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bef7764835
comment line where output as too long, and update typedefs for /lib directory. Also fix case where identifiers were used as variable names in the backend, but as typedefs in ecpg (favor the backend for indenting). Backpatch to 8.1.X.
1194 lines
35 KiB
C
1194 lines
35 KiB
C
/*-------------------------------------------------------------------------
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*
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* prepjointree.c
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* Planner preprocessing for subqueries and join tree manipulation.
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*
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* NOTE: the intended sequence for invoking these operations is
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* pull_up_IN_clauses
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* pull_up_subqueries
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* do expression preprocessing (including flattening JOIN alias vars)
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* reduce_outer_joins
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* simplify_jointree
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*
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*
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* Portions Copyright (c) 1996-2005, PostgreSQL Global Development Group
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* Portions Copyright (c) 1994, Regents of the University of California
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*
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*
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* IDENTIFICATION
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* $PostgreSQL: pgsql/src/backend/optimizer/prep/prepjointree.c,v 1.31.2.1 2005/11/22 18:23:11 momjian Exp $
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*
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*-------------------------------------------------------------------------
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*/
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#include "postgres.h"
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#include "optimizer/clauses.h"
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#include "optimizer/prep.h"
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#include "optimizer/subselect.h"
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#include "optimizer/var.h"
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#include "parser/parsetree.h"
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#include "rewrite/rewriteManip.h"
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#include "utils/lsyscache.h"
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/* These parameters are set by GUC */
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int from_collapse_limit;
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int join_collapse_limit;
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typedef struct reduce_outer_joins_state
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{
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Relids relids; /* base relids within this subtree */
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bool contains_outer; /* does subtree contain outer join(s)? */
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List *sub_states; /* List of states for subtree components */
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} reduce_outer_joins_state;
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static bool is_simple_subquery(Query *subquery);
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static bool has_nullable_targetlist(Query *subquery);
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static void resolvenew_in_jointree(Node *jtnode, int varno,
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RangeTblEntry *rte, List *subtlist);
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static reduce_outer_joins_state *reduce_outer_joins_pass1(Node *jtnode);
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static void reduce_outer_joins_pass2(Node *jtnode,
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reduce_outer_joins_state *state,
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PlannerInfo *root,
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Relids nonnullable_rels);
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static Relids find_nonnullable_rels(Node *node, bool top_level);
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static void fix_in_clause_relids(List *in_info_list, int varno,
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Relids subrelids);
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static Node *find_jointree_node_for_rel(Node *jtnode, int relid);
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/*
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* pull_up_IN_clauses
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* Attempt to pull up top-level IN clauses to be treated like joins.
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*
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* A clause "foo IN (sub-SELECT)" appearing at the top level of WHERE can
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* be processed by pulling the sub-SELECT up to become a rangetable entry
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* and handling the implied equality comparisons as join operators (with
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* special join rules).
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* This optimization *only* works at the top level of WHERE, because
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* it cannot distinguish whether the IN ought to return FALSE or NULL in
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* cases involving NULL inputs. This routine searches for such clauses
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* and does the necessary parsetree transformations if any are found.
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*
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* This routine has to run before preprocess_expression(), so the WHERE
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* clause is not yet reduced to implicit-AND format. That means we need
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* to recursively search through explicit AND clauses, which are
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* probably only binary ANDs. We stop as soon as we hit a non-AND item.
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*
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* Returns the possibly-modified version of the given qual-tree node.
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*/
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Node *
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pull_up_IN_clauses(PlannerInfo *root, Node *node)
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{
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if (node == NULL)
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return NULL;
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if (IsA(node, SubLink))
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{
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SubLink *sublink = (SubLink *) node;
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Node *subst;
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/* Is it a convertible IN clause? If not, return it as-is */
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subst = convert_IN_to_join(root, sublink);
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if (subst == NULL)
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return node;
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return subst;
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}
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if (and_clause(node))
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{
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List *newclauses = NIL;
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ListCell *l;
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foreach(l, ((BoolExpr *) node)->args)
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{
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Node *oldclause = (Node *) lfirst(l);
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newclauses = lappend(newclauses,
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pull_up_IN_clauses(root, oldclause));
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}
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return (Node *) make_andclause(newclauses);
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}
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/* Stop if not an AND */
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return node;
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}
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/*
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* pull_up_subqueries
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* Look for subqueries in the rangetable that can be pulled up into
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* the parent query. If the subquery has no special features like
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* grouping/aggregation then we can merge it into the parent's jointree.
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*
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* below_outer_join is true if this jointree node is within the nullable
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* side of an outer join. This restricts what we can do.
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*
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* A tricky aspect of this code is that if we pull up a subquery we have
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* to replace Vars that reference the subquery's outputs throughout the
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* parent query, including quals attached to jointree nodes above the one
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* we are currently processing! We handle this by being careful not to
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* change the jointree structure while recursing: no nodes other than
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* subquery RangeTblRef entries will be replaced. Also, we can't turn
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* ResolveNew loose on the whole jointree, because it'll return a mutated
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* copy of the tree; we have to invoke it just on the quals, instead.
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*/
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Node *
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pull_up_subqueries(PlannerInfo *root, Node *jtnode, bool below_outer_join)
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{
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if (jtnode == NULL)
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return NULL;
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if (IsA(jtnode, RangeTblRef))
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{
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int varno = ((RangeTblRef *) jtnode)->rtindex;
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Query *parse = root->parse;
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RangeTblEntry *rte = rt_fetch(varno, parse->rtable);
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Query *subquery = rte->subquery;
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/*
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* Is this a subquery RTE, and if so, is the subquery simple enough to
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* pull up? (If not, do nothing at this node.)
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*
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* If we are inside an outer join, only pull up subqueries whose
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* targetlists are nullable --- otherwise substituting their tlist
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* entries for upper Var references would do the wrong thing (the
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* results wouldn't become NULL when they're supposed to).
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*
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* XXX This could be improved by generating pseudo-variables for such
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* expressions; we'd have to figure out how to get the pseudo-
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* variables evaluated at the right place in the modified plan tree.
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* Fix it someday.
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*/
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if (rte->rtekind == RTE_SUBQUERY &&
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is_simple_subquery(subquery) &&
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(!below_outer_join || has_nullable_targetlist(subquery)))
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{
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PlannerInfo *subroot;
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int rtoffset;
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List *subtlist;
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ListCell *rt;
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/*
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* Need a modifiable copy of the subquery to hack on. Even if we
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* didn't sometimes choose not to pull up below, we must do this
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* to avoid problems if the same subquery is referenced from
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* multiple jointree items (which can't happen normally, but might
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* after rule rewriting).
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*/
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subquery = copyObject(subquery);
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/*
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* Create a PlannerInfo data structure for this subquery.
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*
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* NOTE: the next few steps should match the first processing in
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* subquery_planner(). Can we refactor to avoid code duplication,
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* or would that just make things uglier?
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*/
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subroot = makeNode(PlannerInfo);
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subroot->parse = subquery;
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/*
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* Pull up any IN clauses within the subquery's WHERE, so that we
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* don't leave unoptimized INs behind.
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*/
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subroot->in_info_list = NIL;
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if (subquery->hasSubLinks)
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subquery->jointree->quals = pull_up_IN_clauses(subroot,
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subquery->jointree->quals);
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/*
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* Recursively pull up the subquery's subqueries, so that this
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* routine's processing is complete for its jointree and
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* rangetable.
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*
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* Note: 'false' is correct here even if we are within an outer
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* join in the upper query; the lower query starts with a clean
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* slate for outer-join semantics.
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*/
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subquery->jointree = (FromExpr *)
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pull_up_subqueries(subroot, (Node *) subquery->jointree,
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false);
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/*
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* Now we must recheck whether the subquery is still simple enough
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* to pull up. If not, abandon processing it.
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*
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* We don't really need to recheck all the conditions involved,
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* but it's easier just to keep this "if" looking the same as the
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* one above.
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*/
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if (is_simple_subquery(subquery) &&
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(!below_outer_join || has_nullable_targetlist(subquery)))
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{
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/* good to go */
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}
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else
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{
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/*
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* Give up, return unmodified RangeTblRef.
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*
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* Note: The work we just did will be redone when the subquery
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* gets planned on its own. Perhaps we could avoid that by
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* storing the modified subquery back into the rangetable, but
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* I'm not gonna risk it now.
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*/
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return jtnode;
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}
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/*
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* Adjust level-0 varnos in subquery so that we can append its
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* rangetable to upper query's. We have to fix the subquery's
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* in_info_list, as well.
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*/
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rtoffset = list_length(parse->rtable);
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OffsetVarNodes((Node *) subquery, rtoffset, 0);
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OffsetVarNodes((Node *) subroot->in_info_list, rtoffset, 0);
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/*
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* Upper-level vars in subquery are now one level closer to their
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* parent than before.
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*/
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IncrementVarSublevelsUp((Node *) subquery, -1, 1);
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IncrementVarSublevelsUp((Node *) subroot->in_info_list, -1, 1);
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/*
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* Replace all of the top query's references to the subquery's
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* outputs with copies of the adjusted subtlist items, being
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* careful not to replace any of the jointree structure. (This'd
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* be a lot cleaner if we could use query_tree_mutator.)
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*/
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subtlist = subquery->targetList;
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parse->targetList = (List *)
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ResolveNew((Node *) parse->targetList,
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varno, 0, rte,
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subtlist, CMD_SELECT, 0);
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resolvenew_in_jointree((Node *) parse->jointree, varno,
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rte, subtlist);
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Assert(parse->setOperations == NULL);
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parse->havingQual =
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ResolveNew(parse->havingQual,
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varno, 0, rte,
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subtlist, CMD_SELECT, 0);
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root->in_info_list = (List *)
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ResolveNew((Node *) root->in_info_list,
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varno, 0, rte,
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subtlist, CMD_SELECT, 0);
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foreach(rt, parse->rtable)
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{
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RangeTblEntry *otherrte = (RangeTblEntry *) lfirst(rt);
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if (otherrte->rtekind == RTE_JOIN)
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otherrte->joinaliasvars = (List *)
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ResolveNew((Node *) otherrte->joinaliasvars,
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varno, 0, rte,
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subtlist, CMD_SELECT, 0);
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}
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/*
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* Now append the adjusted rtable entries to upper query. (We hold
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* off until after fixing the upper rtable entries; no point in
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* running that code on the subquery ones too.)
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*/
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parse->rtable = list_concat(parse->rtable, subquery->rtable);
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/*
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* Pull up any FOR UPDATE/SHARE markers, too. (OffsetVarNodes
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* already adjusted the marker values, so just list_concat the
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* list.)
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*
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* Executor can't handle multiple FOR UPDATE/SHARE/NOWAIT flags,
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* so complain if they are valid but different
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*/
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if (parse->rowMarks && subquery->rowMarks)
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{
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if (parse->forUpdate != subquery->forUpdate)
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ereport(ERROR,
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(errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
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errmsg("cannot use both FOR UPDATE and FOR SHARE in one query")));
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if (parse->rowNoWait != subquery->rowNoWait)
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ereport(ERROR,
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(errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
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errmsg("cannot use both wait and NOWAIT in one query")));
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}
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parse->rowMarks = list_concat(parse->rowMarks, subquery->rowMarks);
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if (subquery->rowMarks)
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{
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parse->forUpdate = subquery->forUpdate;
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parse->rowNoWait = subquery->rowNoWait;
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}
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/*
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* We also have to fix the relid sets of any parent InClauseInfo
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* nodes. (This could perhaps be done by ResolveNew, but it would
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* clutter that routine's API unreasonably.)
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*/
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if (root->in_info_list)
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{
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Relids subrelids;
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subrelids = get_relids_in_jointree((Node *) subquery->jointree);
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fix_in_clause_relids(root->in_info_list, varno, subrelids);
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}
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/*
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* And now append any subquery InClauseInfos to our list.
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*/
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root->in_info_list = list_concat(root->in_info_list,
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subroot->in_info_list);
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/*
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* Miscellaneous housekeeping.
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*/
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parse->hasSubLinks |= subquery->hasSubLinks;
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/* subquery won't be pulled up if it hasAggs, so no work there */
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/*
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* Return the adjusted subquery jointree to replace the
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* RangeTblRef entry in my jointree.
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*/
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return (Node *) subquery->jointree;
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}
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}
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else if (IsA(jtnode, FromExpr))
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{
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FromExpr *f = (FromExpr *) jtnode;
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ListCell *l;
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foreach(l, f->fromlist)
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lfirst(l) = pull_up_subqueries(root, lfirst(l),
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below_outer_join);
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}
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else if (IsA(jtnode, JoinExpr))
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{
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JoinExpr *j = (JoinExpr *) jtnode;
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/* Recurse, being careful to tell myself when inside outer join */
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switch (j->jointype)
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{
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case JOIN_INNER:
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j->larg = pull_up_subqueries(root, j->larg,
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below_outer_join);
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j->rarg = pull_up_subqueries(root, j->rarg,
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below_outer_join);
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break;
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case JOIN_LEFT:
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j->larg = pull_up_subqueries(root, j->larg,
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below_outer_join);
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j->rarg = pull_up_subqueries(root, j->rarg,
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true);
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break;
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case JOIN_FULL:
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j->larg = pull_up_subqueries(root, j->larg,
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true);
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j->rarg = pull_up_subqueries(root, j->rarg,
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true);
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break;
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case JOIN_RIGHT:
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j->larg = pull_up_subqueries(root, j->larg,
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true);
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j->rarg = pull_up_subqueries(root, j->rarg,
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below_outer_join);
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break;
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case JOIN_UNION:
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/*
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* This is where we fail if upper levels of planner haven't
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* rewritten UNION JOIN as an Append ...
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*/
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ereport(ERROR,
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(errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
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errmsg("UNION JOIN is not implemented")));
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break;
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default:
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elog(ERROR, "unrecognized join type: %d",
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(int) j->jointype);
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break;
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}
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}
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else
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elog(ERROR, "unrecognized node type: %d",
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(int) nodeTag(jtnode));
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return jtnode;
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}
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/*
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* is_simple_subquery
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* Check a subquery in the range table to see if it's simple enough
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* to pull up into the parent query.
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*/
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static bool
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is_simple_subquery(Query *subquery)
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{
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/*
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* Let's just make sure it's a valid subselect ...
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*/
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if (!IsA(subquery, Query) ||
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subquery->commandType != CMD_SELECT ||
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subquery->resultRelation != 0 ||
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subquery->into != NULL)
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elog(ERROR, "subquery is bogus");
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|
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/*
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* Can't currently pull up a query with setops. Maybe after querytree
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* redesign...
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*/
|
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if (subquery->setOperations)
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return false;
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|
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/*
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* Can't pull up a subquery involving grouping, aggregation, sorting, or
|
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* limiting.
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*/
|
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if (subquery->hasAggs ||
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subquery->groupClause ||
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subquery->havingQual ||
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subquery->sortClause ||
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subquery->distinctClause ||
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subquery->limitOffset ||
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subquery->limitCount)
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return false;
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|
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/*
|
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* Don't pull up a subquery that has any set-returning functions in its
|
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* targetlist. Otherwise we might well wind up inserting set-returning
|
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* functions into places where they mustn't go, such as quals of higher
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* queries.
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*/
|
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if (expression_returns_set((Node *) subquery->targetList))
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return false;
|
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|
|
/*
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* 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
|
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* empty FromExpr appears lower down in a jointree. Not worth working hard
|
|
* on this, just to collapse SubqueryScan/Result into Result...
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*/
|
|
if (subquery->jointree->fromlist == NIL)
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return false;
|
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|
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return true;
|
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}
|
|
|
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/*
|
|
* has_nullable_targetlist
|
|
* Check a subquery in the range table to see if all the non-junk
|
|
* targetlist items are simple variables or strict functions of simple
|
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* variables (and, hence, will correctly go to NULL when examined above
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* the point of an outer join).
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|
*
|
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* NOTE: it would be correct (and useful) to ignore output columns that aren't
|
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* actually referenced by the enclosing query ... but we do not have that
|
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* information available at this point.
|
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*/
|
|
static bool
|
|
has_nullable_targetlist(Query *subquery)
|
|
{
|
|
ListCell *l;
|
|
|
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foreach(l, subquery->targetList)
|
|
{
|
|
TargetEntry *tle = (TargetEntry *) lfirst(l);
|
|
|
|
/* ignore resjunk columns */
|
|
if (tle->resjunk)
|
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continue;
|
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|
|
/* Must contain a Var of current level */
|
|
if (!contain_vars_of_level((Node *) tle->expr, 0))
|
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return false;
|
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|
|
/* Must not contain any non-strict constructs */
|
|
if (contain_nonstrict_functions((Node *) tle->expr))
|
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return false;
|
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|
|
/* This one's OK, keep scanning */
|
|
}
|
|
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.)
|
|
*
|
|
* 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);
|
|
}
|
|
|
|
/*
|
|
* 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
|
|
*/
|
|
static void
|
|
reduce_outer_joins_pass2(Node *jtnode,
|
|
reduce_outer_joins_state *state,
|
|
PlannerInfo *root,
|
|
Relids nonnullable_rels)
|
|
{
|
|
/*
|
|
* 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;
|
|
|
|
/* Scan quals to see if we can add any nonnullability constraints */
|
|
pass_nonnullable = find_nonnullable_rels(f->quals, true);
|
|
pass_nonnullable = bms_add_members(pass_nonnullable,
|
|
nonnullable_rels);
|
|
/* 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);
|
|
}
|
|
bms_free(pass_nonnullable);
|
|
}
|
|
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);
|
|
|
|
/* Can we simplify this join? */
|
|
switch (jointype)
|
|
{
|
|
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:
|
|
break;
|
|
}
|
|
if (jointype != j->jointype)
|
|
{
|
|
/* apply the change to both jointree node and RTE */
|
|
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;
|
|
Relids pass_nonnullable;
|
|
|
|
/*
|
|
* If this join is (now) inner, we can add any nonnullability
|
|
* constraints its quals provide to those we got from above. But
|
|
* if it is outer, we can only pass down the local constraints
|
|
* into the nullable side, because an outer join never eliminates
|
|
* any rows from its non-nullable side. If it's a FULL join then
|
|
* it doesn't eliminate anything from either side.
|
|
*/
|
|
if (jointype != JOIN_FULL)
|
|
{
|
|
local_nonnullable = find_nonnullable_rels(j->quals, true);
|
|
local_nonnullable = bms_add_members(local_nonnullable,
|
|
nonnullable_rels);
|
|
}
|
|
else
|
|
local_nonnullable = NULL; /* no use in calculating it */
|
|
|
|
if (left_state->contains_outer)
|
|
{
|
|
if (jointype == JOIN_INNER || jointype == JOIN_RIGHT)
|
|
pass_nonnullable = local_nonnullable;
|
|
else
|
|
pass_nonnullable = nonnullable_rels;
|
|
reduce_outer_joins_pass2(j->larg, left_state, root,
|
|
pass_nonnullable);
|
|
}
|
|
if (right_state->contains_outer)
|
|
{
|
|
if (jointype == JOIN_INNER || jointype == JOIN_LEFT)
|
|
pass_nonnullable = local_nonnullable;
|
|
else
|
|
pass_nonnullable = nonnullable_rels;
|
|
reduce_outer_joins_pass2(j->rarg, right_state, root,
|
|
pass_nonnullable);
|
|
}
|
|
bms_free(local_nonnullable);
|
|
}
|
|
}
|
|
else
|
|
elog(ERROR, "unrecognized node type: %d",
|
|
(int) nodeTag(jtnode));
|
|
}
|
|
|
|
/*
|
|
* find_nonnullable_rels
|
|
* Determine which base rels are forced nonnullable by given quals
|
|
*
|
|
* We don't use expression_tree_walker here because we don't want to
|
|
* descend through very many kinds of nodes; only the ones we can be sure
|
|
* are strict. We can descend through the top level of implicit AND'ing,
|
|
* but not through any explicit ANDs (or ORs) below that, since those are not
|
|
* strict constructs. The List case handles the top-level implicit AND list
|
|
* as well as lists of arguments to strict operators/functions.
|
|
*/
|
|
static Relids
|
|
find_nonnullable_rels(Node *node, bool top_level)
|
|
{
|
|
Relids result = NULL;
|
|
|
|
if (node == NULL)
|
|
return NULL;
|
|
if (IsA(node, Var))
|
|
{
|
|
Var *var = (Var *) node;
|
|
|
|
if (var->varlevelsup == 0)
|
|
result = bms_make_singleton(var->varno);
|
|
}
|
|
else if (IsA(node, List))
|
|
{
|
|
ListCell *l;
|
|
|
|
foreach(l, (List *) node)
|
|
{
|
|
result = bms_join(result, find_nonnullable_rels(lfirst(l),
|
|
top_level));
|
|
}
|
|
}
|
|
else if (IsA(node, FuncExpr))
|
|
{
|
|
FuncExpr *expr = (FuncExpr *) node;
|
|
|
|
if (func_strict(expr->funcid))
|
|
result = find_nonnullable_rels((Node *) expr->args, false);
|
|
}
|
|
else if (IsA(node, OpExpr))
|
|
{
|
|
OpExpr *expr = (OpExpr *) node;
|
|
|
|
if (op_strict(expr->opno))
|
|
result = find_nonnullable_rels((Node *) expr->args, false);
|
|
}
|
|
else if (IsA(node, BoolExpr))
|
|
{
|
|
BoolExpr *expr = (BoolExpr *) node;
|
|
|
|
/* NOT is strict, others are not */
|
|
if (expr->boolop == NOT_EXPR)
|
|
result = find_nonnullable_rels((Node *) expr->args, false);
|
|
}
|
|
else if (IsA(node, RelabelType))
|
|
{
|
|
RelabelType *expr = (RelabelType *) node;
|
|
|
|
result = find_nonnullable_rels((Node *) expr->arg, top_level);
|
|
}
|
|
else if (IsA(node, ConvertRowtypeExpr))
|
|
{
|
|
/* not clear this is useful, but it can't hurt */
|
|
ConvertRowtypeExpr *expr = (ConvertRowtypeExpr *) node;
|
|
|
|
result = find_nonnullable_rels((Node *) expr->arg, top_level);
|
|
}
|
|
else if (IsA(node, NullTest))
|
|
{
|
|
NullTest *expr = (NullTest *) node;
|
|
|
|
/*
|
|
* IS NOT NULL can be considered strict, but only at top level; else
|
|
* we might have something like NOT (x IS NOT NULL).
|
|
*/
|
|
if (top_level && expr->nulltesttype == IS_NOT_NULL)
|
|
result = find_nonnullable_rels((Node *) expr->arg, false);
|
|
}
|
|
else if (IsA(node, BooleanTest))
|
|
{
|
|
BooleanTest *expr = (BooleanTest *) node;
|
|
|
|
/*
|
|
* Appropriate boolean tests are strict at top level.
|
|
*/
|
|
if (top_level &&
|
|
(expr->booltesttype == IS_TRUE ||
|
|
expr->booltesttype == IS_FALSE ||
|
|
expr->booltesttype == IS_NOT_UNKNOWN))
|
|
result = find_nonnullable_rels((Node *) expr->arg, false);
|
|
}
|
|
return result;
|
|
}
|
|
|
|
/*
|
|
* simplify_jointree
|
|
* Attempt to simplify a query's jointree.
|
|
*
|
|
* If we succeed in pulling up a subquery then we might form a jointree
|
|
* in which a FromExpr is a direct child of another FromExpr. In that
|
|
* case we can consider collapsing the two FromExprs into one. This is
|
|
* an optional conversion, since the planner will work correctly either
|
|
* way. But we may find a better plan (at the cost of more planning time)
|
|
* if we merge the two nodes, creating a single join search space out of
|
|
* two. To allow the user to trade off planning time against plan quality,
|
|
* we provide a control parameter from_collapse_limit that limits the size
|
|
* of the join search space that can be created this way.
|
|
*
|
|
* We also consider flattening explicit inner JOINs into FromExprs (which
|
|
* will in turn allow them to be merged into parent FromExprs). The tradeoffs
|
|
* here are the same as for flattening FromExprs, but we use a different
|
|
* control parameter so that the user can use explicit JOINs to control the
|
|
* join order even when they are inner JOINs.
|
|
*
|
|
* NOTE: don't try to do this in the same jointree scan that does subquery
|
|
* pullup! Since we're changing the jointree structure here, that wouldn't
|
|
* work reliably --- see comments for pull_up_subqueries().
|
|
*/
|
|
Node *
|
|
simplify_jointree(PlannerInfo *root, Node *jtnode)
|
|
{
|
|
if (jtnode == NULL)
|
|
return NULL;
|
|
if (IsA(jtnode, RangeTblRef))
|
|
{
|
|
/* nothing to do here... */
|
|
}
|
|
else if (IsA(jtnode, FromExpr))
|
|
{
|
|
FromExpr *f = (FromExpr *) jtnode;
|
|
List *newlist = NIL;
|
|
int children_remaining;
|
|
ListCell *l;
|
|
|
|
children_remaining = list_length(f->fromlist);
|
|
foreach(l, f->fromlist)
|
|
{
|
|
Node *child = (Node *) lfirst(l);
|
|
|
|
children_remaining--;
|
|
/* Recursively simplify this child... */
|
|
child = simplify_jointree(root, child);
|
|
/* Now, is it a FromExpr? */
|
|
if (child && IsA(child, FromExpr))
|
|
{
|
|
/*
|
|
* Yes, so do we want to merge it into parent? Always do so
|
|
* if child has just one element (since that doesn't make the
|
|
* parent's list any longer). Otherwise merge if the
|
|
* resulting join list would be no longer than
|
|
* from_collapse_limit.
|
|
*/
|
|
FromExpr *subf = (FromExpr *) child;
|
|
int childlen = list_length(subf->fromlist);
|
|
int myothers = list_length(newlist) + children_remaining;
|
|
|
|
if (childlen <= 1 ||
|
|
(childlen + myothers) <= from_collapse_limit)
|
|
{
|
|
newlist = list_concat(newlist, subf->fromlist);
|
|
|
|
/*
|
|
* By now, the quals have been converted to implicit-AND
|
|
* lists, so we just need to join the lists. NOTE: we put
|
|
* the pulled-up quals first.
|
|
*/
|
|
f->quals = (Node *) list_concat((List *) subf->quals,
|
|
(List *) f->quals);
|
|
}
|
|
else
|
|
newlist = lappend(newlist, child);
|
|
}
|
|
else
|
|
newlist = lappend(newlist, child);
|
|
}
|
|
f->fromlist = newlist;
|
|
}
|
|
else if (IsA(jtnode, JoinExpr))
|
|
{
|
|
JoinExpr *j = (JoinExpr *) jtnode;
|
|
|
|
/* Recursively simplify the children... */
|
|
j->larg = simplify_jointree(root, j->larg);
|
|
j->rarg = simplify_jointree(root, j->rarg);
|
|
|
|
/*
|
|
* If it is an outer join, we must not flatten it. An inner join is
|
|
* semantically equivalent to a FromExpr; we convert it to one,
|
|
* allowing it to be flattened into its parent, if the resulting
|
|
* FromExpr would have no more than join_collapse_limit members.
|
|
*/
|
|
if (j->jointype == JOIN_INNER && join_collapse_limit > 1)
|
|
{
|
|
int leftlen,
|
|
rightlen;
|
|
|
|
if (j->larg && IsA(j->larg, FromExpr))
|
|
leftlen = list_length(((FromExpr *) j->larg)->fromlist);
|
|
else
|
|
leftlen = 1;
|
|
if (j->rarg && IsA(j->rarg, FromExpr))
|
|
rightlen = list_length(((FromExpr *) j->rarg)->fromlist);
|
|
else
|
|
rightlen = 1;
|
|
if ((leftlen + rightlen) <= join_collapse_limit)
|
|
{
|
|
FromExpr *f = makeNode(FromExpr);
|
|
|
|
f->fromlist = NIL;
|
|
f->quals = NULL;
|
|
|
|
if (j->larg && IsA(j->larg, FromExpr))
|
|
{
|
|
FromExpr *subf = (FromExpr *) j->larg;
|
|
|
|
f->fromlist = subf->fromlist;
|
|
f->quals = subf->quals;
|
|
}
|
|
else
|
|
f->fromlist = list_make1(j->larg);
|
|
|
|
if (j->rarg && IsA(j->rarg, FromExpr))
|
|
{
|
|
FromExpr *subf = (FromExpr *) j->rarg;
|
|
|
|
f->fromlist = list_concat(f->fromlist,
|
|
subf->fromlist);
|
|
f->quals = (Node *) list_concat((List *) f->quals,
|
|
(List *) subf->quals);
|
|
}
|
|
else
|
|
f->fromlist = lappend(f->fromlist, j->rarg);
|
|
|
|
/* pulled-up quals first */
|
|
f->quals = (Node *) list_concat((List *) f->quals,
|
|
(List *) j->quals);
|
|
|
|
return (Node *) f;
|
|
}
|
|
}
|
|
}
|
|
else
|
|
elog(ERROR, "unrecognized node type: %d",
|
|
(int) nodeTag(jtnode));
|
|
return jtnode;
|
|
}
|
|
|
|
/*
|
|
* fix_in_clause_relids: update RT-index sets of InClauseInfo nodes
|
|
*
|
|
* When we pull up a subquery, any InClauseInfo references to the subquery's
|
|
* RT index have to be replaced by the set of substituted relids.
|
|
*
|
|
* We assume we may modify the InClauseInfo nodes in-place.
|
|
*/
|
|
static void
|
|
fix_in_clause_relids(List *in_info_list, int varno, Relids subrelids)
|
|
{
|
|
ListCell *l;
|
|
|
|
foreach(l, in_info_list)
|
|
{
|
|
InClauseInfo *ininfo = (InClauseInfo *) lfirst(l);
|
|
|
|
if (bms_is_member(varno, ininfo->lefthand))
|
|
{
|
|
ininfo->lefthand = bms_del_member(ininfo->lefthand, varno);
|
|
ininfo->lefthand = bms_add_members(ininfo->lefthand, subrelids);
|
|
}
|
|
if (bms_is_member(varno, ininfo->righthand))
|
|
{
|
|
ininfo->righthand = bms_del_member(ininfo->righthand, varno);
|
|
ininfo->righthand = bms_add_members(ininfo->righthand, subrelids);
|
|
}
|
|
}
|
|
}
|
|
|
|
/*
|
|
* get_relids_in_jointree: get set of base RT indexes present in a jointree
|
|
*/
|
|
Relids
|
|
get_relids_in_jointree(Node *jtnode)
|
|
{
|
|
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)));
|
|
}
|
|
}
|
|
else if (IsA(jtnode, JoinExpr))
|
|
{
|
|
JoinExpr *j = (JoinExpr *) jtnode;
|
|
|
|
/* join's own RT index is not wanted in result */
|
|
result = get_relids_in_jointree(j->larg);
|
|
result = bms_join(result, get_relids_in_jointree(j->rarg));
|
|
}
|
|
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
|
|
*
|
|
* NB: this will not work reliably after simplify_jointree() is run,
|
|
* since that may eliminate join nodes from the jointree.
|
|
*/
|
|
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);
|
|
}
|
|
|
|
/*
|
|
* 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;
|
|
}
|