/*------------------------------------------------------------------------- * * prepjointree.c * Planner preprocessing for subqueries and join tree manipulation. * * NOTE: the intended sequence for invoking these operations is * pull_up_sublinks * inline_set_returning_functions * pull_up_subqueries * do expression preprocessing (including flattening JOIN alias vars) * reduce_outer_joins * * * Portions Copyright (c) 1996-2009, PostgreSQL Global Development Group * Portions Copyright (c) 1994, Regents of the University of California * * * IDENTIFICATION * $PostgreSQL: pgsql/src/backend/optimizer/prep/prepjointree.c,v 1.62 2009/01/01 17:23:44 momjian Exp $ * *------------------------------------------------------------------------- */ #include "postgres.h" #include "nodes/makefuncs.h" #include "nodes/nodeFuncs.h" #include "optimizer/clauses.h" #include "optimizer/placeholder.h" #include "optimizer/prep.h" #include "optimizer/subselect.h" #include "optimizer/tlist.h" #include "optimizer/var.h" #include "parser/parsetree.h" #include "rewrite/rewriteManip.h" typedef struct reduce_outer_joins_state { Relids relids; /* base relids within this subtree */ bool contains_outer; /* does subtree contain outer join(s)? */ List *sub_states; /* List of states for subtree components */ } reduce_outer_joins_state; static Node *pull_up_sublinks_jointree_recurse(PlannerInfo *root, Node *jtnode, Relids *relids); static Node *pull_up_sublinks_qual_recurse(PlannerInfo *root, Node *node, Relids available_rels, List **fromlist); static Node *pull_up_simple_subquery(PlannerInfo *root, Node *jtnode, RangeTblEntry *rte, bool below_outer_join, bool append_rel_member); static Node *pull_up_simple_union_all(PlannerInfo *root, Node *jtnode, RangeTblEntry *rte); static void pull_up_union_leaf_queries(Node *setOp, PlannerInfo *root, int parentRTindex, Query *setOpQuery, int childRToffset); static void make_setop_translation_list(Query *query, Index newvarno, List **translated_vars); static bool is_simple_subquery(Query *subquery); static bool is_simple_union_all(Query *subquery); static bool is_simple_union_all_recurse(Node *setOp, Query *setOpQuery, List *colTypes); static List *insert_targetlist_placeholders(PlannerInfo *root, List *tlist, int varno, bool wrap_non_vars); static bool is_safe_append_member(Query *subquery); static void resolvenew_in_jointree(Node *jtnode, int varno, RangeTblEntry *rte, List *subtlist); static reduce_outer_joins_state *reduce_outer_joins_pass1(Node *jtnode); static void reduce_outer_joins_pass2(Node *jtnode, reduce_outer_joins_state *state, PlannerInfo *root, Relids nonnullable_rels, List *nonnullable_vars, List *forced_null_vars); static void substitute_multiple_relids(Node *node, int varno, Relids subrelids); static void fix_append_rel_relids(List *append_rel_list, int varno, Relids subrelids); static Node *find_jointree_node_for_rel(Node *jtnode, int relid); /* * pull_up_sublinks * Attempt to pull up ANY and EXISTS SubLinks to be treated as * semijoins or anti-semijoins. * * A clause "foo op ANY (sub-SELECT)" can be processed by pulling the * sub-SELECT up to become a rangetable entry and treating the implied * comparisons as quals of a semijoin. However, this optimization *only* * works at the top level of WHERE or a JOIN/ON clause, because we cannot * distinguish whether the ANY ought to return FALSE or NULL in cases * involving NULL inputs. Also, in an outer join's ON clause we can only * do this if the sublink is degenerate (ie, references only the nullable * side of the join). In that case we can effectively push the semijoin * down into the nullable side of the join. If the sublink references any * nonnullable-side variables then it would have to be evaluated as part * of the outer join, which makes things way too complicated. * * Under similar conditions, EXISTS and NOT EXISTS clauses can be handled * by pulling up the sub-SELECT and creating a semijoin or anti-semijoin. * * This routine searches for such clauses and does the necessary parsetree * transformations if any are found. * * This routine has to run before preprocess_expression(), so the quals * clauses are not yet reduced to implicit-AND format. That means we need * to recursively search through explicit AND clauses, which are * probably only binary ANDs. We stop as soon as we hit a non-AND item. */ void pull_up_sublinks(PlannerInfo *root) { Relids relids; /* Begin recursion through the jointree */ root->parse->jointree = (FromExpr *) pull_up_sublinks_jointree_recurse(root, (Node *) root->parse->jointree, &relids); } /* * Recurse through jointree nodes for pull_up_sublinks() * * In addition to returning the possibly-modified jointree node, we return * a relids set of the contained rels into *relids. */ static Node * pull_up_sublinks_jointree_recurse(PlannerInfo *root, Node *jtnode, Relids *relids) { if (jtnode == NULL) { *relids = NULL; } else if (IsA(jtnode, RangeTblRef)) { int varno = ((RangeTblRef *) jtnode)->rtindex; *relids = bms_make_singleton(varno); /* jtnode is returned unmodified */ } else if (IsA(jtnode, FromExpr)) { FromExpr *f = (FromExpr *) jtnode; List *newfromlist = NIL; Node *newquals; List *subfromlist = NIL; Relids frelids = NULL; ListCell *l; /* First, recurse to process children and collect their relids */ foreach(l, f->fromlist) { Node *newchild; Relids childrelids; newchild = pull_up_sublinks_jointree_recurse(root, lfirst(l), &childrelids); newfromlist = lappend(newfromlist, newchild); frelids = bms_join(frelids, childrelids); } /* Now process qual --- all children are available for use */ newquals = pull_up_sublinks_qual_recurse(root, f->quals, frelids, &subfromlist); /* Any pulled-up subqueries can just be attached to the fromlist */ newfromlist = list_concat(newfromlist, subfromlist); /* * Although we could include the pulled-up subqueries in the returned * relids, there's no need since upper quals couldn't refer to their * outputs anyway. */ *relids = frelids; jtnode = (Node *) makeFromExpr(newfromlist, newquals); } else if (IsA(jtnode, JoinExpr)) { JoinExpr *j; Relids leftrelids; Relids rightrelids; List *subfromlist = NIL; /* * Make a modifiable copy of join node, but don't bother copying * its subnodes (yet). */ j = (JoinExpr *) palloc(sizeof(JoinExpr)); memcpy(j, jtnode, sizeof(JoinExpr)); /* Recurse to process children and collect their relids */ j->larg = pull_up_sublinks_jointree_recurse(root, j->larg, &leftrelids); j->rarg = pull_up_sublinks_jointree_recurse(root, j->rarg, &rightrelids); /* * Now process qual, showing appropriate child relids as available, * and then attach any pulled-up jointree items at the right place. * The pulled-up items must go below where the quals that refer to * them will be placed. Since the JoinExpr itself can only handle * two child nodes, we hack up a valid jointree by inserting dummy * FromExprs that have no quals. These should get flattened out * during deconstruct_recurse(), so they won't impose any extra * overhead. */ switch (j->jointype) { case JOIN_INNER: j->quals = pull_up_sublinks_qual_recurse(root, j->quals, bms_union(leftrelids, rightrelids), &subfromlist); /* We arbitrarily put pulled-up subqueries into right child */ if (subfromlist) j->rarg = (Node *) makeFromExpr(lcons(j->rarg, subfromlist), NULL); break; case JOIN_LEFT: j->quals = pull_up_sublinks_qual_recurse(root, j->quals, rightrelids, &subfromlist); /* Any pulled-up subqueries must go into right child */ if (subfromlist) j->rarg = (Node *) makeFromExpr(lcons(j->rarg, subfromlist), NULL); break; case JOIN_FULL: /* can't do anything with full-join quals */ break; case JOIN_RIGHT: j->quals = pull_up_sublinks_qual_recurse(root, j->quals, leftrelids, &subfromlist); /* Any pulled-up subqueries must go into left child */ if (subfromlist) j->larg = (Node *) makeFromExpr(lcons(j->larg, subfromlist), NULL); break; default: elog(ERROR, "unrecognized join type: %d", (int) j->jointype); break; } /* * Although we could include the pulled-up subqueries in the returned * relids, there's no need since upper quals couldn't refer to their * outputs anyway. But we *do* need to include the join's own rtindex * because we haven't yet collapsed join alias variables, so upper * levels would mistakenly think they couldn't use references to this * join. */ *relids = bms_add_member(bms_join(leftrelids, rightrelids), j->rtindex); jtnode = (Node *) j; } else elog(ERROR, "unrecognized node type: %d", (int) nodeTag(jtnode)); return jtnode; } /* * Recurse through top-level qual nodes for pull_up_sublinks() * * Caller must have initialized *fromlist to NIL. We append any new * jointree items to that list. */ static Node * pull_up_sublinks_qual_recurse(PlannerInfo *root, Node *node, Relids available_rels, List **fromlist) { if (node == NULL) return NULL; if (IsA(node, SubLink)) { SubLink *sublink = (SubLink *) node; Node *new_qual; List *new_fromlist; /* Is it a convertible ANY or EXISTS clause? */ if (sublink->subLinkType == ANY_SUBLINK) { if (convert_ANY_sublink_to_join(root, sublink, available_rels, &new_qual, &new_fromlist)) { *fromlist = list_concat(*fromlist, new_fromlist); return new_qual; } } else if (sublink->subLinkType == EXISTS_SUBLINK) { if (convert_EXISTS_sublink_to_join(root, sublink, false, available_rels, &new_qual, &new_fromlist)) { *fromlist = list_concat(*fromlist, new_fromlist); return new_qual; } } /* Else return it unmodified */ return node; } if (not_clause(node)) { /* If the immediate argument of NOT is EXISTS, try to convert */ SubLink *sublink = (SubLink *) get_notclausearg((Expr *) node); Node *new_qual; List *new_fromlist; if (sublink && IsA(sublink, SubLink)) { if (sublink->subLinkType == EXISTS_SUBLINK) { if (convert_EXISTS_sublink_to_join(root, sublink, true, available_rels, &new_qual, &new_fromlist)) { *fromlist = list_concat(*fromlist, new_fromlist); return new_qual; } } } /* Else return it unmodified */ return node; } if (and_clause(node)) { /* Recurse into AND clause */ List *newclauses = NIL; ListCell *l; foreach(l, ((BoolExpr *) node)->args) { Node *oldclause = (Node *) lfirst(l); newclauses = lappend(newclauses, pull_up_sublinks_qual_recurse(root, oldclause, available_rels, fromlist)); } return (Node *) make_andclause(newclauses); } /* Stop if not an AND */ return node; } /* * inline_set_returning_functions * Attempt to "inline" set-returning functions in the FROM clause. * * If an RTE_FUNCTION rtable entry invokes a set-returning function that * contains just a simple SELECT, we can convert the rtable entry to an * RTE_SUBQUERY entry exposing the SELECT directly. This is especially * useful if the subquery can then be "pulled up" for further optimization, * but we do it even if not, to reduce executor overhead. * * This has to be done before we have started to do any optimization of * subqueries, else any such steps wouldn't get applied to subqueries * obtained via inlining. However, we do it after pull_up_sublinks * so that we can inline any functions used in SubLink subselects. * * Like most of the planner, this feels free to scribble on its input data * structure. */ void inline_set_returning_functions(PlannerInfo *root) { ListCell *rt; foreach(rt, root->parse->rtable) { RangeTblEntry *rte = (RangeTblEntry *) lfirst(rt); if (rte->rtekind == RTE_FUNCTION) { Query *funcquery; /* Check safety of expansion, and expand if possible */ funcquery = inline_set_returning_function(root, rte); if (funcquery) { /* Successful expansion, replace the rtable entry */ rte->rtekind = RTE_SUBQUERY; rte->subquery = funcquery; rte->funcexpr = NULL; rte->funccoltypes = NIL; rte->funccoltypmods = NIL; } } } } /* * pull_up_subqueries * Look for subqueries in the rangetable that can be pulled up into * the parent query. If the subquery has no special features like * grouping/aggregation then we can merge it into the parent's jointree. * Also, subqueries that are simple UNION ALL structures can be * converted into "append relations". * * below_outer_join is true if this jointree node is within the nullable * side of an outer join. This forces use of the PlaceHolderVar mechanism * for non-nullable targetlist items. * * append_rel_member is true if we are looking at a member subquery of * an append relation. This forces use of the PlaceHolderVar mechanism * for all non-Var targetlist items, and puts some additional restrictions * on what can be pulled up. * * A tricky aspect of this code is that if we pull up a subquery we have * to replace Vars that reference the subquery's outputs throughout the * parent query, including quals attached to jointree nodes above the one * we are currently processing! We handle this by being careful not to * change the jointree structure while recursing: no nodes other than * subquery RangeTblRef entries will be replaced. Also, we can't turn * ResolveNew loose on the whole jointree, because it'll return a mutated * copy of the tree; we have to invoke it just on the quals, instead. */ Node * pull_up_subqueries(PlannerInfo *root, Node *jtnode, bool below_outer_join, bool append_rel_member) { if (jtnode == NULL) return NULL; if (IsA(jtnode, RangeTblRef)) { int varno = ((RangeTblRef *) jtnode)->rtindex; RangeTblEntry *rte = rt_fetch(varno, root->parse->rtable); /* * Is this a subquery RTE, and if so, is the subquery simple enough to * pull up? * * If we are looking at an append-relation member, we can't pull it up * unless is_safe_append_member says so. */ if (rte->rtekind == RTE_SUBQUERY && is_simple_subquery(rte->subquery) && (!append_rel_member || is_safe_append_member(rte->subquery))) return pull_up_simple_subquery(root, jtnode, rte, below_outer_join, append_rel_member); /* * Alternatively, is it a simple UNION ALL subquery? If so, flatten * into an "append relation". * * It's safe to do this regardless of whether this query is * itself an appendrel member. (If you're thinking we should try to * flatten the two levels of appendrel together, you're right; but we * handle that in set_append_rel_pathlist, not here.) */ if (rte->rtekind == RTE_SUBQUERY && is_simple_union_all(rte->subquery)) return pull_up_simple_union_all(root, jtnode, rte); /* Otherwise, do nothing at this node. */ } else if (IsA(jtnode, FromExpr)) { FromExpr *f = (FromExpr *) jtnode; ListCell *l; Assert(!append_rel_member); foreach(l, f->fromlist) lfirst(l) = pull_up_subqueries(root, lfirst(l), below_outer_join, false); } else if (IsA(jtnode, JoinExpr)) { JoinExpr *j = (JoinExpr *) jtnode; Assert(!append_rel_member); /* Recurse, being careful to tell myself when inside outer join */ switch (j->jointype) { case JOIN_INNER: j->larg = pull_up_subqueries(root, j->larg, below_outer_join, false); j->rarg = pull_up_subqueries(root, j->rarg, below_outer_join, false); break; case JOIN_LEFT: j->larg = pull_up_subqueries(root, j->larg, below_outer_join, false); j->rarg = pull_up_subqueries(root, j->rarg, true, false); break; case JOIN_FULL: j->larg = pull_up_subqueries(root, j->larg, true, false); j->rarg = pull_up_subqueries(root, j->rarg, true, false); break; case JOIN_RIGHT: j->larg = pull_up_subqueries(root, j->larg, true, false); j->rarg = pull_up_subqueries(root, j->rarg, below_outer_join, false); break; default: elog(ERROR, "unrecognized join type: %d", (int) j->jointype); break; } } else elog(ERROR, "unrecognized node type: %d", (int) nodeTag(jtnode)); return jtnode; } /* * pull_up_simple_subquery * Attempt to pull up a single simple subquery. * * jtnode is a RangeTblRef that has been tentatively identified as a simple * subquery by pull_up_subqueries. We return the replacement jointree node, * or jtnode itself if we determine that the subquery can't be pulled up after * all. */ static Node * pull_up_simple_subquery(PlannerInfo *root, Node *jtnode, RangeTblEntry *rte, bool below_outer_join, bool append_rel_member) { Query *parse = root->parse; int varno = ((RangeTblRef *) jtnode)->rtindex; Query *subquery; PlannerInfo *subroot; int rtoffset; List *subtlist; ListCell *rt; /* * Need a modifiable copy of the subquery to hack on. Even if we didn't * sometimes choose not to pull up below, we must do this to avoid * problems if the same subquery is referenced from multiple jointree * items (which can't happen normally, but might after rule rewriting). */ subquery = copyObject(rte->subquery); /* * Create a PlannerInfo data structure for this subquery. * * NOTE: the next few steps should match the first processing in * subquery_planner(). Can we refactor to avoid code duplication, or * would that just make things uglier? */ subroot = makeNode(PlannerInfo); subroot->parse = subquery; subroot->glob = root->glob; subroot->query_level = root->query_level; subroot->parent_root = root->parent_root; subroot->planner_cxt = CurrentMemoryContext; subroot->init_plans = NIL; subroot->cte_plan_ids = NIL; subroot->eq_classes = NIL; subroot->append_rel_list = NIL; subroot->hasRecursion = false; subroot->wt_param_id = -1; subroot->non_recursive_plan = NULL; /* No CTEs to worry about */ Assert(subquery->cteList == NIL); /* * Pull up any SubLinks within the subquery's quals, so that we don't * leave unoptimized SubLinks behind. */ if (subquery->hasSubLinks) pull_up_sublinks(subroot); /* * Similarly, inline any set-returning functions in its rangetable. */ inline_set_returning_functions(subroot); /* * Recursively pull up the subquery's subqueries, so that * pull_up_subqueries' processing is complete for its jointree and * rangetable. * * Note: below_outer_join = false is correct here even if we are within an * outer join in the upper query; the lower query starts with a clean * slate for outer-join semantics. Likewise, we say we aren't handling an * appendrel member. */ subquery->jointree = (FromExpr *) pull_up_subqueries(subroot, (Node *) subquery->jointree, false, false); /* * Now we must recheck whether the subquery is still simple enough to pull * up. If not, abandon processing it. * * We don't really need to recheck all the conditions involved, but it's * easier just to keep this "if" looking the same as the one in * pull_up_subqueries. */ if (is_simple_subquery(subquery) && (!append_rel_member || is_safe_append_member(subquery))) { /* good to go */ } else { /* * Give up, return unmodified RangeTblRef. * * Note: The work we just did will be redone when the subquery gets * planned on its own. Perhaps we could avoid that by storing the * modified subquery back into the rangetable, but I'm not gonna risk * it now. */ return jtnode; } /* * Adjust level-0 varnos in subquery so that we can append its rangetable * to upper query's. We have to fix the subquery's append_rel_list * as well. */ rtoffset = list_length(parse->rtable); OffsetVarNodes((Node *) subquery, rtoffset, 0); OffsetVarNodes((Node *) subroot->append_rel_list, rtoffset, 0); /* * Upper-level vars in subquery are now one level closer to their parent * than before. */ IncrementVarSublevelsUp((Node *) subquery, -1, 1); IncrementVarSublevelsUp((Node *) subroot->append_rel_list, -1, 1); /* * The subquery's targetlist items are now in the appropriate form to * insert into the top query, but if we are under an outer join then * non-nullable items have to be turned into PlaceHolderVars. If we * are dealing with an appendrel member then anything that's not a * simple Var has to be turned into a PlaceHolderVar. */ if (below_outer_join || append_rel_member) subtlist = insert_targetlist_placeholders(root, subquery->targetList, varno, append_rel_member); else subtlist = subquery->targetList; /* * Replace all of the top query's references to the subquery's outputs * with copies of the adjusted subtlist items, being careful not to * replace any of the jointree structure. (This'd be a lot cleaner if we * could use query_tree_mutator.) */ parse->targetList = (List *) ResolveNew((Node *) parse->targetList, varno, 0, rte, subtlist, CMD_SELECT, 0); parse->returningList = (List *) ResolveNew((Node *) parse->returningList, varno, 0, rte, subtlist, CMD_SELECT, 0); resolvenew_in_jointree((Node *) parse->jointree, varno, rte, subtlist); Assert(parse->setOperations == NULL); parse->havingQual = ResolveNew(parse->havingQual, varno, 0, rte, subtlist, CMD_SELECT, 0); root->append_rel_list = (List *) ResolveNew((Node *) root->append_rel_list, varno, 0, rte, subtlist, CMD_SELECT, 0); foreach(rt, parse->rtable) { RangeTblEntry *otherrte = (RangeTblEntry *) lfirst(rt); if (otherrte->rtekind == RTE_JOIN) otherrte->joinaliasvars = (List *) ResolveNew((Node *) otherrte->joinaliasvars, varno, 0, rte, subtlist, CMD_SELECT, 0); } /* * Now append the adjusted rtable entries to upper query. (We hold off * until after fixing the upper rtable entries; no point in running that * code on the subquery ones too.) */ parse->rtable = list_concat(parse->rtable, subquery->rtable); /* * Pull up any FOR UPDATE/SHARE markers, too. (OffsetVarNodes already * adjusted the marker rtindexes, so just concat the lists.) */ parse->rowMarks = list_concat(parse->rowMarks, subquery->rowMarks); /* * We also have to fix the relid sets of any FlattenedSubLink and * PlaceHolderVar nodes in the parent query. (This could perhaps be done * by ResolveNew, but it would clutter that routine's API unreasonably.) * Note in particular that any PlaceHolderVar nodes just created by * insert_targetlist_placeholders() will be adjusted, so having created * them with the subquery's varno is correct. * * Likewise, relids appearing in AppendRelInfo nodes have to be fixed. * We already checked that this won't require introducing multiple * subrelids into the single-slot AppendRelInfo structs. */ if (parse->hasSubLinks || root->glob->lastPHId != 0 || root->append_rel_list) { Relids subrelids; subrelids = get_relids_in_jointree((Node *) subquery->jointree, false); substitute_multiple_relids((Node *) parse, varno, subrelids); fix_append_rel_relids(root->append_rel_list, varno, subrelids); } /* * And now add subquery's AppendRelInfos to our list. */ root->append_rel_list = list_concat(root->append_rel_list, subroot->append_rel_list); /* * We don't have to do the equivalent bookkeeping for outer-join info, * because that hasn't been set up yet. placeholder_list likewise. */ Assert(root->join_info_list == NIL); Assert(subroot->join_info_list == NIL); Assert(root->placeholder_list == NIL); Assert(subroot->placeholder_list == NIL); /* * Miscellaneous housekeeping. */ parse->hasSubLinks |= subquery->hasSubLinks; /* * subquery won't be pulled up if it hasAggs or hasWindowFuncs, so no * work needed on those flags */ /* * Return the adjusted subquery jointree to replace the RangeTblRef entry * in parent's jointree. */ return (Node *) subquery->jointree; } /* * pull_up_simple_union_all * Pull up a single simple UNION ALL subquery. * * jtnode is a RangeTblRef that has been identified as a simple UNION ALL * subquery by pull_up_subqueries. We pull up the leaf subqueries and * build an "append relation" for the union set. The result value is just * jtnode, since we don't actually need to change the query jointree. */ static Node * pull_up_simple_union_all(PlannerInfo *root, Node *jtnode, RangeTblEntry *rte) { int varno = ((RangeTblRef *) jtnode)->rtindex; Query *subquery = rte->subquery; int rtoffset; List *rtable; /* * Append the subquery rtable entries to upper query. */ rtoffset = list_length(root->parse->rtable); /* * Append child RTEs to parent rtable. * * Upper-level vars in subquery are now one level closer to their * parent than before. We don't have to worry about offsetting * varnos, though, because any such vars must refer to stuff above the * level of the query we are pulling into. */ rtable = copyObject(subquery->rtable); IncrementVarSublevelsUp_rtable(rtable, -1, 1); root->parse->rtable = list_concat(root->parse->rtable, rtable); /* * Recursively scan the subquery's setOperations tree and add * AppendRelInfo nodes for leaf subqueries to the parent's * append_rel_list. */ Assert(subquery->setOperations); pull_up_union_leaf_queries(subquery->setOperations, root, varno, subquery, rtoffset); /* * Mark the parent as an append relation. */ rte->inh = true; return jtnode; } /* * pull_up_union_leaf_queries -- recursive guts of pull_up_simple_union_all * * Note that setOpQuery is the Query containing the setOp node, whose rtable * is where to look up the RTE if setOp is a RangeTblRef. This is *not* the * same as root->parse, which is the top-level Query we are pulling up into. * * parentRTindex is the appendrel parent's index in root->parse->rtable. * * The child RTEs have already been copied to the parent. childRToffset * tells us where in the parent's range table they were copied. */ static void pull_up_union_leaf_queries(Node *setOp, PlannerInfo *root, int parentRTindex, Query *setOpQuery, int childRToffset) { if (IsA(setOp, RangeTblRef)) { RangeTblRef *rtr = (RangeTblRef *) setOp; int childRTindex; AppendRelInfo *appinfo; /* * Calculate the index in the parent's range table */ childRTindex = childRToffset + rtr->rtindex; /* * Build a suitable AppendRelInfo, and attach to parent's list. */ appinfo = makeNode(AppendRelInfo); appinfo->parent_relid = parentRTindex; appinfo->child_relid = childRTindex; appinfo->parent_reltype = InvalidOid; appinfo->child_reltype = InvalidOid; make_setop_translation_list(setOpQuery, childRTindex, &appinfo->translated_vars); appinfo->parent_reloid = InvalidOid; root->append_rel_list = lappend(root->append_rel_list, appinfo); /* * Recursively apply pull_up_subqueries to the new child RTE. (We * must build the AppendRelInfo first, because this will modify it.) * Note that we can pass below_outer_join = false even if we're * actually under an outer join, because the child's expressions * aren't going to propagate up above the join. */ rtr = makeNode(RangeTblRef); rtr->rtindex = childRTindex; (void) pull_up_subqueries(root, (Node *) rtr, false, true); } else if (IsA(setOp, SetOperationStmt)) { SetOperationStmt *op = (SetOperationStmt *) setOp; /* Recurse to reach leaf queries */ pull_up_union_leaf_queries(op->larg, root, parentRTindex, setOpQuery, childRToffset); pull_up_union_leaf_queries(op->rarg, root, parentRTindex, setOpQuery, childRToffset); } else { elog(ERROR, "unrecognized node type: %d", (int) nodeTag(setOp)); } } /* * make_setop_translation_list * Build the list of translations from parent Vars to child Vars for * a UNION ALL member. (At this point it's just a simple list of * referencing Vars, but if we succeed in pulling up the member * subquery, the Vars will get replaced by pulled-up expressions.) */ static void make_setop_translation_list(Query *query, Index newvarno, List **translated_vars) { List *vars = NIL; ListCell *l; foreach(l, query->targetList) { TargetEntry *tle = (TargetEntry *) lfirst(l); if (tle->resjunk) continue; vars = lappend(vars, makeVar(newvarno, tle->resno, exprType((Node *) tle->expr), exprTypmod((Node *) tle->expr), 0)); } *translated_vars = vars; } /* * is_simple_subquery * Check a subquery in the range table to see if it's simple enough * to pull up into the parent query. */ static bool is_simple_subquery(Query *subquery) { /* * Let's just make sure it's a valid subselect ... */ if (!IsA(subquery, Query) || subquery->commandType != CMD_SELECT || subquery->utilityStmt != NULL || subquery->intoClause != NULL) elog(ERROR, "subquery is bogus"); /* * Can't currently pull up a query with setops (unless it's simple UNION * ALL, which is handled by a different code path). Maybe after querytree * redesign... */ if (subquery->setOperations) return false; /* * Can't pull up a subquery involving grouping, aggregation, sorting, * limiting, or WITH. (XXX WITH could possibly be allowed later) */ if (subquery->hasAggs || subquery->hasWindowFuncs || subquery->groupClause || subquery->havingQual || subquery->sortClause || subquery->distinctClause || subquery->limitOffset || subquery->limitCount || subquery->cteList) return false; /* * Don't pull up a subquery that has any set-returning functions in its * targetlist. Otherwise we might well wind up inserting set-returning * functions into places where they mustn't go, such as quals of higher * queries. */ if (expression_returns_set((Node *) subquery->targetList)) return false; /* * Don't pull up a subquery that has any volatile functions in its * targetlist. Otherwise we might introduce multiple evaluations of these * functions, if they get copied to multiple places in the upper query, * leading to surprising results. (Note: the PlaceHolderVar mechanism * doesn't quite guarantee single evaluation; else we could pull up anyway * and just wrap such items in PlaceHolderVars ...) */ if (contain_volatile_functions((Node *) subquery->targetList)) return false; /* * Hack: don't try to pull up a subquery with an empty jointree. * query_planner() will correctly generate a Result plan for a jointree * that's totally empty, but I don't think the right things happen if an * empty FromExpr appears lower down in a jointree. It would pose a * problem for the PlaceHolderVar mechanism too, since we'd have no * way to identify where to evaluate a PHV coming out of the subquery. * Not worth working hard on this, just to collapse SubqueryScan/Result * into Result; especially since the SubqueryScan can often be optimized * away by setrefs.c anyway. */ if (subquery->jointree->fromlist == NIL) return false; return true; } /* * is_simple_union_all * Check a subquery to see if it's a simple UNION ALL. * * We require all the setops to be UNION ALL (no mixing) and there can't be * any datatype coercions involved, ie, all the leaf queries must emit the * same datatypes. */ static bool is_simple_union_all(Query *subquery) { SetOperationStmt *topop; /* Let's just make sure it's a valid subselect ... */ if (!IsA(subquery, Query) || subquery->commandType != CMD_SELECT || subquery->utilityStmt != NULL || subquery->intoClause != NULL) elog(ERROR, "subquery is bogus"); /* Is it a set-operation query at all? */ topop = (SetOperationStmt *) subquery->setOperations; if (!topop) return false; Assert(IsA(topop, SetOperationStmt)); /* Can't handle ORDER BY, LIMIT/OFFSET, locking, or WITH */ if (subquery->sortClause || subquery->limitOffset || subquery->limitCount || subquery->rowMarks || subquery->cteList) return false; /* Recursively check the tree of set operations */ return is_simple_union_all_recurse((Node *) topop, subquery, topop->colTypes); } static bool is_simple_union_all_recurse(Node *setOp, Query *setOpQuery, List *colTypes) { if (IsA(setOp, RangeTblRef)) { RangeTblRef *rtr = (RangeTblRef *) setOp; RangeTblEntry *rte = rt_fetch(rtr->rtindex, setOpQuery->rtable); Query *subquery = rte->subquery; Assert(subquery != NULL); /* Leaf nodes are OK if they match the toplevel column types */ /* We don't have to compare typmods here */ return tlist_same_datatypes(subquery->targetList, colTypes, true); } else if (IsA(setOp, SetOperationStmt)) { SetOperationStmt *op = (SetOperationStmt *) setOp; /* Must be UNION ALL */ if (op->op != SETOP_UNION || !op->all) return false; /* Recurse to check inputs */ return is_simple_union_all_recurse(op->larg, setOpQuery, colTypes) && is_simple_union_all_recurse(op->rarg, setOpQuery, colTypes); } else { elog(ERROR, "unrecognized node type: %d", (int) nodeTag(setOp)); return false; /* keep compiler quiet */ } } /* * insert_targetlist_placeholders * Insert PlaceHolderVar nodes into any non-junk targetlist items that are * not simple variables or strict functions of simple variables (and hence * might not correctly go to NULL when examined above the point of an outer * join). We assume we can modify the tlist items in-place. * * varno is the upper-query relid of the subquery; this is used as the * syntactic location of the PlaceHolderVars. * If wrap_non_vars is true then *only* simple Var references escape being * wrapped with PlaceHolderVars. */ static List * insert_targetlist_placeholders(PlannerInfo *root, List *tlist, int varno, bool wrap_non_vars) { ListCell *lc; foreach(lc, tlist) { TargetEntry *tle = (TargetEntry *) lfirst(lc); /* ignore resjunk columns */ if (tle->resjunk) continue; /* * Simple Vars always escape being wrapped. This is common enough * to deserve a fast path even if we aren't doing wrap_non_vars. */ if (tle->expr && IsA(tle->expr, Var) && ((Var *) tle->expr)->varlevelsup == 0) continue; if (!wrap_non_vars) { /* * If it contains a Var of current level, and does not contain * any non-strict constructs, then it's certainly nullable and we * don't need to insert a PlaceHolderVar. (Note: in future maybe * we should insert PlaceHolderVars anyway, when a tlist item is * expensive to evaluate? */ if (contain_vars_of_level((Node *) tle->expr, 0) && !contain_nonstrict_functions((Node *) tle->expr)) continue; } /* Else wrap it in a PlaceHolderVar */ tle->expr = (Expr *) make_placeholder_expr(root, tle->expr, bms_make_singleton(varno)); } return tlist; } /* * is_safe_append_member * Check a subquery that is a leaf of a UNION ALL appendrel to see if it's * safe to pull up. */ static bool is_safe_append_member(Query *subquery) { FromExpr *jtnode; /* * It's only safe to pull up the child if its jointree contains exactly * one RTE, else the AppendRelInfo data structure breaks. The one base RTE * could be buried in several levels of FromExpr, however. * * Also, the child can't have any WHERE quals because there's no place to * put them in an appendrel. (This is a bit annoying...) If we didn't * need to check this, we'd just test whether get_relids_in_jointree() * yields a singleton set, to be more consistent with the coding of * fix_append_rel_relids(). */ jtnode = subquery->jointree; while (IsA(jtnode, FromExpr)) { if (jtnode->quals != NULL) return false; if (list_length(jtnode->fromlist) != 1) return false; jtnode = linitial(jtnode->fromlist); } if (!IsA(jtnode, RangeTblRef)) return false; return true; } /* * Helper routine for pull_up_subqueries: do ResolveNew on every expression * in the jointree, without changing the jointree structure itself. Ugly, * but there's no other way... */ static void resolvenew_in_jointree(Node *jtnode, int varno, RangeTblEntry *rte, List *subtlist) { if (jtnode == NULL) return; if (IsA(jtnode, RangeTblRef)) { /* nothing to do here */ } else if (IsA(jtnode, FromExpr)) { FromExpr *f = (FromExpr *) jtnode; ListCell *l; foreach(l, f->fromlist) resolvenew_in_jointree(lfirst(l), varno, rte, subtlist); f->quals = ResolveNew(f->quals, varno, 0, rte, subtlist, CMD_SELECT, 0); } else if (IsA(jtnode, JoinExpr)) { JoinExpr *j = (JoinExpr *) jtnode; resolvenew_in_jointree(j->larg, varno, rte, subtlist); resolvenew_in_jointree(j->rarg, varno, rte, subtlist); j->quals = ResolveNew(j->quals, varno, 0, rte, subtlist, CMD_SELECT, 0); /* * We don't bother to update the colvars list, since it won't be used * again ... */ } else elog(ERROR, "unrecognized node type: %d", (int) nodeTag(jtnode)); } /* * reduce_outer_joins * Attempt to reduce outer joins to plain inner joins. * * The idea here is that given a query like * SELECT ... FROM a LEFT JOIN b ON (...) WHERE b.y = 42; * we can reduce the LEFT JOIN to a plain JOIN if the "=" operator in WHERE * is strict. The strict operator will always return NULL, causing the outer * WHERE to fail, on any row where the LEFT JOIN filled in NULLs for b's * columns. Therefore, there's no need for the join to produce null-extended * rows in the first place --- which makes it a plain join not an outer join. * (This scenario may not be very likely in a query written out by hand, but * it's reasonably likely when pushing quals down into complex views.) * * More generally, an outer join can be reduced in strength if there is a * strict qual above it in the qual tree that constrains a Var from the * nullable side of the join to be non-null. (For FULL joins this applies * to each side separately.) * * Another transformation we apply here is to recognize cases like * SELECT ... FROM a LEFT JOIN b ON (a.x = b.y) WHERE b.y IS NULL; * If the join clause is strict for b.y, then only null-extended rows could * pass the upper WHERE, and we can conclude that what the query is really * specifying is an anti-semijoin. We change the join type from JOIN_LEFT * to JOIN_ANTI. The IS NULL clause then becomes redundant, and must be * removed to prevent bogus selectivity calculations, but we leave it to * distribute_qual_to_rels to get rid of such clauses. * * Also, we get rid of JOIN_RIGHT cases by flipping them around to become * JOIN_LEFT. This saves some code here and in some later planner routines, * but the main reason to do it is to not need to invent a JOIN_REVERSE_ANTI * join type. * * To ease recognition of strict qual clauses, we require this routine to be * run after expression preprocessing (i.e., qual canonicalization and JOIN * alias-var expansion). */ void reduce_outer_joins(PlannerInfo *root) { reduce_outer_joins_state *state; /* * To avoid doing strictness checks on more quals than necessary, we want * to stop descending the jointree as soon as there are no outer joins * below our current point. This consideration forces a two-pass process. * The first pass gathers information about which base rels appear below * each side of each join clause, and about whether there are outer * join(s) below each side of each join clause. The second pass examines * qual clauses and changes join types as it descends the tree. */ state = reduce_outer_joins_pass1((Node *) root->parse->jointree); /* planner.c shouldn't have called me if no outer joins */ if (state == NULL || !state->contains_outer) elog(ERROR, "so where are the outer joins?"); reduce_outer_joins_pass2((Node *) root->parse->jointree, state, root, NULL, NIL, NIL); } /* * reduce_outer_joins_pass1 - phase 1 data collection * * Returns a state node describing the given jointree node. */ static reduce_outer_joins_state * reduce_outer_joins_pass1(Node *jtnode) { reduce_outer_joins_state *result; result = (reduce_outer_joins_state *) palloc(sizeof(reduce_outer_joins_state)); result->relids = NULL; result->contains_outer = false; result->sub_states = NIL; if (jtnode == NULL) return result; if (IsA(jtnode, RangeTblRef)) { int varno = ((RangeTblRef *) jtnode)->rtindex; result->relids = bms_make_singleton(varno); } else if (IsA(jtnode, FromExpr)) { FromExpr *f = (FromExpr *) jtnode; ListCell *l; foreach(l, f->fromlist) { reduce_outer_joins_state *sub_state; sub_state = reduce_outer_joins_pass1(lfirst(l)); result->relids = bms_add_members(result->relids, sub_state->relids); result->contains_outer |= sub_state->contains_outer; result->sub_states = lappend(result->sub_states, sub_state); } } else if (IsA(jtnode, JoinExpr)) { JoinExpr *j = (JoinExpr *) jtnode; reduce_outer_joins_state *sub_state; /* join's own RT index is not wanted in result->relids */ if (IS_OUTER_JOIN(j->jointype)) result->contains_outer = true; sub_state = reduce_outer_joins_pass1(j->larg); result->relids = bms_add_members(result->relids, sub_state->relids); result->contains_outer |= sub_state->contains_outer; result->sub_states = lappend(result->sub_states, sub_state); sub_state = reduce_outer_joins_pass1(j->rarg); result->relids = bms_add_members(result->relids, sub_state->relids); result->contains_outer |= sub_state->contains_outer; result->sub_states = lappend(result->sub_states, sub_state); } else elog(ERROR, "unrecognized node type: %d", (int) nodeTag(jtnode)); return result; } /* * reduce_outer_joins_pass2 - phase 2 processing * * jtnode: current jointree node * state: state data collected by phase 1 for this node * root: toplevel planner state * nonnullable_rels: set of base relids forced non-null by upper quals * nonnullable_vars: list of Vars forced non-null by upper quals * forced_null_vars: list of Vars forced null by upper quals */ static void reduce_outer_joins_pass2(Node *jtnode, reduce_outer_joins_state *state, PlannerInfo *root, Relids nonnullable_rels, List *nonnullable_vars, List *forced_null_vars) { /* * pass 2 should never descend as far as an empty subnode or base rel, * because it's only called on subtrees marked as contains_outer. */ if (jtnode == NULL) elog(ERROR, "reached empty jointree"); if (IsA(jtnode, RangeTblRef)) elog(ERROR, "reached base rel"); else if (IsA(jtnode, FromExpr)) { FromExpr *f = (FromExpr *) jtnode; ListCell *l; ListCell *s; Relids pass_nonnullable_rels; List *pass_nonnullable_vars; List *pass_forced_null_vars; /* Scan quals to see if we can add any constraints */ pass_nonnullable_rels = find_nonnullable_rels(f->quals); pass_nonnullable_rels = bms_add_members(pass_nonnullable_rels, nonnullable_rels); /* NB: we rely on list_concat to not damage its second argument */ pass_nonnullable_vars = find_nonnullable_vars(f->quals); pass_nonnullable_vars = list_concat(pass_nonnullable_vars, nonnullable_vars); pass_forced_null_vars = find_forced_null_vars(f->quals); pass_forced_null_vars = list_concat(pass_forced_null_vars, forced_null_vars); /* And recurse --- but only into interesting subtrees */ Assert(list_length(f->fromlist) == list_length(state->sub_states)); forboth(l, f->fromlist, s, state->sub_states) { reduce_outer_joins_state *sub_state = lfirst(s); if (sub_state->contains_outer) reduce_outer_joins_pass2(lfirst(l), sub_state, root, pass_nonnullable_rels, pass_nonnullable_vars, pass_forced_null_vars); } bms_free(pass_nonnullable_rels); /* can't so easily clean up var lists, unfortunately */ } else if (IsA(jtnode, JoinExpr)) { JoinExpr *j = (JoinExpr *) jtnode; int rtindex = j->rtindex; JoinType jointype = j->jointype; reduce_outer_joins_state *left_state = linitial(state->sub_states); reduce_outer_joins_state *right_state = lsecond(state->sub_states); List *local_nonnullable_vars = NIL; bool computed_local_nonnullable_vars = false; /* Can we simplify this join? */ switch (jointype) { case JOIN_INNER: break; case JOIN_LEFT: if (bms_overlap(nonnullable_rels, right_state->relids)) jointype = JOIN_INNER; break; case JOIN_RIGHT: if (bms_overlap(nonnullable_rels, left_state->relids)) jointype = JOIN_INNER; break; case JOIN_FULL: if (bms_overlap(nonnullable_rels, left_state->relids)) { if (bms_overlap(nonnullable_rels, right_state->relids)) jointype = JOIN_INNER; else jointype = JOIN_LEFT; } else { if (bms_overlap(nonnullable_rels, right_state->relids)) jointype = JOIN_RIGHT; } break; default: elog(ERROR, "unrecognized join type: %d", (int) jointype); break; } /* * Convert JOIN_RIGHT to JOIN_LEFT. Note that in the case where we * reduced JOIN_FULL to JOIN_RIGHT, this will mean the JoinExpr no * longer matches the internal ordering of any CoalesceExpr's built to * represent merged join variables. We don't care about that at * present, but be wary of it ... */ if (jointype == JOIN_RIGHT) { Node *tmparg; tmparg = j->larg; j->larg = j->rarg; j->rarg = tmparg; jointype = JOIN_LEFT; right_state = linitial(state->sub_states); left_state = lsecond(state->sub_states); } /* * See if we can reduce JOIN_LEFT to JOIN_ANTI. This is the case * if the join's own quals are strict for any var that was forced * null by higher qual levels. NOTE: there are other ways that we * could detect an anti-join, in particular if we were to check * whether Vars coming from the RHS must be non-null because of * table constraints. That seems complicated and expensive though * (in particular, one would have to be wary of lower outer joins). * For the moment this seems sufficient. */ if (jointype == JOIN_LEFT) { List *overlap; local_nonnullable_vars = find_nonnullable_vars(j->quals); computed_local_nonnullable_vars = true; /* * It's not sufficient to check whether local_nonnullable_vars * and forced_null_vars overlap: we need to know if the overlap * includes any RHS variables. */ overlap = list_intersection(local_nonnullable_vars, forced_null_vars); if (overlap != NIL && bms_overlap(pull_varnos((Node *) overlap), right_state->relids)) jointype = JOIN_ANTI; } /* Apply the jointype change, if any, to both jointree node and RTE */ if (jointype != j->jointype) { RangeTblEntry *rte = rt_fetch(rtindex, root->parse->rtable); Assert(rte->rtekind == RTE_JOIN); Assert(rte->jointype == j->jointype); rte->jointype = j->jointype = jointype; } /* Only recurse if there's more to do below here */ if (left_state->contains_outer || right_state->contains_outer) { Relids local_nonnullable_rels; List *local_forced_null_vars; Relids pass_nonnullable_rels; List *pass_nonnullable_vars; List *pass_forced_null_vars; /* * If this join is (now) inner, we can add any constraints its * quals provide to those we got from above. But if it is outer, * we can pass down the local constraints only into the nullable * side, because an outer join never eliminates any rows from its * non-nullable side. Also, there is no point in passing upper * constraints into the nullable side, since if there were any * we'd have been able to reduce the join. (In the case of * upper forced-null constraints, we *must not* pass them into * the nullable side --- they either applied here, or not.) * The upshot is that we pass either the local or the upper * constraints, never both, to the children of an outer join. * * At a FULL join we just punt and pass nothing down --- is it * possible to be smarter? */ if (jointype != JOIN_FULL) { local_nonnullable_rels = find_nonnullable_rels(j->quals); if (!computed_local_nonnullable_vars) local_nonnullable_vars = find_nonnullable_vars(j->quals); local_forced_null_vars = find_forced_null_vars(j->quals); if (jointype == JOIN_INNER) { /* OK to merge upper and local constraints */ local_nonnullable_rels = bms_add_members(local_nonnullable_rels, nonnullable_rels); local_nonnullable_vars = list_concat(local_nonnullable_vars, nonnullable_vars); local_forced_null_vars = list_concat(local_forced_null_vars, forced_null_vars); } } else { /* no use in calculating these */ local_nonnullable_rels = NULL; local_forced_null_vars = NIL; } if (left_state->contains_outer) { if (jointype == JOIN_INNER) { /* pass union of local and upper constraints */ pass_nonnullable_rels = local_nonnullable_rels; pass_nonnullable_vars = local_nonnullable_vars; pass_forced_null_vars = local_forced_null_vars; } else if (jointype != JOIN_FULL) /* ie, LEFT or ANTI */ { /* can't pass local constraints to non-nullable side */ pass_nonnullable_rels = nonnullable_rels; pass_nonnullable_vars = nonnullable_vars; pass_forced_null_vars = forced_null_vars; } else { /* no constraints pass through JOIN_FULL */ pass_nonnullable_rels = NULL; pass_nonnullable_vars = NIL; pass_forced_null_vars = NIL; } reduce_outer_joins_pass2(j->larg, left_state, root, pass_nonnullable_rels, pass_nonnullable_vars, pass_forced_null_vars); } if (right_state->contains_outer) { if (jointype != JOIN_FULL) /* ie, INNER, LEFT or ANTI */ { /* pass appropriate constraints, per comment above */ pass_nonnullable_rels = local_nonnullable_rels; pass_nonnullable_vars = local_nonnullable_vars; pass_forced_null_vars = local_forced_null_vars; } else { /* no constraints pass through JOIN_FULL */ pass_nonnullable_rels = NULL; pass_nonnullable_vars = NIL; pass_forced_null_vars = NIL; } reduce_outer_joins_pass2(j->rarg, right_state, root, pass_nonnullable_rels, pass_nonnullable_vars, pass_forced_null_vars); } bms_free(local_nonnullable_rels); } } else elog(ERROR, "unrecognized node type: %d", (int) nodeTag(jtnode)); } /* * substitute_multiple_relids - adjust node relid sets after pulling up * a subquery * * Find any FlattenedSubLink or PlaceHolderVar nodes in the given tree that * reference the pulled-up relid, and change them to reference the replacement * relid(s). We do not need to recurse into subqueries, since no subquery of * the current top query could (yet) contain such a reference. * * NOTE: although this has the form of a walker, we cheat and modify the * nodes in-place. This should be OK since the tree was copied by ResolveNew * earlier. Avoid scribbling on the original values of the bitmapsets, though, * because expression_tree_mutator doesn't copy those. */ typedef struct { int varno; Relids subrelids; } substitute_multiple_relids_context; static bool substitute_multiple_relids_walker(Node *node, substitute_multiple_relids_context *context) { if (node == NULL) return false; if (IsA(node, FlattenedSubLink)) { FlattenedSubLink *fslink = (FlattenedSubLink *) node; if (bms_is_member(context->varno, fslink->lefthand)) { fslink->lefthand = bms_union(fslink->lefthand, context->subrelids); fslink->lefthand = bms_del_member(fslink->lefthand, context->varno); } if (bms_is_member(context->varno, fslink->righthand)) { fslink->righthand = bms_union(fslink->righthand, context->subrelids); fslink->righthand = bms_del_member(fslink->righthand, context->varno); } /* fall through to examine children */ } if (IsA(node, PlaceHolderVar)) { PlaceHolderVar *phv = (PlaceHolderVar *) node; if (bms_is_member(context->varno, phv->phrels)) { phv->phrels = bms_union(phv->phrels, context->subrelids); phv->phrels = bms_del_member(phv->phrels, context->varno); } /* fall through to examine children */ } /* Shouldn't need to handle planner auxiliary nodes here */ Assert(!IsA(node, SpecialJoinInfo)); Assert(!IsA(node, AppendRelInfo)); Assert(!IsA(node, PlaceHolderInfo)); return expression_tree_walker(node, substitute_multiple_relids_walker, (void *) context); } static void substitute_multiple_relids(Node *node, int varno, Relids subrelids) { substitute_multiple_relids_context context; context.varno = varno; context.subrelids = subrelids; /* * Must be prepared to start with a Query or a bare expression tree. */ query_or_expression_tree_walker(node, substitute_multiple_relids_walker, (void *) &context, 0); } /* * fix_append_rel_relids: update RT-index fields of AppendRelInfo nodes * * When we pull up a subquery, any AppendRelInfo references to the subquery's * RT index have to be replaced by the substituted relid (and there had better * be only one). We also need to apply substitute_multiple_relids to their * translated_vars lists, since those might contain PlaceHolderVars. * * We assume we may modify the AppendRelInfo nodes in-place. */ static void fix_append_rel_relids(List *append_rel_list, int varno, Relids subrelids) { ListCell *l; int subvarno = -1; /* * We only want to extract the member relid once, but we mustn't fail * immediately if there are multiple members; it could be that none of the * AppendRelInfo nodes refer to it. So compute it on first use. Note that * bms_singleton_member will complain if set is not singleton. */ foreach(l, append_rel_list) { AppendRelInfo *appinfo = (AppendRelInfo *) lfirst(l); /* The parent_relid shouldn't ever be a pullup target */ Assert(appinfo->parent_relid != varno); if (appinfo->child_relid == varno) { if (subvarno < 0) subvarno = bms_singleton_member(subrelids); appinfo->child_relid = subvarno; } /* Also finish fixups for its translated vars */ substitute_multiple_relids((Node *) appinfo->translated_vars, varno, subrelids); } } /* * get_relids_in_jointree: get set of RT indexes present in a jointree * * If include_joins is true, join RT indexes are included; if false, * only base rels are included. */ Relids get_relids_in_jointree(Node *jtnode, bool include_joins) { Relids result = NULL; if (jtnode == NULL) return result; if (IsA(jtnode, RangeTblRef)) { int varno = ((RangeTblRef *) jtnode)->rtindex; result = bms_make_singleton(varno); } else if (IsA(jtnode, FromExpr)) { FromExpr *f = (FromExpr *) jtnode; ListCell *l; foreach(l, f->fromlist) { result = bms_join(result, get_relids_in_jointree(lfirst(l), include_joins)); } } else if (IsA(jtnode, JoinExpr)) { JoinExpr *j = (JoinExpr *) jtnode; result = get_relids_in_jointree(j->larg, include_joins); result = bms_join(result, get_relids_in_jointree(j->rarg, include_joins)); if (include_joins) result = bms_add_member(result, j->rtindex); } else elog(ERROR, "unrecognized node type: %d", (int) nodeTag(jtnode)); return result; } /* * get_relids_for_join: get set of base RT indexes making up a join */ Relids get_relids_for_join(PlannerInfo *root, int joinrelid) { Node *jtnode; jtnode = find_jointree_node_for_rel((Node *) root->parse->jointree, joinrelid); if (!jtnode) elog(ERROR, "could not find join node %d", joinrelid); return get_relids_in_jointree(jtnode, false); } /* * find_jointree_node_for_rel: locate jointree node for a base or join RT index * * Returns NULL if not found */ static Node * find_jointree_node_for_rel(Node *jtnode, int relid) { if (jtnode == NULL) return NULL; if (IsA(jtnode, RangeTblRef)) { int varno = ((RangeTblRef *) jtnode)->rtindex; if (relid == varno) return jtnode; } else if (IsA(jtnode, FromExpr)) { FromExpr *f = (FromExpr *) jtnode; ListCell *l; foreach(l, f->fromlist) { jtnode = find_jointree_node_for_rel(lfirst(l), relid); if (jtnode) return jtnode; } } else if (IsA(jtnode, JoinExpr)) { JoinExpr *j = (JoinExpr *) jtnode; if (relid == j->rtindex) return jtnode; jtnode = find_jointree_node_for_rel(j->larg, relid); if (jtnode) return jtnode; jtnode = find_jointree_node_for_rel(j->rarg, relid); if (jtnode) return jtnode; } else elog(ERROR, "unrecognized node type: %d", (int) nodeTag(jtnode)); return NULL; }