| /* |
| * Licensed to the Apache Software Foundation (ASF) under one |
| * or more contributor license agreements. See the NOTICE file |
| * distributed with this work for additional information |
| * regarding copyright ownership. The ASF licenses this file |
| * to you under the Apache License, Version 2.0 (the |
| * "License"); you may not use this file except in compliance |
| * with the License. You may obtain a copy of the License at |
| * |
| * http://www.apache.org/licenses/LICENSE-2.0 |
| * |
| * Unless required by applicable law or agreed to in writing, software |
| * distributed under the License is distributed on an "AS IS" BASIS, |
| * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. |
| * See the License for the specific language governing permissions and |
| * limitations under the License. |
| */ |
| |
| /*------------------------------------------------------------------------- |
| * |
| * initsplan.c |
| * Target list, qualification, joininfo initialization routines |
| * |
| * Portions Copyright (c) 2006-2008, Greenplum inc |
| * Portions Copyright (c) 1996-2008, PostgreSQL Global Development Group |
| * Portions Copyright (c) 1994, Regents of the University of California |
| * |
| * |
| * IDENTIFICATION |
| * $PostgreSQL: pgsql/src/backend/optimizer/plan/initsplan.c,v 1.123.2.2 2007/01/08 16:47:35 tgl Exp $ |
| * |
| *------------------------------------------------------------------------- |
| */ |
| #include "postgres.h" |
| |
| #include "catalog/pg_operator.h" |
| #include "catalog/pg_type.h" |
| #include "optimizer/clauses.h" |
| #include "optimizer/cost.h" |
| #include "optimizer/joininfo.h" |
| #include "optimizer/pathnode.h" |
| #include "optimizer/paths.h" |
| #include "optimizer/planmain.h" |
| #include "optimizer/prep.h" |
| #include "optimizer/restrictinfo.h" |
| #include "optimizer/var.h" |
| #include "parser/parse_expr.h" |
| #include "parser/parse_oper.h" |
| #include "utils/builtins.h" |
| #include "utils/lsyscache.h" |
| #include "utils/syscache.h" |
| |
| |
| /* These parameters are set by GUC */ |
| int from_collapse_limit; |
| int join_collapse_limit; |
| |
| static List *deconstruct_recurse(PlannerInfo *root, Node *jtnode, |
| bool below_outer_join, |
| Relids *qualscope, Relids *inner_join_rels, |
| List **ptrToLocalEquiKeyList); |
| static OuterJoinInfo *make_outerjoininfo(PlannerInfo *root, |
| Relids left_rels, Relids right_rels, |
| Relids inner_join_rels, |
| JoinType join_type, Node *clause, |
| List *leftEquiKeyList, List *rightEquiKeyList); |
| static bool qual_is_redundant(PlannerInfo *root, RestrictInfo *restrictinfo, |
| List *restrictlist); |
| static void check_mergejoinable(RestrictInfo *restrictinfo); |
| static void check_hashjoinable(RestrictInfo *restrictinfo); |
| |
| |
| /***************************************************************************** |
| * |
| * JOIN TREES |
| * |
| *****************************************************************************/ |
| |
| /* |
| * add_base_rels_to_query |
| * |
| * Scan the query's jointree and create baserel RelOptInfos for all |
| * the base relations (ie, table, subquery, and function RTEs) |
| * appearing in the jointree. |
| * |
| * The initial invocation must pass root->parse->jointree as the value of |
| * jtnode. Internally, the function recurses through the jointree. |
| * |
| * At the end of this process, there should be one baserel RelOptInfo for |
| * every non-join RTE that is used in the query. Therefore, this routine |
| * is the only place that should call build_simple_rel with reloptkind |
| * RELOPT_BASEREL. (Note: build_simple_rel recurses internally to build |
| * "other rel" RelOptInfos for the members of any appendrels we find here.) |
| */ |
| void |
| add_base_rels_to_query(PlannerInfo *root, Node *jtnode) |
| { |
| if (jtnode == NULL) |
| return; |
| if (IsA(jtnode, RangeTblRef)) |
| { |
| int varno = ((RangeTblRef *) jtnode)->rtindex; |
| |
| (void) build_simple_rel(root, varno, RELOPT_BASEREL); |
| } |
| else if (IsA(jtnode, FromExpr)) |
| { |
| FromExpr *f = (FromExpr *) jtnode; |
| ListCell *l; |
| |
| foreach(l, f->fromlist) |
| add_base_rels_to_query(root, lfirst(l)); |
| } |
| else if (IsA(jtnode, JoinExpr)) |
| { |
| JoinExpr *j = (JoinExpr *) jtnode; |
| ListCell *l; |
| |
| add_base_rels_to_query(root, j->larg); |
| add_base_rels_to_query(root, j->rarg); |
| |
| foreach(l, j->subqfromlist) |
| add_base_rels_to_query(root, lfirst(l)); |
| } |
| else |
| elog(ERROR, "unrecognized node type: %d", |
| (int) nodeTag(jtnode)); |
| } |
| |
| |
| /***************************************************************************** |
| * |
| * TARGET LISTS |
| * |
| *****************************************************************************/ |
| |
| /* |
| * build_base_rel_tlists |
| * Add targetlist entries for each var needed in the query's final tlist |
| * to the appropriate base relations. |
| * |
| * We mark such vars as needed by "relation 0" to ensure that they will |
| * propagate up through all join plan steps. |
| */ |
| void |
| build_base_rel_tlists(PlannerInfo *root, List *final_tlist) |
| { |
| List *tlist_vars = pull_var_clause((Node *) final_tlist, false); |
| |
| if (tlist_vars != NIL) |
| { |
| add_vars_to_targetlist(root, tlist_vars, bms_make_singleton(0)); |
| list_free(tlist_vars); |
| } |
| } |
| |
| /* |
| * add_IN_vars_to_tlists |
| * Add targetlist entries for each var needed in InClauseInfo entries |
| * to the appropriate base relations. |
| * |
| * Normally this is a waste of time because scanning of the WHERE clause |
| * will have added them. But it is possible that eval_const_expressions() |
| * simplified away all references to the vars after the InClauseInfos were |
| * made. We need the IN's righthand-side vars to be available at the join |
| * anyway, in case we try to unique-ify the subselect's outputs. (The only |
| * known case that provokes this is "WHERE false AND foo IN (SELECT ...)". |
| * We don't try to be very smart about such cases, just correct.) |
| */ |
| void |
| add_IN_vars_to_tlists(PlannerInfo *root) |
| { |
| ListCell *l; |
| |
| foreach(l, root->in_info_list) |
| { |
| InClauseInfo *ininfo = (InClauseInfo *) lfirst(l); |
| List *in_vars; |
| |
| in_vars = pull_var_clause((Node *) ininfo->sub_targetlist, false); |
| if (in_vars != NIL) |
| { |
| add_vars_to_targetlist(root, in_vars, |
| bms_union(ininfo->lefthand, |
| ininfo->righthand)); |
| list_free(in_vars); |
| } |
| } |
| } |
| |
| /* |
| * add_vars_to_targetlist |
| * CDB: This function has been moved to relnode.c |
| */ |
| |
| /***************************************************************************** |
| * |
| * JOIN TREE PROCESSING |
| * |
| *****************************************************************************/ |
| |
| /* |
| * deconstruct_jointree |
| * Recursively scan the query's join tree for WHERE and JOIN/ON qual |
| * clauses, and add these to the appropriate restrictinfo and joininfo |
| * lists belonging to base RelOptInfos. Also, add OuterJoinInfo nodes |
| * to root->oj_info_list for any outer joins appearing in the query tree. |
| * Return a "joinlist" data structure showing the join order decisions |
| * that need to be made by make_one_rel(). |
| * |
| * The "joinlist" result is a list of items that are either RangeTblRef |
| * jointree nodes or sub-joinlists. All the items at the same level of |
| * joinlist must be joined in an order to be determined by make_one_rel() |
| * (note that legal orders may be constrained by OuterJoinInfo nodes). |
| * A sub-joinlist represents a subproblem to be planned separately. Currently |
| * sub-joinlists arise only from FULL OUTER JOIN or when collapsing of |
| * subproblems is stopped by join_collapse_limit or from_collapse_limit. |
| * |
| * NOTE: when dealing with inner joins, it is appropriate to let a qual clause |
| * be evaluated at the lowest level where all the variables it mentions are |
| * available. However, we cannot push a qual down into the nullable side(s) |
| * of an outer join since the qual might eliminate matching rows and cause a |
| * NULL row to be incorrectly emitted by the join. Therefore, we artificially |
| * OR the minimum-relids of such an outer join into the required_relids of |
| * clauses appearing above it. This forces those clauses to be delayed until |
| * application of the outer join (or maybe even higher in the join tree). |
| */ |
| List * |
| deconstruct_jointree(PlannerInfo *root) |
| { |
| Relids qualscope; |
| Relids inner_join_rels; |
| |
| /* Start recursion at top of jointree */ |
| Assert(root->parse->jointree != NULL && |
| IsA(root->parse->jointree, FromExpr)); |
| |
| return deconstruct_recurse(root, (Node *) root->parse->jointree, false, |
| &qualscope, &inner_join_rels, NULL); |
| } |
| |
| /* |
| * deconstruct_recurse |
| * One recursion level of deconstruct_jointree processing. |
| * |
| * Inputs: |
| * jtnode is the jointree node to examine |
| * below_outer_join is TRUE if this node is within the nullable side of a |
| * higher-level outer join |
| * Outputs: |
| * *qualscope gets the set of base Relids syntactically included in this |
| * jointree node (do not modify or free this, as it may also be pointed |
| * to by RestrictInfo and OuterJoinInfo nodes) |
| * *inner_join_rels gets the set of base Relids syntactically included in |
| * inner joins appearing at or below this jointree node (do not modify |
| * or free this, either) |
| * if non-NULL, the equikey list at *ptrToLocalEquiKeyList may have its |
| * equi key list expanded with any local equikey lists (equivalent |
| * values under the nullable side of an outer join are local equikeys |
| * but not global equikeys) |
| * Return value is the appropriate joinlist for this jointree node |
| * |
| * In addition, entries will be added to root->oj_info_list for outer joins. |
| */ |
| static List * |
| deconstruct_recurse(PlannerInfo *root, Node *jtnode, bool below_outer_join, |
| Relids *qualscope, Relids *inner_join_rels, |
| List **ptrToLocalEquiKeyList) |
| { |
| List *joinlist; |
| |
| if (jtnode == NULL) |
| { |
| *qualscope = NULL; |
| *inner_join_rels = NULL; |
| return NIL; |
| } |
| if (IsA(jtnode, RangeTblRef)) |
| { |
| int varno = ((RangeTblRef *) jtnode)->rtindex; |
| |
| /* No quals to deal with, just return correct result */ |
| *qualscope = bms_make_singleton(varno); |
| /* A single baserel does not create an inner join */ |
| *inner_join_rels = NULL; |
| joinlist = list_make1(jtnode); |
| } |
| else if (IsA(jtnode, FromExpr)) |
| { |
| FromExpr *f = (FromExpr *) jtnode; |
| int remaining; |
| ListCell *l; |
| |
| /* |
| * First, recurse to handle child joins. We collapse subproblems into |
| * a single joinlist whenever the resulting joinlist wouldn't exceed |
| * from_collapse_limit members. Also, always collapse one-element |
| * subproblems, since that won't lengthen the joinlist anyway. |
| */ |
| *qualscope = NULL; |
| *inner_join_rels = NULL; |
| joinlist = NIL; |
| remaining = list_length(f->fromlist); |
| foreach(l, f->fromlist) |
| { |
| Relids sub_qualscope; |
| List *sub_joinlist; |
| int sub_members; |
| |
| sub_joinlist = deconstruct_recurse(root, lfirst(l), |
| below_outer_join, |
| &sub_qualscope, |
| inner_join_rels, |
| ptrToLocalEquiKeyList); |
| *qualscope = bms_add_members(*qualscope, sub_qualscope); |
| sub_members = list_length(sub_joinlist); |
| remaining--; |
| if (sub_members <= 1 || |
| list_length(joinlist) + sub_members + remaining <= from_collapse_limit) |
| joinlist = list_concat(joinlist, sub_joinlist); |
| else |
| joinlist = lappend(joinlist, sub_joinlist); |
| } |
| |
| /* |
| * A FROM with more than one list element is an inner join subsuming |
| * all below it, so we should report inner_join_rels = qualscope. |
| * If there was exactly one element, we should (and already did) report |
| * whatever its inner_join_rels were. If there were no elements |
| * (is that possible?) the initialization before the loop fixed it. |
| */ |
| if (list_length(f->fromlist) > 1) |
| *inner_join_rels = *qualscope; |
| |
| /* |
| * Now process the top-level quals. |
| */ |
| foreach(l, (List *) f->quals) |
| distribute_qual_to_rels(root, (Node *) lfirst(l), |
| false, false, below_outer_join, |
| *qualscope, NULL, NULL, |
| ptrToLocalEquiKeyList); |
| } |
| else if (IsA(jtnode, JoinExpr)) |
| { |
| JoinExpr *j = (JoinExpr *) jtnode; |
| Relids leftids = NULL; |
| Relids rightids = NULL; |
| Relids left_inners = NULL; |
| Relids right_inners = NULL; |
| Relids nonnullable_rels; |
| Relids ojscope; |
| List *leftjoinlist, |
| *rightjoinlist; |
| OuterJoinInfo *ojinfo; |
| ListCell *cell; |
| ListCell *qual; |
| |
| List *localLeftEquiKeyList = NIL; |
| List *localRightEquiKeyList = NIL; |
| /* |
| * Order of operations here is subtle and critical. First we recurse |
| * to handle sub-JOINs. Their join quals will be placed without |
| * regard for whether this level is an outer join, which is correct. |
| * Then we place our own join quals, which are restricted by lower |
| * outer joins in any case, and are forced to this level if this is an |
| * outer join and they mention the outer side. Finally, if this is an |
| * outer join, we create an oj_info_list entry for the join. This |
| * will prevent quals above us in the join tree that use those rels |
| * from being pushed down below this level. (It's okay for upper |
| * quals to be pushed down to the outer side, however.) |
| */ |
| switch (j->jointype) |
| { |
| case JOIN_INNER: |
| leftjoinlist = deconstruct_recurse(root, j->larg, |
| below_outer_join, |
| &leftids, &left_inners, |
| ptrToLocalEquiKeyList); |
| rightjoinlist = deconstruct_recurse(root, j->rarg, |
| below_outer_join, |
| &rightids, &right_inners, |
| ptrToLocalEquiKeyList); |
| *qualscope = bms_union(leftids, rightids); |
| *inner_join_rels = bms_copy(*qualscope); |
| /* Inner join adds no restrictions for quals */ |
| nonnullable_rels = NULL; |
| break; |
| case JOIN_LEFT: |
| case JOIN_LASJ: |
| case JOIN_LASJ_NOTIN: |
| leftjoinlist = deconstruct_recurse(root, j->larg, |
| below_outer_join, |
| &leftids, &left_inners, |
| ptrToLocalEquiKeyList); |
| rightjoinlist = deconstruct_recurse(root, j->rarg, |
| true, |
| &rightids, &right_inners, |
| &localRightEquiKeyList); |
| *qualscope = bms_union(leftids, rightids); |
| *inner_join_rels = bms_union(left_inners, right_inners); |
| nonnullable_rels = leftids; |
| break; |
| case JOIN_FULL: |
| leftjoinlist = deconstruct_recurse(root, j->larg, |
| true, |
| &leftids, &left_inners, |
| &localLeftEquiKeyList); |
| rightjoinlist = deconstruct_recurse(root, j->rarg, |
| true, |
| &rightids, &right_inners, |
| &localRightEquiKeyList); |
| *qualscope = bms_union(leftids, rightids); |
| *inner_join_rels = bms_union(left_inners, right_inners); |
| /* each side is both outer and inner */ |
| nonnullable_rels = *qualscope; |
| break; |
| case JOIN_RIGHT: |
| /* notice we switch leftids, rightids, and localRightEquiKeyList */ |
| leftjoinlist = deconstruct_recurse(root, j->larg, |
| true, |
| &rightids, &right_inners, |
| &localRightEquiKeyList); |
| rightjoinlist = deconstruct_recurse(root, j->rarg, |
| below_outer_join, |
| &leftids, &left_inners, |
| ptrToLocalEquiKeyList); |
| *qualscope = bms_union(leftids, rightids); |
| *inner_join_rels = bms_union(left_inners, right_inners); |
| nonnullable_rels = leftids; |
| break; |
| default: |
| elog(ERROR, "unrecognized join type: %d", |
| (int) j->jointype); |
| nonnullable_rels = NULL; /* keep compiler quiet */ |
| leftjoinlist = rightjoinlist = NIL; |
| break; |
| } |
| |
| /* |
| * CDB: If subqueries from the JOIN...ON search condition were |
| * flattened, 'subqfromlist' is a list of jointree nodes to be |
| * included in the cross product with larg and rarg. |
| * |
| * For left or right joins, the flattened subquery tables must be |
| * associated with the null-augmented side (right side of LEFT JOIN). |
| * For inner joins either side is ok. For full outer joins the |
| * subqfromlist is not used at present. |
| */ |
| foreach(cell, j->subqfromlist) |
| { |
| List *sub_joinlist; |
| Relids sub_qualscope = NULL; |
| Relids sub_inners; |
| |
| List **localEquiKeyList; |
| switch (j->jointype) |
| { |
| case JOIN_INNER: |
| localEquiKeyList = ptrToLocalEquiKeyList; |
| break; |
| case JOIN_LEFT: |
| localEquiKeyList = &localRightEquiKeyList; |
| break; |
| case JOIN_RIGHT: |
| localEquiKeyList = &localRightEquiKeyList; |
| break; |
| default: |
| Assert(0); |
| localEquiKeyList = NULL; /* should not hit */ |
| break; |
| } |
| |
| sub_joinlist = deconstruct_recurse(root, lfirst(cell), |
| below_outer_join || |
| (j->jointype != JOIN_INNER), |
| &sub_qualscope, |
| &sub_inners, |
| localEquiKeyList |
| ); |
| rightids = bms_add_members(rightids, sub_qualscope); |
| *qualscope = bms_add_members(*qualscope, sub_qualscope); |
| *inner_join_rels = bms_add_members(*inner_join_rels, rightids); |
| switch (j->jointype) |
| { |
| case JOIN_INNER: |
| case JOIN_LEFT: |
| rightjoinlist = list_concat(rightjoinlist, sub_joinlist); |
| break; |
| case JOIN_RIGHT: |
| leftjoinlist = list_concat(leftjoinlist, sub_joinlist); |
| break; |
| default: |
| Assert(0); |
| } |
| } |
| |
| /* |
| * For an OJ, form the OuterJoinInfo now, because we need the OJ's |
| * semantic scope (ojscope) to pass to distribute_qual_to_rels. But |
| * we mustn't add it to oj_info_list just yet, because we don't want |
| * distribute_qual_to_rels to think it is an outer join below us. |
| */ |
| if (j->jointype != JOIN_INNER) |
| { |
| ojinfo = make_outerjoininfo(root, |
| leftids, rightids, |
| *inner_join_rels, |
| j->jointype, |
| j->quals, |
| localLeftEquiKeyList, |
| localRightEquiKeyList); |
| ojscope = bms_union(ojinfo->min_lefthand, ojinfo->min_righthand); |
| } |
| else |
| { |
| ojinfo = NULL; |
| ojscope = NULL; |
| } |
| |
| /* Process the qual clauses */ |
| foreach(qual, (List *) j->quals) |
| distribute_qual_to_rels(root, (Node *) lfirst(qual), |
| false, false, below_outer_join, |
| *qualscope, ojscope, nonnullable_rels, |
| ptrToLocalEquiKeyList); |
| |
| /* Now we can add the OuterJoinInfo to oj_info_list */ |
| if (ojinfo) |
| root->oj_info_list = lappend(root->oj_info_list, ojinfo); |
| |
| /* |
| * Finally, compute the output joinlist. We fold subproblems together |
| * except at a FULL JOIN or where join_collapse_limit would be |
| * exceeded. |
| */ |
| if (j->jointype == JOIN_FULL || j->jointype == JOIN_LASJ || j->jointype == JOIN_LASJ_NOTIN) |
| { |
| /* force the join order exactly at this node */ |
| joinlist = list_make1(list_make2(leftjoinlist, rightjoinlist)); |
| } |
| else if (list_length(leftjoinlist) + list_length(rightjoinlist) <= |
| join_collapse_limit) |
| { |
| /* OK to combine subproblems */ |
| joinlist = list_concat(leftjoinlist, rightjoinlist); |
| } |
| else |
| { |
| /* can't combine, but needn't force join order above here */ |
| Node *leftpart, |
| *rightpart; |
| |
| /* avoid creating useless 1-element sublists */ |
| if (list_length(leftjoinlist) == 1) |
| leftpart = (Node *) linitial(leftjoinlist); |
| else |
| leftpart = (Node *) leftjoinlist; |
| if (list_length(rightjoinlist) == 1) |
| rightpart = (Node *) linitial(rightjoinlist); |
| else |
| rightpart = (Node *) rightjoinlist; |
| joinlist = list_make2(leftpart, rightpart); |
| } |
| } |
| else |
| { |
| elog(ERROR, "unrecognized node type: %d", |
| (int) nodeTag(jtnode)); |
| joinlist = NIL; /* keep compiler quiet */ |
| } |
| return joinlist; |
| } |
| |
| /* |
| * make_outerjoininfo |
| * Build an OuterJoinInfo for the current outer join |
| * |
| * Inputs: |
| * left_rels: the base Relids syntactically on outer side of join |
| * right_rels: the base Relids syntactically on inner side of join |
| * inner_join_rels: base Relids participating in inner joins below this one |
| * join_type: what it says |
| * clause: the outer join's join condition |
| * |
| * If the join is a RIGHT JOIN, left_rels and right_rels are switched by |
| * the caller, so that left_rels is always the nonnullable side. Hence |
| * we need only distinguish the LEFT and FULL cases. |
| * |
| * The node should eventually be appended to root->oj_info_list, but we |
| * do not do that here. |
| * |
| * Note: we assume that this function is invoked bottom-up, so that |
| * root->oj_info_list already contains entries for all outer joins that are |
| * syntactically below this one. |
| */ |
| static OuterJoinInfo * |
| make_outerjoininfo(PlannerInfo *root, |
| Relids left_rels, Relids right_rels, |
| Relids inner_join_rels, |
| JoinType join_type, Node *clause, |
| List *leftEquiKeyList, List *rightEquiKeyList) |
| { |
| OuterJoinInfo *ojinfo = makeNode(OuterJoinInfo); |
| Relids clause_relids; |
| Relids strict_relids; |
| Relids min_lefthand; |
| Relids min_righthand; |
| ListCell *l; |
| |
| /* |
| * Presently the executor cannot support FOR UPDATE/SHARE marking of rels |
| * appearing on the nullable side of an outer join. (It's somewhat unclear |
| * what that would mean, anyway: what should we mark when a result row is |
| * generated from no element of the nullable relation?) So, complain if |
| * any nullable rel is FOR UPDATE/SHARE. |
| * |
| * You might be wondering why this test isn't made far upstream in the |
| * parser. It's because the parser hasn't got enough info --- consider |
| * FOR UPDATE applied to a view. Only after rewriting and flattening do |
| * we know whether the view contains an outer join. |
| */ |
| foreach(l, root->parse->rowMarks) |
| { |
| RowMarkClause *rc = (RowMarkClause *) lfirst(l); |
| |
| if (bms_is_member(rc->rti, right_rels) || |
| (join_type == JOIN_FULL && bms_is_member(rc->rti, left_rels))) |
| ereport(ERROR, |
| (errcode(ERRCODE_FEATURE_NOT_SUPPORTED), |
| errmsg("SELECT FOR UPDATE/SHARE cannot be applied to the nullable side of an outer join"))); |
| } |
| |
| /* this always starts out false */ |
| ojinfo->delay_upper_joins = false; |
| ojinfo->left_equi_key_list = leftEquiKeyList; |
| ojinfo->right_equi_key_list = rightEquiKeyList; |
| |
| /* If it's a full join, no need to be very smart */ |
| ojinfo->syn_lefthand = left_rels; |
| ojinfo->syn_righthand = right_rels; |
| ojinfo->join_type = join_type; |
| if (join_type == JOIN_FULL) |
| { |
| ojinfo->min_lefthand = left_rels; |
| ojinfo->min_righthand = right_rels; |
| ojinfo->lhs_strict = false; /* don't care about this */ |
| return ojinfo; |
| } |
| |
| /* |
| * Retrieve all relids mentioned within the join clause. |
| */ |
| clause_relids = pull_varnos(clause); |
| |
| /* |
| * For which relids is the clause strict, ie, it cannot succeed if the |
| * rel's columns are all NULL? |
| */ |
| strict_relids = find_nonnullable_rels(clause); |
| |
| /* Remember whether the clause is strict for any LHS relations */ |
| ojinfo->lhs_strict = bms_overlap(strict_relids, left_rels); |
| |
| /* |
| * Required LHS always includes the LHS rels mentioned in the clause. |
| * We may have to add more rels based on lower outer joins; see below. |
| */ |
| min_lefthand = bms_intersect(clause_relids, left_rels); |
| |
| /* |
| * Similarly for required RHS. But here, we must also include any lower |
| * inner joins, to ensure we don't try to commute with any of them. |
| */ |
| min_righthand = bms_int_members(bms_union(clause_relids, inner_join_rels), |
| right_rels); |
| |
| foreach(l, root->oj_info_list) |
| { |
| OuterJoinInfo *otherinfo = (OuterJoinInfo *) lfirst(l); |
| |
| /* ignore full joins --- other mechanisms preserve their ordering */ |
| if (otherinfo->join_type == JOIN_FULL) |
| continue; |
| |
| /* |
| * For a lower OJ in our LHS, if our join condition uses the lower |
| * join's RHS and is not strict for that rel, we must preserve the |
| * ordering of the two OJs, so add lower OJ's full syntactic relset to |
| * min_lefthand. (We must use its full syntactic relset, not just |
| * its min_lefthand + min_righthand. This is because there might |
| * be other OJs below this one that this one can commute with, |
| * but we cannot commute with them if we don't with this one.) |
| * |
| * Note: I believe we have to insist on being strict for at least one |
| * rel in the lower OJ's min_righthand, not its whole syn_righthand. |
| */ |
| if (bms_overlap(left_rels, otherinfo->syn_righthand) && |
| bms_overlap(clause_relids, otherinfo->syn_righthand) && |
| !bms_overlap(strict_relids, otherinfo->min_righthand)) |
| { |
| min_lefthand = bms_add_members(min_lefthand, |
| otherinfo->syn_lefthand); |
| min_lefthand = bms_add_members(min_lefthand, |
| otherinfo->syn_righthand); |
| } |
| |
| /* |
| * For a lower OJ in our RHS, if our join condition does not use the |
| * lower join's RHS and the lower OJ's join condition is strict, we |
| * can interchange the ordering of the two OJs; otherwise we must |
| * add lower OJ's full syntactic relset to min_righthand. |
| * |
| * Here, we have to consider that "our join condition" includes |
| * any clauses that syntactically appeared above the lower OJ and |
| * below ours; those are equivalent to degenerate clauses in our |
| * OJ and must be treated as such. Such clauses obviously can't |
| * reference our LHS, and they must be non-strict for the lower OJ's |
| * RHS (else reduce_outer_joins would have reduced the lower OJ to |
| * a plain join). Hence the other ways in which we handle clauses |
| * within our join condition are not affected by them. The net |
| * effect is therefore sufficiently represented by the |
| * delay_upper_joins flag saved for us by distribute_qual_to_rels. |
| */ |
| if (bms_overlap(right_rels, otherinfo->syn_righthand)) |
| { |
| if (bms_overlap(clause_relids, otherinfo->syn_righthand) || |
| !otherinfo->lhs_strict || otherinfo->delay_upper_joins) |
| { |
| min_righthand = bms_add_members(min_righthand, |
| otherinfo->syn_lefthand); |
| min_righthand = bms_add_members(min_righthand, |
| otherinfo->syn_righthand); |
| } |
| } |
| } |
| |
| /* |
| * If we found nothing to put in min_lefthand, punt and make it the full |
| * LHS, to avoid having an empty min_lefthand which will confuse later |
| * processing. (We don't try to be smart about such cases, just correct.) |
| * Likewise for min_righthand. |
| */ |
| if (bms_is_empty(min_lefthand)) |
| min_lefthand = bms_copy(left_rels); |
| if (bms_is_empty(min_righthand)) |
| min_righthand = bms_copy(right_rels); |
| |
| /* Now they'd better be nonempty */ |
| Assert(!bms_is_empty(min_lefthand)); |
| Assert(!bms_is_empty(min_righthand)); |
| /* Shouldn't overlap either */ |
| Assert(!bms_overlap(min_lefthand, min_righthand)); |
| |
| ojinfo->min_lefthand = min_lefthand; |
| ojinfo->min_righthand = min_righthand; |
| |
| return ojinfo; |
| } |
| |
| |
| /***************************************************************************** |
| * |
| * QUALIFICATIONS |
| * |
| *****************************************************************************/ |
| |
| /* |
| * distribute_qual_to_rels |
| * Add clause information to either the baserestrictinfo or joininfo list |
| * (depending on whether the clause is a join) of each base relation |
| * mentioned in the clause. A RestrictInfo node is created and added to |
| * the appropriate list for each rel. Also, if the clause uses a |
| * mergejoinable operator and is not delayed by outer-join rules, enter |
| * the left- and right-side expressions into the query's lists of |
| * equijoined vars. |
| * |
| * 'clause': the qual clause to be distributed |
| * 'is_deduced': TRUE if the qual came from implied-equality deduction |
| * 'below_outer_join': TRUE if the qual is from a JOIN/ON that is below the |
| * nullable side of a higher-level outer join. |
| * 'qualscope': set of baserels the qual's syntactic scope covers |
| * 'ojscope': NULL if not an outer-join qual, else the minimum set of baserels |
| * needed to form this join |
| * 'outerjoin_nonnullable': NULL if not an outer-join qual, else the set of |
| * baserels appearing on the outer (nonnullable) side of the join |
| * (for FULL JOIN this includes both sides of the join, and must in fact |
| * equal qualscope) |
| * |
| * 'qualscope' identifies what level of JOIN the qual came from syntactically. |
| * 'ojscope' is needed if we decide to force the qual up to the outer-join |
| * level, which will be ojscope not necessarily qualscope. |
| * |
| * 'ptrToLocalEquiKeyList': the equiKeyList at *ptrToLocalEquiKeyList may have |
| * its equi key list expanded. ptrToLocalEquiKeyList may be null |
| */ |
| void |
| distribute_qual_to_rels(PlannerInfo *root, Node *clause, |
| bool is_deduced, bool is_deduced_but_not_equijoin, |
| bool below_outer_join, |
| Relids qualscope, |
| Relids ojscope, |
| Relids outerjoin_nonnullable, |
| List **ptrToLocalEquiKeyList) |
| { |
| Relids relids; |
| bool is_pushed_down; |
| bool outerjoin_delayed; |
| bool pseudoconstant = false; |
| bool maybe_equijoin; |
| bool maybe_outer_join; |
| bool maybe_local_equijoin; |
| RestrictInfo *restrictinfo; |
| RelOptInfo *rel; |
| List *vars; |
| |
| /* |
| * Retrieve all relids mentioned within the clause. |
| */ |
| relids = pull_varnos(clause); |
| |
| /* |
| * Cross-check: clause should contain no relids not within its scope. |
| * Otherwise the parser messed up. |
| */ |
| if (!bms_is_subset(relids, qualscope)) |
| elog(ERROR, "JOIN qualification may not refer to other relations"); |
| if (ojscope && !bms_is_subset(relids, ojscope)) |
| elog(ERROR, "JOIN qualification may not refer to other relations"); |
| |
| /* |
| * If the clause is variable-free, our normal heuristic for pushing it |
| * down to just the mentioned rels doesn't work, because there are none. |
| * |
| * If the clause is an outer-join clause, we must force it to the OJ's |
| * semantic level to preserve semantics. |
| * |
| * Otherwise, when the clause contains volatile functions, we force it to |
| * be evaluated at its original syntactic level. This preserves the |
| * expected semantics. |
| * |
| * When the clause contains no volatile functions either, it is actually a |
| * pseudoconstant clause that will not change value during any one |
| * execution of the plan, and hence can be used as a one-time qual in a |
| * gating Result plan node. We put such a clause into the regular |
| * RestrictInfo lists for the moment, but eventually createplan.c will |
| * pull it out and make a gating Result node immediately above whatever |
| * plan node the pseudoconstant clause is assigned to. It's usually best |
| * to put a gating node as high in the plan tree as possible. If we are |
| * not below an outer join, we can actually push the pseudoconstant qual |
| * all the way to the top of the tree. If we are below an outer join, we |
| * leave the qual at its original syntactic level (we could push it up to |
| * just below the outer join, but that seems more complex than it's |
| * worth). |
| */ |
| if (bms_is_empty(relids)) |
| { |
| if (ojscope) |
| { |
| /* clause is attached to outer join, eval it there */ |
| relids = ojscope; |
| /* mustn't use as gating qual, so don't mark pseudoconstant */ |
| } |
| else |
| { |
| /* eval at original syntactic level */ |
| relids = qualscope; |
| if (!contain_volatile_functions(clause)) |
| { |
| /* mark as gating qual */ |
| pseudoconstant = true; |
| /* tell createplan.c to check for gating quals */ |
| root->hasPseudoConstantQuals = true; |
| /* if not below outer join, push it to top of tree */ |
| if (!below_outer_join) |
| relids = get_relids_in_jointree((Node *) root->parse->jointree); |
| } |
| } |
| } |
| |
| /*---------- |
| * Check to see if clause application must be delayed by outer-join |
| * considerations. |
| * |
| * A word about is_pushed_down: we mark the qual as "pushed down" if |
| * it is (potentially) applicable at a level different from its original |
| * syntactic level. This flag is used to distinguish OUTER JOIN ON quals |
| * from other quals pushed down to the same joinrel. The rules are: |
| * WHERE quals and INNER JOIN quals: is_pushed_down = true. |
| * Non-degenerate OUTER JOIN quals: is_pushed_down = false. |
| * Degenerate OUTER JOIN quals: is_pushed_down = true. |
| * A "degenerate" OUTER JOIN qual is one that doesn't mention the |
| * non-nullable side, and hence can be pushed down into the nullable side |
| * without changing the join result. It is correct to treat it as a |
| * regular filter condition at the level where it is evaluated. |
| * |
| * Note: it is not immediately obvious that a simple boolean is enough |
| * for this: if for some reason we were to attach a degenerate qual to |
| * its original join level, it would need to be treated as an outer join |
| * qual there. However, this cannot happen, because all the rels the |
| * clause mentions must be in the outer join's min_righthand, therefore |
| * the join it needs must be formed before the outer join; and we always |
| * attach quals to the lowest level where they can be evaluated. But |
| * if we were ever to re-introduce a mechanism for delaying evaluation |
| * of "expensive" quals, this area would need work. |
| *---------- |
| */ |
| if (is_deduced) |
| { |
| /* |
| * If the qual came from implied-equality deduction, we always |
| * evaluate the qual at its natural semantic level. It is the |
| * responsibility of the deducer not to create any quals that should |
| * be delayed by outer-join rules. |
| */ |
| Assert(bms_equal(relids, qualscope)); |
| Assert(!ojscope); |
| Assert(!pseudoconstant); |
| is_pushed_down = true; |
| /* Needn't feed it back for more deductions */ |
| outerjoin_delayed = false; |
| maybe_equijoin = false; |
| maybe_local_equijoin = false; |
| maybe_outer_join = false; |
| } |
| else if (bms_overlap(relids, outerjoin_nonnullable)) |
| { |
| /* |
| * The qual is attached to an outer join and mentions (some of the) |
| * rels on the nonnullable side, so it's not degenerate. Force the |
| * qual to be evaluated exactly at the level of joining corresponding |
| * to the outer join. We cannot let it get pushed down into the |
| * nonnullable side, since then we'd produce no output rows, rather |
| * than the intended single null-extended row, for any |
| * nonnullable-side rows failing the qual. |
| */ |
| Assert(ojscope); |
| relids = ojscope; |
| is_pushed_down = false; |
| outerjoin_delayed = true; |
| Assert(!pseudoconstant); |
| |
| /* |
| * We can't use such a clause to deduce equijoin (the left and right |
| * sides might be unequal above the join because one of them has gone |
| * to NULL) ... but we might be able to use it for more limited |
| * purposes. Note: for the current uses of deductions from an |
| * outer-join clause, it seems safe to make the deductions even when |
| * the clause is below a higher-level outer join; so we do not check |
| * below_outer_join here. |
| */ |
| maybe_equijoin = false; |
| maybe_local_equijoin = true; |
| maybe_outer_join = true; |
| } |
| else |
| { |
| /* |
| * Normal qual clause or degenerate outer-join clause. Either way, |
| * we can mark it as pushed-down. |
| * |
| * For a pushed-down qual, we can evaluate the qual as soon as (1) |
| * we have all the rels it mentions, and (2) we are at or above any |
| * outer joins that can null any of these rels and are below the |
| * syntactic location of the given qual. We must enforce (2) because |
| * pushing down such a clause below the OJ might cause the OJ to emit |
| * null-extended rows that should not have been formed, or that should |
| * have been rejected by the clause. (This is only an issue for |
| * non-strict quals, since if we can prove a qual mentioning only |
| * nullable rels is strict, we'd have reduced the outer join to an |
| * inner join in reduce_outer_joins().) |
| * |
| * To enforce (2), scan the oj_info_list and merge the required-relid |
| * sets of any such OJs into the clause's own reference list. At the |
| * time we are called, the oj_info_list contains only outer joins |
| * below this qual. We have to repeat the scan until no new relids |
| * get added; this ensures that the qual is suitably delayed regardless |
| * of the order in which OJs get executed. As an example, if we have |
| * one OJ with LHS=A, RHS=B, and one with LHS=B, RHS=C, it is implied |
| * that these can be done in either order; if the B/C join is done |
| * first then the join to A can null C, so a qual actually mentioning |
| * only C cannot be applied below the join to A. |
| */ |
| bool found_some; |
| |
| is_pushed_down = true; |
| outerjoin_delayed = false; |
| do { |
| ListCell *l; |
| |
| found_some = false; |
| foreach(l, root->oj_info_list) |
| { |
| OuterJoinInfo *ojinfo = (OuterJoinInfo *) lfirst(l); |
| |
| /* do we have any nullable rels of this OJ? */ |
| if (bms_overlap(relids, ojinfo->min_righthand) || |
| (ojinfo->join_type == JOIN_FULL && |
| bms_overlap(relids, ojinfo->min_lefthand))) |
| { |
| /* yes; do we have all its rels? */ |
| if (!bms_is_subset(ojinfo->min_lefthand, relids) || |
| !bms_is_subset(ojinfo->min_righthand, relids)) |
| { |
| /* no, so add them in */ |
| relids = bms_add_members(relids, |
| ojinfo->min_lefthand); |
| relids = bms_add_members(relids, |
| ojinfo->min_righthand); |
| outerjoin_delayed = true; |
| /* we'll need another iteration */ |
| found_some = true; |
| } |
| /* set delay_upper_joins if needed */ |
| if (ojinfo->join_type != JOIN_FULL && |
| bms_overlap(relids, ojinfo->min_lefthand)) |
| ojinfo->delay_upper_joins = true; |
| } |
| } |
| } while (found_some); |
| |
| if (outerjoin_delayed) |
| { |
| /* Should still be a subset of current scope ... */ |
| Assert(bms_is_subset(relids, qualscope)); |
| /* |
| * Because application of the qual will be delayed by outer join, |
| * we mustn't assume its vars are equal everywhere. |
| */ |
| maybe_equijoin = false; |
| } |
| else |
| { |
| /* |
| * Qual is not delayed by any lower outer-join restriction. If it |
| * is not itself below or within an outer join, we can consider it |
| * "valid everywhere", so consider feeding it to the equijoin |
| * machinery. (If it is within an outer join, we can't consider |
| * it "valid everywhere": once the contained variables have gone |
| * to NULL, we'd be asserting things like NULL = NULL, which is |
| * not true.) |
| */ |
| if (!below_outer_join && outerjoin_nonnullable == NULL) |
| maybe_equijoin = true; |
| else |
| maybe_equijoin = false; |
| maybe_local_equijoin = true; |
| } |
| |
| /* Since it doesn't mention the LHS, it's certainly not an OJ clause */ |
| maybe_outer_join = false; |
| |
| /* the clause should always be considered a part of the set of |
| local equijoins managed by its closest RHS parent */ |
| maybe_local_equijoin = true; |
| } |
| |
| /* |
| * Build the RestrictInfo node itself. |
| */ |
| restrictinfo = make_restrictinfo((Expr *) clause, |
| is_pushed_down, |
| outerjoin_delayed, |
| pseudoconstant, |
| relids); |
| |
| /* |
| * Figure out where to attach it. |
| */ |
| switch (bms_membership(relids)) |
| { |
| case BMS_SINGLETON: |
| |
| /* |
| * There is only one relation participating in 'clause', so |
| * 'clause' is a restriction clause for that relation. |
| */ |
| rel = find_base_rel(root, bms_singleton_member(relids)); |
| |
| /* |
| * Check for a "mergejoinable" clause even though it's not a join |
| * clause. This is so that we can recognize that "a.x = a.y" |
| * makes x and y eligible to be considered equal, even when they |
| * belong to the same rel. Without this, we would not recognize |
| * that "a.x = a.y AND a.x = b.z AND a.y = c.q" allows us to |
| * consider z and q equal after their rels are joined. |
| */ |
| check_mergejoinable(restrictinfo); |
| |
| /* |
| * If the clause was deduced from implied equality, check to see |
| * whether it is redundant with restriction clauses we already |
| * have for this rel. Note we cannot apply this check to |
| * user-written clauses, since we haven't found the canonical |
| * pathkey sets yet while processing user clauses. (NB: no |
| * comparable check is done in the join-clause case; redundancy |
| * will be detected when the join clause is moved into a join |
| * rel's restriction list.) |
| */ |
| if (!is_deduced || |
| is_deduced_but_not_equijoin || |
| !qual_is_redundant(root, restrictinfo, |
| rel->baserestrictinfo)) |
| { |
| /* Add clause to rel's restriction list */ |
| rel->baserestrictinfo = lappend(rel->baserestrictinfo, |
| restrictinfo); |
| } |
| break; |
| case BMS_MULTIPLE: |
| |
| /* |
| * 'clause' is a join clause, since there is more than one rel in |
| * the relid set. |
| */ |
| |
| /* |
| * Check for hash or mergejoinable operators. |
| * |
| * We don't bother setting the hashjoin info if we're not going to |
| * need it. We do want to know about mergejoinable ops in all |
| * cases, however, because we use mergejoinable ops for other |
| * purposes such as detecting redundant clauses. |
| */ |
| check_mergejoinable(restrictinfo); |
| if (root->config->enable_hashjoin) |
| check_hashjoinable(restrictinfo); |
| |
| /* |
| * Add clause to the join lists of all the relevant relations. |
| */ |
| add_join_clause_to_rels(root, restrictinfo, relids); |
| |
| /* |
| * Add vars used in the join clause to targetlists of their |
| * relations, so that they will be emitted by the plan nodes that |
| * scan those relations (else they won't be available at the join |
| * node!). |
| */ |
| vars = pull_var_clause(clause, false); |
| add_vars_to_targetlist(root, vars, relids); |
| list_free(vars); |
| break; |
| default: |
| |
| /* |
| * 'clause' references no rels, and therefore we have no place to |
| * attach it. Shouldn't get here if callers are working properly. |
| */ |
| elog(ERROR, "cannot cope with variable-free clause"); |
| break; |
| } |
| |
| /* |
| * If the clause has a mergejoinable operator, we may be able to deduce |
| * more things from it under the principle of transitivity. |
| * |
| * If it is not an outer-join qualification nor bubbled up due to an outer |
| * join, then the two sides represent equivalent PathKeyItems for path |
| * keys: any path that is sorted by one side will also be sorted by the |
| * other (as soon as the two rels are joined, that is). Pass such clauses |
| * to add_equijoined_keys. |
| * |
| * If it is a left or right outer-join qualification that relates the two |
| * sides of the outer join (no funny business like leftvar1 = leftvar2 + |
| * rightvar), we add it to root->left_join_clauses or |
| * root->right_join_clauses according to which side the nonnullable |
| * variable appears on. |
| * |
| * If it is a full outer-join qualification, we add it to |
| * root->full_join_clauses. (Ideally we'd discard cases that aren't |
| * leftvar = rightvar, as we do for left/right joins, but this routine |
| * doesn't have the info needed to do that; and the current usage of the |
| * full_join_clauses list doesn't require that, so it's not currently |
| * worth complicating this routine's API to make it possible.) |
| */ |
| if (restrictinfo->mergejoinoperator != InvalidOid) |
| { |
| if (maybe_local_equijoin && ptrToLocalEquiKeyList != NULL) |
| add_equijoined_keys_to_list(ptrToLocalEquiKeyList, restrictinfo); |
| |
| if (maybe_equijoin) |
| add_equijoined_keys(root, restrictinfo); |
| else if (maybe_outer_join && restrictinfo->can_join) |
| { |
| if (bms_is_subset(restrictinfo->left_relids, |
| outerjoin_nonnullable) && |
| !bms_overlap(restrictinfo->right_relids, |
| outerjoin_nonnullable)) |
| { |
| /* we have outervar = innervar */ |
| root->left_join_clauses = lappend(root->left_join_clauses, |
| restrictinfo); |
| } |
| else if (bms_is_subset(restrictinfo->right_relids, |
| outerjoin_nonnullable) && |
| !bms_overlap(restrictinfo->left_relids, |
| outerjoin_nonnullable)) |
| { |
| /* we have innervar = outervar */ |
| root->right_join_clauses = lappend(root->right_join_clauses, |
| restrictinfo); |
| } |
| else if (bms_equal(outerjoin_nonnullable, qualscope)) |
| { |
| /* FULL JOIN (above tests cannot match in this case) */ |
| root->full_join_clauses = lappend(root->full_join_clauses, |
| restrictinfo); |
| } |
| } |
| } |
| } |
| |
| /* |
| * process_implied_equality |
| * Check to see whether we already have a restrictinfo item that says |
| * item1 = item2, and create one if not; or if delete_it is true, |
| * remove any such restrictinfo item. |
| * |
| * This processing is a consequence of transitivity of mergejoin equality: |
| * if we have mergejoinable clauses A = B and B = C, we can deduce A = C |
| * (where = is an appropriate mergejoinable operator). See path/pathkeys.c |
| * for more details. |
| */ |
| void |
| process_implied_equality(PlannerInfo *root, |
| Node *item1, Node *item2, |
| Oid sortop1, Oid sortop2, |
| Relids item1_relids, Relids item2_relids, |
| bool delete_it) |
| { |
| Relids relids; |
| BMS_Membership membership; |
| RelOptInfo *rel1; |
| List *restrictlist; |
| ListCell *itm; |
| Oid ltype, |
| rtype; |
| Operator eq_operator; |
| Form_pg_operator pgopform; |
| Expr *clause; |
| |
| /* Get set of relids referenced in the two expressions */ |
| relids = bms_union(item1_relids, item2_relids); |
| membership = bms_membership(relids); |
| |
| /* |
| * generate_implied_equalities() shouldn't call me on two constants. |
| */ |
| Assert(membership != BMS_EMPTY_SET); |
| |
| /* |
| * If the exprs involve a single rel, we need to look at that rel's |
| * baserestrictinfo list. If multiple rels, we can scan the joininfo list |
| * of any of 'em. |
| */ |
| if (membership == BMS_SINGLETON) |
| { |
| rel1 = find_base_rel(root, bms_singleton_member(relids)); |
| restrictlist = rel1->baserestrictinfo; |
| } |
| else |
| { |
| Relids other_rels; |
| int first_rel; |
| |
| /* Copy relids, find and remove one member */ |
| other_rels = bms_copy(relids); |
| first_rel = bms_first_member(other_rels); |
| bms_free(other_rels); |
| |
| rel1 = find_base_rel(root, first_rel); |
| restrictlist = rel1->joininfo; |
| } |
| |
| /* |
| * Scan to see if equality is already known. If so, we're done in the add |
| * case, and done after removing it in the delete case. |
| */ |
| foreach(itm, restrictlist) |
| { |
| RestrictInfo *restrictinfo = (RestrictInfo *) lfirst(itm); |
| Node *left, |
| *right; |
| |
| if (restrictinfo->mergejoinoperator == InvalidOid) |
| continue; /* ignore non-mergejoinable clauses */ |
| /* We now know the restrictinfo clause is a binary opclause */ |
| left = get_leftop(restrictinfo->clause); |
| right = get_rightop(restrictinfo->clause); |
| if ((equal(item1, left) && equal(item2, right)) || |
| (equal(item2, left) && equal(item1, right))) |
| { |
| /* found a matching clause */ |
| if (delete_it) |
| { |
| if (membership == BMS_SINGLETON) |
| { |
| /* delete it from local restrictinfo list */ |
| rel1->baserestrictinfo = list_delete_ptr(rel1->baserestrictinfo, |
| restrictinfo); |
| } |
| else |
| { |
| /* let joininfo.c do it */ |
| remove_join_clause_from_rels(root, restrictinfo, relids); |
| } |
| } |
| return; /* done */ |
| } |
| } |
| |
| /* Didn't find it. Done if deletion requested */ |
| if (delete_it) |
| return; |
| |
| /* |
| * This equality is new information, so construct a clause representing it |
| * to add to the query data structures. |
| */ |
| ltype = exprType(item1); |
| rtype = exprType(item2); |
| eq_operator = compatible_oper(NULL, list_make1(makeString("=")), |
| ltype, rtype, |
| true, -1); |
| if (!HeapTupleIsValid(eq_operator)) |
| { |
| /* |
| * Would it be safe to just not add the equality to the query if we |
| * have no suitable equality operator for the combination of |
| * datatypes? NO, because sortkey selection may screw up anyway. |
| */ |
| ereport(ERROR, |
| (errcode(ERRCODE_UNDEFINED_FUNCTION), |
| errmsg("could not identify an equality operator for types %s and %s", |
| format_type_be(ltype), format_type_be(rtype)))); |
| } |
| pgopform = (Form_pg_operator) GETSTRUCT(eq_operator); |
| |
| /* |
| * Let's just make sure this appears to be a compatible operator. |
| */ |
| if (pgopform->oprlsortop != sortop1 || |
| pgopform->oprrsortop != sortop2 || |
| pgopform->oprresult != BOOLOID) |
| ereport(ERROR, |
| (errcode(ERRCODE_INVALID_FUNCTION_DEFINITION), |
| errmsg("equality operator for types %s and %s should be merge-joinable, but isn't", |
| format_type_be(ltype), format_type_be(rtype)))); |
| |
| /* |
| * Now we can build the new clause. Copy to ensure it shares no |
| * substructure with original (this is necessary in case there are |
| * subselects in there...) |
| */ |
| clause = make_opclause(oprid(eq_operator), /* opno */ |
| BOOLOID, /* opresulttype */ |
| false, /* opretset */ |
| (Expr *) copyObject(item1), |
| (Expr *) copyObject(item2)); |
| |
| ReleaseOperator(eq_operator); |
| |
| /* |
| * Push the new clause into all the appropriate restrictinfo lists. |
| */ |
| distribute_qual_to_rels(root, (Node *) clause, |
| true, true, false, relids, NULL, NULL, |
| NULL |
| /* NULL is okay for local equi list because |
| * we are recording a global equivalence |
| */ |
| ); |
| } |
| |
| /* |
| * qual_is_redundant |
| * Detect whether an implied-equality qual that turns out to be a |
| * restriction clause for a single base relation is redundant with |
| * already-known restriction clauses for that rel. This occurs with, |
| * for example, |
| * SELECT * FROM tab WHERE f1 = f2 AND f2 = f3; |
| * We need to suppress the redundant condition to avoid computing |
| * too-small selectivity, not to mention wasting time at execution. |
| * |
| * Note: quals of the form "var = const" are never considered redundant, |
| * only those of the form "var = var". This is needed because when we |
| * have constants in an implied-equality set, we use a different strategy |
| * that suppresses all "var = var" deductions. We must therefore keep |
| * all the "var = const" quals. |
| */ |
| static bool |
| qual_is_redundant(PlannerInfo *root, |
| RestrictInfo *restrictinfo, |
| List *restrictlist) |
| { |
| Node *newleft; |
| Node *newright; |
| List *oldquals; |
| ListCell *olditem; |
| List *equalexprs; |
| bool someadded; |
| |
| /* Never redundant unless vars appear on both sides */ |
| if (bms_is_empty(restrictinfo->left_relids) || |
| bms_is_empty(restrictinfo->right_relids)) |
| return false; |
| |
| newleft = get_leftop(restrictinfo->clause); |
| newright = get_rightop(restrictinfo->clause); |
| |
| /* |
| * Set cached pathkeys. NB: it is okay to do this now because this |
| * routine is only invoked while we are generating implied equalities. |
| * Therefore, the equi_key_list is already complete and so we can |
| * correctly determine canonical pathkeys. |
| */ |
| cache_mergeclause_pathkeys(root, restrictinfo); |
| /* If different, say "not redundant" (should never happen) */ |
| if (restrictinfo->left_pathkey != restrictinfo->right_pathkey) |
| return false; |
| |
| /* |
| * Scan existing quals to find those referencing same pathkeys. Usually |
| * there will be few, if any, so build a list of just the interesting |
| * ones. |
| */ |
| oldquals = NIL; |
| foreach(olditem, restrictlist) |
| { |
| RestrictInfo *oldrinfo = (RestrictInfo *) lfirst(olditem); |
| |
| if (oldrinfo->mergejoinoperator != InvalidOid) |
| { |
| cache_mergeclause_pathkeys(root, oldrinfo); |
| if (restrictinfo->left_pathkey == oldrinfo->left_pathkey && |
| restrictinfo->right_pathkey == oldrinfo->right_pathkey) |
| oldquals = lcons(oldrinfo, oldquals); |
| } |
| } |
| if (oldquals == NIL) |
| return false; |
| |
| /* |
| * Now, we want to develop a list of exprs that are known equal to the |
| * left side of the new qual. We traverse the old-quals list repeatedly |
| * to transitively expand the exprs list. If at any point we find we can |
| * reach the right-side expr of the new qual, we are done. We give up |
| * when we can't expand the equalexprs list any more. |
| */ |
| equalexprs = list_make1(newleft); |
| do |
| { |
| someadded = false; |
| /* cannot use foreach here because of possible list_delete */ |
| olditem = list_head(oldquals); |
| while (olditem) |
| { |
| RestrictInfo *oldrinfo = (RestrictInfo *) lfirst(olditem); |
| Node *oldleft = get_leftop(oldrinfo->clause); |
| Node *oldright = get_rightop(oldrinfo->clause); |
| Node *newguy = NULL; |
| |
| /* must advance olditem before list_delete possibly pfree's it */ |
| olditem = lnext(olditem); |
| |
| if (list_member(equalexprs, oldleft)) |
| newguy = oldright; |
| else if (list_member(equalexprs, oldright)) |
| newguy = oldleft; |
| else |
| continue; |
| if (equal(newguy, newright)) |
| return true; /* we proved new clause is redundant */ |
| equalexprs = lcons(newguy, equalexprs); |
| someadded = true; |
| |
| /* |
| * Remove this qual from list, since we don't need it anymore. |
| */ |
| oldquals = list_delete_ptr(oldquals, oldrinfo); |
| } |
| } while (someadded); |
| |
| return false; /* it's not redundant */ |
| } |
| |
| |
| /***************************************************************************** |
| * |
| * CHECKS FOR MERGEJOINABLE AND HASHJOINABLE CLAUSES |
| * |
| *****************************************************************************/ |
| |
| /* |
| * check_mergejoinable |
| * If the restrictinfo's clause is mergejoinable, set the mergejoin |
| * info fields in the restrictinfo. |
| * |
| * Currently, we support mergejoin for binary opclauses where |
| * the operator is a mergejoinable operator. The arguments can be |
| * anything --- as long as there are no volatile functions in them. |
| */ |
| static void |
| check_mergejoinable(RestrictInfo *restrictinfo) |
| { |
| Expr *clause = restrictinfo->clause; |
| Oid opno, |
| leftOp, |
| rightOp; |
| |
| if (restrictinfo->pseudoconstant) |
| return; |
| if (!is_opclause(clause)) |
| return; |
| if (list_length(((OpExpr *) clause)->args) != 2) |
| return; |
| |
| opno = ((OpExpr *) clause)->opno; |
| |
| if (op_mergejoinable(opno, |
| &leftOp, |
| &rightOp) && |
| !contain_volatile_functions((Node *) clause)) |
| { |
| restrictinfo->mergejoinoperator = opno; |
| restrictinfo->left_sortop = leftOp; |
| restrictinfo->right_sortop = rightOp; |
| } |
| } |
| |
| /* |
| * check_hashjoinable |
| * If the restrictinfo's clause is hashjoinable, set the hashjoin |
| * info fields in the restrictinfo. |
| * |
| * Currently, we support hashjoin for binary opclauses where |
| * the operator is a hashjoinable operator. The arguments can be |
| * anything --- as long as there are no volatile functions in them. |
| */ |
| static void |
| check_hashjoinable(RestrictInfo *restrictinfo) |
| { |
| Expr *clause = restrictinfo->clause; |
| Oid opno; |
| |
| /** |
| * If this is a IS NOT FALSE boolean test, we can peek underneath. |
| */ |
| if (IsA(clause, BooleanTest)) |
| { |
| BooleanTest *bt = (BooleanTest *) clause; |
| |
| if (bt->booltesttype == IS_NOT_FALSE) |
| { |
| clause = bt->arg; |
| } |
| } |
| |
| if (restrictinfo->pseudoconstant) |
| return; |
| if (!is_opclause(clause)) |
| return; |
| if (list_length(((OpExpr *) clause)->args) != 2) |
| return; |
| |
| opno = ((OpExpr *) clause)->opno; |
| |
| if (op_hashjoinable(opno) && |
| !contain_volatile_functions((Node *) clause)) |
| restrictinfo->hashjoinoperator = opno; |
| } |