "miscadmin.h"
#include "nodes/makefuncs.h"
#ifdef OPTIMIZER_DEBUG
#include "optimizer/subselect.h"
#include "optimizer/tlist.h"
#include "optimizer/var.h"
-#include "parser/analyze.h"
#include "parser/parsetree.h"
#include "parser/parse_expr.h"
#include "parser/parse_oper.h"
#include "utils/syscache.h"
+ParamListInfo PlannerBoundParamList = NULL; /* current boundParams */
+
+
/* Expression kind codes for preprocess_expression */
#define EXPRKIND_QUAL 0
#define EXPRKIND_TARGET 1
#define EXPRKIND_ININFO 4
-static Node *preprocess_expression(Query *parse, Node *expr, int kind);
-static void preprocess_qual_conditions(Query *parse, Node *jtnode);
-static Plan *inheritance_planner(Query *parse, List *inheritlist);
-static Plan *grouping_planner(Query *parse, double tuple_fraction);
-static bool hash_safe_grouping(Query *parse);
-static List *make_subplanTargetList(Query *parse, List *tlist,
+static Node *preprocess_expression(PlannerInfo *root, Node *expr, int kind);
+static void preprocess_qual_conditions(PlannerInfo *root, Node *jtnode);
+static Plan *inheritance_planner(PlannerInfo *root, List *inheritlist);
+static Plan *grouping_planner(PlannerInfo *root, double tuple_fraction);
+static double adjust_tuple_fraction_for_limit(PlannerInfo *root,
+ double tuple_fraction);
+static bool choose_hashed_grouping(PlannerInfo *root, double tuple_fraction,
+ Path *cheapest_path, Path *sorted_path,
+ List *sort_pathkeys, List *group_pathkeys,
+ double dNumGroups, AggClauseCounts *agg_counts);
+static bool hash_safe_grouping(PlannerInfo *root);
+static List *make_subplanTargetList(PlannerInfo *root, List *tlist,
AttrNumber **groupColIdx, bool *need_tlist_eval);
-static void locate_grouping_columns(Query *parse,
+static void locate_grouping_columns(PlannerInfo *root,
List *tlist,
List *sub_tlist,
AttrNumber *groupColIdx);
*
*****************************************************************************/
Plan *
-planner(Query *parse, bool isCursor, int cursorOptions)
+planner(Query *parse, bool isCursor, int cursorOptions,
+ ParamListInfo boundParams)
{
double tuple_fraction;
Plan *result_plan;
Index save_PlannerQueryLevel;
List *save_PlannerParamList;
+ ParamListInfo save_PlannerBoundParamList;
/*
* 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.
*
- * These vars cannot be moved into the Query structure since their whole
- * purpose is communication across multiple sub-Queries.
+ * 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
*/
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;
/* Determine what fraction of the plan is likely to be scanned */
if (isCursor)
}
/* primary planning entry point (may recurse for subqueries) */
- result_plan = subquery_planner(parse, tuple_fraction);
+ result_plan = subquery_planner(parse, tuple_fraction, NULL);
+ /* check we popped out the right number of levels */
Assert(PlannerQueryLevel == 0);
/*
result_plan = materialize_finished_plan(result_plan);
}
- /* executor wants to know total number of Params used overall */
- result_plan->nParamExec = length(PlannerParamList);
-
/* final cleanup of the plan */
- set_plan_references(result_plan, parse->rtable);
+ 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);
/* restore state for outer planner, if any */
PlannerQueryLevel = save_PlannerQueryLevel;
PlannerParamList = save_PlannerParamList;
+ PlannerBoundParamList = save_PlannerBoundParamList;
return result_plan;
}
* 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.
+ *
* 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;
*--------------------
*/
Plan *
-subquery_planner(Query *parse, double tuple_fraction)
+subquery_planner(Query *parse, double tuple_fraction,
+ List **subquery_pathkeys)
{
List *saved_initplan = PlannerInitPlan;
int saved_planid = PlannerPlanId;
- bool hasOuterJoins;
+ PlannerInfo *root;
Plan *plan;
List *newHaving;
List *lst;
+ 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;
+
/*
* 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.
*/
- parse->in_info_list = NIL;
+ root->in_info_list = NIL;
if (parse->hasSubLinks)
- parse->jointree->quals = pull_up_IN_clauses(parse,
- parse->jointree->quals);
+ parse->jointree->quals = pull_up_IN_clauses(root,
+ parse->jointree->quals);
/*
* Check to see if any subqueries in the rangetable can be merged into
* this query.
*/
parse->jointree = (FromExpr *)
- pull_up_subqueries(parse, (Node *) parse->jointree, false);
+ pull_up_subqueries(root, (Node *) parse->jointree, false);
/*
* 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(). This must be done after we have done
+ * 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.
*/
- parse->hasJoinRTEs = false;
- hasOuterJoins = false;
- foreach(lst, parse->rtable)
+ root->hasJoinRTEs = false;
+ root->hasOuterJoins = false;
+ foreach(l, parse->rtable)
{
- RangeTblEntry *rte = (RangeTblEntry *) lfirst(lst);
+ RangeTblEntry *rte = (RangeTblEntry *) lfirst(l);
if (rte->rtekind == RTE_JOIN)
{
- parse->hasJoinRTEs = true;
+ root->hasJoinRTEs = true;
if (IS_OUTER_JOIN(rte->jointype))
{
- hasOuterJoins = true;
+ root->hasOuterJoins = true;
/* Can quit scanning once we find an outer join */
break;
}
}
}
+ /*
+ * 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.
*/
parse->targetList = (List *)
- preprocess_expression(parse, (Node *) parse->targetList,
+ preprocess_expression(root, (Node *) parse->targetList,
EXPRKIND_TARGET);
- preprocess_qual_conditions(parse, (Node *) parse->jointree);
+ preprocess_qual_conditions(root, (Node *) parse->jointree);
- parse->havingQual = preprocess_expression(parse, parse->havingQual,
+ parse->havingQual = preprocess_expression(root, parse->havingQual,
EXPRKIND_QUAL);
- parse->limitOffset = preprocess_expression(parse, parse->limitOffset,
+ parse->limitOffset = preprocess_expression(root, parse->limitOffset,
EXPRKIND_LIMIT);
- parse->limitCount = preprocess_expression(parse, parse->limitCount,
+ parse->limitCount = preprocess_expression(root, parse->limitCount,
EXPRKIND_LIMIT);
- parse->in_info_list = (List *)
- preprocess_expression(parse, (Node *) parse->in_info_list,
+ root->in_info_list = (List *)
+ preprocess_expression(root, (Node *) root->in_info_list,
EXPRKIND_ININFO);
/* Also need to preprocess expressions for function RTEs */
- foreach(lst, parse->rtable)
+ foreach(l, parse->rtable)
{
- RangeTblEntry *rte = (RangeTblEntry *) lfirst(lst);
+ RangeTblEntry *rte = (RangeTblEntry *) lfirst(l);
if (rte->rtekind == RTE_FUNCTION)
- rte->funcexpr = preprocess_expression(parse, rte->funcexpr,
+ rte->funcexpr = preprocess_expression(root, rte->funcexpr,
EXPRKIND_RTFUNC);
}
/*
- * A HAVING clause without aggregates is equivalent to a WHERE clause
- * (except it can only refer to grouped fields). Transfer any
- * agg-free clauses of the HAVING qual into WHERE. This may seem like
- * wasting cycles to cater to stupidly-written queries, but there are
- * other reasons for doing it. Firstly, if the query contains no aggs
- * at all, then we aren't going to generate an Agg plan node, and so
- * there'll be no place to execute HAVING conditions; without this
- * transfer, we'd lose the HAVING condition entirely, which is wrong.
- * Secondly, when we push down a qual condition into a sub-query, it's
- * easiest to push the qual into HAVING always, in case it contains
- * aggs, and then let this code sort it out.
+ * 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). 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(lst, (List *) parse->havingQual)
+ foreach(l, (List *) parse->havingQual)
{
- Node *havingclause = (Node *) lfirst(lst);
+ Node *havingclause = (Node *) lfirst(l);
- if (contain_agg_clause(havingclause))
+ if (contain_agg_clause(havingclause) ||
+ contain_volatile_functions(havingclause) ||
+ contain_subplans(havingclause))
+ {
+ /* keep it in HAVING */
newHaving = lappend(newHaving, havingclause);
- else
+ }
+ else if (parse->groupClause)
+ {
+ /* 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;
* joins. This step is most easily done after we've done expression
* preprocessing.
*/
- if (hasOuterJoins)
- reduce_outer_joins(parse);
+ if (root->hasOuterJoins)
+ reduce_outer_joins(root);
/*
* See if we can simplify the jointree; opportunities for this may
* after reduce_outer_joins, anyway.
*/
parse->jointree = (FromExpr *)
- simplify_jointree(parse, (Node *) parse->jointree);
+ simplify_jointree(root, (Node *) parse->jointree);
/*
* Do the main planning. If we have an inherited target relation,
* grouping_planner.
*/
if (parse->resultRelation &&
- (lst = expand_inherited_rtentry(parse, parse->resultRelation,
- false)) != NIL)
- plan = inheritance_planner(parse, lst);
+ (lst = expand_inherited_rtentry(root, parse->resultRelation)) != NIL)
+ plan = inheritance_planner(root, lst);
else
- plan = grouping_planner(parse, tuple_fraction);
+ plan = grouping_planner(root, tuple_fraction);
/*
* If any subplans were generated, or if we're inside a subplan, build
- * initPlan list and extParam/allParam sets for plan nodes.
+ * initPlan list and extParam/allParam sets for plan nodes, and attach
+ * the initPlans to the top plan node.
*/
if (PlannerPlanId != saved_planid || PlannerQueryLevel > 1)
- {
- Cost initplan_cost = 0;
-
- /* Prepare extParam/allParam sets for all nodes in tree */
SS_finalize_plan(plan, parse->rtable);
- /*
- * SS_finalize_plan doesn't handle initPlans, so we have to
- * manually attach them to the topmost plan node, and add their
- * extParams to the topmost node's, too.
- *
- * We also add the total_cost of each initPlan to the startup cost of
- * the top node. This is a conservative overestimate, since in
- * fact each initPlan might be executed later than plan startup,
- * or even not at all.
- */
- plan->initPlan = PlannerInitPlan;
-
- foreach(lst, plan->initPlan)
- {
- SubPlan *initplan = (SubPlan *) lfirst(lst);
-
- plan->extParam = bms_add_members(plan->extParam,
- initplan->plan->extParam);
- initplan_cost += initplan->plan->total_cost;
- }
-
- plan->startup_cost += initplan_cost;
- plan->total_cost += initplan_cost;
- }
+ /* Return sort ordering info if caller wants it */
+ if (subquery_pathkeys)
+ *subquery_pathkeys = root->query_pathkeys;
/* Return to outer subquery context */
PlannerQueryLevel--;
* conditions), or a HAVING clause.
*/
static Node *
-preprocess_expression(Query *parse, Node *expr, int kind)
+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 before sublink processing,
* else sublinks expanded out from join aliases wouldn't get
* processed.
*/
- if (parse->hasJoinRTEs)
- expr = flatten_join_alias_vars(parse, expr);
+ if (root->hasJoinRTEs)
+ expr = flatten_join_alias_vars(root, expr);
/*
- * If it's a qual or havingQual, canonicalize it. It seems most useful
- * to do this before applying eval_const_expressions, since the latter
- * can optimize flattened AND/ORs better than unflattened ones.
+ * Simplify constant expressions.
+ *
+ * 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.
*
- * Note: 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);
+
+ /*
+ * If it's a qual or havingQual, canonicalize it.
*/
if (kind == EXPRKIND_QUAL)
{
#endif
}
- /*
- * Simplify constant expressions.
- */
- expr = eval_const_expressions(expr);
-
/* Expand SubLinks to SubPlans */
- if (parse->hasSubLinks)
+ if (root->parse->hasSubLinks)
expr = SS_process_sublinks(expr, (kind == EXPRKIND_QUAL));
/*
/*
* 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,
+ * latter would be unable to simplify a top-level AND correctly. Also,
* SS_process_sublinks expects explicit-AND format.)
*/
if (kind == EXPRKIND_QUAL)
* preprocessing work on each qual condition found therein.
*/
static void
-preprocess_qual_conditions(Query *parse, Node *jtnode)
+preprocess_qual_conditions(PlannerInfo *root, Node *jtnode)
{
if (jtnode == NULL)
return;
else if (IsA(jtnode, FromExpr))
{
FromExpr *f = (FromExpr *) jtnode;
- List *l;
+ ListCell *l;
foreach(l, f->fromlist)
- preprocess_qual_conditions(parse, lfirst(l));
+ preprocess_qual_conditions(root, lfirst(l));
- f->quals = preprocess_expression(parse, f->quals, EXPRKIND_QUAL);
+ f->quals = preprocess_expression(root, f->quals, EXPRKIND_QUAL);
}
else if (IsA(jtnode, JoinExpr))
{
JoinExpr *j = (JoinExpr *) jtnode;
- preprocess_qual_conditions(parse, j->larg);
- preprocess_qual_conditions(parse, j->rarg);
+ preprocess_qual_conditions(root, j->larg);
+ preprocess_qual_conditions(root, j->rarg);
- j->quals = preprocess_expression(parse, j->quals, EXPRKIND_QUAL);
+ j->quals = preprocess_expression(root, j->quals, EXPRKIND_QUAL);
}
else
elog(ERROR, "unrecognized node type: %d",
* can never be the nullable side of an outer join, so it's OK to generate
* the plan this way.
*
- * parse is the querytree produced by the parser & rewriter.
* inheritlist is an integer list of RT indexes for the result relation set.
*
* Returns a query plan.
*--------------------
*/
static Plan *
-inheritance_planner(Query *parse, List *inheritlist)
+inheritance_planner(PlannerInfo *root, List *inheritlist)
{
+ Query *parse = root->parse;
int parentRTindex = parse->resultRelation;
Oid parentOID = getrelid(parentRTindex, parse->rtable);
- int mainrtlength = length(parse->rtable);
+ int mainrtlength = list_length(parse->rtable);
List *subplans = NIL;
List *tlist = NIL;
- List *l;
+ ListCell *l;
foreach(l, inheritlist)
{
- int childRTindex = lfirsti(l);
+ int childRTindex = lfirst_int(l);
Oid childOID = getrelid(childRTindex, parse->rtable);
- int subrtlength;
- Query *subquery;
+ PlannerInfo subroot;
Plan *subplan;
- /* Generate modified query with this rel as target */
- subquery = (Query *) adjust_inherited_attrs((Node *) parse,
- parentRTindex, parentOID,
- childRTindex, childOID);
+ /*
+ * 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.
+ */
+ memcpy(&subroot, root, sizeof(PlannerInfo));
+ subroot.parse = (Query *)
+ adjust_inherited_attrs((Node *) parse,
+ parentRTindex, parentOID,
+ childRTindex, childOID);
+ subroot.in_info_list = (List *)
+ adjust_inherited_attrs((Node *) root->in_info_list,
+ parentRTindex, parentOID,
+ childRTindex, childOID);
+
/* Generate plan */
- subplan = grouping_planner(subquery, 0.0 /* retrieve all tuples */ );
+ subplan = grouping_planner(&subroot, 0.0 /* retrieve all tuples */ );
+
subplans = lappend(subplans, subplan);
/*
- * It's possible that additional RTEs got added to the rangetable
- * due to expansion of inherited source tables (see allpaths.c).
- * If so, we must copy 'em back to the main parse tree's rtable.
+ * XXX my goodness this next bit is ugly. Really need to think about
+ * ways to rein in planner's habit of scribbling on its input.
*
- * XXX my goodness this is ugly. Really need to think about ways to
- * rein in planner's habit of scribbling on its input.
+ * Planning of the subquery might have modified the rangetable,
+ * either by addition of RTEs due to expansion of inherited source
+ * tables, or by changes of the Query structures inside subquery
+ * RTEs. We have to ensure that this gets propagated back to the
+ * master copy. However, if we aren't done planning yet, we also
+ * need to ensure that subsequent calls to grouping_planner have
+ * virgin sub-Queries to work from. So, if we are at the last
+ * list entry, just copy the subquery rangetable back to the master
+ * copy; if we are not, then extend the master copy by adding
+ * whatever the subquery added. (We assume these added entries
+ * will go untouched by the future grouping_planner calls. We are
+ * also effectively assuming that sub-Queries will get planned
+ * identically each time, or at least that the impacts on their
+ * rangetables will be the same each time. Did I say this is ugly?)
*/
- subrtlength = length(subquery->rtable);
- if (subrtlength > mainrtlength)
+ if (lnext(l) == NULL)
+ parse->rtable = subroot.parse->rtable;
+ else
{
- List *subrt = subquery->rtable;
+ int subrtlength = list_length(subroot.parse->rtable);
- while (mainrtlength-- > 0) /* wish we had nthcdr() */
- subrt = lnext(subrt);
- parse->rtable = nconc(parse->rtable, subrt);
- mainrtlength = subrtlength;
+ if (subrtlength > mainrtlength)
+ {
+ List *subrt;
+
+ subrt = list_copy_tail(subroot.parse->rtable, mainrtlength);
+ parse->rtable = list_concat(parse->rtable, subrt);
+ mainrtlength = subrtlength;
+ }
}
+
/* Save preprocessed tlist from first rel for use in Append */
if (tlist == NIL)
tlist = subplan->targetlist;
parse->resultRelations = inheritlist;
/* Mark result as unordered (probably unnecessary) */
- parse->query_pathkeys = NIL;
+ root->query_pathkeys = NIL;
return (Plan *) make_append(subplans, true, tlist);
}
* This primarily means adding top-level processing to the basic
* query plan produced by query_planner.
*
- * parse is the querytree produced by the parser & rewriter.
* tuple_fraction is the fraction of tuples we expect will be retrieved
*
* tuple_fraction is interpreted as follows:
* tuple_fraction >= 1: tuple_fraction is the absolute number of tuples
* expected to be retrieved (ie, a LIMIT specification)
*
- * Returns a query plan. Also, parse->query_pathkeys is returned as the
+ * Returns a query plan. Also, root->query_pathkeys is returned as the
* actual output ordering of the plan (in pathkey format).
*--------------------
*/
static Plan *
-grouping_planner(Query *parse, double tuple_fraction)
+grouping_planner(PlannerInfo *root, double tuple_fraction)
{
+ Query *parse = root->parse;
List *tlist = parse->targetList;
Plan *result_plan;
List *current_pathkeys;
List *sort_pathkeys;
+ /* Tweak caller-supplied tuple_fraction if have LIMIT */
+ if (parse->limitCount != NULL)
+ tuple_fraction = adjust_tuple_fraction_for_limit(root, tuple_fraction);
+
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.
+ */
+ 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.
*/
- result_plan = plan_set_operations(parse);
+ result_plan = plan_set_operations(root, tuple_fraction,
+ &set_sortclauses);
+
+ /*
+ * Calculate pathkeys representing the sort order (if any) of the
+ * set 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);
/*
* We should not need to call preprocess_targetlist, since we must
tlist = postprocess_setop_tlist(result_plan->targetlist, tlist);
/*
- * Can't handle FOR UPDATE here (parser should have checked
+ * Can't handle FOR UPDATE/SHARE here (parser should have checked
* already, but let's make sure).
*/
if (parse->rowMarks)
ereport(ERROR,
(errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
- errmsg("SELECT FOR UPDATE is not allowed with UNION/INTERSECT/EXCEPT")));
-
- /*
- * We set current_pathkeys NIL indicating we do not know sort
- * order. This is correct when the top set operation is UNION
- * ALL, since the appended-together results are unsorted even if
- * the subplans were sorted. For other set operations we could be
- * smarter --- room for future improvement!
- */
- current_pathkeys = NIL;
+ errmsg("SELECT FOR UPDATE/SHARE is not allowed with UNION/INTERSECT/EXCEPT")));
/*
- * Calculate pathkeys that represent ordering requirements
+ * Calculate pathkeys that represent result ordering requirements
*/
sort_pathkeys = make_pathkeys_for_sortclauses(parse->sortClause,
tlist);
- sort_pathkeys = canonicalize_pathkeys(parse, sort_pathkeys);
+ sort_pathkeys = canonicalize_pathkeys(root, sort_pathkeys);
}
else
{
double sub_tuple_fraction;
Path *cheapest_path;
Path *sorted_path;
+ Path *best_path;
double dNumGroups = 0;
long numGroups = 0;
- int numAggs = 0;
- int numGroupCols = length(parse->groupClause);
+ AggClauseCounts agg_counts;
+ int numGroupCols = list_length(parse->groupClause);
bool use_hashed_grouping = false;
- /* Preprocess targetlist in case we are inside an INSERT/UPDATE. */
- tlist = preprocess_targetlist(tlist,
- parse->commandType,
- parse->resultRelation,
- parse->rtable);
+ MemSet(&agg_counts, 0, sizeof(AggClauseCounts));
- /*
- * Add TID targets for rels selected FOR UPDATE (should this be
- * done in preprocess_targetlist?). The executor uses the TID to
- * know which rows to lock, much as for UPDATE or DELETE.
- */
- if (parse->rowMarks)
- {
- List *l;
-
- /*
- * We've got trouble if the FOR UPDATE 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.
- */
- CheckSelectForUpdate(parse);
-
- /*
- * Currently the executor only supports FOR UPDATE at top
- * level
- */
- if (PlannerQueryLevel > 1)
- ereport(ERROR,
- (errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
- errmsg("SELECT FOR UPDATE is not allowed in subqueries")));
-
- foreach(l, parse->rowMarks)
- {
- Index rti = lfirsti(l);
- char *resname;
- Resdom *resdom;
- Var *var;
- TargetEntry *ctid;
-
- resname = (char *) palloc(32);
- snprintf(resname, 32, "ctid%u", rti);
- resdom = makeResdom(length(tlist) + 1,
- TIDOID,
- -1,
- resname,
- true);
-
- var = makeVar(rti,
- SelfItemPointerAttributeNumber,
- TIDOID,
- -1,
- 0);
-
- ctid = makeTargetEntry(resdom, (Expr *) var);
- tlist = lappend(tlist, ctid);
- }
- }
+ /* Preprocess targetlist */
+ tlist = preprocess_targetlist(root, tlist);
/*
* Generate appropriate target list for subplan; may be different
* from tlist if grouping or aggregation is needed.
*/
- sub_tlist = make_subplanTargetList(parse, tlist,
+ sub_tlist = make_subplanTargetList(root, tlist,
&groupColIdx, &need_tlist_eval);
/*
/*
* Will need actual number of aggregates for estimating costs.
- * Also, it's possible that optimization has eliminated all
- * aggregates, and we may as well check for that here.
*
* Note: we do not attempt to detect duplicate aggregates here; a
* somewhat-overestimated count is okay for our present purposes.
+ *
+ * Note: think not that we can turn off hasAggs if we find no aggs.
+ * It is possible for constant-expression simplification to remove
+ * all explicit references to aggs, but we still have to follow
+ * the aggregate semantics (eg, producing only one output row).
*/
if (parse->hasAggs)
{
- numAggs = count_agg_clause((Node *) tlist) +
- count_agg_clause(parse->havingQual);
- if (numAggs == 0)
- parse->hasAggs = false;
+ count_agg_clauses((Node *) tlist, &agg_counts);
+ count_agg_clauses(parse->havingQual, &agg_counts);
}
/*
* Needs more thought...)
*/
if (parse->groupClause)
- parse->query_pathkeys = group_pathkeys;
+ root->query_pathkeys = group_pathkeys;
else if (parse->sortClause)
- parse->query_pathkeys = sort_pathkeys;
+ root->query_pathkeys = sort_pathkeys;
else
- parse->query_pathkeys = NIL;
-
- /*
- * Adjust tuple_fraction if we see that we are going to apply
- * limiting/grouping/aggregation/etc. This is not overridable by
- * the caller, since it reflects plan actions that this routine
- * will certainly take, not assumptions about context.
- */
- if (parse->limitCount != NULL)
- {
- /*
- * A LIMIT clause limits the absolute number of tuples
- * returned. However, if it's not a constant LIMIT then we
- * have to punt; for lack of a better idea, assume 10% of the
- * plan's result is wanted.
- */
- double limit_fraction = 0.0;
-
- if (IsA(parse->limitCount, Const))
- {
- Const *limitc = (Const *) parse->limitCount;
- int32 count = DatumGetInt32(limitc->constvalue);
-
- /*
- * A NULL-constant LIMIT represents "LIMIT ALL", which we
- * treat the same as no limit (ie, expect to retrieve all
- * the tuples).
- */
- if (!limitc->constisnull && count > 0)
- {
- limit_fraction = (double) count;
- /* We must also consider the OFFSET, if present */
- if (parse->limitOffset != NULL)
- {
- if (IsA(parse->limitOffset, Const))
- {
- int32 offset;
-
- limitc = (Const *) parse->limitOffset;
- offset = DatumGetInt32(limitc->constvalue);
- if (!limitc->constisnull && offset > 0)
- limit_fraction += (double) offset;
- }
- else
- {
- /* OFFSET is an expression ... punt ... */
- limit_fraction = 0.10;
- }
- }
- }
- }
- else
- {
- /* LIMIT is an expression ... punt ... */
- limit_fraction = 0.10;
- }
-
- if (limit_fraction > 0.0)
- {
- /*
- * If we have absolute limits from both caller and LIMIT,
- * use the smaller value; if one is fractional and the
- * other absolute, treat the fraction as a fraction of the
- * absolute value; else we can multiply the two fractions
- * together.
- */
- if (tuple_fraction >= 1.0)
- {
- if (limit_fraction >= 1.0)
- {
- /* both absolute */
- tuple_fraction = Min(tuple_fraction, limit_fraction);
- }
- else
- {
- /* caller absolute, limit fractional */
- tuple_fraction *= limit_fraction;
- if (tuple_fraction < 1.0)
- tuple_fraction = 1.0;
- }
- }
- else if (tuple_fraction > 0.0)
- {
- if (limit_fraction >= 1.0)
- {
- /* caller fractional, limit absolute */
- tuple_fraction *= limit_fraction;
- if (tuple_fraction < 1.0)
- tuple_fraction = 1.0;
- }
- else
- {
- /* both fractional */
- tuple_fraction *= limit_fraction;
- }
- }
- else
- {
- /* no info from caller, just use limit */
- tuple_fraction = limit_fraction;
- }
- }
- }
+ root->query_pathkeys = NIL;
/*
* With grouping or aggregation, the tuple fraction to pass to
* Generate the best unsorted and presorted paths for this Query
* (but note there may not be any presorted path).
*/
- query_planner(parse, sub_tlist, sub_tuple_fraction,
+ query_planner(root, sub_tlist, sub_tuple_fraction,
&cheapest_path, &sorted_path);
/*
* We couldn't canonicalize group_pathkeys and sort_pathkeys
* before running query_planner(), so do it now.
*/
- group_pathkeys = canonicalize_pathkeys(parse, group_pathkeys);
- sort_pathkeys = canonicalize_pathkeys(parse, sort_pathkeys);
+ group_pathkeys = canonicalize_pathkeys(root, group_pathkeys);
+ sort_pathkeys = canonicalize_pathkeys(root, sort_pathkeys);
/*
- * Consider whether we might want to use hashed grouping.
+ * If grouping, estimate the number of groups. (We can't do this
+ * until after running query_planner(), either.) Then decide
+ * whether we want to use hashed grouping.
*/
if (parse->groupClause)
{
List *groupExprs;
double cheapest_path_rows;
- int cheapest_path_width;
/*
- * Beware in this section of the possibility that
- * cheapest_path->parent is NULL. This could happen if user
- * does something silly like SELECT 'foo' GROUP BY 1;
+ * Beware of the possibility that cheapest_path->parent is NULL.
+ * This could happen if user does something silly like
+ * SELECT 'foo' GROUP BY 1;
*/
if (cheapest_path->parent)
- {
cheapest_path_rows = cheapest_path->parent->rows;
- cheapest_path_width = cheapest_path->parent->width;
- }
else
- {
cheapest_path_rows = 1; /* assume non-set result */
- cheapest_path_width = 100; /* arbitrary */
- }
- /*
- * Always estimate the number of groups. We can't do this
- * until after running query_planner(), either.
- */
groupExprs = get_sortgrouplist_exprs(parse->groupClause,
parse->targetList);
- dNumGroups = estimate_num_groups(parse,
+ dNumGroups = estimate_num_groups(root,
groupExprs,
cheapest_path_rows);
/* Also want it as a long int --- but 'ware overflow! */
numGroups = (long) Min(dNumGroups, (double) LONG_MAX);
- /*
- * 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.)
- */
- if (!enable_hashagg || !hash_safe_grouping(parse))
- use_hashed_grouping = false;
- else if (parse->hasAggs &&
- (contain_distinct_agg_clause((Node *) tlist) ||
- contain_distinct_agg_clause(parse->havingQual)))
- use_hashed_grouping = false;
- else
- {
- /*
- * Use hashed grouping if (a) we think we can fit the
- * hashtable into work_mem, *and* (b) 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.
- *
- * In most cases we have no good way to estimate the size of
- * the transition value needed by an aggregate;
- * arbitrarily assume it is 100 bytes. Also set the
- * overhead per hashtable entry at 64 bytes.
- */
- int hashentrysize = cheapest_path_width + 64 + numAggs * 100;
-
- if (hashentrysize * dNumGroups <= work_mem * 1024L)
- {
- /*
- * Okay, do the cost comparison. We need to consider
- * cheapest_path + hashagg [+ final sort] versus
- * either cheapest_path [+ sort] + group or agg [+
- * final sort] or presorted_path + group or agg [+
- * final sort] where brackets indicate a step that may
- * not be needed. We assume query_planner() will have
- * returned a presorted path only if it's a winner
- * compared to cheapest_path for this purpose.
- *
- * These path variables are dummies that just hold cost
- * fields; we don't make actual Paths for these steps.
- */
- Path hashed_p;
- Path sorted_p;
-
- cost_agg(&hashed_p, parse,
- AGG_HASHED, numAggs,
- numGroupCols, dNumGroups,
- cheapest_path->startup_cost,
- cheapest_path->total_cost,
- cheapest_path_rows);
- /* Result of hashed agg is always unsorted */
- if (sort_pathkeys)
- cost_sort(&hashed_p, parse, sort_pathkeys,
- hashed_p.total_cost,
- dNumGroups,
- cheapest_path_width);
-
- if (sorted_path)
- {
- sorted_p.startup_cost = sorted_path->startup_cost;
- sorted_p.total_cost = sorted_path->total_cost;
- current_pathkeys = sorted_path->pathkeys;
- }
- else
- {
- sorted_p.startup_cost = cheapest_path->startup_cost;
- sorted_p.total_cost = cheapest_path->total_cost;
- current_pathkeys = cheapest_path->pathkeys;
- }
- if (!pathkeys_contained_in(group_pathkeys,
- current_pathkeys))
- {
- cost_sort(&sorted_p, parse, group_pathkeys,
- sorted_p.total_cost,
- cheapest_path_rows,
- cheapest_path_width);
- current_pathkeys = group_pathkeys;
- }
- if (parse->hasAggs)
- cost_agg(&sorted_p, parse,
- AGG_SORTED, numAggs,
- numGroupCols, dNumGroups,
- sorted_p.startup_cost,
- sorted_p.total_cost,
- cheapest_path_rows);
- else
- cost_group(&sorted_p, parse,
- numGroupCols, dNumGroups,
- sorted_p.startup_cost,
- sorted_p.total_cost,
- cheapest_path_rows);
- /* The Agg or Group node will preserve ordering */
- if (sort_pathkeys &&
- !pathkeys_contained_in(sort_pathkeys,
- current_pathkeys))
- {
- cost_sort(&sorted_p, parse, sort_pathkeys,
- sorted_p.total_cost,
- dNumGroups,
- cheapest_path_width);
- }
-
- /*
- * 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 /= dNumGroups;
-
- if (compare_fractional_path_costs(&hashed_p, &sorted_p,
- tuple_fraction) < 0)
- {
- /* Hashed is cheaper, so use it */
- use_hashed_grouping = true;
- }
- }
- }
+ use_hashed_grouping =
+ choose_hashed_grouping(root, tuple_fraction,
+ cheapest_path, sorted_path,
+ sort_pathkeys, group_pathkeys,
+ dNumGroups, &agg_counts);
}
/*
- * Select the best path and create a plan to execute it.
- *
- * If we are doing hashed grouping, we will always read all the input
- * tuples, so use the cheapest-total path. Otherwise, trust
- * query_planner's decision about which to use.
+ * Select the best path. If we are doing hashed grouping, we will
+ * always read all the input tuples, so use the cheapest-total
+ * path. Otherwise, trust query_planner's decision about which to use.
*/
- if (sorted_path && !use_hashed_grouping)
- {
- result_plan = create_plan(parse, sorted_path);
- current_pathkeys = sorted_path->pathkeys;
- }
+ if (use_hashed_grouping || !sorted_path)
+ best_path = cheapest_path;
else
- {
- result_plan = create_plan(parse, cheapest_path);
- current_pathkeys = cheapest_path->pathkeys;
- }
+ best_path = sorted_path;
/*
- * create_plan() returns a plan with just a "flat" tlist of
- * required Vars. Usually we need to insert the sub_tlist as the
- * tlist of the top plan node. However, we can skip that if we
- * determined that whatever query_planner chose to return will be
- * good enough.
+ * Check to see if it's possible to optimize MIN/MAX aggregates.
+ * If so, we will forget all the work we did so far to choose a
+ * "regular" path ... but we had to do it anyway to be able to
+ * tell which way is cheaper.
*/
- if (need_tlist_eval)
+ result_plan = optimize_minmax_aggregates(root,
+ tlist,
+ best_path);
+ if (result_plan != NULL)
{
/*
- * If the top-level plan node is one that cannot do expression
- * evaluation, we must insert a Result node to project the
- * desired tlist.
+ * optimize_minmax_aggregates generated the full plan, with
+ * the right tlist, and it has no sort order.
*/
- if (!is_projection_capable_plan(result_plan))
- {
- result_plan = (Plan *) make_result(sub_tlist, NULL,
- result_plan);
- }
- else
- {
- /*
- * Otherwise, just replace the subplan's flat tlist with
- * the desired tlist.
- */
- result_plan->targetlist = sub_tlist;
- }
-
- /*
- * Also, account for the cost of evaluation of the sub_tlist.
- *
- * Up to now, we have only been dealing with "flat" tlists,
- * containing just Vars. So their evaluation cost is zero
- * according to the model used by cost_qual_eval() (or if you
- * prefer, the cost is factored into cpu_tuple_cost). Thus we
- * can avoid accounting for tlist cost throughout
- * query_planner() and subroutines. But now we've inserted a
- * tlist that might contain actual operators, sub-selects, etc
- * --- so we'd better account for its cost.
- *
- * 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.
- */
- cost_qual_eval(&tlist_cost, sub_tlist);
- result_plan->startup_cost += tlist_cost.startup;
- result_plan->total_cost += tlist_cost.startup +
- tlist_cost.per_tuple * result_plan->plan_rows;
+ current_pathkeys = NIL;
}
else
{
/*
- * Since we're using query_planner's tlist and not the one
- * make_subplanTargetList calculated, we have to refigure any
- * grouping-column indexes make_subplanTargetList computed.
+ * Normal case --- create a plan according to query_planner's
+ * results.
*/
- locate_grouping_columns(parse, tlist, result_plan->targetlist,
- groupColIdx);
- }
-
- /*
- * Insert AGG or GROUP node if needed, plus an explicit sort step
- * if necessary.
- *
- * HAVING clause, if any, becomes qual of the Agg node
- */
- if (use_hashed_grouping)
- {
- /* Hashed aggregate plan --- no sort needed */
- result_plan = (Plan *) make_agg(parse,
- tlist,
- (List *) parse->havingQual,
- AGG_HASHED,
- numGroupCols,
- groupColIdx,
- numGroups,
- numAggs,
- result_plan);
- /* Hashed aggregation produces randomly-ordered results */
- current_pathkeys = NIL;
- }
- else if (parse->hasAggs)
- {
- /* Plain aggregate plan --- sort if needed */
- AggStrategy aggstrategy;
+ result_plan = create_plan(root, best_path);
+ current_pathkeys = best_path->pathkeys;
- if (parse->groupClause)
+ /*
+ * create_plan() returns a plan with just a "flat" tlist of
+ * required Vars. Usually we need to insert the sub_tlist as the
+ * tlist of the top plan node. However, we can skip that if we
+ * determined that whatever query_planner chose to return will be
+ * good enough.
+ */
+ if (need_tlist_eval)
{
- if (!pathkeys_contained_in(group_pathkeys, current_pathkeys))
+ /*
+ * If the top-level plan node is one that cannot do expression
+ * evaluation, we must insert a Result node to project the
+ * desired tlist.
+ */
+ if (!is_projection_capable_plan(result_plan))
{
- result_plan = (Plan *)
- make_sort_from_groupcols(parse,
- parse->groupClause,
- groupColIdx,
- result_plan);
- current_pathkeys = group_pathkeys;
+ result_plan = (Plan *) make_result(sub_tlist, NULL,
+ result_plan);
+ }
+ else
+ {
+ /*
+ * Otherwise, just replace the subplan's flat tlist with
+ * the desired tlist.
+ */
+ result_plan->targetlist = sub_tlist;
}
- aggstrategy = AGG_SORTED;
/*
- * The AGG node will not change the sort ordering of its
- * groups, so current_pathkeys describes the result too.
+ * Also, account for the cost of evaluation of the sub_tlist.
+ *
+ * Up to now, we have only been dealing with "flat" tlists,
+ * containing just Vars. So their evaluation cost is zero
+ * according to the model used by cost_qual_eval() (or if you
+ * prefer, the cost is factored into cpu_tuple_cost). Thus we
+ * can avoid accounting for tlist cost throughout
+ * query_planner() and subroutines. But now we've inserted a
+ * tlist that might contain actual operators, sub-selects, etc
+ * --- so we'd better account for its cost.
+ *
+ * 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.
*/
+ cost_qual_eval(&tlist_cost, sub_tlist);
+ result_plan->startup_cost += tlist_cost.startup;
+ result_plan->total_cost += tlist_cost.startup +
+ tlist_cost.per_tuple * result_plan->plan_rows;
}
else
{
- aggstrategy = AGG_PLAIN;
- /* Result will be only one row anyway; no sort order */
- current_pathkeys = NIL;
+ /*
+ * Since we're using query_planner's tlist and not the one
+ * make_subplanTargetList calculated, we have to refigure any
+ * grouping-column indexes make_subplanTargetList computed.
+ */
+ locate_grouping_columns(root, tlist, result_plan->targetlist,
+ groupColIdx);
}
- result_plan = (Plan *) make_agg(parse,
- tlist,
- (List *) parse->havingQual,
- aggstrategy,
- numGroupCols,
- groupColIdx,
- numGroups,
- numAggs,
- result_plan);
- }
- else
- {
/*
- * If there are no Aggs, we shouldn't have any HAVING qual
- * anymore
+ * Insert AGG or GROUP node if needed, plus an explicit sort step
+ * if necessary.
+ *
+ * HAVING clause, if any, becomes qual of the Agg or Group node.
*/
- Assert(parse->havingQual == NULL);
+ if (use_hashed_grouping)
+ {
+ /* Hashed aggregate plan --- no sort needed */
+ result_plan = (Plan *) make_agg(root,
+ tlist,
+ (List *) parse->havingQual,
+ AGG_HASHED,
+ numGroupCols,
+ groupColIdx,
+ numGroups,
+ agg_counts.numAggs,
+ result_plan);
+ /* Hashed aggregation produces randomly-ordered results */
+ current_pathkeys = NIL;
+ }
+ else if (parse->hasAggs)
+ {
+ /* Plain aggregate plan --- sort if needed */
+ AggStrategy aggstrategy;
- /*
- * If we have a GROUP BY clause, insert a group node (plus the
- * appropriate sort node, if necessary).
- */
- if (parse->groupClause)
+ if (parse->groupClause)
+ {
+ if (!pathkeys_contained_in(group_pathkeys,
+ current_pathkeys))
+ {
+ result_plan = (Plan *)
+ make_sort_from_groupcols(root,
+ parse->groupClause,
+ groupColIdx,
+ result_plan);
+ current_pathkeys = group_pathkeys;
+ }
+ aggstrategy = AGG_SORTED;
+
+ /*
+ * The AGG node will not change the sort ordering of its
+ * groups, so current_pathkeys describes the result too.
+ */
+ }
+ else
+ {
+ aggstrategy = AGG_PLAIN;
+ /* Result will be only one row anyway; no sort order */
+ current_pathkeys = NIL;
+ }
+
+ result_plan = (Plan *) make_agg(root,
+ tlist,
+ (List *) parse->havingQual,
+ aggstrategy,
+ numGroupCols,
+ groupColIdx,
+ numGroups,
+ agg_counts.numAggs,
+ result_plan);
+ }
+ else if (parse->groupClause)
{
/*
+ * GROUP BY without aggregation, so insert a group node (plus
+ * the appropriate sort node, if necessary).
+ *
* 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))
{
result_plan = (Plan *)
- make_sort_from_groupcols(parse,
+ make_sort_from_groupcols(root,
parse->groupClause,
groupColIdx,
result_plan);
current_pathkeys = group_pathkeys;
}
- result_plan = (Plan *) make_group(parse,
+ result_plan = (Plan *) make_group(root,
tlist,
+ (List *) parse->havingQual,
numGroupCols,
groupColIdx,
dNumGroups,
result_plan);
/* The Group node won't change sort ordering */
}
- }
+ else if (root->hasHavingQual)
+ {
+ /*
+ * No aggregates, and no GROUP BY, but we have a HAVING qual.
+ * This is a degenerate case in which we are supposed to emit
+ * either 0 or 1 row 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 routine
+ * to avoid having to generate the plan in the first place.
+ */
+ result_plan = (Plan *) make_result(tlist,
+ parse->havingQual,
+ NULL);
+ }
+ } /* end of non-minmax-aggregate case */
} /* end of if (setOperations) */
/*
if (!pathkeys_contained_in(sort_pathkeys, current_pathkeys))
{
result_plan = (Plan *)
- make_sort_from_sortclauses(parse,
+ make_sort_from_sortclauses(root,
parse->sortClause,
result_plan);
current_pathkeys = sort_pathkeys;
* it's reasonable to assume the UNIQUE filter has effects
* comparable to GROUP BY.
*/
- if (!parse->groupClause && !parse->hasAggs)
+ if (!parse->groupClause && !root->hasHavingQual && !parse->hasAggs)
{
List *distinctExprs;
distinctExprs = get_sortgrouplist_exprs(parse->distinctClause,
parse->targetList);
- result_plan->plan_rows = estimate_num_groups(parse,
+ result_plan->plan_rows = estimate_num_groups(root,
distinctExprs,
result_plan->plan_rows);
}
* Return the actual output ordering in query_pathkeys for possible
* use by an outer query level.
*/
- parse->query_pathkeys = current_pathkeys;
+ root->query_pathkeys = current_pathkeys;
return result_plan;
}
+/*
+ * adjust_tuple_fraction_for_limit - adjust tuple fraction for LIMIT
+ *
+ * If the query contains LIMIT, we adjust the caller-supplied tuple_fraction
+ * accordingly. This is not overridable by the caller, since it reflects plan
+ * actions that grouping_planner() will certainly take, not assumptions about
+ * context.
+ */
+static double
+adjust_tuple_fraction_for_limit(PlannerInfo *root, double tuple_fraction)
+{
+ Query *parse = root->parse;
+ double limit_fraction = 0.0;
+
+ /* Should not be called unless LIMIT */
+ Assert(parse->limitCount != NULL);
+
+ /*
+ * A LIMIT clause limits the absolute number of tuples returned. However,
+ * if it's not a constant LIMIT then we have to punt; for lack of a better
+ * idea, assume 10% of the plan's result is wanted.
+ */
+ if (IsA(parse->limitCount, Const))
+ {
+ Const *limitc = (Const *) parse->limitCount;
+ int32 count = DatumGetInt32(limitc->constvalue);
+
+ /*
+ * A NULL-constant LIMIT represents "LIMIT ALL", which we treat the
+ * same as no limit (ie, expect to retrieve all the tuples).
+ */
+ if (!limitc->constisnull && count > 0)
+ {
+ limit_fraction = (double) count;
+ /* We must also consider the OFFSET, if present */
+ if (parse->limitOffset != NULL)
+ {
+ if (IsA(parse->limitOffset, Const))
+ {
+ int32 offset;
+
+ limitc = (Const *) parse->limitOffset;
+ offset = DatumGetInt32(limitc->constvalue);
+ if (!limitc->constisnull && offset > 0)
+ limit_fraction += (double) offset;
+ }
+ else
+ {
+ /* OFFSET is an expression ... punt ... */
+ limit_fraction = 0.10;
+ }
+ }
+ }
+ }
+ else
+ {
+ /* LIMIT is an expression ... punt ... */
+ limit_fraction = 0.10;
+ }
+
+ if (limit_fraction > 0.0)
+ {
+ /*
+ * If we have absolute limits from both caller and LIMIT, use the
+ * smaller value; if one is fractional and the other absolute,
+ * treat the fraction as a fraction of the absolute value;
+ * else we can multiply the two fractions together.
+ */
+ if (tuple_fraction >= 1.0)
+ {
+ if (limit_fraction >= 1.0)
+ {
+ /* both absolute */
+ tuple_fraction = Min(tuple_fraction, limit_fraction);
+ }
+ else
+ {
+ /* caller absolute, limit fractional */
+ tuple_fraction *= limit_fraction;
+ if (tuple_fraction < 1.0)
+ tuple_fraction = 1.0;
+ }
+ }
+ else if (tuple_fraction > 0.0)
+ {
+ if (limit_fraction >= 1.0)
+ {
+ /* caller fractional, limit absolute */
+ tuple_fraction *= limit_fraction;
+ if (tuple_fraction < 1.0)
+ tuple_fraction = 1.0;
+ }
+ else
+ {
+ /* both fractional */
+ tuple_fraction *= limit_fraction;
+ }
+ }
+ else
+ {
+ /* no info from caller, just use limit */
+ tuple_fraction = limit_fraction;
+ }
+ }
+
+ return tuple_fraction;
+}
+
+/*
+ * choose_hashed_grouping - should we use hashed grouping?
+ */
+static bool
+choose_hashed_grouping(PlannerInfo *root, double tuple_fraction,
+ Path *cheapest_path, Path *sorted_path,
+ List *sort_pathkeys, List *group_pathkeys,
+ double dNumGroups, AggClauseCounts *agg_counts)
+{
+ int numGroupCols = list_length(root->parse->groupClause);
+ double cheapest_path_rows;
+ int cheapest_path_width;
+ Size hashentrysize;
+ 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.)
+ */
+ 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
+ * work_mem.
+ *
+ * Beware here of the possibility that cheapest_path->parent is NULL.
+ * This could happen if user does something silly like
+ * SELECT 'foo' GROUP BY 1;
+ */
+ if (cheapest_path->parent)
+ {
+ cheapest_path_rows = cheapest_path->parent->rows;
+ cheapest_path_width = cheapest_path->parent->width;
+ }
+ else
+ {
+ cheapest_path_rows = 1; /* assume non-set result */
+ cheapest_path_width = 100; /* arbitrary */
+ }
+
+ /* Estimate per-hash-entry space at tuple width... */
+ hashentrysize = cheapest_path_width;
+ /* plus space for pass-by-ref transition values... */
+ hashentrysize += agg_counts->transitionSpace;
+ /* plus the per-hash-entry overhead */
+ hashentrysize += hash_agg_entry_size(agg_counts->numAggs);
+
+ if (hashentrysize * dNumGroups > 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
+ * cheapest_path + hashagg [+ final sort]
+ * versus either
+ * cheapest_path [+ sort] + group or agg [+ final sort]
+ * or
+ * presorted_path + group or agg [+ final sort]
+ * where brackets indicate a step that may not be needed. We assume
+ * query_planner() will have returned a presorted path only if it's a
+ * winner compared to cheapest_path for this purpose.
+ *
+ * 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, agg_counts->numAggs,
+ numGroupCols, dNumGroups,
+ cheapest_path->startup_cost, cheapest_path->total_cost,
+ cheapest_path_rows);
+ /* Result of hashed agg is always unsorted */
+ if (sort_pathkeys)
+ cost_sort(&hashed_p, root, sort_pathkeys, hashed_p.total_cost,
+ dNumGroups, cheapest_path_width);
+
+ if (sorted_path)
+ {
+ sorted_p.startup_cost = sorted_path->startup_cost;
+ sorted_p.total_cost = sorted_path->total_cost;
+ current_pathkeys = sorted_path->pathkeys;
+ }
+ else
+ {
+ sorted_p.startup_cost = cheapest_path->startup_cost;
+ sorted_p.total_cost = cheapest_path->total_cost;
+ current_pathkeys = cheapest_path->pathkeys;
+ }
+ if (!pathkeys_contained_in(group_pathkeys,
+ current_pathkeys))
+ {
+ cost_sort(&sorted_p, root, group_pathkeys, sorted_p.total_cost,
+ cheapest_path_rows, cheapest_path_width);
+ current_pathkeys = group_pathkeys;
+ }
+
+ if (root->parse->hasAggs)
+ cost_agg(&sorted_p, root, AGG_SORTED, agg_counts->numAggs,
+ numGroupCols, dNumGroups,
+ sorted_p.startup_cost, sorted_p.total_cost,
+ cheapest_path_rows);
+ else
+ cost_group(&sorted_p, root, numGroupCols, dNumGroups,
+ sorted_p.startup_cost, sorted_p.total_cost,
+ cheapest_path_rows);
+ /* The Agg or Group node will preserve ordering */
+ if (sort_pathkeys &&
+ !pathkeys_contained_in(sort_pathkeys, current_pathkeys))
+ cost_sort(&sorted_p, root, sort_pathkeys, sorted_p.total_cost,
+ dNumGroups, cheapest_path_width);
+
+ /*
+ * 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 /= dNumGroups;
+
+ if (compare_fractional_path_costs(&hashed_p, &sorted_p,
+ tuple_fraction) < 0)
+ {
+ /* Hashed is cheaper, so use it */
+ return true;
+ }
+ return false;
+}
+
/*
* hash_safe_grouping - are grouping operators hashable?
*
* is marked hashjoinable.
*/
static bool
-hash_safe_grouping(Query *parse)
+hash_safe_grouping(PlannerInfo *root)
{
- List *gl;
+ ListCell *gl;
- foreach(gl, parse->groupClause)
+ foreach(gl, root->parse->groupClause)
{
GroupClause *grpcl = (GroupClause *) lfirst(gl);
- TargetEntry *tle = get_sortgroupclause_tle(grpcl, parse->targetList);
+ TargetEntry *tle = get_sortgroupclause_tle(grpcl,
+ root->parse->targetList);
Operator optup;
bool oprcanhash;
- optup = equality_oper(tle->resdom->restype, true);
+ optup = equality_oper(exprType((Node *) tle->expr), true);
if (!optup)
return false;
oprcanhash = ((Form_pg_operator) GETSTRUCT(optup))->oprcanhash;
* make_subplanTargetList
* Generate appropriate target list when grouping is required.
*
- * When grouping_planner inserts Aggregate or Group plan nodes above
- * the result of query_planner, we typically want to pass a different
+ * When grouping_planner inserts Aggregate, Group, or Result plan nodes
+ * above the result of query_planner, we typically want to pass a different
* target list to query_planner than the outer plan nodes should have.
* This routine generates the correct target list for the subplan.
*
* The initial 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, if we are doing either
- * grouping or aggregation, we flatten all expressions except GROUP BY items
- * into their component variables; the other expressions will be computed by
- * the inserted nodes rather than by the subplan. For example,
- * given a query like
+ * variables to the subplan target list. Also, we flatten all expressions
+ * except GROUP BY items into their component variables; the other expressions
+ * will be computed by the inserted 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,a+b
* need to force it to be evaluated, because all the Vars it contains
* should be present in the output of query_planner anyway.
*
- * 'parse' is the query being processed.
* 'tlist' is the query's target list.
* 'groupColIdx' receives an array of column numbers for the GROUP BY
* expressions (if there are any) in the subplan's target list.
*---------------
*/
static List *
-make_subplanTargetList(Query *parse,
+make_subplanTargetList(PlannerInfo *root,
List *tlist,
AttrNumber **groupColIdx,
bool *need_tlist_eval)
{
+ Query *parse = root->parse;
List *sub_tlist;
List *extravars;
int numCols;
*groupColIdx = NULL;
/*
- * If we're not grouping or aggregating, nothing to do here;
+ * 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)
+ if (!parse->hasAggs && !parse->groupClause && !root->hasHavingQual)
{
*need_tlist_eval = true;
return tlist;
sub_tlist = flatten_tlist(tlist);
extravars = pull_var_clause(parse->havingQual, false);
sub_tlist = add_to_flat_tlist(sub_tlist, extravars);
- freeList(extravars);
+ list_free(extravars);
*need_tlist_eval = false; /* only eval if not flat tlist */
/*
* already), and make an array showing where the group columns are in
* the sub_tlist.
*/
- numCols = length(parse->groupClause);
+ numCols = list_length(parse->groupClause);
if (numCols > 0)
{
int keyno = 0;
AttrNumber *grpColIdx;
- List *gl;
+ ListCell *gl;
grpColIdx = (AttrNumber *) palloc(sizeof(AttrNumber) * numCols);
*groupColIdx = grpColIdx;
GroupClause *grpcl = (GroupClause *) lfirst(gl);
Node *groupexpr = get_sortgroupclause_expr(grpcl, tlist);
TargetEntry *te = NULL;
- List *sl;
+ ListCell *sl;
/* Find or make a matching sub_tlist entry */
foreach(sl, sub_tlist)
}
if (!sl)
{
- te = makeTargetEntry(makeResdom(length(sub_tlist) + 1,
- exprType(groupexpr),
- exprTypmod(groupexpr),
- NULL,
- false),
- (Expr *) groupexpr);
+ te = makeTargetEntry((Expr *) groupexpr,
+ list_length(sub_tlist) + 1,
+ NULL,
+ false);
sub_tlist = lappend(sub_tlist, te);
*need_tlist_eval = true; /* it's not flat anymore */
}
/* and save its resno */
- grpColIdx[keyno++] = te->resdom->resno;
+ grpColIdx[keyno++] = te->resno;
}
}
* by that routine and re-locate the grouping vars in the real sub_tlist.
*/
static void
-locate_grouping_columns(Query *parse,
+locate_grouping_columns(PlannerInfo *root,
List *tlist,
List *sub_tlist,
AttrNumber *groupColIdx)
{
int keyno = 0;
- List *gl;
+ ListCell *gl;
/*
* No work unless grouping.
*/
- if (!parse->groupClause)
+ if (!root->parse->groupClause)
{
Assert(groupColIdx == NULL);
return;
}
Assert(groupColIdx != NULL);
- foreach(gl, parse->groupClause)
+ foreach(gl, root->parse->groupClause)
{
GroupClause *grpcl = (GroupClause *) lfirst(gl);
Node *groupexpr = get_sortgroupclause_expr(grpcl, tlist);
TargetEntry *te = NULL;
- List *sl;
+ ListCell *sl;
foreach(sl, sub_tlist)
{
if (!sl)
elog(ERROR, "failed to locate grouping columns");
- groupColIdx[keyno++] = te->resdom->resno;
+ groupColIdx[keyno++] = te->resno;
}
}
static List *
postprocess_setop_tlist(List *new_tlist, List *orig_tlist)
{
- List *l;
+ ListCell *l;
+ ListCell *orig_tlist_item = list_head(orig_tlist);
foreach(l, new_tlist)
{
TargetEntry *orig_tle;
/* ignore resjunk columns in setop result */
- if (new_tle->resdom->resjunk)
+ if (new_tle->resjunk)
continue;
- Assert(orig_tlist != NIL);
- orig_tle = (TargetEntry *) lfirst(orig_tlist);
- orig_tlist = lnext(orig_tlist);
- if (orig_tle->resdom->resjunk) /* should not happen */
+ Assert(orig_tlist_item != NULL);
+ orig_tle = (TargetEntry *) lfirst(orig_tlist_item);
+ orig_tlist_item = lnext(orig_tlist_item);
+ if (orig_tle->resjunk) /* should not happen */
elog(ERROR, "resjunk output columns are not implemented");
- Assert(new_tle->resdom->resno == orig_tle->resdom->resno);
- Assert(new_tle->resdom->restype == orig_tle->resdom->restype);
- new_tle->resdom->ressortgroupref = orig_tle->resdom->ressortgroupref;
+ Assert(new_tle->resno == orig_tle->resno);
+ new_tle->ressortgroupref = orig_tle->ressortgroupref;
}
- if (orig_tlist != NIL)
+ if (orig_tlist_item != NULL)
elog(ERROR, "resjunk output columns are not implemented");
return new_tlist;
}
projects / postgresql / blobdiff