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another rename of optimizer
This commit is contained in:
Bruce Momjian
432
src/backend/optimizer/path/pathkeys.c
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432
src/backend/optimizer/path/pathkeys.c
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@ -0,0 +1,432 @@
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/*-------------------------------------------------------------------------
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*
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* joinutils.c
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* Utilities for matching and building join and path keys
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*
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* 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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* $Header: /cvsroot/pgsql/src/backend/optimizer/path/pathkeys.c,v 1.1 1999/02/20 15:27:42 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 "nodes/pg_list.h"
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#include "nodes/relation.h"
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#include "nodes/plannodes.h"
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#include "optimizer/internal.h"
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#include "optimizer/paths.h"
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#include "optimizer/var.h"
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#include "optimizer/keys.h"
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#include "optimizer/tlist.h"
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#include "optimizer/joininfo.h"
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#include "optimizer/ordering.h"
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static int match_pathkey_joinkeys(List *pathkey, List *joinkeys,
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int outer_or_inner);
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static bool joinkeys_pathkeys_match(List *joinkeys, List *pathkey,
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int outer_or_inner);
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static List *new_join_pathkey(List *subkeys, List *considered_subkeys,
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List *join_rel_tlist, List *joinclauses);
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static List *new_matching_subkeys(Var *subkey, List *considered_subkeys,
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List *join_rel_tlist, List *joinclauses);
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/****************************************************************************
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* KEY COMPARISONS
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****************************************************************************/
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/*
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* order_joinkeys_by_pathkeys
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* Attempts to match the keys of a path against the keys of join clauses.
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* This is done by looking for a matching join key in 'joinkeys' for
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* every path key in the list 'path.keys'. If there is a matching join key
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* (not necessarily unique) for every path key, then the list of
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* corresponding join keys and join clauses are returned in the order in
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* which the keys matched the path keys.
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*
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* 'pathkeys' is a list of path keys:
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* ( ( (var) (var) ... ) ( (var) ... ) )
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* 'joinkeys' is a list of join keys:
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* ( (outer inner) (outer inner) ... )
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* 'joinclauses' is a list of clauses corresponding to the join keys in
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* 'joinkeys'
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* 'outer_or_inner' is a flag that selects the desired subkey of a join key
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* in 'joinkeys'
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*
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* Returns the join keys and corresponding join clauses in a list if all
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* of the path keys were matched:
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* (
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* ( (outerkey0 innerkey0) ... (outerkeyN innerkeyN) )
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* ( clause0 ... clauseN )
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* )
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* and nil otherwise.
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*
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* Returns a list of matched join keys and a list of matched join clauses
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* in matchedJoinClausesPtr. - ay 11/94
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*/
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List *
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order_joinkeys_by_pathkeys(List *pathkeys,
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List *joinkeys,
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List *joinclauses,
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int outer_or_inner,
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List **matchedJoinClausesPtr)
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{
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List *matched_joinkeys = NIL;
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List *matched_joinclauses = NIL;
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List *pathkey = NIL;
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List *i = NIL;
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int matched_joinkey_index = -1;
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foreach(i, pathkeys)
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{
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pathkey = lfirst(i);
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matched_joinkey_index = match_pathkey_joinkeys(pathkey, joinkeys,
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outer_or_inner);
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if (matched_joinkey_index != -1)
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{
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List *xjoinkey = nth(matched_joinkey_index, joinkeys);
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List *joinclause = nth(matched_joinkey_index, joinclauses);
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matched_joinkeys = lappend(matched_joinkeys, xjoinkey);
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matched_joinclauses = lappend(matched_joinclauses, joinclause);
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}
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else
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{
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*matchedJoinClausesPtr = NIL;
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return NIL;
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}
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}
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*matchedJoinClausesPtr = matched_joinclauses;
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return matched_joinkeys;
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}
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/*
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* match_pathkey_joinkeys
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* Returns the 0-based index into 'joinkeys' of the first joinkey whose
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* outer or inner subkey matches any subkey of 'pathkey'.
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*/
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static int
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match_pathkey_joinkeys(List *pathkey,
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List *joinkeys,
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int outer_or_inner)
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{
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Var *path_subkey;
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int pos;
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List *i = NIL;
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List *x = NIL;
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JoinKey *jk;
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foreach(i, pathkey)
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{
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path_subkey = (Var *) lfirst(i);
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pos = 0;
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foreach(x, joinkeys)
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{
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jk = (JoinKey *) lfirst(x);
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if (var_equal(path_subkey,
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extract_join_key(jk, outer_or_inner)))
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return pos;
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pos++;
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}
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}
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return -1; /* no index found */
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}
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/*
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* get_cheapest_path_for_joinkeys
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* Attempts to find a path in 'paths' whose keys match a set of join
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* keys 'joinkeys'. To match,
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* 1. the path node ordering must equal 'ordering'.
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* 2. each subkey of a given path must match(i.e., be(var_equal) to) the
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* appropriate subkey of the corresponding join key in 'joinkeys',
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* i.e., the Nth path key must match its subkeys against the subkey of
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* the Nth join key in 'joinkeys'.
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*
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* 'joinkeys' is the list of key pairs to which the path keys must be
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* matched
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* 'ordering' is the ordering of the(outer) path to which 'joinkeys'
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* must correspond
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* 'paths' is a list of(inner) paths which are to be matched against
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* each join key in 'joinkeys'
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* 'outer_or_inner' is a flag that selects the desired subkey of a join key
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* in 'joinkeys'
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*
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* Find the cheapest path that matches the join keys
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*/
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Path *
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get_cheapest_path_for_joinkeys(List *joinkeys,
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PathOrder *ordering,
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List *paths,
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int outer_or_inner)
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{
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Path *matched_path = NULL;
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List *i = NIL;
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foreach(i, paths)
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{
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Path *path = (Path *) lfirst(i);
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int better_sort, better_key;
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if (joinkeys_pathkeys_match(joinkeys, path->pathkeys, outer_or_inner) &&
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length(joinkeys) == length(path->pathkeys) &&
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pathorder_match(ordering, path->pathorder, &better_sort) &&
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better_sort == 0)
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{
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if (matched_path)
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if (path->path_cost < matched_path->path_cost)
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matched_path = path;
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else
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matched_path = path;
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}
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}
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return matched_path;
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}
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/*
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* extract_path_keys
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* Builds a subkey list for a path by pulling one of the subkeys from
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* a list of join keys 'joinkeys' and then finding the var node in the
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* target list 'tlist' that corresponds to that subkey.
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*
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* 'joinkeys' is a list of join key pairs
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* 'tlist' is a relation target list
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* 'outer_or_inner' is a flag that selects the desired subkey of a join key
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* in 'joinkeys'
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*
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* Returns a list of pathkeys: ((tlvar1)(tlvar2)...(tlvarN)).
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* It is a list of lists because of multi-key indexes.
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*/
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List *
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extract_path_keys(List *joinkeys,
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List *tlist,
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int outer_or_inner)
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{
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List *pathkeys = NIL;
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List *jk;
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foreach(jk, joinkeys)
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{
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JoinKey *jkey = (JoinKey *) lfirst(jk);
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Var *var,
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*key;
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List *p;
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/*
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* find the right Var in the target list for this key
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*/
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var = (Var *) extract_join_key(jkey, outer_or_inner);
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key = (Var *) matching_tlist_var(var, tlist);
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/*
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* Include it in the pathkeys list if we haven't already done so
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*/
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foreach(p, pathkeys)
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{
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Var *pkey = lfirst((List *) lfirst(p)); /* XXX fix me */
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if (key == pkey)
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break;
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}
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if (p != NIL)
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continue; /* key already in pathkeys */
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pathkeys = lappend(pathkeys, lcons(key, NIL));
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}
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return pathkeys;
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}
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/*
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* joinkeys_pathkeys_match
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*/
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static bool
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joinkeys_pathkeys_match(List *joinkeys, List *pathkey, int outer_or_inner)
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{
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JoinKey *xjoinkey;
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Var *temp;
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Var *tempkey = NULL;
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bool found = false;
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List *i = NIL;
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List *j = NIL;
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foreach(i, joinkeys)
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{
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xjoinkey = (JoinKey *) lfirst(i);
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found = false;
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foreach(j, pathkey)
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{
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temp = (Var *) lfirst((List *) lfirst(j));
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if (temp == NULL)
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continue;
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tempkey = extract_join_key(xjoinkey, outer_or_inner);
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if (var_equal(tempkey, temp))
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{
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found = true;
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break;
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}
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}
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if (found == false)
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return false;
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}
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return found;
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}
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/****************************************************************************
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* NEW PATHKEY FORMATION
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****************************************************************************/
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/*
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* new_join_pathkeys
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* Find the path keys for a join relation by finding all vars in the list
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* of join clauses 'joinclauses' such that:
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* (1) the var corresponding to the outer join relation is a
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* key on the outer path
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* (2) the var appears in the target list of the join relation
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* In other words, add to each outer path key the inner path keys that
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* are required for qualification.
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*
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* 'outer_pathkeys' is the list of the outer path's path keys
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* 'join_rel_tlist' is the target list of the join relation
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* 'joinclauses' is the list of restricting join clauses
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*
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* Returns the list of new path keys.
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*
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*/
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List *
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new_join_pathkeys(List *outer_pathkeys,
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List *join_rel_tlist,
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List *joinclauses)
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{
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List *outer_pathkey = NIL;
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List *t_list = NIL;
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List *x;
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List *i = NIL;
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foreach(i, outer_pathkeys)
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{
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outer_pathkey = lfirst(i);
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x = new_join_pathkey(outer_pathkey, NIL, join_rel_tlist, joinclauses);
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if (x != NIL)
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t_list = lappend(t_list, x);
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}
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return t_list;
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}
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/*
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* new_join_pathkey
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* Finds new vars that become subkeys due to qualification clauses that
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* contain any previously considered subkeys. These new subkeys plus the
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* subkeys from 'subkeys' form a new pathkey for the join relation.
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*
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* Note that each returned subkey is the var node found in
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* 'join_rel_tlist' rather than the joinclause var node.
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*
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* 'subkeys' is a list of subkeys for which matching subkeys are to be
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* found
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* 'considered_subkeys' is the current list of all subkeys corresponding
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* to a given pathkey
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*
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* Returns a new pathkey(list of subkeys).
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*
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*/
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static List *
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new_join_pathkey(List *subkeys,
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List *considered_subkeys,
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List *join_rel_tlist,
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List *joinclauses)
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{
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List *t_list = NIL;
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Var *subkey;
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List *i = NIL;
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List *matched_subkeys = NIL;
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Expr *tlist_key = (Expr *) NULL;
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List *newly_considered_subkeys = NIL;
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foreach(i, subkeys)
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{
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subkey = (Var *) lfirst(i);
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if (subkey == NULL)
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break; /* XXX something is wrong */
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matched_subkeys = new_matching_subkeys(subkey, considered_subkeys,
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join_rel_tlist, joinclauses);
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tlist_key = matching_tlist_var(subkey, join_rel_tlist);
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newly_considered_subkeys = NIL;
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if (tlist_key)
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{
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if (!member(tlist_key, matched_subkeys))
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newly_considered_subkeys = lcons(tlist_key, matched_subkeys);
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}
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else
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newly_considered_subkeys = matched_subkeys;
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considered_subkeys = append(considered_subkeys, newly_considered_subkeys);
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t_list = nconc(t_list, newly_considered_subkeys);
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}
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return t_list;
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}
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/*
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* new_matching_subkeys
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* Returns a list of new subkeys:
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* (1) which are not listed in 'considered_subkeys'
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* (2) for which the "other" variable in some clause in 'joinclauses' is
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* 'subkey'
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* (3) which are mentioned in 'join_rel_tlist'
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*
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* Note that each returned subkey is the var node found in
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* 'join_rel_tlist' rather than the joinclause var node.
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*
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* 'subkey' is the var node for which we are trying to find matching
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* clauses
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*
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* Returns a list of new subkeys.
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*
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*/
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static List *
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new_matching_subkeys(Var *subkey,
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List *considered_subkeys,
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List *join_rel_tlist,
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List *joinclauses)
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{
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List *t_list = NIL;
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Expr *joinclause;
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List *i;
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Expr *tlist_other_var;
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foreach(i, joinclauses)
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{
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joinclause = lfirst(i);
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tlist_other_var = matching_tlist_var(
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other_join_clause_var(subkey, joinclause),
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join_rel_tlist);
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if (tlist_other_var &&
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!(member(tlist_other_var, considered_subkeys)))
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{
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/* XXX was "push" function */
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considered_subkeys = lappend(considered_subkeys,
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tlist_other_var);
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/*
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* considered_subkeys = nreverse(considered_subkeys); XXX -- I
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* am not sure of this.
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*/
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t_list = lappend(t_list, tlist_other_var);
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}
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}
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return t_list;
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}
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