/*-------------------------------------------------------------------------
*
- * planner.c--
+ * planner.c
* The query optimizer external interface.
*
- * Copyright (c) 1994, Regents of the University of California
+ * Portions Copyright (c) 1996-2001, 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 1.30 1998/08/29 04:09:25 momjian Exp $
+ * $Header: /cvsroot/pgsql/src/backend/optimizer/plan/planner.c,v 1.117 2002/05/12 23:43:03 tgl Exp $
*
*-------------------------------------------------------------------------
*/
-#include <sys/types.h>
-#include <string.h>
#include "postgres.h"
-#include "nodes/pg_list.h"
-#include "nodes/plannodes.h"
-#include "nodes/parsenodes.h"
-#include "nodes/relation.h"
-#include "parser/parse_expr.h"
-
-#include "utils/elog.h"
-#include "utils/lsyscache.h"
-#include "access/heapam.h"
-
-#include "optimizer/internal.h"
+#include "catalog/pg_type.h"
+#include "nodes/makefuncs.h"
+#ifdef OPTIMIZER_DEBUG
+#include "nodes/print.h"
+#endif
+#include "optimizer/clauses.h"
+#include "optimizer/paths.h"
+#include "optimizer/planmain.h"
#include "optimizer/planner.h"
-#include "optimizer/plancat.h"
#include "optimizer/prep.h"
-#include "optimizer/planmain.h"
#include "optimizer/subselect.h"
-#include "optimizer/paths.h"
-#include "optimizer/cost.h"
-
-/* DATA STRUCTURE CREATION/MANIPULATION ROUTINES */
-#include "nodes/relation.h"
-#include "optimizer/clauseinfo.h"
-#include "optimizer/joininfo.h"
-#include "optimizer/keys.h"
-#include "optimizer/ordering.h"
-#include "optimizer/pathnode.h"
-#include "optimizer/clauses.h"
#include "optimizer/tlist.h"
#include "optimizer/var.h"
+#include "parser/analyze.h"
+#include "parser/parsetree.h"
+#include "parser/parse_expr.h"
+#include "rewrite/rewriteManip.h"
+#include "utils/lsyscache.h"
+
+
+/* Expression kind codes for preprocess_expression */
+#define EXPRKIND_TARGET 0
+#define EXPRKIND_WHERE 1
+#define EXPRKIND_HAVING 2
-#include "executor/executor.h"
-static Plan *make_sortplan(List *tlist, List *sortcls, Plan *plannode);
-extern Plan *
-make_groupPlan(List **tlist, bool tuplePerGroup,
- List *groupClause, Plan *subplan);
+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 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);
+static List *postprocess_setop_tlist(List *new_tlist, List *orig_tlist);
+
/*****************************************************************************
*
planner(Query *parse)
{
Plan *result_plan;
+ Index save_PlannerQueryLevel;
+ List *save_PlannerParamVar;
- PlannerQueryLevel = 1;
- PlannerVarParam = NULL;
- PlannerParamVar = NULL;
- PlannerInitPlan = NULL;
- PlannerPlanId = 0;
+ /*
+ * 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.
+ *
+ * Note we do NOT save and restore PlannerPlanId: it exists to assign
+ * unique IDs to SubPlan nodes, and we want those IDs to be unique for
+ * the life of a backend. Also, PlannerInitPlan is saved/restored in
+ * subquery_planner, not here.
+ */
+ save_PlannerQueryLevel = PlannerQueryLevel;
+ save_PlannerParamVar = PlannerParamVar;
- result_plan = union_planner(parse);
+ /* Initialize state for handling outer-level references and params */
+ PlannerQueryLevel = 0; /* will be 1 in top-level subquery_planner */
+ PlannerParamVar = NIL;
- Assert(PlannerQueryLevel == 1);
- if (PlannerPlanId > 0)
- {
- result_plan->initPlan = PlannerInitPlan;
- (void) SS_finalize_plan(result_plan);
- }
+ /* primary planning entry point (may recurse for subqueries) */
+ result_plan = subquery_planner(parse, -1.0 /* default case */ );
+
+ Assert(PlannerQueryLevel == 0);
+
+ /* executor wants to know total number of Params used overall */
result_plan->nParamExec = length(PlannerParamVar);
- return (result_plan);
+ /* final cleanup of the plan */
+ set_plan_references(parse, result_plan);
+
+ /* restore state for outer planner, if any */
+ PlannerQueryLevel = save_PlannerQueryLevel;
+ PlannerParamVar = save_PlannerParamVar;
+
+ return result_plan;
}
-/*
- * union_planner--
+
+/*--------------------
+ * subquery_planner
+ * Invokes the planner on a subquery. We recurse to here for each
+ * sub-SELECT found in the query tree.
*
- * Invokes the planner on union queries if there are any left,
- * recursing if necessary to get them all, then processes normal plans.
+ * 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 explained for grouping_planner, below.
*
- * Returns a query 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;
+ * that's not currently true, but we keep the separation between the two
+ * routines anyway, in case we need it again someday.
+ *
+ * subquery_planner will be called recursively to handle sub-Query nodes
+ * found within the query's expressions and rangetable.
*
+ * Returns a query plan.
+ *--------------------
*/
Plan *
-union_planner(Query *parse)
+subquery_planner(Query *parse, double tuple_fraction)
{
- List *tlist = parse->targetList;
+ List *saved_initplan = PlannerInitPlan;
+ int saved_planid = PlannerPlanId;
+ Plan *plan;
+ List *newHaving;
+ List *lst;
+
+ /* Set up for a new level of subquery */
+ PlannerQueryLevel++;
+ PlannerInitPlan = NIL;
+
+#ifdef ENABLE_KEY_SET_QUERY
+ /* this should go away sometime soon */
+ transformKeySetQuery(parse);
+#endif
+
+ /*
+ * 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);
- /* copy the original tlist, we will need the original one
- * for the AGG node later on */
- List *new_tlist = new_unsorted_tlist(tlist);
-
- List *rangetable = parse->rtable;
+ /*
+ * If so, we may have created opportunities to simplify the jointree.
+ */
+ parse->jointree = (FromExpr *)
+ preprocess_jointree(parse, (Node *) parse->jointree);
- Plan *result_plan = (Plan *) NULL;
+ /*
+ * Do expression preprocessing on targetlist and quals.
+ */
+ parse->targetList = (List *)
+ preprocess_expression(parse, (Node *) parse->targetList,
+ EXPRKIND_TARGET);
- Index rt_index;
+ preprocess_qual_conditions(parse, (Node *) parse->jointree);
+ parse->havingQual = preprocess_expression(parse, parse->havingQual,
+ EXPRKIND_HAVING);
- if (parse->unionClause)
- {
- result_plan = (Plan *) plan_union_queries(parse);
- /* XXX do we need to do this? bjm 12/19/97 */
- tlist = preprocess_targetlist(tlist,
- parse->commandType,
- parse->resultRelation,
- parse->rtable);
- }
- else if ((rt_index =
- first_inherit_rt_entry(rangetable)) != -1)
+ /*
+ * 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
+ * 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.
+ *
+ * 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.
+ */
+ newHaving = NIL;
+ foreach(lst, (List *) parse->havingQual)
{
- result_plan = (Plan *) plan_inherit_queries(parse, rt_index);
- /* XXX do we need to do this? bjm 12/19/97 */
- tlist = preprocess_targetlist(tlist,
- parse->commandType,
- parse->resultRelation,
- parse->rtable);
+ Node *havingclause = (Node *) lfirst(lst);
+
+ if (contain_agg_clause(havingclause))
+ newHaving = lappend(newHaving, havingclause);
+ else
+ parse->jointree->quals = (Node *)
+ lappend((List *) parse->jointree->quals, havingclause);
}
+ parse->havingQual = (Node *) newHaving;
+
+ /*
+ * 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)
+ 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.
+ */
+ if (PlannerPlanId != saved_planid || PlannerQueryLevel > 1)
{
- List **vpm = NULL;
-
- /* This is only necessary if aggregates are in use in queries like:
- * SELECT sid
- * FROM part
- * GROUP BY sid
- * HAVING MIN(pid) > 1; (pid is used but never selected for!!!)
- * because the function 'query_planner' creates the plan for the lefttree
- * of the 'GROUP' node and returns only those attributes contained in 'tlist'.
- * The original 'tlist' contains only 'sid' here and that's why we have to
- * to extend it to attributes which are not selected but are used in the
- * havingQual. */
-
- /* 'check_having_qual_for_vars' takes the havingQual and the actual 'tlist'
- * as arguments and recursively scans the havingQual for attributes
- * (VAR nodes) that are not contained in 'tlist' yet. If so, it creates
- * a new entry and attaches it to the list 'new_tlist' (consisting of the
- * VAR node and the RESDOM node as usual with tlists :-) ) */
- if (parse->hasAggs)
- {
- if (parse->havingQual != NULL)
+ (void) SS_finalize_plan(plan);
+
+ /*
+ * At the moment, SS_finalize_plan doesn't handle initPlans and so
+ * we assign them to the topmost plan node.
+ */
+ plan->initPlan = PlannerInitPlan;
+ /* Must add the initPlans' extParams to the topmost node's, too */
+ foreach(lst, plan->initPlan)
{
- new_tlist = check_having_qual_for_vars(parse->havingQual,new_tlist);
+ SubPlan *subplan = (SubPlan *) lfirst(lst);
+
+ plan->extParam = set_unioni(plan->extParam,
+ subplan->plan->extParam);
}
- }
-
- new_tlist = preprocess_targetlist(new_tlist,
- parse->commandType,
- parse->resultRelation,
- parse->rtable);
-
- /* Here starts the original (pre having) code */
- tlist = preprocess_targetlist(tlist,
- parse->commandType,
- parse->resultRelation,
- parse->rtable);
-
- if (parse->rtable != NULL)
- {
- vpm = (List **) palloc(length(parse->rtable) * sizeof(List *));
- memset(vpm, 0, length(parse->rtable) * sizeof(List *));
- }
- PlannerVarParam = lcons(vpm, PlannerVarParam);
- result_plan = query_planner(parse,
- parse->commandType,
- new_tlist,
- (List *) parse->qual);
- PlannerVarParam = lnext(PlannerVarParam);
- if (vpm != NULL)
- pfree(vpm);
}
-
- /*
- * If we have a GROUP BY clause, insert a group node (with the
- * appropriate sort node.)
- */
- if (parse->groupClause)
+
+ /* Return to outer subquery context */
+ PlannerQueryLevel--;
+ PlannerInitPlan = saved_initplan;
+ /* we do NOT restore PlannerPlanId; that's not an oversight! */
+
+ 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))
{
- bool tuplePerGroup;
+ int varno = ((RangeTblRef *) jtnode)->rtindex;
+ RangeTblEntry *rte = rt_fetch(varno, parse->rtable);
+ Query *subquery = rte->subquery;
/*
- * 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.)
+ * 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.
*/
- tuplePerGroup = parse->hasAggs;
+ 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;
- /* Use 'new_tlist' instead of 'tlist' */
- result_plan =
- make_groupPlan(&new_tlist,
- tuplePerGroup,
- parse->groupClause,
- result_plan);
+ 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)
+{
/*
- * If aggregate is present, insert the agg node
+ * Let's just make sure it's a valid subselect ...
*/
- if (parse->hasAggs)
- {
- int old_length=0, new_length=0;
-
- /* Create the AGG node but use 'tlist' not 'new_tlist' as target list because we
- * don't want the additional attributes (only used for the havingQual, see above)
- * to show up in the result */
- result_plan = (Plan *) make_agg(tlist, result_plan);
+ 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;
- /*
- * set the varno/attno entries to the appropriate references to
- * the result tuple of the subplans.
- */
- ((Agg *) result_plan)->aggs =
- set_agg_tlist_references((Agg *) result_plan);
-
-
- if(parse->havingQual!=NULL)
- {
- List *clause;
- List **vpm = NULL;
-
-
- /* stuff copied from above to handle the use of attributes from outside
- * in subselects */
-
- if (parse->rtable != NULL)
- {
- vpm = (List **) palloc(length(parse->rtable) * sizeof(List *));
- memset(vpm, 0, length(parse->rtable) * sizeof(List *));
- }
- PlannerVarParam = lcons(vpm, PlannerVarParam);
-
- /* There is a subselect in the havingQual, so we have to process it
- * using the same function as for a subselect in 'where' */
- if (parse->hasSubLinks)
- {
- parse->havingQual = SS_process_sublinks((Node *) parse->havingQual);
- }
-
- /* convert the havingQual to conjunctive normal form (cnf) */
- parse->havingQual = (Node * ) cnfify((Expr *)(Node *) parse->havingQual,true);
-
- /* Calculate the opfids from the opnos (=select the correct functions for
- * the used VAR datatypes) */
- parse->havingQual = (Node * ) fix_opids((List *) parse->havingQual);
-
- ((Agg *) result_plan)->plan.qual=(List *) parse->havingQual;
-
- /* Check every clause of the havingQual for aggregates used and append
- * them to result_plan->aggs */
- foreach(clause, ((Agg *) result_plan)->plan.qual)
- {
- /* Make sure there are aggregates in the havingQual
- * if so, the list must be longer after check_having_qual_for_aggs */
- old_length=length(((Agg *) result_plan)->aggs);
-
- ((Agg *) result_plan)->aggs = nconc(((Agg *) result_plan)->aggs,
- check_having_qual_for_aggs((Node *) lfirst(clause),
- ((Agg *) result_plan)->plan.lefttree->targetlist,
- ((List *) parse->groupClause)));
-
- /* Have a look at the length of the returned list. If there is no
- * difference, no aggregates have been found and that means, that
- * the Qual belongs to the where clause */
- if (((new_length=length(((Agg *) result_plan)->aggs)) == old_length) ||
- (new_length == 0))
- {
- elog(ERROR,"This could have been done in a where clause!!");
- return (Plan *)NIL;
- }
- }
- PlannerVarParam = lnext(PlannerVarParam);
- if (vpm != NULL)
- pfree(vpm);
- }
- }
-
/*
- * For now, before we hand back the plan, check to see if there is a
- * user-specified sort that needs to be done. Eventually, this will
- * be moved into the guts of the planner s.t. user specified sorts
- * will be considered as part of the planning process. Since we can
- * only make use of user-specified sorts in special cases, we can do
- * the optimization step later.
+ * 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;
+}
- if (parse->uniqueFlag)
+/*
+ * 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)
{
- Plan *sortplan = make_sortplan(tlist, parse->sortClause, result_plan);
+ TargetEntry *tle = (TargetEntry *) lfirst(l);
+
+ /* ignore resjunk columns */
+ if (tle->resdom->resjunk)
+ continue;
- return ((Plan *) make_unique(tlist, sortplan, parse->uniqueFlag));
+ /* Okay if tlist item is a simple Var */
+ if (tle->expr && IsA(tle->expr, Var))
+ continue;
+
+ return false;
}
- else
+ 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))
{
- if (parse->sortClause)
- return (make_sortplan(tlist, parse->sortClause, result_plan));
- else
- return ((Plan *) result_plan);
+ /* 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));
}
/*
- * make_sortplan--
- * Returns a sortplan which is basically a SORT node attached to the
- * top of the plan returned from the planner. It also adds the
- * cost of sorting into the plan.
+ * 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.
*
- * sortkeys: ( resdom1 resdom2 resdom3 ...)
- * sortops: (sortop1 sortop2 sortop3 ...)
+ * 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 Plan *
-make_sortplan(List *tlist, List *sortcls, Plan *plannode)
+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(f->quals, subf->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,
+ * which can be a targetlist, a WHERE clause (including JOIN/ON
+ * conditions), or a HAVING clause.
+ */
+static Node *
+preprocess_expression(Query *parse, Node *expr, int kind)
{
- Plan *sortplan = (Plan *) NULL;
- List *temp_tlist = NIL;
- List *i = NIL;
- Resdom *resnode = (Resdom *) NULL;
- Resdom *resdom = (Resdom *) NULL;
- int keyno = 1;
+ bool has_join_rtes;
+ List *rt;
/*
- * First make a copy of the tlist so that we don't corrupt the the
- * original .
+ * 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);
- temp_tlist = new_unsorted_tlist(tlist);
-
- foreach(i, sortcls)
+ /*
+ * If it's a qual or havingQual, canonicalize it, and convert it to
+ * implicit-AND format.
+ *
+ * XXX Is there any value in re-applying eval_const_expressions after
+ * canonicalize_qual?
+ */
+ if (kind != EXPRKIND_TARGET)
{
- SortClause *sortcl = (SortClause *) lfirst(i);
-
- resnode = sortcl->resdom;
- resdom = tlist_resdom(temp_tlist, resnode);
+ expr = (Node *) canonicalize_qual((Expr *) expr, true);
- /*
- * Order the resdom keys and replace the operator OID for each key
- * with the regproc OID.
- */
- resdom->reskey = keyno;
- resdom->reskeyop = get_opcode(sortcl->opoid);
- keyno += 1;
+#ifdef OPTIMIZER_DEBUG
+ printf("After canonicalize_qual()\n");
+ pprint(expr);
+#endif
}
- sortplan = (Plan *) make_sort(temp_tlist,
- _TEMP_RELATION_ID_,
- (Plan *) plannode,
- length(sortcls));
+ /* 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);
/*
- * XXX Assuming that an internal sort has no. cost. This is wrong, but
- * given that at this point, we don't know the no. of tuples returned,
- * etc, we can't do better than to add a constant cost. This will be
- * fixed once we move the sort further into the planner, but for now
- * ... functionality....
+ * 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.
*/
+ has_join_rtes = false;
+ foreach(rt, parse->rtable)
+ {
+ RangeTblEntry *rte = lfirst(rt);
- sortplan->cost = plannode->cost;
+ if (rte->rtekind == RTE_JOIN)
+ {
+ has_join_rtes = true;
+ break;
+ }
+ }
+ if (has_join_rtes)
+ expr = flatten_join_alias_vars(expr, parse, false);
- return (sortplan);
+ return expr;
}
/*
- * pg_checkretval() -- check return value of a list of sql parse
- * trees.
+ * preprocess_qual_conditions
+ * Recursively scan the query's jointree and do subquery_planner's
+ * preprocessing work on each qual condition found therein.
+ */
+static void
+preprocess_qual_conditions(Query *parse, Node *jtnode)
+{
+ 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)
+ preprocess_qual_conditions(parse, lfirst(l));
+
+ f->quals = preprocess_expression(parse, f->quals, EXPRKIND_WHERE);
+ }
+ else if (IsA(jtnode, JoinExpr))
+ {
+ JoinExpr *j = (JoinExpr *) jtnode;
+
+ preprocess_qual_conditions(parse, j->larg);
+ preprocess_qual_conditions(parse, j->rarg);
+
+ j->quals = preprocess_expression(parse, j->quals, EXPRKIND_WHERE);
+ }
+ else
+ elog(ERROR, "preprocess_qual_conditions: unexpected node type %d",
+ nodeTag(jtnode));
+}
+
+/*--------------------
+ * inheritance_planner
+ * Generate a plan in the case where the result relation is an
+ * inheritance set.
*
- * The return value of a sql function is the value returned by
- * the final query in the function. We do some ad-hoc define-time
- * type checking here to be sure that the user is returning the
- * type he claims.
+ * We have to handle this case differently from cases where a source
+ * relation is an inheritance set. Source inheritance is expanded at
+ * the bottom of the plan tree (see allpaths.c), but target inheritance
+ * has to be expanded at the top. The reason is that for UPDATE, each
+ * target relation needs a different targetlist matching its own column
+ * set. (This is not so critical for DELETE, but for simplicity we treat
+ * inherited DELETE the same way.) Fortunately, the UPDATE/DELETE target
+ * 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.
+ *--------------------
*/
-void
-pg_checkretval(Oid rettype, QueryTreeList *queryTreeList)
+static Plan *
+inheritance_planner(Query *parse, List *inheritlist)
{
- Query *parse;
- List *tlist;
- List *rt;
- int cmd;
- Type typ;
- Resdom *resnode;
- Relation reln;
- Oid relid;
- Oid tletype;
- int relnatts;
- int i;
-
- /* find the final query */
- parse = queryTreeList->qtrees[queryTreeList->len - 1];
+ int parentRTindex = parse->resultRelation;
+ Oid parentOID = getrelid(parentRTindex, parse->rtable);
+ List *subplans = NIL;
+ List *tlist = NIL;
+ List *l;
- /*
- * test 1: if the last query is a utility invocation, then there had
- * better not be a return value declared.
- */
- if (parse->commandType == CMD_UTILITY)
+ foreach(l, inheritlist)
+ {
+ int childRTindex = lfirsti(l);
+ Oid childOID = getrelid(childRTindex, parse->rtable);
+ Query *subquery;
+ Plan *subplan;
+
+ /* Generate modified query with this rel as target */
+ subquery = (Query *) adjust_inherited_attrs((Node *) parse,
+ parentRTindex, parentOID,
+ childRTindex, childOID);
+ /* Generate plan */
+ subplan = grouping_planner(subquery, 0.0 /* retrieve all tuples */ );
+ subplans = lappend(subplans, subplan);
+ /* 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;
+
+ return (Plan *) make_append(subplans, true, tlist);
+}
+
+/*--------------------
+ * grouping_planner
+ * Perform planning steps related to grouping, aggregation, etc.
+ * 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:
+ * < 0: determine fraction by inspection of query (normal case)
+ * 0: expect all tuples to be retrieved
+ * 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.
+ *--------------------
+ */
+static Plan *
+grouping_planner(Query *parse, double tuple_fraction)
+{
+ List *tlist = parse->targetList;
+ Plan *result_plan;
+ List *current_pathkeys;
+ List *group_pathkeys;
+ List *sort_pathkeys;
+ AttrNumber *groupColIdx = NULL;
+
+ if (parse->setOperations)
{
- if (rettype == InvalidOid)
- return;
+ /*
+ * 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);
+
+ /*
+ * We should not need to call preprocess_targetlist, since we must
+ * be in a SELECT query node. Instead, use the targetlist
+ * returned by plan_set_operations (since this tells whether it
+ * returned any resjunk columns!), and transfer any sort key
+ * information from the original tlist.
+ */
+ Assert(parse->commandType == CMD_SELECT);
+
+ tlist = postprocess_setop_tlist(result_plan->targetlist, tlist);
+
+ /*
+ * Can't handle FOR UPDATE here (parser should have checked
+ * already, but let's make sure).
+ */
+ if (parse->rowMarks)
+ elog(ERROR, "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;
+
+ /*
+ * Calculate pathkeys that represent grouping/ordering
+ * requirements (grouping should always be null, but...)
+ */
+ group_pathkeys = make_pathkeys_for_sortclauses(parse->groupClause,
+ tlist);
+ sort_pathkeys = make_pathkeys_for_sortclauses(parse->sortClause,
+ tlist);
+ }
+ else
+ {
+ List *sub_tlist;
+
+ /* Preprocess targetlist in case we are inside an INSERT/UPDATE. */
+ tlist = preprocess_targetlist(tlist,
+ parse->commandType,
+ parse->resultRelation,
+ parse->rtable);
+
+ /*
+ * 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)
+ elog(ERROR, "SELECT FOR UPDATE is not allowed in subselects");
+
+ foreach(l, parse->rowMarks)
+ {
+ Index rti = lfirsti(l);
+ char *resname;
+ Resdom *resdom;
+ Var *var;
+ TargetEntry *ctid;
+
+ resname = (char *) palloc(32);
+ sprintf(resname, "ctid%u", rti);
+ resdom = makeResdom(length(tlist) + 1,
+ TIDOID,
+ -1,
+ resname,
+ true);
+
+ var = makeVar(rti,
+ SelfItemPointerAttributeNumber,
+ TIDOID,
+ -1,
+ 0);
+
+ ctid = makeTargetEntry(resdom, (Node *) 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);
+
+ /*
+ * Calculate pathkeys that represent grouping/ordering
+ * requirements
+ */
+ group_pathkeys = make_pathkeys_for_sortclauses(parse->groupClause,
+ tlist);
+ sort_pathkeys = make_pathkeys_for_sortclauses(parse->sortClause,
+ tlist);
+
+ /*
+ * Figure out whether we need a sorted result from query_planner.
+ *
+ * If we have a GROUP BY clause, then we want a result sorted
+ * properly for grouping. Otherwise, if there is an ORDER BY
+ * clause, we want to sort by the ORDER BY clause. (Note: if we
+ * have both, and ORDER BY is a superset of GROUP BY, it would be
+ * tempting to request sort by ORDER BY --- but that might just
+ * leave us failing to exploit an available sort order at all.
+ * Needs more thought...)
+ */
+ if (parse->groupClause)
+ parse->query_pathkeys = group_pathkeys;
+ else if (parse->sortClause)
+ parse->query_pathkeys = sort_pathkeys;
else
- elog(ERROR, "return type mismatch in function decl: final query is a catalog utility");
+ 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
+ * 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;
+ }
+ }
+ }
+
+ if (parse->groupClause)
+ {
+ /*
+ * In GROUP BY mode, we have the little problem that we don't
+ * really know how many input tuples will be needed to make a
+ * group, so we can't translate an output LIMIT count into an
+ * input count. For lack of a better idea, assume 25% of the
+ * input data will be processed if there is any output limit.
+ * However, if the caller gave us a fraction rather than an
+ * absolute count, we can keep using that fraction (which
+ * amounts to assuming that all the groups are about the same
+ * size).
+ */
+ if (tuple_fraction >= 1.0)
+ tuple_fraction = 0.25;
+
+ /*
+ * If both GROUP BY and ORDER BY are specified, we will need
+ * two levels of sort --- and, therefore, certainly need to
+ * read all the input tuples --- unless ORDER BY is a subset
+ * of GROUP BY. (We have not yet canonicalized the pathkeys,
+ * so must use the slower noncanonical comparison method.)
+ */
+ if (parse->groupClause && parse->sortClause &&
+ !noncanonical_pathkeys_contained_in(sort_pathkeys,
+ group_pathkeys))
+ tuple_fraction = 0.0;
+ }
+ else if (parse->hasAggs)
+ {
+ /*
+ * Ungrouped aggregate will certainly want all the input
+ * tuples.
+ */
+ tuple_fraction = 0.0;
+ }
+ else if (parse->distinctClause)
+ {
+ /*
+ * SELECT DISTINCT, like GROUP, will absorb an unpredictable
+ * number of input tuples per output tuple. Handle the same
+ * way.
+ */
+ if (tuple_fraction >= 1.0)
+ tuple_fraction = 0.25;
+ }
+
+ /* Generate the basic plan for this Query */
+ result_plan = query_planner(parse,
+ sub_tlist,
+ tuple_fraction);
+
+ /*
+ * query_planner returns actual sort order (which is not
+ * necessarily what we requested) in query_pathkeys.
+ */
+ current_pathkeys = parse->query_pathkeys;
}
- /* okay, it's an ordinary query */
- tlist = parse->targetList;
- rt = parse->rtable;
- cmd = parse->commandType;
+ /*
+ * 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);
/*
- * test 2: if the function is declared to return no value, then the
- * final query had better not be a retrieve.
+ * If we have a GROUP BY clause, insert a group node (plus the
+ * appropriate sort node, if necessary).
*/
- if (rettype == InvalidOid)
+ if (parse->groupClause)
{
- if (cmd == CMD_SELECT)
- elog(ERROR,
- "function declared with no return type, but final query is a retrieve");
+ bool tuplePerGroup;
+ List *group_tlist;
+ bool is_sorted;
+
+ /*
+ * 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 :-(
+ */
+ tuplePerGroup = parse->hasAggs;
+
+ /*
+ * 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.
+ */
+ if (parse->hasAggs)
+ group_tlist = new_unsorted_tlist(result_plan->targetlist);
else
- return;
- }
+ group_tlist = tlist;
+
+ /*
+ * Figure out whether the path result is already ordered the way
+ * we need it --- if so, no need for an explicit sort step.
+ */
+ if (pathkeys_contained_in(group_pathkeys, current_pathkeys))
+ {
+ is_sorted = true; /* no sort needed now */
+ /* current_pathkeys remains unchanged */
+ }
+ 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.
+ */
+ is_sorted = false;
+ current_pathkeys = group_pathkeys;
+ }
- /* by here, the function is declared to return some type */
- if ((typ = typeidType(rettype)) == NULL)
- elog(ERROR, "can't find return type %d for function\n", rettype);
+ result_plan = make_groupplan(parse,
+ group_tlist,
+ tuplePerGroup,
+ parse->groupClause,
+ groupColIdx,
+ is_sorted,
+ result_plan);
+ }
/*
- * test 3: if the function is declared to return a value, then the
- * final query had better be a retrieve.
+ * If aggregate is present, insert the Agg node
+ *
+ * HAVING clause, if any, becomes qual of the Agg node
*/
- if (cmd != CMD_SELECT)
- elog(ERROR, "function declared to return type %s, but final query is not a retrieve", typeTypeName(typ));
+ 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);
+ }
/*
- * test 4: for base type returns, the target list should have exactly
- * one entry, and its type should agree with what the user declared.
+ * If we were not able to make the plan come out in the right order,
+ * add an explicit sort step.
*/
-
- if (typeTypeRelid(typ) == InvalidOid)
+ if (parse->sortClause)
{
- if (ExecTargetListLength(tlist) > 1)
- elog(ERROR, "function declared to return %s returns multiple values in final retrieve", typeTypeName(typ));
-
- resnode = (Resdom *) ((TargetEntry *) lfirst(tlist))->resdom;
- if (resnode->restype != rettype)
- elog(ERROR, "return type mismatch in function: declared to return %s, returns %s", typeTypeName(typ), typeidTypeName(resnode->restype));
-
- /* by here, base return types match */
- return;
+ if (!pathkeys_contained_in(sort_pathkeys, current_pathkeys))
+ result_plan = make_sortplan(parse, tlist, result_plan,
+ parse->sortClause);
}
/*
- * If the target list is of length 1, and the type of the varnode in
- * the target list is the same as the declared return type, this is
- * okay. This can happen, for example, where the body of the function
- * is 'retrieve (x = func2())', where func2 has the same return type
- * as the function that's calling it.
+ * If there is a DISTINCT clause, add the UNIQUE node.
*/
- if (ExecTargetListLength(tlist) == 1)
+ if (parse->distinctClause)
{
- resnode = (Resdom *) ((TargetEntry *) lfirst(tlist))->resdom;
- if (resnode->restype == rettype)
- return;
+ result_plan = (Plan *) make_unique(tlist, result_plan,
+ parse->distinctClause);
}
/*
- * By here, the procedure returns a (set of) tuples. This part of the
- * typechecking is a hack. We look up the relation that is the
- * declared return type, and be sure that attributes 1 .. n in the
- * target list match the declared types.
+ * Finally, if there is a LIMIT/OFFSET clause, add the LIMIT node.
*/
- reln = heap_open(typeTypeRelid(typ));
+ if (parse->limitOffset || parse->limitCount)
+ {
+ result_plan = (Plan *) make_limit(tlist, result_plan,
+ parse->limitOffset,
+ parse->limitCount);
+ }
+
+ return result_plan;
+}
+
+/*---------------
+ * make_subplanTargetList
+ * Generate appropriate target list when grouping is required.
+ *
+ * When grouping_planner inserts Aggregate and/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 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
+ * 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
+ * where the a+b target will be used by the Sort/Group steps, and the
+ * other targets will be used for computing the final results. (In the
+ * above example we could theoretically suppress the a and b targets and
+ * pass down only c,d,a+b, but it's not really worth the trouble to
+ * eliminate simple var references from the subplan. We will avoid doing
+ * the extra computation to recompute a+b at the outer level; see
+ * replace_vars_with_subplan_refs() in setrefs.c.)
+ *
+ * '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.
+ *
+ * The result is the targetlist to be passed to the subplan.
+ *---------------
+ */
+static List *
+make_subplanTargetList(Query *parse,
+ List *tlist,
+ AttrNumber **groupColIdx)
+{
+ List *sub_tlist;
+ List *extravars;
+ int numCols;
- if (!RelationIsValid(reln))
- elog(ERROR, "cannot open relation relid %d", typeTypeRelid(typ));
+ *groupColIdx = NULL;
- relid = reln->rd_id;
- relnatts = reln->rd_rel->relnatts;
+ /*
+ * 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)
+ return tlist;
- if (ExecTargetListLength(tlist) != relnatts)
- elog(ERROR, "function declared to return type %s does not retrieve (%s.*)", typeTypeName(typ), typeTypeName(typ));
+ /*
+ * Otherwise, start with a "flattened" tlist (having just the vars
+ * mentioned in the targetlist and HAVING qual --- but not upper-
+ * level Vars; they will be replaced by Params later on).
+ */
+ sub_tlist = flatten_tlist(tlist);
+ extravars = pull_var_clause(parse->havingQual, false);
+ sub_tlist = add_to_flat_tlist(sub_tlist, extravars);
+ freeList(extravars);
- /* expect attributes 1 .. n in order */
- for (i = 1; i <= relnatts; i++)
+ /*
+ * If grouping, create sub_tlist entries for all GROUP BY expressions
+ * (GROUP BY items that are simple Vars should be in the list
+ * already), and make an array showing where the group columns are in
+ * the sub_tlist.
+ */
+ numCols = length(parse->groupClause);
+ if (numCols > 0)
{
- TargetEntry *tle = lfirst(tlist);
- Node *thenode = tle->expr;
-
- tlist = lnext(tlist);
- tletype = exprType(thenode);
-
-#if 0 /* fix me */
- /* this is tedious */
- if (IsA(thenode, Var))
- tletype = (Oid) ((Var *) thenode)->vartype;
- else if (IsA(thenode, Const))
- tletype = (Oid) ((Const *) thenode)->consttype;
- else if (IsA(thenode, Param))
- tletype = (Oid) ((Param *) thenode)->paramtype;
- else if (IsA(thenode, Expr))
- tletype = Expr;
-
- else if (IsA(thenode, LispList))
+ int keyno = 0;
+ AttrNumber *grpColIdx;
+ List *gl;
+
+ grpColIdx = (AttrNumber *) palloc(sizeof(AttrNumber) * numCols);
+ *groupColIdx = grpColIdx;
+
+ foreach(gl, parse->groupClause)
{
- thenode = lfirst(thenode);
- if (IsA(thenode, Oper))
- tletype = (Oid) get_opresulttype((Oper *) thenode);
- else if (IsA(thenode, Func))
- tletype = (Oid) get_functype((Func *) thenode);
- else
- elog(ERROR, "function declared to return type %s does not retrieve (%s.all)", typeTypeName(typ), typeTypeName(typ));
+ GroupClause *grpcl = (GroupClause *) lfirst(gl);
+ Node *groupexpr = get_sortgroupclause_expr(grpcl, tlist);
+ TargetEntry *te = NULL;
+ List *sl;
+
+ /* Find or make a matching sub_tlist entry */
+ foreach(sl, sub_tlist)
+ {
+ te = (TargetEntry *) lfirst(sl);
+ if (equal(groupexpr, te->expr))
+ break;
+ }
+ if (!sl)
+ {
+ te = makeTargetEntry(makeResdom(length(sub_tlist) + 1,
+ exprType(groupexpr),
+ exprTypmod(groupexpr),
+ NULL,
+ false),
+ groupexpr);
+ sub_tlist = lappend(sub_tlist, te);
+ }
+
+ /* and save its resno */
+ grpColIdx[keyno++] = te->resdom->resno;
}
- else
- elog(ERROR, "function declared to return type %s does not retrieve (%s.all)", typeTypeName(typ), typeTypeName(typ));
-#endif
- /* reach right in there, why don't you? */
- if (tletype != reln->rd_att->attrs[i - 1]->atttypid)
- elog(ERROR, "function declared to return type %s does not retrieve (%s.all)", typeTypeName(typ), typeTypeName(typ));
}
- heap_close(reln);
+ return sub_tlist;
+}
+
+/*
+ * 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);
+ }
- /* success */
- return;
+ return (Plan *) make_group(group_tlist, tuplePerGroup, numCols,
+ grpColIdx, subplan);
}
+/*
+ * make_sortplan
+ * Add a Sort node to implement an explicit ORDER BY clause.
+ */
+Plan *
+make_sortplan(Query *parse, List *tlist, Plan *plannode, List *sortcls)
+{
+ List *sort_tlist;
+ List *i;
+ int keyno = 0;
+
+ /*
+ * First make a copy of the tlist so that we don't corrupt the
+ * original.
+ */
+ sort_tlist = new_unsorted_tlist(tlist);
+
+ foreach(i, sortcls)
+ {
+ SortClause *sortcl = (SortClause *) lfirst(i);
+ TargetEntry *tle = get_sortgroupclause_tle(sortcl, sort_tlist);
+ Resdom *resdom = tle->resdom;
+
+ /*
+ * 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)
+ {
+ /* OK, insert the ordering info needed by the executor. */
+ resdom->reskey = ++keyno;
+ resdom->reskeyop = sortcl->sortop;
+ }
+ }
+
+ Assert(keyno > 0);
+ return (Plan *) make_sort(parse, sort_tlist, plannode, keyno);
+}
+/*
+ * postprocess_setop_tlist
+ * Fix up targetlist returned by plan_set_operations().
+ *
+ * We need to transpose sort key info from the orig_tlist into new_tlist.
+ * NOTE: this would not be good enough if we supported resjunk sort keys
+ * for results of set operations --- then, we'd need to project a whole
+ * new tlist to evaluate the resjunk columns. For now, just elog if we
+ * find any resjunk columns in orig_tlist.
+ */
+static List *
+postprocess_setop_tlist(List *new_tlist, List *orig_tlist)
+{
+ List *l;
+
+ foreach(l, new_tlist)
+ {
+ TargetEntry *new_tle = (TargetEntry *) lfirst(l);
+ TargetEntry *orig_tle;
+
+ /* ignore resjunk columns in setop result */
+ if (new_tle->resdom->resjunk)
+ continue;
+
+ 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");
+ 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");
+ return new_tlist;
+}
projects / postgresql / blobdiff