diff options
Diffstat (limited to 'src/backend/optimizer/plan/planner.c')
| -rw-r--r-- | src/backend/optimizer/plan/planner.c | 222 |
1 files changed, 115 insertions, 107 deletions
diff --git a/src/backend/optimizer/plan/planner.c b/src/backend/optimizer/plan/planner.c index 1896982f02e..c2aec37470a 100644 --- a/src/backend/optimizer/plan/planner.c +++ b/src/backend/optimizer/plan/planner.c @@ -8,7 +8,7 @@ * * * IDENTIFICATION - * $Header: /cvsroot/pgsql/src/backend/optimizer/plan/planner.c,v 1.157 2003/07/25 00:01:07 tgl Exp $ + * $Header: /cvsroot/pgsql/src/backend/optimizer/plan/planner.c,v 1.158 2003/08/04 00:43:20 momjian Exp $ * *------------------------------------------------------------------------- */ @@ -45,10 +45,10 @@ /* Expression kind codes for preprocess_expression */ #define EXPRKIND_QUAL 0 -#define EXPRKIND_TARGET 1 -#define EXPRKIND_RTFUNC 2 +#define EXPRKIND_TARGET 1 +#define EXPRKIND_RTFUNC 2 #define EXPRKIND_LIMIT 3 -#define EXPRKIND_ININFO 4 +#define EXPRKIND_ININFO 4 static Node *preprocess_expression(Query *parse, Node *expr, int kind); @@ -59,9 +59,9 @@ static bool hash_safe_grouping(Query *parse); static List *make_subplanTargetList(Query *parse, List *tlist, AttrNumber **groupColIdx, bool *need_tlist_eval); static void locate_grouping_columns(Query *parse, - List *tlist, - List *sub_tlist, - AttrNumber *groupColIdx); + List *tlist, + List *sub_tlist, + AttrNumber *groupColIdx); static List *postprocess_setop_tlist(List *new_tlist, List *orig_tlist); @@ -103,9 +103,9 @@ planner(Query *parse, bool isCursor, int cursorOptions) { /* * 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?) + * FETCH from a cursor, but it seems a good bet that he doesn't + * want 'em all. Optimize for 10% retrieval (you gotta better + * number? Should this be a SETtable parameter?) */ tuple_fraction = 0.10; } @@ -121,8 +121,8 @@ planner(Query *parse, bool isCursor, int cursorOptions) Assert(PlannerQueryLevel == 0); /* - * If creating a plan for a scrollable cursor, make sure it can - * run backwards on demand. Add a Material node at the top at need. + * If creating a plan for a scrollable cursor, make sure it can run + * backwards on demand. Add a Material node at the top at need. */ if (isCursor && (cursorOptions & CURSOR_OPT_SCROLL)) { @@ -181,14 +181,14 @@ subquery_planner(Query *parse, double tuple_fraction) /* * Look for IN clauses at the top level of WHERE, and transform them - * into joins. Note that this step only handles IN clauses originally - * at top level of WHERE; if we pull up any subqueries in the next step, - * their INs are processed just before pulling them up. + * into joins. Note that this step only handles IN clauses originally + * at top level of WHERE; if we pull up any subqueries in the next + * step, their INs are processed just before pulling them up. */ parse->in_info_list = NIL; if (parse->hasSubLinks) parse->jointree->quals = pull_up_IN_clauses(parse, - parse->jointree->quals); + parse->jointree->quals); /* * Check to see if any subqueries in the rangetable can be merged into @@ -198,10 +198,11 @@ subquery_planner(Query *parse, double tuple_fraction) pull_up_subqueries(parse, (Node *) parse->jointree, false); /* - * Detect whether any rangetable entries are RTE_JOIN kind; if not, - * we can avoid the expense of doing flatten_join_alias_vars(). Also - * check for outer joins --- if none, we can skip reduce_outer_joins(). - * This must be done after we have done pull_up_subqueries, of course. + * Detect whether any rangetable entries are RTE_JOIN kind; if not, we + * can avoid the expense of doing flatten_join_alias_vars(). Also + * check for outer joins --- if none, we can skip + * reduce_outer_joins(). This must be done after we have done + * pull_up_subqueries, of course. */ parse->hasJoinRTEs = false; hasOuterJoins = false; @@ -283,19 +284,20 @@ subquery_planner(Query *parse, double tuple_fraction) parse->havingQual = (Node *) newHaving; /* - * If we have any outer joins, try to reduce them to plain inner joins. - * This step is most easily done after we've done expression preprocessing. + * If we have any outer joins, try to reduce them to plain inner + * joins. This step is most easily done after we've done expression + * preprocessing. */ if (hasOuterJoins) reduce_outer_joins(parse); /* - * See if we can simplify the jointree; opportunities for this may come - * from having pulled up subqueries, or from flattening explicit JOIN - * syntax. We must do this after flattening JOIN alias variables, since - * eliminating explicit JOIN nodes from the jointree will cause - * get_relids_for_join() to fail. But it should happen after - * reduce_outer_joins, anyway. + * See if we can simplify the jointree; opportunities for this may + * come from having pulled up subqueries, or from flattening explicit + * JOIN syntax. We must do this after flattening JOIN alias + * variables, since eliminating explicit JOIN nodes from the jointree + * will cause get_relids_for_join() to fail. But it should happen + * after reduce_outer_joins, anyway. */ parse->jointree = (FromExpr *) simplify_jointree(parse, (Node *) parse->jointree); @@ -318,26 +320,26 @@ subquery_planner(Query *parse, double tuple_fraction) */ if (PlannerPlanId != saved_planid || PlannerQueryLevel > 1) { - Cost initplan_cost = 0; + Cost initplan_cost = 0; /* Prepare extParam/allParam sets for all nodes in tree */ SS_finalize_plan(plan, parse->rtable); /* - * SS_finalize_plan doesn't handle initPlans, so we have to manually - * attach them to the topmost plan node, and add their extParams to - * the topmost node's, too. + * SS_finalize_plan doesn't handle initPlans, so we have to + * manually attach them to the topmost plan node, and add their + * extParams to the topmost node's, too. * - * We also add the total_cost of each initPlan to the startup cost - * of the top node. This is a conservative overestimate, since in - * fact each initPlan might be executed later than plan startup, or - * even not at all. + * We also add the total_cost of each initPlan to the startup cost of + * the top node. This is a conservative overestimate, since in + * fact each initPlan might be executed later than plan startup, + * or even not at all. */ plan->initPlan = PlannerInitPlan; foreach(lst, plan->initPlan) { - SubPlan *initplan = (SubPlan *) lfirst(lst); + SubPlan *initplan = (SubPlan *) lfirst(lst); plan->extParam = bms_add_members(plan->extParam, initplan->plan->extParam); @@ -368,7 +370,8 @@ preprocess_expression(Query *parse, Node *expr, int kind) /* * If the query has any join RTEs, replace join alias variables with * base-relation variables. We must do this before sublink processing, - * else sublinks expanded out from join aliases wouldn't get processed. + * else sublinks expanded out from join aliases wouldn't get + * processed. */ if (parse->hasJoinRTEs) expr = flatten_join_alias_vars(parse, expr); @@ -403,8 +406,8 @@ preprocess_expression(Query *parse, Node *expr, int kind) expr = SS_process_sublinks(expr, (kind == EXPRKIND_QUAL)); /* - * XXX do not insert anything here unless you have grokked the comments - * in SS_replace_correlation_vars ... + * XXX do not insert anything here unless you have grokked the + * comments in SS_replace_correlation_vars ... */ /* Replace uplevel vars with Param nodes */ @@ -498,20 +501,21 @@ inheritance_planner(Query *parse, List *inheritlist) /* Generate plan */ subplan = grouping_planner(subquery, 0.0 /* retrieve all tuples */ ); subplans = lappend(subplans, subplan); + /* * It's possible that additional RTEs got added to the rangetable * due to expansion of inherited source tables (see allpaths.c). * If so, we must copy 'em back to the main parse tree's rtable. * - * XXX my goodness this is ugly. Really need to think about ways - * to rein in planner's habit of scribbling on its input. + * XXX my goodness this is ugly. Really need to think about ways to + * rein in planner's habit of scribbling on its input. */ subrtlength = length(subquery->rtable); if (subrtlength > mainrtlength) { - List *subrt = subquery->rtable; + List *subrt = subquery->rtable; - while (mainrtlength-- > 0) /* wish we had nthcdr() */ + while (mainrtlength-- > 0) /* wish we had nthcdr() */ subrt = lnext(subrt); parse->rtable = nconc(parse->rtable, subrt); mainrtlength = subrtlength; @@ -684,7 +688,7 @@ grouping_planner(Query *parse, double tuple_fraction) * from tlist if grouping or aggregation is needed. */ sub_tlist = make_subplanTargetList(parse, tlist, - &groupColIdx, &need_tlist_eval); + &groupColIdx, &need_tlist_eval); /* * Calculate pathkeys that represent grouping/ordering @@ -700,8 +704,8 @@ grouping_planner(Query *parse, double tuple_fraction) * Also, it's possible that optimization has eliminated all * aggregates, and we may as well check for that here. * - * Note: we do not attempt to detect duplicate aggregates here; - * a somewhat-overestimated count is okay for our present purposes. + * Note: we do not attempt to detect duplicate aggregates here; a + * somewhat-overestimated count is okay for our present purposes. */ if (parse->hasAggs) { @@ -892,8 +896,8 @@ grouping_planner(Query *parse, double tuple_fraction) &cheapest_path, &sorted_path); /* - * We couldn't canonicalize group_pathkeys and sort_pathkeys before - * running query_planner(), so do it now. + * 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); @@ -903,9 +907,9 @@ grouping_planner(Query *parse, double tuple_fraction) */ if (parse->groupClause) { - List *groupExprs; - double cheapest_path_rows; - int cheapest_path_width; + List *groupExprs; + double cheapest_path_rows; + int cheapest_path_width; /* * Beware in this section of the possibility that @@ -919,13 +923,13 @@ grouping_planner(Query *parse, double tuple_fraction) } else { - cheapest_path_rows = 1; /* assume non-set result */ - cheapest_path_width = 100; /* arbitrary */ + cheapest_path_rows = 1; /* assume non-set result */ + cheapest_path_width = 100; /* arbitrary */ } /* - * Always estimate the number of groups. We can't do this until - * after running query_planner(), either. + * Always estimate the number of groups. We can't do this + * until after running query_planner(), either. */ groupExprs = get_sortgrouplist_exprs(parse->groupClause, parse->targetList); @@ -936,12 +940,13 @@ grouping_planner(Query *parse, double tuple_fraction) numGroups = (long) Min(dNumGroups, (double) LONG_MAX); /* - * Check can't-do-it conditions, including whether the grouping - * operators are hashjoinable. + * Check can't-do-it conditions, including whether the + * grouping operators are hashjoinable. * * Executor doesn't support hashed aggregation with DISTINCT - * aggregates. (Doing so would imply storing *all* the input - * values in the hash table, which seems like a certain loser.) + * aggregates. (Doing so would imply storing *all* the input + * values in the hash table, which seems like a certain + * loser.) */ if (!enable_hashagg || !hash_safe_grouping(parse)) use_hashed_grouping = false; @@ -953,32 +958,30 @@ grouping_planner(Query *parse, double tuple_fraction) { /* * Use hashed grouping if (a) we think we can fit the - * hashtable into SortMem, *and* (b) the estimated cost - * is no more than doing it the other way. While avoiding + * hashtable into SortMem, *and* (b) the estimated cost is + * no more than doing it the other way. While avoiding * the need for sorted input is usually a win, the fact * that the output won't be sorted may be a loss; so we * need to do an actual cost comparison. * * In most cases we have no good way to estimate the size of - * the transition value needed by an aggregate; arbitrarily - * assume it is 100 bytes. Also set the overhead per hashtable - * entry at 64 bytes. + * the transition value needed by an aggregate; + * arbitrarily assume it is 100 bytes. Also set the + * overhead per hashtable entry at 64 bytes. */ - int hashentrysize = cheapest_path_width + 64 + numAggs * 100; + int hashentrysize = cheapest_path_width + 64 + numAggs * 100; if (hashentrysize * dNumGroups <= SortMem * 1024L) { /* * Okay, do the cost comparison. We need to consider - * cheapest_path + hashagg [+ final sort] - * versus either - * cheapest_path [+ sort] + group or agg [+ final sort] - * or - * presorted_path + group or agg [+ final sort] - * where brackets indicate a step that may not be needed. - * We assume query_planner() will have returned a - * presorted path only if it's a winner compared to - * cheapest_path for this purpose. + * cheapest_path + hashagg [+ final sort] versus + * either cheapest_path [+ sort] + group or agg [+ + * final sort] or presorted_path + group or agg [+ + * final sort] where brackets indicate a step that may + * not be needed. We assume query_planner() will have + * returned a presorted path only if it's a winner + * compared to cheapest_path for this purpose. * * These path variables are dummies that just hold cost * fields; we don't make actual Paths for these steps. @@ -1065,9 +1068,9 @@ grouping_planner(Query *parse, double tuple_fraction) /* * Select the best path and create a plan to execute it. * - * If we are doing hashed grouping, we will always read all the - * input tuples, so use the cheapest-total path. Otherwise, - * trust query_planner's decision about which to use. + * If we are doing hashed grouping, we will always read all the input + * tuples, so use the cheapest-total path. Otherwise, trust + * query_planner's decision about which to use. */ if (sorted_path && !use_hashed_grouping) { @@ -1081,19 +1084,19 @@ grouping_planner(Query *parse, double tuple_fraction) } /* - * create_plan() returns a plan with just a "flat" tlist of required - * Vars. Usually we need to insert the sub_tlist as the tlist of the - * top plan node. However, we can skip that if we determined that - * whatever query_planner chose to return will be good enough. + * create_plan() returns a plan with just a "flat" tlist of + * required Vars. Usually we need to insert the sub_tlist as the + * tlist of the top plan node. However, we can skip that if we + * determined that whatever query_planner chose to return will be + * good enough. */ if (need_tlist_eval) { /* * If the top-level plan node is one that cannot do expression - * evaluation, we must insert a Result node to project the desired - * tlist. - * Currently, the only plan node we might see here that falls into - * that category is Append. + * evaluation, we must insert a Result node to project the + * desired tlist. Currently, the only plan node we might see + * here that falls into that category is Append. */ if (IsA(result_plan, Append)) { @@ -1108,23 +1111,25 @@ grouping_planner(Query *parse, double tuple_fraction) */ result_plan->targetlist = sub_tlist; } + /* * Also, account for the cost of evaluation of the sub_tlist. * * Up to now, we have only been dealing with "flat" tlists, * containing just Vars. So their evaluation cost is zero * according to the model used by cost_qual_eval() (or if you - * prefer, the cost is factored into cpu_tuple_cost). Thus we can - * avoid accounting for tlist cost throughout query_planner() and - * subroutines. But now we've inserted a tlist that might contain - * actual operators, sub-selects, etc --- so we'd better account - * for its cost. + * prefer, the cost is factored into cpu_tuple_cost). Thus we + * can avoid accounting for tlist cost throughout + * query_planner() and subroutines. But now we've inserted a + * tlist that might contain actual operators, sub-selects, etc + * --- so we'd better account for its cost. * - * Below this point, any tlist eval cost for added-on nodes should - * be accounted for as we create those nodes. Presently, of the - * node types we can add on, only Agg and Group project new tlists - * (the rest just copy their input tuples) --- so make_agg() and - * make_group() are responsible for computing the added cost. + * Below this point, any tlist eval cost for added-on nodes + * should be accounted for as we create those nodes. + * Presently, of the node types we can add on, only Agg and + * Group project new tlists (the rest just copy their input + * tuples) --- so make_agg() and make_group() are responsible + * for computing the added cost. */ cost_qual_eval(&tlist_cost, sub_tlist); result_plan->startup_cost += tlist_cost.startup; @@ -1135,8 +1140,8 @@ grouping_planner(Query *parse, double tuple_fraction) { /* * Since we're using query_planner's tlist and not the one - * make_subplanTargetList calculated, we have to refigure - * any grouping-column indexes make_subplanTargetList computed. + * make_subplanTargetList calculated, we have to refigure any + * grouping-column indexes make_subplanTargetList computed. */ locate_grouping_columns(parse, tlist, result_plan->targetlist, groupColIdx); @@ -1180,6 +1185,7 @@ grouping_planner(Query *parse, double tuple_fraction) current_pathkeys = group_pathkeys; } aggstrategy = AGG_SORTED; + /* * The AGG node will not change the sort ordering of its * groups, so current_pathkeys describes the result too. @@ -1205,7 +1211,8 @@ grouping_planner(Query *parse, double tuple_fraction) else { /* - * If there are no Aggs, we shouldn't have any HAVING qual anymore + * If there are no Aggs, we shouldn't have any HAVING qual + * anymore */ Assert(parse->havingQual == NULL); @@ -1216,8 +1223,8 @@ grouping_planner(Query *parse, double tuple_fraction) if (parse->groupClause) { /* - * Add an explicit sort if we couldn't make the path come out - * the way the GROUP node needs it. + * Add an explicit sort if we couldn't make the path come + * out the way the GROUP node needs it. */ if (!pathkeys_contained_in(group_pathkeys, current_pathkeys)) { @@ -1238,7 +1245,7 @@ grouping_planner(Query *parse, double tuple_fraction) /* The Group node won't change sort ordering */ } } - } /* end of if (setOperations) */ + } /* end of if (setOperations) */ /* * If we were not able to make the plan come out in the right order, @@ -1264,6 +1271,7 @@ grouping_planner(Query *parse, double tuple_fraction) { result_plan = (Plan *) make_unique(tlist, result_plan, parse->distinctClause); + /* * If there was grouping or aggregation, leave plan_rows as-is * (ie, assume the result was already mostly unique). If not, @@ -1272,13 +1280,13 @@ grouping_planner(Query *parse, double tuple_fraction) */ if (!parse->groupClause && !parse->hasAggs) { - List *distinctExprs; + List *distinctExprs; distinctExprs = get_sortgrouplist_exprs(parse->distinctClause, parse->targetList); result_plan->plan_rows = estimate_num_groups(parse, distinctExprs, - result_plan->plan_rows); + result_plan->plan_rows); } } @@ -1443,7 +1451,7 @@ make_subplanTargetList(Query *parse, false), (Expr *) groupexpr); sub_tlist = lappend(sub_tlist, te); - *need_tlist_eval = true; /* it's not flat anymore */ + *need_tlist_eval = true; /* it's not flat anymore */ } /* and save its resno */ @@ -1459,7 +1467,7 @@ make_subplanTargetList(Query *parse, * Locate grouping columns in the tlist chosen by query_planner. * * This is only needed if we don't use the sub_tlist chosen by - * make_subplanTargetList. We have to forget the column indexes found + * make_subplanTargetList. We have to forget the column indexes found * by that routine and re-locate the grouping vars in the real sub_tlist. */ static void @@ -1528,7 +1536,7 @@ postprocess_setop_tlist(List *new_tlist, List *orig_tlist) Assert(orig_tlist != NIL); orig_tle = (TargetEntry *) lfirst(orig_tlist); orig_tlist = lnext(orig_tlist); - if (orig_tle->resdom->resjunk) /* should not happen */ + if (orig_tle->resdom->resjunk) /* should not happen */ elog(ERROR, "resjunk output columns are not implemented"); Assert(new_tle->resdom->resno == orig_tle->resdom->resno); Assert(new_tle->resdom->restype == orig_tle->resdom->restype); |