1 /*-------------------------------------------------------------------------
4 * Routines to plan a single query
6 * Copyright (c) 1994, Regents of the University of California
10 * $Header: /cvsroot/pgsql/src/backend/optimizer/plan/planmain.c,v 1.34 1999/02/21 03:48:49 scrappy Exp $
12 *-------------------------------------------------------------------------
14 #include <sys/types.h>
18 #include "nodes/pg_list.h"
19 #include "nodes/plannodes.h"
20 #include "nodes/parsenodes.h"
21 #include "nodes/print.h"
22 #include "nodes/relation.h"
23 #include "nodes/makefuncs.h"
25 #include "optimizer/planmain.h"
26 #include "optimizer/subselect.h"
27 #include "optimizer/internal.h"
28 #include "optimizer/prep.h"
29 #include "optimizer/paths.h"
30 #include "optimizer/clauses.h"
31 #include "optimizer/keys.h"
32 #include "optimizer/tlist.h"
33 #include "optimizer/var.h"
34 #include "optimizer/xfunc.h"
35 #include "optimizer/cost.h"
37 #include "tcop/dest.h"
38 #include "utils/elog.h"
39 #include "utils/palloc.h"
40 #include "nodes/memnodes.h"
41 #include "utils/mcxt.h"
42 #include "utils/lsyscache.h"
44 static Plan *subplanner(Query *root, List *flat_tlist, List *qual);
45 static Result *make_result(List *tlist, Node *resconstantqual, Plan *subplan);
47 extern Plan *make_groupPlan(List **tlist, bool tuplePerGroup,
48 List *groupClause, Plan *subplan);
52 * Routine to create a query plan. It does so by first creating a
53 * subplan for the topmost level of attributes in the query. Then,
54 * it modifies all target list and qualifications to consider the next
55 * level of nesting and creates a plan for this modified query by
56 * recursively calling itself. The two pieces are then merged together
57 * by creating a result node that indicates which attributes should
58 * be placed where and any relation level qualifications to be
61 * command-type is the query command, e.g., select, delete, etc.
62 * tlist is the target list of the query
63 * qual is the qualification of the query
65 * Returns a query plan.
68 query_planner(Query *root,
73 List *constant_qual = NIL;
74 List *var_only_tlist = NIL;
75 List *level_tlist = NIL;
78 if (PlannerQueryLevel > 1)
80 /* should copy be made ? */
81 tlist = (List *) SS_replace_correlation_vars((Node *) tlist);
82 qual = (List *) SS_replace_correlation_vars((Node *) qual);
84 if (root->hasSubLinks)
85 qual = (List *) SS_process_sublinks((Node *) qual);
87 qual = cnfify((Expr *) qual, true);
88 #ifdef OPTIMIZER_DEBUG
89 printf("After cnfify()\n");
94 * A command without a target list or qualification is an error,
95 * except for "delete foo".
97 if (tlist == NIL && qual == NULL)
99 if (command_type == CMD_DELETE)
101 return ((Plan *) make_seqscan(NIL,
103 root->resultRelation,
107 return (Plan *) NULL;
111 * Pull out any non-variable qualifications so these can be put in the
112 * topmost result node. The opids for the remaining qualifications
113 * will be changed to regprocs later.
115 qual = pull_constant_clauses(qual, &constant_qual);
116 fix_opids(constant_qual);
119 * Create a target list that consists solely of (resdom var) target
120 * list entries, i.e., contains no arbitrary expressions.
122 var_only_tlist = flatten_tlist(tlist);
124 level_tlist = var_only_tlist;
126 /* from old code. the logic is beyond me. - ay 2/95 */
130 * A query may have a non-variable target list and a non-variable
131 * qualification only under certain conditions: - the query creates
132 * all-new tuples, or - the query is a replace (a scan must still be
133 * done in this case).
135 if (var_only_tlist == NULL && qual == NULL)
137 switch (command_type)
141 return ((Plan *) make_result(tlist,
142 (Node *) constant_qual,
148 SeqScan *scan = make_seqscan(tlist,
150 root->resultRelation,
153 if (constant_qual != NULL)
154 return ((Plan *) make_result(tlist,
155 (Node *) constant_qual,
158 return (Plan *) scan;
162 return (Plan *) NULL;
167 * Find the subplan (access path) and destructively modify the target
168 * list of the newly created subplan to contain the appropriate join
171 subplan = subplanner(root, level_tlist, qual);
173 set_tlist_references(subplan);
176 * Build a result node linking the plan if we have constant quals
180 subplan = (Plan *) make_result((!root->hasAggs &&
181 !root->groupClause &&
183 ? tlist : subplan->targetlist,
184 (Node *) constant_qual,
188 * Change all varno's of the Result's node target list.
190 if (!root->hasAggs && !root->groupClause && !root->havingQual)
191 set_tlist_references(subplan);
197 * fix up the flattened target list of the plan root node so that
198 * expressions are evaluated. this forces expression evaluations that
199 * may involve expensive function calls to be delayed to the very last
200 * stage of query execution. this could be bad. but it is joey's
201 * responsibility to optimally push these expressions down the plan
204 * But now nothing to do if there are GroupBy and/or Aggregates: 1.
205 * make_groupPlan fixes tlist; 2. flatten_tlist_vars does nothing with
206 * aggregates fixing only other entries (i.e. - GroupBy-ed and so
207 * fixed by make_groupPlan). - vadim 04/05/97
211 if (!root->hasAggs && !root->groupClause && !root->havingQual)
212 subplan->targetlist = flatten_tlist_vars(tlist,
213 subplan->targetlist);
219 * Destructively modify the query plan's targetlist to add fjoin lists
220 * to flatten functions that return sets of base types
222 subplan->targetlist = generate_fjoin(subplan->targetlist);
230 * Subplanner creates an entire plan consisting of joins and scans
231 * for processing a single level of attributes.
233 * flat_tlist is the flattened target list
234 * qual is the qualification to be satisfied
240 subplanner(Query *root,
244 RelOptInfo *final_rel;
247 * Initialize the targetlist and qualification, adding entries to
248 * base_rel_list as relation references are found (e.g., in the
249 * qualification, the targetlist, etc.)
251 root->base_rel_list = NIL;
252 root->join_rel_list = NIL;
254 make_var_only_tlist(root, flat_tlist);
255 add_restrict_and_join_to_rels(root, qual);
256 add_missing_vars_to_tlist(root, flat_tlist);
258 set_joininfo_mergeable_hashable(root->base_rel_list);
260 final_rel = make_one_rel(root, root->base_rel_list);
262 #ifdef NOT_USED /* fix xfunc */
265 * Perform Predicate Migration on each path, to optimize and correctly
266 * assess the cost of each before choosing the cheapest one. -- JMH,
269 * Needn't do so if the top rel is pruneable: that means there's no
270 * expensive functions left to pull up. -- JMH, 11/22/92
272 if (XfuncMode != XFUNC_OFF && XfuncMode != XFUNC_NOPM &&
273 XfuncMode != XFUNC_NOPULL && !final_rel->pruneable)
277 foreach(pathnode, final_rel->pathlist)
279 if (xfunc_do_predmig((Path *) lfirst(pathnode)))
280 set_cheapest(final_rel, final_rel->pathlist);
286 * Determine the cheapest path and create a subplan corresponding to
290 return create_plan((Path *) final_rel->cheapestpath);
293 elog(NOTICE, "final relation is null");
294 return create_plan((Path *) NULL);
299 /*****************************************************************************
301 *****************************************************************************/
304 make_result(List *tlist,
305 Node *resconstantqual,
308 Result *node = makeNode(Result);
309 Plan *plan = &node->plan;
312 tlist = generate_fjoin(tlist);
314 plan->cost = (subplan ? subplan->cost : 0);
315 plan->state = (EState *) NULL;
316 plan->targetlist = tlist;
317 plan->lefttree = subplan;
318 plan->righttree = NULL;
319 node->resconstantqual = resconstantqual;
320 node->resstate = NULL;
325 /*****************************************************************************
327 *****************************************************************************/
330 make_groupPlan(List **tlist,
338 List *glc = listCopy(groupClause);
339 List *otles = NIL; /* list of removed non-GroupBy entries */
340 List *otlvars = NIL; /* list of var in them */
345 AttrNumber *grpColIdx;
348 numCols = length(groupClause);
349 grpColIdx = (AttrNumber *) palloc(sizeof(AttrNumber) * numCols);
351 sort_tlist = new_unsorted_tlist(*tlist); /* it's copy */
354 * Make template TL for subplan, Sort & Group: 1. If there are
355 * aggregates (tuplePerGroup is true) then take away non-GroupBy
356 * entries and re-set resno-s accordantly. 2. Make grpColIdx
358 * Note: we assume that TLEs in *tlist are ordered in accordance with
359 * their resdom->resno.
361 foreach(sl, sort_tlist)
363 Resdom *resdom = NULL;
364 TargetEntry *te = (TargetEntry *) lfirst(sl);
367 foreach(gl, groupClause)
369 GroupClause *grpcl = (GroupClause *) lfirst(gl);
372 if (grpcl->entry->resdom->resno == te->resdom->resno)
376 resdom->reskey = keyno;
377 resdom->reskeyop = get_opcode(grpcl->grpOpoid);
378 resdom->resno = last_resno; /* re-set */
379 grpColIdx[keyno - 1] = last_resno++;
380 glc = lremove(lfirst(gl), glc); /* TLE found for it */
386 * Non-GroupBy entry: remove it from Group/Sort TL if there are
387 * aggregates in query - it will be evaluated by Aggregate plan
393 otlvars = nconc(otlvars, pull_var_clause(te->expr));
394 otles = lcons(te, otles);
395 sort_tlist = lremove(te, sort_tlist);
398 te->resdom->resno = last_resno++;
402 if (length(glc) != 0)
403 elog(ERROR, "group attribute disappeared from target list");
406 * If non-GroupBy entries were removed from TL - we are to add Vars
407 * for them to the end of TL if there are no such Vars in TL already.
410 otlvcnt = length(otlvars);
413 Var *v = (Var *) lfirst(gl);
415 if (tlist_member(v, sort_tlist) == NULL)
417 sort_tlist = lappend(sort_tlist,
418 create_tl_element(v, last_resno));
425 /* Now otlvcnt is number of Vars added in TL for non-GroupBy entries */
427 /* Make TL for subplan: substitute Vars from subplan TL into new TL */
428 sl = flatten_tlist_vars(sort_tlist, subplan->targetlist);
430 subplan->targetlist = new_unsorted_tlist(sl); /* there */
433 * Make Sort/Group TL : 1. make Var nodes (with varno = 1 and varnoold
434 * = -1) for all functions, 'couse they will be evaluated by subplan;
435 * 2. for real Vars: set varno = 1 and varattno to its resno in
438 foreach(sl, sort_tlist)
440 TargetEntry *te = (TargetEntry *) lfirst(sl);
441 Resdom *resdom = te->resdom;
442 Node *expr = te->expr;
446 #ifdef NOT_USED /* subplanVar->resdom->resno expected to
447 * be = te->resdom->resno */
448 TargetEntry *subplanVar;
450 subplanVar = match_varid((Var *) expr, subplan->targetlist);
451 ((Var *) expr)->varattno = subplanVar->resdom->resno;
453 ((Var *) expr)->varattno = te->resdom->resno;
454 ((Var *) expr)->varno = 1;
457 te->expr = (Node *) makeVar(1, resdom->resno,
460 0, -1, resdom->resno);
463 sortplan = make_sort(sort_tlist,
464 _NONAME_RELATION_ID_,
467 sortplan->plan.cost = subplan->cost; /* XXX assume no cost */
470 * make the Group node
472 sort_tlist = copyObject(sort_tlist);
473 grpplan = make_group(sort_tlist, tuplePerGroup, numCols,
474 grpColIdx, sortplan);
477 * Make TL for parent: "restore" non-GroupBy entries (if they were
478 * removed) and set resno-s of others accordantly.
481 sort_tlist = NIL; /* to be new parent TL */
485 TargetEntry *te = (TargetEntry *) lfirst(gl);
487 foreach(temp, otles) /* Is it removed non-GroupBy entry ? */
489 TargetEntry *ote = (TargetEntry *) lfirst(temp);
491 if (ote->resdom->resno == te->resdom->resno)
493 otles = lremove(ote, otles);
497 if (temp == NIL) /* It's "our" TLE - we're to return */
498 { /* it from Sort/Group plans */
499 TargetEntry *my = (TargetEntry *) lfirst(sl); /* get it */
501 sl = sl->next; /* prepare for the next "our" */
503 my->resdom->resno = te->resdom->resno; /* order of parent TL */
504 sort_tlist = lappend(sort_tlist, my);
507 /* else - it's TLE of an non-GroupBy entry */
508 sort_tlist = lappend(sort_tlist, copyObject(te));
512 * Pure non-GroupBy entries Vars were at the end of Group' TL. They
513 * shouldn't appear in parent TL, all others shouldn't disappear.
515 Assert(otlvcnt == length(sl));
516 Assert(length(otles) == 0);
520 return (Plan *) grpplan;