* planner.c
* The query optimizer external interface.
*
- * Portions Copyright (c) 1996-2001, PostgreSQL Global Development Group
+ * Portions Copyright (c) 1996-2002, PostgreSQL Global Development Group
* Portions Copyright (c) 1994, Regents of the University of California
*
*
* IDENTIFICATION
- * $Header: /cvsroot/pgsql/src/backend/optimizer/plan/planner.c,v 1.121 2002/06/16 00:09:11 momjian Exp $
+ * $Header: /cvsroot/pgsql/src/backend/optimizer/plan/planner.c,v 1.157 2003/07/25 00:01:07 tgl Exp $
*
*-------------------------------------------------------------------------
*/
#include "postgres.h"
+#include <limits.h>
+
+#include "catalog/pg_operator.h"
#include "catalog/pg_type.h"
+#include "executor/executor.h"
+#include "miscadmin.h"
#include "nodes/makefuncs.h"
#ifdef OPTIMIZER_DEBUG
#include "nodes/print.h"
#endif
#include "optimizer/clauses.h"
+#include "optimizer/cost.h"
+#include "optimizer/pathnode.h"
#include "optimizer/paths.h"
#include "optimizer/planmain.h"
#include "optimizer/planner.h"
#include "parser/analyze.h"
#include "parser/parsetree.h"
#include "parser/parse_expr.h"
-#include "rewrite/rewriteManip.h"
-#include "utils/lsyscache.h"
+#include "parser/parse_oper.h"
+#include "utils/selfuncs.h"
+#include "utils/syscache.h"
/* Expression kind codes for preprocess_expression */
-#define EXPRKIND_TARGET 0
-#define EXPRKIND_WHERE 1
-#define EXPRKIND_HAVING 2
+#define EXPRKIND_QUAL 0
+#define EXPRKIND_TARGET 1
+#define EXPRKIND_RTFUNC 2
+#define EXPRKIND_LIMIT 3
+#define EXPRKIND_ININFO 4
-static Node *pull_up_subqueries(Query *parse, Node *jtnode,
- bool below_outer_join);
-static bool is_simple_subquery(Query *subquery);
-static bool has_nullable_targetlist(Query *subquery);
-static void resolvenew_in_jointree(Node *jtnode, int varno, List *subtlist);
-static Node *preprocess_jointree(Query *parse, Node *jtnode);
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,
- AttrNumber **groupColIdx);
-static Plan *make_groupplan(Query *parse,
- List *group_tlist, bool tuplePerGroup,
- List *groupClause, AttrNumber *grpColIdx,
- bool is_presorted, Plan *subplan);
+ AttrNumber **groupColIdx, bool *need_tlist_eval);
+static void locate_grouping_columns(Query *parse,
+ List *tlist,
+ List *sub_tlist,
+ AttrNumber *groupColIdx);
static List *postprocess_setop_tlist(List *new_tlist, List *orig_tlist);
*
*****************************************************************************/
Plan *
-planner(Query *parse)
+planner(Query *parse, bool isCursor, int cursorOptions)
{
+ double tuple_fraction;
Plan *result_plan;
Index save_PlannerQueryLevel;
- List *save_PlannerParamVar;
+ List *save_PlannerParamList;
/*
* The planner can be called recursively (an example is when
* subquery_planner, not here.
*/
save_PlannerQueryLevel = PlannerQueryLevel;
- save_PlannerParamVar = PlannerParamVar;
+ save_PlannerParamList = PlannerParamList;
/* Initialize state for handling outer-level references and params */
PlannerQueryLevel = 0; /* will be 1 in top-level subquery_planner */
- PlannerParamVar = NIL;
+ PlannerParamList = NIL;
+
+ /* Determine what fraction of the plan is likely to be scanned */
+ if (isCursor)
+ {
+ /*
+ * 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?)
+ */
+ tuple_fraction = 0.10;
+ }
+ else
+ {
+ /* Default assumption is we need all the tuples */
+ tuple_fraction = 0.0;
+ }
/* primary planning entry point (may recurse for subqueries) */
- result_plan = subquery_planner(parse, -1.0 /* default case */ );
+ result_plan = subquery_planner(parse, tuple_fraction);
Assert(PlannerQueryLevel == 0);
+ /*
+ * 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 (!ExecSupportsBackwardScan(result_plan))
+ result_plan = materialize_finished_plan(result_plan);
+ }
+
/* executor wants to know total number of Params used overall */
- result_plan->nParamExec = length(PlannerParamVar);
+ result_plan->nParamExec = length(PlannerParamList);
/* final cleanup of the plan */
set_plan_references(result_plan, parse->rtable);
/* restore state for outer planner, if any */
PlannerQueryLevel = save_PlannerQueryLevel;
- PlannerParamVar = save_PlannerParamVar;
+ PlannerParamList = save_PlannerParamList;
return result_plan;
}
{
List *saved_initplan = PlannerInitPlan;
int saved_planid = PlannerPlanId;
+ bool hasOuterJoins;
Plan *plan;
List *newHaving;
List *lst;
PlannerQueryLevel++;
PlannerInitPlan = NIL;
+ /*
+ * 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;
+ if (parse->hasSubLinks)
+ parse->jointree->quals = pull_up_IN_clauses(parse,
+ parse->jointree->quals);
+
/*
* Check to see if any subqueries in the rangetable can be merged into
* this query.
pull_up_subqueries(parse, (Node *) parse->jointree, false);
/*
- * If so, we may have created opportunities to simplify the jointree.
+ * 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 pull_up_subqueries, of course.
*/
- parse->jointree = (FromExpr *)
- preprocess_jointree(parse, (Node *) parse->jointree);
+ parse->hasJoinRTEs = false;
+ hasOuterJoins = false;
+ foreach(lst, parse->rtable)
+ {
+ RangeTblEntry *rte = (RangeTblEntry *) lfirst(lst);
+
+ if (rte->rtekind == RTE_JOIN)
+ {
+ parse->hasJoinRTEs = true;
+ if (IS_OUTER_JOIN(rte->jointype))
+ {
+ hasOuterJoins = true;
+ /* Can quit scanning once we find an outer join */
+ break;
+ }
+ }
+ }
/*
* Do expression preprocessing on targetlist and quals.
preprocess_qual_conditions(parse, (Node *) parse->jointree);
parse->havingQual = preprocess_expression(parse, parse->havingQual,
- EXPRKIND_HAVING);
+ EXPRKIND_QUAL);
+
+ parse->limitOffset = preprocess_expression(parse, parse->limitOffset,
+ EXPRKIND_LIMIT);
+ parse->limitCount = preprocess_expression(parse, parse->limitCount,
+ EXPRKIND_LIMIT);
+
+ parse->in_info_list = (List *)
+ preprocess_expression(parse, (Node *) parse->in_info_list,
+ EXPRKIND_ININFO);
/* Also need to preprocess expressions for function RTEs */
foreach(lst, parse->rtable)
if (rte->rtekind == RTE_FUNCTION)
rte->funcexpr = preprocess_expression(parse, rte->funcexpr,
- EXPRKIND_TARGET);
- /* These are not targetlist items, but close enough... */
+ EXPRKIND_RTFUNC);
}
- /*
- * Check for ungrouped variables passed to subplans in targetlist and
- * HAVING clause (but not in WHERE or JOIN/ON clauses, since those are
- * evaluated before grouping). We can't do this any earlier because
- * we must use the preprocessed targetlist for comparisons of grouped
- * expressions.
- */
- if (parse->hasSubLinks &&
- (parse->groupClause != NIL || parse->hasAggs))
- check_subplans_for_ungrouped_vars(parse);
-
/*
* A HAVING clause without aggregates is equivalent to a WHERE clause
* (except it can only refer to grouped fields). Transfer any
*
* Note that both havingQual and parse->jointree->quals are in
* implicitly-ANDed-list form at this point, even though they are
- * declared as Node *. Also note that contain_agg_clause does not
- * recurse into sub-selects, which is exactly what we need here.
+ * declared as Node *.
*/
newHaving = NIL;
foreach(lst, (List *) parse->havingQual)
}
parse->havingQual = (Node *) newHaving;
+ /*
+ * If we have any outer joins, try to reduce them to plain inner joins.
+ * This step is most easily done after we've done expression preprocessing.
+ */
+ if (hasOuterJoins)
+ reduce_outer_joins(parse);
+
+ /*
+ * See if we can simplify the jointree; opportunities for this may come
+ * from having pulled up subqueries, or from flattening explicit JOIN
+ * syntax. We must do this after flattening JOIN alias variables, since
+ * eliminating explicit JOIN nodes from the jointree will cause
+ * get_relids_for_join() to fail. But it should happen after
+ * reduce_outer_joins, anyway.
+ */
+ parse->jointree = (FromExpr *)
+ simplify_jointree(parse, (Node *) parse->jointree);
+
/*
* Do the main planning. If we have an inherited target relation,
* that needs special processing, else go straight to
* grouping_planner.
*/
if (parse->resultRelation &&
- (lst = expand_inherted_rtentry(parse, parse->resultRelation, false))
- != NIL)
+ (lst = expand_inherited_rtentry(parse, parse->resultRelation,
+ false)) != NIL)
plan = inheritance_planner(parse, lst);
else
plan = grouping_planner(parse, tuple_fraction);
/*
* If any subplans were generated, or if we're inside a subplan, build
- * subPlan, extParam and locParam lists for plan nodes.
+ * initPlan list and extParam/allParam sets for plan nodes.
*/
if (PlannerPlanId != saved_planid || PlannerQueryLevel > 1)
{
- (void) SS_finalize_plan(plan, parse->rtable);
+ Cost initplan_cost = 0;
+
+ /* Prepare extParam/allParam sets for all nodes in tree */
+ SS_finalize_plan(plan, parse->rtable);
/*
- * At the moment, SS_finalize_plan doesn't handle initPlans and so
- * we assign them to the topmost plan node.
+ * 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;
- /* Must add the initPlans' extParams to the topmost node's, too */
+
foreach(lst, plan->initPlan)
{
- SubPlan *subplan = (SubPlan *) lfirst(lst);
+ SubPlan *initplan = (SubPlan *) lfirst(lst);
- plan->extParam = set_unioni(plan->extParam,
- subplan->plan->extParam);
+ 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 to outer subquery context */
return plan;
}
-/*
- * pull_up_subqueries
- * Look for subqueries in the rangetable that can be pulled up into
- * the parent query. If the subquery has no special features like
- * grouping/aggregation then we can merge it into the parent's jointree.
- *
- * below_outer_join is true if this jointree node is within the nullable
- * side of an outer join. This restricts what we can do.
- *
- * A tricky aspect of this code is that if we pull up a subquery we have
- * to replace Vars that reference the subquery's outputs throughout the
- * parent query, including quals attached to jointree nodes above the one
- * we are currently processing! We handle this by being careful not to
- * change the jointree structure while recursing: no nodes other than
- * subquery RangeTblRef entries will be replaced. Also, we can't turn
- * ResolveNew loose on the whole jointree, because it'll return a mutated
- * copy of the tree; we have to invoke it just on the quals, instead.
- */
-static Node *
-pull_up_subqueries(Query *parse, Node *jtnode, bool below_outer_join)
-{
- if (jtnode == NULL)
- return NULL;
- if (IsA(jtnode, RangeTblRef))
- {
- int varno = ((RangeTblRef *) jtnode)->rtindex;
- RangeTblEntry *rte = rt_fetch(varno, parse->rtable);
- Query *subquery = rte->subquery;
-
- /*
- * Is this a subquery RTE, and if so, is the subquery simple
- * enough to pull up? (If not, do nothing at this node.)
- *
- * If we are inside an outer join, only pull up subqueries whose
- * targetlists are nullable --- otherwise substituting their tlist
- * entries for upper Var references would do the wrong thing
- * (the results wouldn't become NULL when they're supposed to).
- * XXX This could be improved by generating pseudo-variables for
- * such expressions; we'd have to figure out how to get the pseudo-
- * variables evaluated at the right place in the modified plan tree.
- * Fix it someday.
- *
- * Note: even if the subquery itself is simple enough, we can't pull
- * it up if there is a reference to its whole tuple result. Perhaps
- * a pseudo-variable is the answer here too.
- */
- if (rte->rtekind == RTE_SUBQUERY && is_simple_subquery(subquery) &&
- (!below_outer_join || has_nullable_targetlist(subquery)) &&
- !contain_whole_tuple_var((Node *) parse, varno, 0))
- {
- int rtoffset;
- List *subtlist;
- List *rt;
-
- /*
- * First, recursively pull up the subquery's subqueries, so
- * that this routine's processing is complete for its jointree
- * and rangetable. NB: if the same subquery is referenced
- * from multiple jointree items (which can't happen normally,
- * but might after rule rewriting), then we will invoke this
- * processing multiple times on that subquery. OK because
- * nothing will happen after the first time. We do have to be
- * careful to copy everything we pull up, however, or risk
- * having chunks of structure multiply linked.
- */
- subquery->jointree = (FromExpr *)
- pull_up_subqueries(subquery, (Node *) subquery->jointree,
- below_outer_join);
-
- /*
- * Now make a modifiable copy of the subquery that we can
- * run OffsetVarNodes on.
- */
- subquery = copyObject(subquery);
-
- /*
- * Adjust varnos in subquery so that we can append its
- * rangetable to upper query's.
- */
- rtoffset = length(parse->rtable);
- OffsetVarNodes((Node *) subquery, rtoffset, 0);
-
- /*
- * Replace all of the top query's references to the subquery's
- * outputs with copies of the adjusted subtlist items, being
- * careful not to replace any of the jointree structure.
- * (This'd be a lot cleaner if we could use query_tree_mutator.)
- */
- subtlist = subquery->targetList;
- parse->targetList = (List *)
- ResolveNew((Node *) parse->targetList,
- varno, 0, subtlist, CMD_SELECT, 0);
- resolvenew_in_jointree((Node *) parse->jointree, varno, subtlist);
- Assert(parse->setOperations == NULL);
- parse->havingQual =
- ResolveNew(parse->havingQual,
- varno, 0, subtlist, CMD_SELECT, 0);
-
- foreach(rt, parse->rtable)
- {
- RangeTblEntry *rte = (RangeTblEntry *) lfirst(rt);
-
- if (rte->rtekind == RTE_JOIN)
- rte->joinaliasvars = (List *)
- ResolveNew((Node *) rte->joinaliasvars,
- varno, 0, subtlist, CMD_SELECT, 0);
- }
-
- /*
- * Now append the adjusted rtable entries to upper query.
- * (We hold off until after fixing the upper rtable entries;
- * no point in running that code on the subquery ones too.)
- */
- parse->rtable = nconc(parse->rtable, subquery->rtable);
-
- /*
- * Pull up any FOR UPDATE markers, too. (OffsetVarNodes
- * already adjusted the marker values, so just nconc the list.)
- */
- parse->rowMarks = nconc(parse->rowMarks, subquery->rowMarks);
-
- /*
- * Miscellaneous housekeeping.
- */
- parse->hasSubLinks |= subquery->hasSubLinks;
- /* subquery won't be pulled up if it hasAggs, so no work there */
-
- /*
- * Return the adjusted subquery jointree to replace the
- * RangeTblRef entry in my jointree.
- */
- return (Node *) subquery->jointree;
- }
- }
- else if (IsA(jtnode, FromExpr))
- {
- FromExpr *f = (FromExpr *) jtnode;
- List *l;
-
- foreach(l, f->fromlist)
- lfirst(l) = pull_up_subqueries(parse, lfirst(l),
- below_outer_join);
- }
- else if (IsA(jtnode, JoinExpr))
- {
- JoinExpr *j = (JoinExpr *) jtnode;
-
- /* Recurse, being careful to tell myself when inside outer join */
- switch (j->jointype)
- {
- case JOIN_INNER:
- j->larg = pull_up_subqueries(parse, j->larg,
- below_outer_join);
- j->rarg = pull_up_subqueries(parse, j->rarg,
- below_outer_join);
- break;
- case JOIN_LEFT:
- j->larg = pull_up_subqueries(parse, j->larg,
- below_outer_join);
- j->rarg = pull_up_subqueries(parse, j->rarg,
- true);
- break;
- case JOIN_FULL:
- j->larg = pull_up_subqueries(parse, j->larg,
- true);
- j->rarg = pull_up_subqueries(parse, j->rarg,
- true);
- break;
- case JOIN_RIGHT:
- j->larg = pull_up_subqueries(parse, j->larg,
- true);
- j->rarg = pull_up_subqueries(parse, j->rarg,
- below_outer_join);
- break;
- case JOIN_UNION:
-
- /*
- * This is where we fail if upper levels of planner
- * haven't rewritten UNION JOIN as an Append ...
- */
- elog(ERROR, "UNION JOIN is not implemented yet");
- break;
- default:
- elog(ERROR, "pull_up_subqueries: unexpected join type %d",
- j->jointype);
- break;
- }
- }
- else
- elog(ERROR, "pull_up_subqueries: unexpected node type %d",
- nodeTag(jtnode));
- return jtnode;
-}
-
-/*
- * is_simple_subquery
- * Check a subquery in the range table to see if it's simple enough
- * to pull up into the parent query.
- */
-static bool
-is_simple_subquery(Query *subquery)
-{
- /*
- * Let's just make sure it's a valid subselect ...
- */
- if (!IsA(subquery, Query) ||
- subquery->commandType != CMD_SELECT ||
- subquery->resultRelation != 0 ||
- subquery->into != NULL ||
- subquery->isPortal)
- elog(ERROR, "is_simple_subquery: subquery is bogus");
-
- /*
- * Can't currently pull up a query with setops. Maybe after querytree
- * redesign...
- */
- if (subquery->setOperations)
- return false;
-
- /*
- * Can't pull up a subquery involving grouping, aggregation, sorting,
- * or limiting.
- */
- if (subquery->hasAggs ||
- subquery->groupClause ||
- subquery->havingQual ||
- subquery->sortClause ||
- subquery->distinctClause ||
- subquery->limitOffset ||
- subquery->limitCount)
- return false;
-
- /*
- * Don't pull up a subquery that has any set-returning functions in
- * its targetlist. Otherwise we might well wind up inserting
- * set-returning functions into places where they mustn't go,
- * such as quals of higher queries.
- */
- if (expression_returns_set((Node *) subquery->targetList))
- return false;
-
- /*
- * Hack: don't try to pull up a subquery with an empty jointree.
- * query_planner() will correctly generate a Result plan for a
- * jointree that's totally empty, but I don't think the right things
- * happen if an empty FromExpr appears lower down in a jointree. Not
- * worth working hard on this, just to collapse SubqueryScan/Result
- * into Result...
- */
- if (subquery->jointree->fromlist == NIL)
- return false;
-
- return true;
-}
-
-/*
- * has_nullable_targetlist
- * Check a subquery in the range table to see if all the non-junk
- * targetlist items are simple variables (and, hence, will correctly
- * go to NULL when examined above the point of an outer join).
- *
- * A possible future extension is to accept strict functions of simple
- * variables, eg, "x + 1".
- */
-static bool
-has_nullable_targetlist(Query *subquery)
-{
- List *l;
-
- foreach(l, subquery->targetList)
- {
- TargetEntry *tle = (TargetEntry *) lfirst(l);
-
- /* ignore resjunk columns */
- if (tle->resdom->resjunk)
- continue;
-
- /* Okay if tlist item is a simple Var */
- if (tle->expr && IsA(tle->expr, Var))
- continue;
-
- return false;
- }
- return true;
-}
-
-/*
- * Helper routine for pull_up_subqueries: do ResolveNew on every expression
- * in the jointree, without changing the jointree structure itself. Ugly,
- * but there's no other way...
- */
-static void
-resolvenew_in_jointree(Node *jtnode, int varno, List *subtlist)
-{
- if (jtnode == NULL)
- return;
- if (IsA(jtnode, RangeTblRef))
- {
- /* nothing to do here */
- }
- else if (IsA(jtnode, FromExpr))
- {
- FromExpr *f = (FromExpr *) jtnode;
- List *l;
-
- foreach(l, f->fromlist)
- resolvenew_in_jointree(lfirst(l), varno, subtlist);
- f->quals = ResolveNew(f->quals,
- varno, 0, subtlist, CMD_SELECT, 0);
- }
- else if (IsA(jtnode, JoinExpr))
- {
- JoinExpr *j = (JoinExpr *) jtnode;
-
- resolvenew_in_jointree(j->larg, varno, subtlist);
- resolvenew_in_jointree(j->rarg, varno, subtlist);
- j->quals = ResolveNew(j->quals,
- varno, 0, subtlist, CMD_SELECT, 0);
-
- /*
- * We don't bother to update the colvars list, since it won't be
- * used again ...
- */
- }
- else
- elog(ERROR, "resolvenew_in_jointree: unexpected node type %d",
- nodeTag(jtnode));
-}
-
-/*
- * preprocess_jointree
- * Attempt to simplify a query's jointree.
- *
- * If we succeed in pulling up a subquery then we might form a jointree
- * in which a FromExpr is a direct child of another FromExpr. In that
- * case we can consider collapsing the two FromExprs into one. This is
- * an optional conversion, since the planner will work correctly either
- * way. But we may find a better plan (at the cost of more planning time)
- * if we merge the two nodes.
- *
- * NOTE: don't try to do this in the same jointree scan that does subquery
- * pullup! Since we're changing the jointree structure here, that wouldn't
- * work reliably --- see comments for pull_up_subqueries().
- */
-static Node *
-preprocess_jointree(Query *parse, Node *jtnode)
-{
- if (jtnode == NULL)
- return NULL;
- if (IsA(jtnode, RangeTblRef))
- {
- /* nothing to do here... */
- }
- else if (IsA(jtnode, FromExpr))
- {
- FromExpr *f = (FromExpr *) jtnode;
- List *newlist = NIL;
- List *l;
-
- foreach(l, f->fromlist)
- {
- Node *child = (Node *) lfirst(l);
-
- /* Recursively simplify the child... */
- child = preprocess_jointree(parse, child);
- /* Now, is it a FromExpr? */
- if (child && IsA(child, FromExpr))
- {
- /*
- * Yes, so do we want to merge it into parent? Always do
- * so if child has just one element (since that doesn't
- * make the parent's list any longer). Otherwise we have
- * to be careful about the increase in planning time
- * caused by combining the two join search spaces into
- * one. Our heuristic is to merge if the merge will
- * produce a join list no longer than GEQO_RELS/2.
- * (Perhaps need an additional user parameter?)
- */
- FromExpr *subf = (FromExpr *) child;
- int childlen = length(subf->fromlist);
- int myothers = length(newlist) + length(lnext(l));
-
- if (childlen <= 1 || (childlen + myothers) <= geqo_rels / 2)
- {
- newlist = nconc(newlist, subf->fromlist);
- f->quals = make_and_qual(subf->quals, f->quals);
- }
- else
- newlist = lappend(newlist, child);
- }
- else
- newlist = lappend(newlist, child);
- }
- f->fromlist = newlist;
- }
- else if (IsA(jtnode, JoinExpr))
- {
- JoinExpr *j = (JoinExpr *) jtnode;
-
- /* Can't usefully change the JoinExpr, but recurse on children */
- j->larg = preprocess_jointree(parse, j->larg);
- j->rarg = preprocess_jointree(parse, j->rarg);
- }
- else
- elog(ERROR, "preprocess_jointree: unexpected node type %d",
- nodeTag(jtnode));
- return jtnode;
-}
-
/*
* preprocess_expression
* Do subquery_planner's preprocessing work for an expression,
static Node *
preprocess_expression(Query *parse, Node *expr, int kind)
{
- bool has_join_rtes;
- List *rt;
+ /*
+ * 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);
/*
* Simplify constant expressions.
*
* Note that at this point quals have not yet been converted to
* implicit-AND form, so we can apply eval_const_expressions directly.
- * Also note that we need to do this before SS_process_sublinks,
- * because that routine inserts bogus "Const" nodes.
*/
expr = eval_const_expressions(expr);
* XXX Is there any value in re-applying eval_const_expressions after
* canonicalize_qual?
*/
- if (kind != EXPRKIND_TARGET)
+ if (kind == EXPRKIND_QUAL)
{
expr = (Node *) canonicalize_qual((Expr *) expr, true);
/* Expand SubLinks to SubPlans */
if (parse->hasSubLinks)
- expr = SS_process_sublinks(expr);
-
- /* Replace uplevel vars with Param nodes */
- if (PlannerQueryLevel > 1)
- expr = SS_replace_correlation_vars(expr);
+ expr = SS_process_sublinks(expr, (kind == EXPRKIND_QUAL));
/*
- * If the query has any join RTEs, try to replace join alias variables
- * with base-relation variables, to allow quals to be pushed down.
- * We must do this after sublink processing, since it does not recurse
- * into sublinks.
- *
- * The flattening pass is expensive enough that it seems worthwhile to
- * scan the rangetable to see if we can avoid it.
+ * XXX do not insert anything here unless you have grokked the comments
+ * in SS_replace_correlation_vars ...
*/
- has_join_rtes = false;
- foreach(rt, parse->rtable)
- {
- RangeTblEntry *rte = lfirst(rt);
- if (rte->rtekind == RTE_JOIN)
- {
- has_join_rtes = true;
- break;
- }
- }
- if (has_join_rtes)
- expr = flatten_join_alias_vars(expr, parse->rtable, false);
+ /* Replace uplevel vars with Param nodes */
+ if (PlannerQueryLevel > 1)
+ expr = SS_replace_correlation_vars(expr);
return expr;
}
foreach(l, f->fromlist)
preprocess_qual_conditions(parse, lfirst(l));
- f->quals = preprocess_expression(parse, f->quals, EXPRKIND_WHERE);
+ f->quals = preprocess_expression(parse, f->quals, EXPRKIND_QUAL);
}
else if (IsA(jtnode, JoinExpr))
{
preprocess_qual_conditions(parse, j->larg);
preprocess_qual_conditions(parse, j->rarg);
- j->quals = preprocess_expression(parse, j->quals, EXPRKIND_WHERE);
+ j->quals = preprocess_expression(parse, j->quals, EXPRKIND_QUAL);
}
else
- elog(ERROR, "preprocess_qual_conditions: unexpected node type %d",
- nodeTag(jtnode));
+ elog(ERROR, "unrecognized node type: %d",
+ (int) nodeTag(jtnode));
}
/*--------------------
{
int parentRTindex = parse->resultRelation;
Oid parentOID = getrelid(parentRTindex, parse->rtable);
+ int mainrtlength = length(parse->rtable);
List *subplans = NIL;
List *tlist = NIL;
List *l;
{
int childRTindex = lfirsti(l);
Oid childOID = getrelid(childRTindex, parse->rtable);
+ int subrtlength;
Query *subquery;
Plan *subplan;
/* Generate plan */
subplan = grouping_planner(subquery, 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 is ugly. Really need to think about ways
+ * to rein in planner's habit of scribbling on its input.
+ */
+ subrtlength = length(subquery->rtable);
+ if (subrtlength > mainrtlength)
+ {
+ List *subrt = subquery->rtable;
+
+ while (mainrtlength-- > 0) /* wish we had nthcdr() */
+ subrt = lnext(subrt);
+ parse->rtable = nconc(parse->rtable, subrt);
+ mainrtlength = subrtlength;
+ }
/* Save preprocessed tlist from first rel for use in Append */
if (tlist == NIL)
tlist = subplan->targetlist;
/* Save the target-relations list for the executor, too */
parse->resultRelations = inheritlist;
+ /* Mark result as unordered (probably unnecessary) */
+ parse->query_pathkeys = NIL;
+
return (Plan *) make_append(subplans, true, tlist);
}
* tuple_fraction is the fraction of tuples we expect will be retrieved
*
* tuple_fraction is interpreted as follows:
- * < 0: determine fraction by inspection of query (normal case)
- * 0: expect all tuples to be retrieved
+ * 0: expect all tuples to be retrieved (normal case)
* 0 < tuple_fraction < 1: expect the given fraction of tuples available
* from the plan to be retrieved
* tuple_fraction >= 1: tuple_fraction is the absolute number of tuples
* expected to be retrieved (ie, a LIMIT specification)
- * The normal case is to pass -1, but some callers pass values >= 0 to
- * override this routine's determination of the appropriate fraction.
*
- * Returns a query plan.
+ * Returns a query plan. Also, parse->query_pathkeys is returned as the
+ * actual output ordering of the plan (in pathkey format).
*--------------------
*/
static Plan *
List *tlist = parse->targetList;
Plan *result_plan;
List *current_pathkeys;
- List *group_pathkeys;
List *sort_pathkeys;
- AttrNumber *groupColIdx = NULL;
if (parse->setOperations)
{
* already, but let's make sure).
*/
if (parse->rowMarks)
- elog(ERROR, "SELECT FOR UPDATE is not allowed with UNION/INTERSECT/EXCEPT");
+ 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
current_pathkeys = NIL;
/*
- * Calculate pathkeys that represent grouping/ordering
- * requirements (grouping should always be null, but...)
+ * Calculate pathkeys that represent ordering requirements
*/
- group_pathkeys = make_pathkeys_for_sortclauses(parse->groupClause,
- tlist);
sort_pathkeys = make_pathkeys_for_sortclauses(parse->sortClause,
tlist);
+ sort_pathkeys = canonicalize_pathkeys(parse, sort_pathkeys);
}
else
{
+ /* No set operations, do regular planning */
List *sub_tlist;
+ List *group_pathkeys;
+ AttrNumber *groupColIdx = NULL;
+ bool need_tlist_eval = true;
+ QualCost tlist_cost;
+ double sub_tuple_fraction;
+ Path *cheapest_path;
+ Path *sorted_path;
+ double dNumGroups = 0;
+ long numGroups = 0;
+ int numAggs = 0;
+ int numGroupCols = length(parse->groupClause);
+ bool use_hashed_grouping = false;
/* Preprocess targetlist in case we are inside an INSERT/UPDATE. */
tlist = preprocess_targetlist(tlist,
* level
*/
if (PlannerQueryLevel > 1)
- elog(ERROR, "SELECT FOR UPDATE is not allowed in subselects");
+ ereport(ERROR,
+ (errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
+ errmsg("SELECT FOR UPDATE is not allowed in subselects")));
foreach(l, parse->rowMarks)
{
TargetEntry *ctid;
resname = (char *) palloc(32);
- sprintf(resname, "ctid%u", rti);
+ snprintf(resname, 32, "ctid%u", rti);
resdom = makeResdom(length(tlist) + 1,
TIDOID,
-1,
-1,
0);
- ctid = makeTargetEntry(resdom, (Node *) var);
+ ctid = makeTargetEntry(resdom, (Expr *) var);
tlist = lappend(tlist, ctid);
}
}
* Generate appropriate target list for subplan; may be different
* from tlist if grouping or aggregation is needed.
*/
- sub_tlist = make_subplanTargetList(parse, tlist, &groupColIdx);
+ sub_tlist = make_subplanTargetList(parse, tlist,
+ &groupColIdx, &need_tlist_eval);
/*
* Calculate pathkeys that represent grouping/ordering
sort_pathkeys = make_pathkeys_for_sortclauses(parse->sortClause,
tlist);
+ /*
+ * 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.
+ */
+ if (parse->hasAggs)
+ {
+ numAggs = count_agg_clause((Node *) tlist) +
+ count_agg_clause(parse->havingQual);
+ if (numAggs == 0)
+ parse->hasAggs = false;
+ }
+
/*
* Figure out whether we need a sorted result from query_planner.
*
else
parse->query_pathkeys = NIL;
- /*
- * Figure out whether we expect to retrieve all the tuples that
- * the plan can generate, or to stop early due to outside factors
- * such as a cursor. If the caller passed a value >= 0, believe
- * that value, else do our own examination of the query context.
- */
- if (tuple_fraction < 0.0)
- {
- /* Initial assumption is we need all the tuples */
- tuple_fraction = 0.0;
-
- /*
- * Check for retrieve-into-portal, ie DECLARE CURSOR.
- *
- * 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?)
- */
- if (parse->isPortal)
- tuple_fraction = 0.10;
- }
-
/*
* Adjust tuple_fraction if we see that we are going to apply
* limiting/grouping/aggregation/etc. This is not overridable by
}
}
+ /*
+ * With grouping or aggregation, the tuple fraction to pass to
+ * query_planner() may be different from what it is at top level.
+ */
+ sub_tuple_fraction = tuple_fraction;
+
if (parse->groupClause)
{
/*
* amounts to assuming that all the groups are about the same
* size).
*/
- if (tuple_fraction >= 1.0)
- tuple_fraction = 0.25;
+ if (sub_tuple_fraction >= 1.0)
+ sub_tuple_fraction = 0.25;
/*
* If both GROUP BY and ORDER BY are specified, we will need
if (parse->groupClause && parse->sortClause &&
!noncanonical_pathkeys_contained_in(sort_pathkeys,
group_pathkeys))
- tuple_fraction = 0.0;
+ sub_tuple_fraction = 0.0;
}
else if (parse->hasAggs)
{
* Ungrouped aggregate will certainly want all the input
* tuples.
*/
- tuple_fraction = 0.0;
+ sub_tuple_fraction = 0.0;
}
else if (parse->distinctClause)
{
* number of input tuples per output tuple. Handle the same
* way.
*/
- if (tuple_fraction >= 1.0)
- tuple_fraction = 0.25;
+ if (sub_tuple_fraction >= 1.0)
+ sub_tuple_fraction = 0.25;
}
- /* Generate the basic plan for this Query */
- result_plan = query_planner(parse,
- sub_tlist,
- tuple_fraction);
+ /*
+ * 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,
+ &cheapest_path, &sorted_path);
/*
- * query_planner returns actual sort order (which is not
- * necessarily what we requested) in query_pathkeys.
+ * We couldn't canonicalize group_pathkeys and sort_pathkeys before
+ * running query_planner(), so do it now.
*/
- current_pathkeys = parse->query_pathkeys;
- }
+ group_pathkeys = canonicalize_pathkeys(parse, group_pathkeys);
+ sort_pathkeys = canonicalize_pathkeys(parse, sort_pathkeys);
- /*
- * 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);
+ /*
+ * Consider whether we might want to use hashed grouping.
+ */
+ if (parse->groupClause)
+ {
+ List *groupExprs;
+ double cheapest_path_rows;
+ int cheapest_path_width;
- /*
- * If we have a GROUP BY clause, insert a group node (plus the
- * appropriate sort node, if necessary).
- */
- if (parse->groupClause)
- {
- bool tuplePerGroup;
- List *group_tlist;
- bool is_sorted;
+ /*
+ * 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;
+ */
+ 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,
+ 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 SortMem, *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 <= SortMem * 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;
+ }
+ }
+ }
+ }
/*
- * Decide whether how many tuples per group the Group node needs
- * to return. (Needs only one tuple per group if no aggregate is
- * present. Otherwise, need every tuple from the group to do the
- * aggregation.) Note tuplePerGroup is named backwards :-(
+ * 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.
*/
- tuplePerGroup = parse->hasAggs;
+ if (sorted_path && !use_hashed_grouping)
+ {
+ result_plan = create_plan(parse, sorted_path);
+ current_pathkeys = sorted_path->pathkeys;
+ }
+ else
+ {
+ result_plan = create_plan(parse, cheapest_path);
+ current_pathkeys = cheapest_path->pathkeys;
+ }
/*
- * If there are aggregates then the Group node should just return
- * the same set of vars as the subplan did. If there are no aggs
- * then the Group node had better compute the final tlist.
+ * 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 (parse->hasAggs)
- group_tlist = new_unsorted_tlist(result_plan->targetlist);
+ if (need_tlist_eval)
+ {
+ /*
+ * If the top-level plan node is one that cannot do expression
+ * evaluation, we must insert a Result node to project the desired
+ * tlist.
+ * Currently, the only plan node we might see here that falls into
+ * that category is Append.
+ */
+ if (IsA(result_plan, Append))
+ {
+ 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;
+ }
else
- group_tlist = tlist;
+ {
+ /*
+ * 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(parse, tlist, result_plan->targetlist,
+ groupColIdx);
+ }
/*
- * Figure out whether the path result is already ordered the way
- * we need it --- if so, no need for an explicit sort step.
+ * 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 (pathkeys_contained_in(group_pathkeys, current_pathkeys))
+ if (use_hashed_grouping)
{
- is_sorted = true; /* no sort needed now */
- /* current_pathkeys remains unchanged */
+ /* 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;
+
+ if (parse->groupClause)
+ {
+ if (!pathkeys_contained_in(group_pathkeys, current_pathkeys))
+ {
+ result_plan = (Plan *)
+ make_sort_from_groupcols(parse,
+ 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(parse,
+ tlist,
+ (List *) parse->havingQual,
+ aggstrategy,
+ numGroupCols,
+ groupColIdx,
+ numGroups,
+ numAggs,
+ result_plan);
}
else
{
/*
- * We will need to do an explicit sort by the GROUP BY clause.
- * make_groupplan will do the work, but set current_pathkeys
- * to indicate the resulting order.
+ * If there are no Aggs, we shouldn't have any HAVING qual anymore
*/
- is_sorted = false;
- current_pathkeys = group_pathkeys;
- }
+ Assert(parse->havingQual == NULL);
- result_plan = make_groupplan(parse,
- group_tlist,
- tuplePerGroup,
- parse->groupClause,
- groupColIdx,
- is_sorted,
- result_plan);
- }
+ /*
+ * If we have a GROUP BY clause, insert a group node (plus the
+ * appropriate sort node, if necessary).
+ */
+ if (parse->groupClause)
+ {
+ /*
+ * 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,
+ parse->groupClause,
+ groupColIdx,
+ result_plan);
+ current_pathkeys = group_pathkeys;
+ }
- /*
- * If aggregate is present, insert the Agg node
- *
- * HAVING clause, if any, becomes qual of the Agg node
- */
- if (parse->hasAggs)
- {
- result_plan = (Plan *) make_agg(tlist,
- (List *) parse->havingQual,
- result_plan);
- /* Note: Agg does not affect any existing sort order of the tuples */
- }
- else
- {
- /* If there are no Aggs, we shouldn't have any HAVING qual anymore */
- Assert(parse->havingQual == NULL);
- }
+ result_plan = (Plan *) make_group(parse,
+ tlist,
+ numGroupCols,
+ groupColIdx,
+ dNumGroups,
+ result_plan);
+ /* The Group node won't change sort ordering */
+ }
+ }
+ } /* end of if (setOperations) */
/*
* If we were not able to make the plan come out in the right order,
if (parse->sortClause)
{
if (!pathkeys_contained_in(sort_pathkeys, current_pathkeys))
- result_plan = make_sortplan(parse, tlist, result_plan,
- parse->sortClause);
+ {
+ result_plan = (Plan *)
+ make_sort_from_sortclauses(parse,
+ tlist,
+ result_plan,
+ parse->sortClause);
+ current_pathkeys = sort_pathkeys;
+ }
}
/*
{
result_plan = (Plan *) make_unique(tlist, 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,
+ * it's reasonable to assume the UNIQUE filter has effects
+ * comparable to GROUP BY.
+ */
+ if (!parse->groupClause && !parse->hasAggs)
+ {
+ List *distinctExprs;
+
+ distinctExprs = get_sortgrouplist_exprs(parse->distinctClause,
+ parse->targetList);
+ result_plan->plan_rows = estimate_num_groups(parse,
+ distinctExprs,
+ result_plan->plan_rows);
+ }
}
/*
parse->limitCount);
}
+ /*
+ * Return the actual output ordering in query_pathkeys for possible
+ * use by an outer query level.
+ */
+ parse->query_pathkeys = current_pathkeys;
+
return result_plan;
}
+/*
+ * hash_safe_grouping - are grouping operators hashable?
+ *
+ * We assume hashed aggregation will work if the datatype's equality operator
+ * is marked hashjoinable.
+ */
+static bool
+hash_safe_grouping(Query *parse)
+{
+ List *gl;
+
+ foreach(gl, parse->groupClause)
+ {
+ GroupClause *grpcl = (GroupClause *) lfirst(gl);
+ TargetEntry *tle = get_sortgroupclause_tle(grpcl, parse->targetList);
+ Operator optup;
+ bool oprcanhash;
+
+ optup = equality_oper(tle->resdom->restype, false);
+ oprcanhash = ((Form_pg_operator) GETSTRUCT(optup))->oprcanhash;
+ ReleaseSysCache(optup);
+ if (!oprcanhash)
+ return false;
+ }
+ return true;
+}
+
/*---------------
* make_subplanTargetList
* Generate appropriate target list when grouping is required.
*
- * When grouping_planner inserts Aggregate and/or Group plan nodes above
+ * When grouping_planner inserts Aggregate or Group 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 extra computation to recompute a+b at the outer level; see
* replace_vars_with_subplan_refs() 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
+ * 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.
+ * expressions (if there are any) in the subplan's target list.
+ * 'need_tlist_eval' is set true if we really need to evaluate the
+ * result tlist.
*
* The result is the targetlist to be passed to the subplan.
*---------------
static List *
make_subplanTargetList(Query *parse,
List *tlist,
- AttrNumber **groupColIdx)
+ AttrNumber **groupColIdx,
+ bool *need_tlist_eval)
{
List *sub_tlist;
List *extravars;
* If we're not grouping or aggregating, nothing to do here;
* query_planner should receive the unmodified target list.
*/
- if (!parse->hasAggs && !parse->groupClause && !parse->havingQual)
+ if (!parse->hasAggs && !parse->groupClause)
+ {
+ *need_tlist_eval = true;
return tlist;
+ }
/*
* Otherwise, start with a "flattened" tlist (having just the vars
extravars = pull_var_clause(parse->havingQual, false);
sub_tlist = add_to_flat_tlist(sub_tlist, extravars);
freeList(extravars);
+ *need_tlist_eval = false; /* only eval if not flat tlist */
/*
* If grouping, create sub_tlist entries for all GROUP BY expressions
exprTypmod(groupexpr),
NULL,
false),
- groupexpr);
+ (Expr *) groupexpr);
sub_tlist = lappend(sub_tlist, te);
+ *need_tlist_eval = true; /* it's not flat anymore */
}
/* and save its resno */
}
/*
- * make_groupplan
- * Add a Group node for GROUP BY processing.
- * If we couldn't make the subplan produce presorted output for grouping,
- * first add an explicit Sort node.
- */
-static Plan *
-make_groupplan(Query *parse,
- List *group_tlist,
- bool tuplePerGroup,
- List *groupClause,
- AttrNumber *grpColIdx,
- bool is_presorted,
- Plan *subplan)
-{
- int numCols = length(groupClause);
-
- if (!is_presorted)
- {
- /*
- * The Sort node always just takes a copy of the subplan's tlist
- * plus ordering information. (This might seem inefficient if the
- * subplan contains complex GROUP BY expressions, but in fact Sort
- * does not evaluate its targetlist --- it only outputs the same
- * tuples in a new order. So the expressions we might be copying
- * are just dummies with no extra execution cost.)
- */
- List *sort_tlist = new_unsorted_tlist(subplan->targetlist);
- int keyno = 0;
- List *gl;
-
- foreach(gl, groupClause)
- {
- GroupClause *grpcl = (GroupClause *) lfirst(gl);
- TargetEntry *te = nth(grpColIdx[keyno] - 1, sort_tlist);
- Resdom *resdom = te->resdom;
-
- /*
- * Check for the possibility of duplicate group-by clauses ---
- * the parser should have removed 'em, but the Sort executor
- * will get terribly confused if any get through!
- */
- if (resdom->reskey == 0)
- {
- /* OK, insert the ordering info needed by the executor. */
- resdom->reskey = ++keyno;
- resdom->reskeyop = grpcl->sortop;
- }
- }
-
- Assert(keyno > 0);
-
- subplan = (Plan *) make_sort(parse, sort_tlist, subplan, keyno);
- }
-
- return (Plan *) make_group(group_tlist, tuplePerGroup, numCols,
- grpColIdx, subplan);
-}
-
-/*
- * make_sortplan
- * Add a Sort node to implement an explicit ORDER BY clause.
+ * locate_grouping_columns
+ * Locate grouping columns in the tlist chosen by query_planner.
+ *
+ * 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.
*/
-Plan *
-make_sortplan(Query *parse, List *tlist, Plan *plannode, List *sortcls)
+static void
+locate_grouping_columns(Query *parse,
+ List *tlist,
+ List *sub_tlist,
+ AttrNumber *groupColIdx)
{
- List *sort_tlist;
- List *i;
int keyno = 0;
+ List *gl;
/*
- * First make a copy of the tlist so that we don't corrupt the
- * original.
+ * No work unless grouping.
*/
- sort_tlist = new_unsorted_tlist(tlist);
+ if (!parse->groupClause)
+ {
+ Assert(groupColIdx == NULL);
+ return;
+ }
+ Assert(groupColIdx != NULL);
- foreach(i, sortcls)
+ foreach(gl, parse->groupClause)
{
- SortClause *sortcl = (SortClause *) lfirst(i);
- TargetEntry *tle = get_sortgroupclause_tle(sortcl, sort_tlist);
- Resdom *resdom = tle->resdom;
+ GroupClause *grpcl = (GroupClause *) lfirst(gl);
+ Node *groupexpr = get_sortgroupclause_expr(grpcl, tlist);
+ TargetEntry *te = NULL;
+ List *sl;
- /*
- * Check for the possibility of duplicate order-by clauses --- the
- * parser should have removed 'em, but the executor will get
- * terribly confused if any get through!
- */
- if (resdom->reskey == 0)
+ foreach(sl, sub_tlist)
{
- /* OK, insert the ordering info needed by the executor. */
- resdom->reskey = ++keyno;
- resdom->reskeyop = sortcl->sortop;
+ te = (TargetEntry *) lfirst(sl);
+ if (equal(groupexpr, te->expr))
+ break;
}
- }
-
- Assert(keyno > 0);
+ if (!sl)
+ elog(ERROR, "failed to locate grouping columns");
- return (Plan *) make_sort(parse, sort_tlist, plannode, keyno);
+ groupColIdx[keyno++] = te->resdom->resno;
+ }
}
/*
* We need to transpose sort key info from the orig_tlist into new_tlist.
* NOTE: this would not be good enough if we supported resjunk sort keys
* for results of set operations --- then, we'd need to project a whole
- * new tlist to evaluate the resjunk columns. For now, just elog if we
+ * new tlist to evaluate the resjunk columns. For now, just ereport if we
* find any resjunk columns in orig_tlist.
*/
static List *
Assert(orig_tlist != NIL);
orig_tle = (TargetEntry *) lfirst(orig_tlist);
orig_tlist = lnext(orig_tlist);
- if (orig_tle->resdom->resjunk)
- elog(ERROR, "postprocess_setop_tlist: resjunk output columns not implemented");
+ if (orig_tle->resdom->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;
}
if (orig_tlist != NIL)
- elog(ERROR, "postprocess_setop_tlist: resjunk output columns not implemented");
+ elog(ERROR, "resjunk output columns are not implemented");
return new_tlist;
}
projects / postgresql / blobdiff