diff options
Diffstat (limited to 'src/backend/optimizer/plan/subselect.c')
| -rw-r--r-- | src/backend/optimizer/plan/subselect.c | 173 |
1 files changed, 93 insertions, 80 deletions
diff --git a/src/backend/optimizer/plan/subselect.c b/src/backend/optimizer/plan/subselect.c index 780bed6c2bf..154804d3d0f 100644 --- a/src/backend/optimizer/plan/subselect.c +++ b/src/backend/optimizer/plan/subselect.c @@ -7,7 +7,7 @@ * Portions Copyright (c) 1994, Regents of the University of California * * IDENTIFICATION - * $Header: /cvsroot/pgsql/src/backend/optimizer/plan/subselect.c,v 1.79 2003/07/25 00:01:08 tgl Exp $ + * $Header: /cvsroot/pgsql/src/backend/optimizer/plan/subselect.c,v 1.80 2003/08/04 00:43:20 momjian Exp $ * *------------------------------------------------------------------------- */ @@ -71,26 +71,26 @@ typedef struct PlannerParamItem { Node *item; /* the Var, Aggref, or Param */ Index abslevel; /* its absolute query level */ -} PlannerParamItem; +} PlannerParamItem; typedef struct finalize_primnode_context { - Bitmapset *paramids; /* Set of PARAM_EXEC paramids found */ - Bitmapset *outer_params; /* Set of accessible outer paramids */ -} finalize_primnode_context; + Bitmapset *paramids; /* Set of PARAM_EXEC paramids found */ + Bitmapset *outer_params; /* Set of accessible outer paramids */ +} finalize_primnode_context; static List *convert_sublink_opers(List *lefthand, List *operOids, - List *targetlist, int rtindex, - List **righthandIds); + List *targetlist, int rtindex, + List **righthandIds); static bool subplan_is_hashable(SubLink *slink, SubPlan *node); static Node *replace_correlation_vars_mutator(Node *node, void *context); static Node *process_sublinks_mutator(Node *node, bool *isTopQual); static Bitmapset *finalize_plan(Plan *plan, List *rtable, - Bitmapset *outer_params, - Bitmapset *valid_params); -static bool finalize_primnode(Node *node, finalize_primnode_context *context); + Bitmapset * outer_params, + Bitmapset * valid_params); +static bool finalize_primnode(Node *node, finalize_primnode_context * context); /* @@ -125,7 +125,7 @@ replace_outer_var(Var *var) pitem = (PlannerParamItem *) lfirst(ppl); if (pitem->abslevel == abslevel && IsA(pitem->item, Var)) { - Var *pvar = (Var *) pitem->item; + Var *pvar = (Var *) pitem->item; if (pvar->varno == var->varno && pvar->varattno == var->varattno && @@ -177,7 +177,7 @@ replace_outer_agg(Aggref *agg) * Just make a new slot every time. */ agg = (Aggref *) copyObject(agg); - IncrementVarSublevelsUp((Node *) agg, - ((int) agg->agglevelsup), 0); + IncrementVarSublevelsUp((Node *) agg, -((int) agg->agglevelsup), 0); Assert(agg->agglevelsup == 0); pitem = (PlannerParamItem *) palloc(sizeof(PlannerParamItem)); @@ -238,7 +238,7 @@ generate_new_param(Oid paramtype, int32 paramtypmod) static Node * make_subplan(SubLink *slink, List *lefthand, bool isTopQual) { - SubPlan *node = makeNode(SubPlan); + SubPlan *node = makeNode(SubPlan); Query *subquery = (Query *) (slink->subselect); double tuple_fraction; Plan *plan; @@ -268,8 +268,8 @@ make_subplan(SubLink *slink, List *lefthand, bool isTopQual) * in path/costsize.c. * * XXX If an ALL/ANY subplan is uncorrelated, we may decide to hash or - * materialize its result below. In that case it would've been better to - * specify full retrieval. At present, however, we can only detect + * materialize its result below. In that case it would've been better + * to specify full retrieval. At present, however, we can only detect * correlation or lack of it after we've made the subplan :-(. Perhaps * detection of correlation should be done as a separate step. * Meanwhile, we don't want to be too optimistic about the percentage @@ -323,12 +323,13 @@ make_subplan(SubLink *slink, List *lefthand, bool isTopQual) bms_free(tmpset); /* - * Un-correlated or undirect correlated plans of EXISTS, EXPR, ARRAY, or - * MULTIEXPR types can be used as initPlans. For EXISTS, EXPR, or ARRAY, - * we just produce a Param referring to the result of evaluating the - * initPlan. For MULTIEXPR, we must build an AND or OR-clause of the - * individual comparison operators, using the appropriate lefthand - * side expressions and Params for the initPlan's target items. + * Un-correlated or undirect correlated plans of EXISTS, EXPR, ARRAY, + * or MULTIEXPR types can be used as initPlans. For EXISTS, EXPR, or + * ARRAY, we just produce a Param referring to the result of + * evaluating the initPlan. For MULTIEXPR, we must build an AND or + * OR-clause of the individual comparison operators, using the + * appropriate lefthand side expressions and Params for the initPlan's + * target items. */ if (node->parParam == NIL && slink->subLinkType == EXISTS_SUBLINK) { @@ -368,7 +369,7 @@ make_subplan(SubLink *slink, List *lefthand, bool isTopQual) } else if (node->parParam == NIL && slink->subLinkType == MULTIEXPR_SUBLINK) { - List *exprs; + List *exprs; /* Convert the lefthand exprs and oper OIDs into executable exprs */ exprs = convert_sublink_opers(lefthand, @@ -378,6 +379,7 @@ make_subplan(SubLink *slink, List *lefthand, bool isTopQual) &node->paramIds); node->setParam = listCopy(node->paramIds); PlannerInitPlan = lappend(PlannerInitPlan, node); + /* * The executable expressions are returned to become part of the * outer plan's expression tree; they are not kept in the initplan @@ -402,15 +404,16 @@ make_subplan(SubLink *slink, List *lefthand, bool isTopQual) */ if (subplan_is_hashable(slink, node)) node->useHashTable = true; + /* - * Otherwise, we have the option to tack a MATERIAL node onto the top - * of the subplan, to reduce the cost of reading it repeatedly. This - * is pointless for a direct-correlated subplan, since we'd have to - * recompute its results each time anyway. For uncorrelated/undirect - * correlated subplans, we add MATERIAL if the subplan's top plan node - * is anything more complicated than a plain sequential scan, and we - * do it even for seqscan if the qual appears selective enough to - * eliminate many tuples. + * Otherwise, we have the option to tack a MATERIAL node onto the + * top of the subplan, to reduce the cost of reading it + * repeatedly. This is pointless for a direct-correlated subplan, + * since we'd have to recompute its results each time anyway. For + * uncorrelated/undirect correlated subplans, we add MATERIAL if + * the subplan's top plan node is anything more complicated than a + * plain sequential scan, and we do it even for seqscan if the + * qual appears selective enough to eliminate many tuples. */ else if (node->parParam == NIL) { @@ -448,9 +451,7 @@ make_subplan(SubLink *slink, List *lefthand, bool isTopQual) break; } if (use_material) - { node->plan = plan = materialize_finished_plan(plan); - } } /* Convert the lefthand exprs and oper OIDs into executable exprs */ @@ -470,7 +471,7 @@ make_subplan(SubLink *slink, List *lefthand, bool isTopQual) /* * The Var or Aggref has already been adjusted to have the - * correct varlevelsup or agglevelsup. We probably don't even + * correct varlevelsup or agglevelsup. We probably don't even * need to copy it again, but be safe. */ args = lappend(args, copyObject(pitem->item)); @@ -485,14 +486,14 @@ make_subplan(SubLink *slink, List *lefthand, bool isTopQual) /* * convert_sublink_opers: given a lefthand-expressions list and a list of - * operator OIDs, build a list of actually executable expressions. The + * operator OIDs, build a list of actually executable expressions. The * righthand sides of the expressions are Params or Vars representing the * results of the sub-select. * * If rtindex is 0, we build Params to represent the sub-select outputs. * The paramids of the Params created are returned in the *righthandIds list. * - * If rtindex is not 0, we build Vars using that rtindex as varno. The + * If rtindex is not 0, we build Vars using that rtindex as varno. The * Vars themselves are returned in *righthandIds (this is a bit of a type * cheat, but we can get away with it). */ @@ -549,10 +550,10 @@ convert_sublink_opers(List *lefthand, List *operOids, /* * Make the expression node. * - * Note: we use make_op_expr in case runtime type conversion - * function calls must be inserted for this operator! (But we - * are not expecting to have to resolve unknown Params, so - * it's okay to pass a null pstate.) + * Note: we use make_op_expr in case runtime type conversion function + * calls must be inserted for this operator! (But we are not + * expecting to have to resolve unknown Params, so it's okay to + * pass a null pstate.) */ result = lappend(result, make_op_expr(NULL, @@ -584,9 +585,9 @@ subplan_is_hashable(SubLink *slink, SubPlan *node) List *opids; /* - * The sublink type must be "= ANY" --- that is, an IN operator. - * (We require the operator name to be unqualified, which may be - * overly paranoid, or may not be.) XXX since we also check that the + * The sublink type must be "= ANY" --- that is, an IN operator. (We + * require the operator name to be unqualified, which may be overly + * paranoid, or may not be.) XXX since we also check that the * operators are hashable, the test on operator name may be redundant? */ if (slink->subLinkType != ANY_SUBLINK) @@ -594,33 +595,37 @@ subplan_is_hashable(SubLink *slink, SubPlan *node) if (length(slink->operName) != 1 || strcmp(strVal(lfirst(slink->operName)), "=") != 0) return false; + /* * The subplan must not have any direct correlation vars --- else we'd - * have to recompute its output each time, so that the hashtable wouldn't - * gain anything. + * have to recompute its output each time, so that the hashtable + * wouldn't gain anything. */ if (node->parParam != NIL) return false; + /* - * The estimated size of the subquery result must fit in SortMem. - * (XXX what about hashtable overhead?) + * The estimated size of the subquery result must fit in SortMem. (XXX + * what about hashtable overhead?) */ subquery_size = node->plan->plan_rows * (MAXALIGN(node->plan->plan_width) + MAXALIGN(sizeof(HeapTupleData))); if (subquery_size > SortMem * 1024L) return false; + /* - * The combining operators must be hashable, strict, and self-commutative. - * The need for hashability is obvious, since we want to use hashing. - * Without strictness, behavior in the presence of nulls is too - * unpredictable. (We actually must assume even more than plain - * strictness, see nodeSubplan.c for details.) And commutativity ensures - * that the left and right datatypes are the same; this allows us to - * assume that the combining operators are equality for the righthand - * datatype, so that they can be used to compare righthand tuples as - * well as comparing lefthand to righthand tuples. (This last restriction - * could be relaxed by using two different sets of operators with the - * hash table, but there is no obvious usefulness to that at present.) + * The combining operators must be hashable, strict, and + * self-commutative. The need for hashability is obvious, since we + * want to use hashing. Without strictness, behavior in the presence + * of nulls is too unpredictable. (We actually must assume even more + * than plain strictness, see nodeSubplan.c for details.) And + * commutativity ensures that the left and right datatypes are the + * same; this allows us to assume that the combining operators are + * equality for the righthand datatype, so that they can be used to + * compare righthand tuples as well as comparing lefthand to righthand + * tuples. (This last restriction could be relaxed by using two + * different sets of operators with the hash table, but there is no + * obvious usefulness to that at present.) */ foreach(opids, slink->operOids) { @@ -665,25 +670,27 @@ convert_IN_to_join(Query *parse, SubLink *sublink) int rtindex; RangeTblEntry *rte; RangeTblRef *rtr; - InClauseInfo *ininfo; + InClauseInfo *ininfo; List *exprs; /* - * The sublink type must be "= ANY" --- that is, an IN operator. - * (We require the operator name to be unqualified, which may be - * overly paranoid, or may not be.) + * The sublink type must be "= ANY" --- that is, an IN operator. (We + * require the operator name to be unqualified, which may be overly + * paranoid, or may not be.) */ if (sublink->subLinkType != ANY_SUBLINK) return NULL; if (length(sublink->operName) != 1 || strcmp(strVal(lfirst(sublink->operName)), "=") != 0) return NULL; + /* * The sub-select must not refer to any Vars of the parent query. * (Vars of higher levels should be okay, though.) */ if (contain_vars_of_level((Node *) subselect, 1)) return NULL; + /* * The left-hand expressions must contain some Vars of the current * query, else it's not gonna be a join. @@ -691,6 +698,7 @@ convert_IN_to_join(Query *parse, SubLink *sublink) left_varnos = pull_varnos((Node *) sublink->lefthand); if (bms_is_empty(left_varnos)) return NULL; + /* * The left-hand expressions mustn't be volatile. (Perhaps we should * test the combining operators, too? We'd only need to point the @@ -698,13 +706,14 @@ convert_IN_to_join(Query *parse, SubLink *sublink) */ if (contain_volatile_functions((Node *) sublink->lefthand)) return NULL; + /* * Okay, pull up the sub-select into top range table and jointree. * * We rely here on the assumption that the outer query has no references * to the inner (necessarily true, other than the Vars that we build - * below). Therefore this is a lot easier than what pull_up_subqueries - * has to go through. + * below). Therefore this is a lot easier than what + * pull_up_subqueries has to go through. */ rte = addRangeTableEntryForSubquery(NULL, subselect, @@ -715,6 +724,7 @@ convert_IN_to_join(Query *parse, SubLink *sublink) rtr = makeNode(RangeTblRef); rtr->rtindex = rtindex; parse->jointree->fromlist = lappend(parse->jointree->fromlist, rtr); + /* * Now build the InClauseInfo node. */ @@ -722,6 +732,7 @@ convert_IN_to_join(Query *parse, SubLink *sublink) ininfo->lefthand = left_varnos; ininfo->righthand = bms_make_singleton(rtindex); parse->in_info_list = lcons(ininfo, parse->in_info_list); + /* * Build the result qual expressions. As a side effect, * ininfo->sub_targetlist is filled with a list of the Vars @@ -744,9 +755,9 @@ convert_IN_to_join(Query *parse, SubLink *sublink) * Since we do not recurse into the arguments of uplevel aggregates, they will * get copied to the appropriate subplan args list in the parent query with * uplevel vars not replaced by Params, but only adjusted in level (see - * replace_outer_agg). That's exactly what we want for the vars of the parent + * replace_outer_agg). That's exactly what we want for the vars of the parent * level --- but if an aggregate's argument contains any further-up variables, - * they have to be replaced with Params in their turn. That will happen when + * they have to be replaced with Params in their turn. That will happen when * the parent level runs SS_replace_correlation_vars. Therefore it must do * so after expanding its sublinks to subplans. And we don't want any steps * in between, else those steps would never get applied to the aggregate @@ -796,7 +807,7 @@ SS_process_sublinks(Node *expr, bool isQual) static Node * process_sublinks_mutator(Node *node, bool *isTopQual) { - bool locTopQual; + bool locTopQual; if (node == NULL) return NULL; @@ -806,11 +817,13 @@ process_sublinks_mutator(Node *node, bool *isTopQual) List *lefthand; /* - * First, recursively process the lefthand-side expressions, if any. + * First, recursively process the lefthand-side expressions, if + * any. */ locTopQual = false; lefthand = (List *) process_sublinks_mutator((Node *) sublink->lefthand, &locTopQual); + /* * Now build the SubPlan node and make the expr to return. */ @@ -818,9 +831,9 @@ process_sublinks_mutator(Node *node, bool *isTopQual) } /* - * We should never see a SubPlan expression in the input (since this is - * the very routine that creates 'em to begin with). We shouldn't find - * ourselves invoked directly on a Query, either. + * We should never see a SubPlan expression in the input (since this + * is the very routine that creates 'em to begin with). We shouldn't + * find ourselves invoked directly on a Query, either. */ Assert(!is_subplan(node)); Assert(!IsA(node, Query)); @@ -854,9 +867,9 @@ SS_finalize_plan(Plan *plan, List *rtable) List *lst; /* - * First, scan the param list to discover the sets of params that - * are available from outer query levels and my own query level. - * We do this once to save time in the per-plan recursion steps. + * First, scan the param list to discover the sets of params that are + * available from outer query levels and my own query level. We do + * this once to save time in the per-plan recursion steps. */ paramid = 0; foreach(lst, PlannerParamList) @@ -896,7 +909,7 @@ SS_finalize_plan(Plan *plan, List *rtable) */ static Bitmapset * finalize_plan(Plan *plan, List *rtable, - Bitmapset *outer_params, Bitmapset *valid_params) + Bitmapset * outer_params, Bitmapset * valid_params) { finalize_primnode_context context; List *lst; @@ -1038,8 +1051,8 @@ finalize_plan(Plan *plan, List *rtable, plan->allParam = context.paramids; /* - * For speed at execution time, make sure extParam/allParam are actually - * NULL if they are empty sets. + * For speed at execution time, make sure extParam/allParam are + * actually NULL if they are empty sets. */ if (bms_is_empty(plan->extParam)) { @@ -1060,7 +1073,7 @@ finalize_plan(Plan *plan, List *rtable, * expression tree to the result set. */ static bool -finalize_primnode(Node *node, finalize_primnode_context *context) +finalize_primnode(Node *node, finalize_primnode_context * context) { if (node == NULL) return false; @@ -1076,12 +1089,12 @@ finalize_primnode(Node *node, finalize_primnode_context *context) } if (is_subplan(node)) { - SubPlan *subplan = (SubPlan *) node; + SubPlan *subplan = (SubPlan *) node; /* Add outer-level params needed by the subplan to paramids */ context->paramids = bms_join(context->paramids, - bms_intersect(subplan->plan->extParam, - context->outer_params)); + bms_intersect(subplan->plan->extParam, + context->outer_params)); /* fall through to recurse into subplan args */ } return expression_tree_walker(node, finalize_primnode, |