* planner.c
* The query optimizer external interface.
*
- * Portions Copyright (c) 1996-2000, PostgreSQL, Inc
+ * 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 1.90 2000/09/25 18:09:28 tgl Exp $
+ * $Header: /cvsroot/pgsql/src/backend/optimizer/plan/planner.c,v 1.124 2002/09/04 20:31:21 momjian Exp $
*
*-------------------------------------------------------------------------
*/
#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/subselect.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"
-static void preprocess_join_conditions(Query *parse, Node *jtnode);
+/* Expression kind codes for preprocess_expression */
+#define EXPRKIND_TARGET 0
+#define EXPRKIND_WHERE 1
+#define EXPRKIND_HAVING 2
+
+
+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(List *group_tlist, bool tuplePerGroup,
+static Plan *make_groupplan(Query *parse,
+ List *group_tlist, bool tuplePerGroup,
List *groupClause, AttrNumber *grpColIdx,
bool is_presorted, Plan *subplan);
-static Plan *make_sortplan(List *tlist, Plan *plannode, List *sortcls);
+static List *postprocess_setop_tlist(List *new_tlist, List *orig_tlist);
+
/*****************************************************************************
*
{
Plan *result_plan;
Index save_PlannerQueryLevel;
- List *save_PlannerInitPlan;
List *save_PlannerParamVar;
- int save_PlannerPlanId;
/*
* The planner can be called recursively (an example is when
- * eval_const_expressions tries to simplify an SQL function).
- * So, global state variables must be saved and restored.
+ * 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.
*
- * (Perhaps these should be moved into the Query structure instead?)
+ * 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_PlannerInitPlan = PlannerInitPlan;
save_PlannerParamVar = PlannerParamVar;
- save_PlannerPlanId = PlannerPlanId;
- /* Initialize state for subselects */
- PlannerQueryLevel = 1;
- PlannerInitPlan = NULL;
- PlannerParamVar = NULL;
- PlannerPlanId = 0;
+ /* Initialize state for handling outer-level references and params */
+ PlannerQueryLevel = 0; /* will be 1 in top-level subquery_planner */
+ PlannerParamVar = NIL;
- /* this should go away sometime soon */
- transformKeySetQuery(parse);
-
- /* primary planning entry point (may recurse for subplans) */
+ /* primary planning entry point (may recurse for subqueries) */
result_plan = subquery_planner(parse, -1.0 /* default case */ );
- Assert(PlannerQueryLevel == 1);
-
- /* if top-level query had subqueries, do housekeeping for them */
- if (PlannerPlanId > 0)
- {
- (void) SS_finalize_plan(result_plan);
- result_plan->initPlan = PlannerInitPlan;
- }
+ Assert(PlannerQueryLevel == 0);
/* executor wants to know total number of Params used overall */
result_plan->nParamExec = length(PlannerParamVar);
/* final cleanup of the plan */
- set_plan_references(result_plan);
+ set_plan_references(result_plan, parse->rtable);
/* restore state for outer planner, if any */
PlannerQueryLevel = save_PlannerQueryLevel;
- PlannerInitPlan = save_PlannerInitPlan;
PlannerParamVar = save_PlannerParamVar;
- PlannerPlanId = save_PlannerPlanId;
return result_plan;
}
*
* 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 union_planner, below.
+ * tuple_fraction is interpreted as explained for grouping_planner, below.
*
* Basically, this routine does the stuff that should only be done once
- * per Query object. It then calls union_planner, which may be called
- * recursively on the same Query node in order to handle UNIONs and/or
- * inheritance. subquery_planner is called recursively from subselect.c
- * to handle sub-Query nodes found within the query's expressions.
+ * 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.
*
- * prepunion.c uses an unholy combination of calling union_planner when
- * recursing on the primary Query node, or subquery_planner when recursing
- * on a UNION'd Query node that hasn't previously been seen by
- * subquery_planner. That whole chunk of code needs rewritten from scratch.
+ * subquery_planner will be called recursively to handle sub-Query nodes
+ * found within the query's expressions and rangetable.
*
* Returns a query plan.
*--------------------
Plan *
subquery_planner(Query *parse, double tuple_fraction)
{
+ 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;
+
/*
- * A HAVING clause without aggregates is equivalent to a WHERE clause
- * (except it can only refer to grouped fields). If there are no aggs
- * anywhere in the query, then we don't want to create an Agg plan
- * node, so merge the HAVING condition into WHERE. (We used to
- * consider this an error condition, but it seems to be legal SQL.)
+ * 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);
+
+ /*
+ * If so, we may have created opportunities to simplify the jointree.
*/
- if (parse->havingQual != NULL && !parse->hasAggs)
+ parse->jointree = (FromExpr *)
+ preprocess_jointree(parse, (Node *) parse->jointree);
+
+ /*
+ * Do expression preprocessing on targetlist and quals.
+ */
+ parse->targetList = (List *)
+ preprocess_expression(parse, (Node *) parse->targetList,
+ EXPRKIND_TARGET);
+
+ preprocess_qual_conditions(parse, (Node *) parse->jointree);
+
+ parse->havingQual = preprocess_expression(parse, parse->havingQual,
+ EXPRKIND_HAVING);
+
+ /* Also need to preprocess expressions for function RTEs */
+ foreach(lst, parse->rtable)
{
- if (parse->qual == NULL)
- parse->qual = parse->havingQual;
- else
- parse->qual = (Node *) make_andclause(lappend(lcons(parse->qual,
- NIL),
- parse->havingQual));
- parse->havingQual = NULL;
+ RangeTblEntry *rte = (RangeTblEntry *) lfirst(lst);
+
+ if (rte->rtekind == RTE_FUNCTION)
+ rte->funcexpr = preprocess_expression(parse, rte->funcexpr,
+ EXPRKIND_TARGET);
+ /* These are not targetlist items, but close enough... */
}
/*
- * Simplify constant expressions in targetlist and quals.
- *
- * Note that at this point the qual has 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.
+ * 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.
*/
- parse->targetList = (List *)
- eval_const_expressions((Node *) parse->targetList);
- parse->qual = eval_const_expressions(parse->qual);
- parse->havingQual = eval_const_expressions(parse->havingQual);
+ if (parse->hasSubLinks &&
+ (parse->groupClause != NIL || parse->hasAggs))
+ check_subplans_for_ungrouped_vars(parse);
/*
- * Canonicalize the qual, and convert it to implicit-AND format.
+ * 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.
*
- * XXX Is there any value in re-applying eval_const_expressions after
- * canonicalize_qual?
+ * 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.
*/
- parse->qual = (Node *) canonicalize_qual((Expr *) parse->qual, true);
+ newHaving = NIL;
+ foreach(lst, (List *) parse->havingQual)
+ {
+ Node *havingclause = (Node *) lfirst(lst);
-#ifdef OPTIMIZER_DEBUG
- printf("After canonicalize_qual()\n");
- pprint(parse->qual);
-#endif
+ if (contain_agg_clause(havingclause))
+ newHaving = lappend(newHaving, havingclause);
+ else
+ parse->jointree->quals = (Node *)
+ lappend((List *) parse->jointree->quals, havingclause);
+ }
+ parse->havingQual = (Node *) newHaving;
/*
- * Ditto for the havingQual
+ * Do the main planning. If we have an inherited target relation,
+ * that needs special processing, else go straight to
+ * grouping_planner.
*/
- parse->havingQual = (Node *) canonicalize_qual((Expr *) parse->havingQual,
- true);
+ if (parse->resultRelation &&
+ (lst = expand_inherted_rtentry(parse, parse->resultRelation, false))
+ != NIL)
+ plan = inheritance_planner(parse, lst);
+ else
+ plan = grouping_planner(parse, tuple_fraction);
- /* Expand SubLinks to SubPlans */
- if (parse->hasSubLinks)
+ /*
+ * 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)
+ {
+ (void) 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.
+ */
+ plan->initPlan = PlannerInitPlan;
+ /* Must add the initPlans' extParams to the topmost node's, too */
+ foreach(lst, plan->initPlan)
+ {
+ SubPlan *subplan = (SubPlan *) lfirst(lst);
+
+ plan->extParam = set_unioni(plan->extParam,
+ subplan->plan->extParam);
+ }
+ }
+
+ /* 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))
{
- parse->targetList = (List *)
- SS_process_sublinks((Node *) parse->targetList);
- parse->qual = SS_process_sublinks(parse->qual);
- parse->havingQual = SS_process_sublinks(parse->havingQual);
+ int varno = ((RangeTblRef *) jtnode)->rtindex;
+ RangeTblEntry *rte = rt_fetch(varno, parse->rtable);
+ Query *subquery = rte->subquery;
- if (parse->groupClause != NIL || parse->hasAggs)
+ /*
+ * 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;
/*
- * Check for ungrouped variables passed to subplans. Note we
- * do NOT do this for subplans in WHERE; it's legal there
- * because WHERE is evaluated pre-GROUP.
- *
- * An interesting fine point: if we reassigned a HAVING qual into
- * WHERE above, then we will accept references to ungrouped
- * vars from subplans in the HAVING qual. This is not
- * entirely consistent, but it doesn't seem particularly
- * harmful...
+ * 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.
*/
- check_subplans_for_ungrouped_vars((Node *) parse->targetList,
- parse);
- check_subplans_for_ungrouped_vars(parse->havingQual, parse);
+ return (Node *) subquery->jointree;
}
}
+ else if (IsA(jtnode, FromExpr))
+ {
+ FromExpr *f = (FromExpr *) jtnode;
+ List *l;
- /* Replace uplevel vars with Param nodes */
- if (PlannerQueryLevel > 1)
+ foreach(l, f->fromlist)
+ lfirst(l) = pull_up_subqueries(parse, lfirst(l),
+ below_outer_join);
+ }
+ else if (IsA(jtnode, JoinExpr))
{
- parse->targetList = (List *)
- SS_replace_correlation_vars((Node *) parse->targetList);
- parse->qual = SS_replace_correlation_vars(parse->qual);
- parse->havingQual = SS_replace_correlation_vars(parse->havingQual);
+ 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;
+}
- /* Do all the above for each qual condition (ON clause) in the join tree */
- preprocess_join_conditions(parse, (Node *) parse->jointree);
+/*
+ * 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");
- /* Do the main planning (potentially recursive) */
+ /*
+ * Can't currently pull up a query with setops. Maybe after querytree
+ * redesign...
+ */
+ if (subquery->setOperations)
+ return false;
- return union_planner(parse, tuple_fraction);
+ /*
+ * 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;
/*
- * XXX should any more of union_planner's activity be moved here?
- *
- * That would take careful study of the interactions with prepunion.c,
- * but I suspect it would pay off in simplicity and avoidance of
- * wasted cycles.
+ * 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;
}
/*
- * preprocess_join_conditions
- * Recursively scan the query's jointree and do subquery_planner's
- * qual preprocessing work on each ON condition found therein.
+ * 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
-preprocess_join_conditions(Query *parse, Node *jtnode)
+resolvenew_in_jointree(Node *jtnode, int varno, List *subtlist)
{
if (jtnode == NULL)
return;
- if (IsA(jtnode, List))
+ if (IsA(jtnode, RangeTblRef))
{
+ /* nothing to do here */
+ }
+ else if (IsA(jtnode, FromExpr))
+ {
+ FromExpr *f = (FromExpr *) jtnode;
List *l;
- foreach(l, (List *) jtnode)
- preprocess_join_conditions(parse, lfirst(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, RangeTblRef))
+ else if (IsA(jtnode, JoinExpr))
{
- /* nothing to do here */
+ 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;
- preprocess_join_conditions(parse, j->larg);
- preprocess_join_conditions(parse, j->rarg);
+ /* 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;
+}
- /* Simplify constant expressions */
- j->quals = eval_const_expressions(j->quals);
+/*
+ * 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)
+{
+ bool has_join_rtes;
+ List *rt;
- /* Canonicalize the qual, and convert it to implicit-AND format */
- j->quals = (Node *) canonicalize_qual((Expr *) j->quals, true);
+ /*
+ * 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);
- /* Expand SubLinks to SubPlans */
- if (parse->hasSubLinks)
+ /*
+ * 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)
+ {
+ expr = (Node *) canonicalize_qual((Expr *) expr, true);
+
+#ifdef OPTIMIZER_DEBUG
+ printf("After canonicalize_qual()\n");
+ pprint(expr);
+#endif
+ }
+
+ /* 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);
+
+ /*
+ * 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);
+
+ if (rte->rtekind == RTE_JOIN)
{
- j->quals = SS_process_sublinks(j->quals);
- /*
- * ON conditions, like WHERE clauses, are evaluated pre-GROUP;
- * so we allow ungrouped vars in them.
- */
+ 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)
- j->quals = SS_replace_correlation_vars(j->quals);
+ return expr;
+}
+
+/*
+ * preprocess_qual_conditions
+ * Recursively scan the query's jointree and do subquery_planner's
+ * preprocessing work on each qual condition found therein.
+ */
+static void
+preprocess_qual_conditions(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_join_conditions: unexpected node type %d",
+ elog(ERROR, "preprocess_qual_conditions: unexpected node type %d",
nodeTag(jtnode));
}
/*--------------------
- * union_planner
- * Invokes the planner on union-type queries (both regular UNIONs and
- * appends produced by inheritance), recursing if necessary to get them
- * all, then processes normal plans.
+ * inheritance_planner
+ * Generate a plan in the case where the result relation is an
+ * inheritance set.
+ *
+ * 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.
+ *--------------------
+ */
+static Plan *
+inheritance_planner(Query *parse, List *inheritlist)
+{
+ int parentRTindex = parse->resultRelation;
+ Oid parentOID = getrelid(parentRTindex, parse->rtable);
+ List *subplans = NIL;
+ List *tlist = NIL;
+ List *l;
+
+ 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
* Returns a query plan.
*--------------------
*/
-Plan *
-union_planner(Query *parse,
- double tuple_fraction)
+static Plan *
+grouping_planner(Query *parse, double tuple_fraction)
{
List *tlist = parse->targetList;
- List *rangetable = parse->rtable;
- Plan *result_plan = (Plan *) NULL;
- AttrNumber *groupColIdx = NULL;
- List *current_pathkeys = NIL;
+ Plan *result_plan;
+ List *current_pathkeys;
List *group_pathkeys;
List *sort_pathkeys;
- Index rt_index;
- List *inheritors;
+ AttrNumber *groupColIdx = NULL;
- if (parse->unionClause)
+ if (parse->setOperations)
{
- result_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);
-
/*
- * We leave current_pathkeys NIL indicating we do not know sort
- * order. This is correct for the appended-together subplan
- * results, even if the subplans themselves produced sorted results.
+ * 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);
/*
- * Calculate pathkeys that represent grouping/ordering
- * requirements
+ * 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.
*/
- group_pathkeys = make_pathkeys_for_sortclauses(parse->groupClause,
- tlist);
- sort_pathkeys = make_pathkeys_for_sortclauses(parse->sortClause,
- tlist);
- }
- else if (find_inheritable_rt_entry(rangetable,
- &rt_index, &inheritors))
- {
- List *sub_tlist;
+ Assert(parse->commandType == CMD_SELECT);
- /*
- * Generate appropriate target list for subplan; may be different
- * from tlist if grouping or aggregation is needed.
- */
- sub_tlist = make_subplanTargetList(parse, tlist, &groupColIdx);
+ tlist = postprocess_setop_tlist(result_plan->targetlist, tlist);
/*
- * Recursively plan the subqueries needed for inheritance
+ * Can't handle FOR UPDATE here (parser should have checked
+ * already, but let's make sure).
*/
- result_plan = plan_inherit_queries(parse, sub_tlist,
- rt_index, inheritors);
+ if (parse->rowMarks)
+ elog(ERROR, "SELECT FOR UPDATE is not allowed with UNION/INTERSECT/EXCEPT");
/*
- * Fix up outer target list. NOTE: unlike the case for
- * non-inherited query, we pass the unfixed tlist to subplans,
- * which do their own fixing. But we still want to fix the outer
- * target list afterwards. I *think* this is correct --- doing the
- * fix before recursing is definitely wrong, because
- * preprocess_targetlist() will do the wrong thing if invoked
- * twice on the same list. Maybe that is a bug? tgl 6/6/99
- */
- tlist = preprocess_targetlist(tlist,
- parse->commandType,
- parse->resultRelation,
- parse->rtable);
-
- if (parse->rowMark != NULL)
- elog(ERROR, "SELECT FOR UPDATE is not supported for inherit queries");
-
- /*
- * We leave current_pathkeys NIL indicating we do not know sort
- * order of the Append-ed results.
+ * 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
+ * requirements (grouping should always be null, but...)
*/
group_pathkeys = make_pathkeys_for_sortclauses(parse->groupClause,
tlist);
parse->rtable);
/*
- * Add row-mark targets for UPDATE (should this be done in
- * preprocess_targetlist?)
+ * 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->rowMark != NULL)
+ if (parse->rowMarks)
{
List *l;
- foreach(l, parse->rowMark)
+ /*
+ * 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)
{
- RowMark *rowmark = (RowMark *) lfirst(l);
- TargetEntry *ctid;
+ Index rti = lfirsti(l);
+ char *resname;
Resdom *resdom;
Var *var;
- char *resname;
-
- if (!(rowmark->info & ROW_MARK_FOR_UPDATE))
- continue;
+ TargetEntry *ctid;
resname = (char *) palloc(32);
- sprintf(resname, "ctid%u", rowmark->rti);
+ snprintf(resname, 32, "ctid%u", rti);
resdom = makeResdom(length(tlist) + 1,
TIDOID,
-1,
resname,
true);
- var = makeVar(rowmark->rti, -1, TIDOID, -1, 0);
+ var = makeVar(rti,
+ SelfItemPointerAttributeNumber,
+ TIDOID,
+ -1,
+ 0);
ctid = makeTargetEntry(resdom, (Node *) var);
tlist = lappend(tlist, ctid);
/*
* Figure out whether we expect to retrieve all the tuples that
- * the plan can generate, or to stop early due to a LIMIT or other
- * factors. If the caller passed a value >= 0, believe that
- * value, else do our own examination of the query context.
+ * 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)
{
tuple_fraction = 0.0;
/*
- * Check for a LIMIT clause.
+ * 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->limitCount != NULL)
+ 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))
{
- 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)
{
- Const *limitc = (Const *) parse->limitCount;
- int count = (int) (limitc->constvalue);
-
- /*
- * The constant can legally be either 0 ("ALL") or a
- * positive integer. If it is not ALL, we also need
- * to consider the OFFSET part of LIMIT.
- */
- if (count > 0)
+ limit_fraction = (double) count;
+ /* We must also consider the OFFSET, if present */
+ if (parse->limitOffset != NULL)
{
- tuple_fraction = (double) count;
- if (parse->limitOffset != NULL)
+ if (IsA(parse->limitOffset, Const))
{
- if (IsA(parse->limitOffset, Const))
- {
- int offset;
-
- limitc = (Const *) parse->limitOffset;
- offset = (int) (limitc->constvalue);
- if (offset > 0)
- tuple_fraction += (double) offset;
- }
- else
- {
- /* It's a PARAM ... punt ... */
- tuple_fraction = 0.10;
- }
+ 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
{
-
- /*
- * COUNT is a PARAM ... don't know exactly what the
- * limit will be, but for lack of a better idea assume
- * 10% of the plan's result is wanted.
- */
- tuple_fraction = 0.10;
+ /* no info from caller, just use limit */
+ tuple_fraction = limit_fraction;
}
}
-
- /*
- * Check for a 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?)
- */
- if (parse->isPortal)
- tuple_fraction = 0.10;
}
- /*
- * Adjust tuple_fraction if we see that we are going to apply
- * 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->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
* 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. (Although we are comparing non-canonicalized
- * pathkeys here, it should be OK since they will both contain
- * only single-element sublists at this point. See
- * pathkeys.c.)
+ * of GROUP BY. (We have not yet canonicalized the pathkeys,
+ * so must use the slower noncanonical comparison method.)
*/
if (parse->groupClause && parse->sortClause &&
- !pathkeys_contained_in(sort_pathkeys, group_pathkeys))
+ !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.
}
else if (parse->distinctClause)
{
-
/*
* SELECT DISTINCT, like GROUP, will absorb an unpredictable
* number of input tuples per output tuple. Handle the same
tuple_fraction = 0.25;
}
- /* Generate the (sub) plan */
+ /* Generate the basic plan for this Query */
result_plan = query_planner(parse,
sub_tlist,
tuple_fraction);
current_pathkeys = parse->query_pathkeys;
}
- /* query_planner returns NULL if it thinks plan is bogus */
- if (!result_plan)
- elog(ERROR, "union_planner: failed to create plan");
-
/*
* We couldn't canonicalize group_pathkeys and sort_pathkeys before
* running query_planner(), so do it now.
/*
* If there are aggregates then the Group node should just return
- * the same set of vars as the subplan did (but we can exclude any
- * GROUP BY expressions). If there are no aggregates then the
- * Group node had better compute the final tlist.
+ * 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 = flatten_tlist(result_plan->targetlist);
+ group_tlist = new_unsorted_tlist(result_plan->targetlist);
else
group_tlist = tlist;
}
else
{
-
/*
* We will need to do an explicit sort by the GROUP BY clause.
* make_groupplan will do the work, but set current_pathkeys
current_pathkeys = group_pathkeys;
}
- result_plan = make_groupplan(group_tlist,
+ result_plan = make_groupplan(parse,
+ group_tlist,
tuplePerGroup,
parse->groupClause,
groupColIdx,
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);
+ }
/*
* 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(tlist, result_plan,
+ result_plan = make_sortplan(parse, tlist, result_plan,
parse->sortClause);
}
/*
- * Finally, if there is a DISTINCT clause, add the UNIQUE node.
+ * If there is a DISTINCT clause, add the UNIQUE node.
*/
if (parse->distinctClause)
{
parse->distinctClause);
}
+ /*
+ * Finally, if there is a LIMIT/OFFSET clause, add the LIMIT node.
+ */
+ 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 union_planner inserts Aggregate and/or Group plan nodes above
+ * 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.
* 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
- * use only a+b, but it's not really worth the trouble.)
+ * 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.
* first add an explicit Sort node.
*/
static Plan *
-make_groupplan(List *group_tlist,
+make_groupplan(Query *parse,
+ List *group_tlist,
bool tuplePerGroup,
List *groupClause,
AttrNumber *grpColIdx,
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
{
/* OK, insert the ordering info needed by the executor. */
resdom->reskey = ++keyno;
- resdom->reskeyop = get_opcode(grpcl->sortop);
+ resdom->reskeyop = grpcl->sortop;
}
}
Assert(keyno > 0);
- subplan = (Plan *) make_sort(sort_tlist, subplan, keyno);
+ subplan = (Plan *) make_sort(parse, sort_tlist, subplan, keyno);
}
return (Plan *) make_group(group_tlist, tuplePerGroup, numCols,
* make_sortplan
* Add a Sort node to implement an explicit ORDER BY clause.
*/
-static Plan *
-make_sortplan(List *tlist, Plan *plannode, List *sortcls)
+Plan *
+make_sortplan(Query *parse, List *tlist, Plan *plannode, List *sortcls)
{
List *sort_tlist;
List *i;
{
/* OK, insert the ordering info needed by the executor. */
resdom->reskey = ++keyno;
- resdom->reskeyop = get_opcode(sortcl->sortop);
+ resdom->reskeyop = sortcl->sortop;
}
}
Assert(keyno > 0);
- return (Plan *) make_sort(sort_tlist, plannode, keyno);
+ 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;
}
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