diff options
Diffstat (limited to 'src/backend/optimizer/path/pathkeys.c')
| -rw-r--r-- | src/backend/optimizer/path/pathkeys.c | 83 |
1 files changed, 45 insertions, 38 deletions
diff --git a/src/backend/optimizer/path/pathkeys.c b/src/backend/optimizer/path/pathkeys.c index 09a5b8a51f1..eee8a027a83 100644 --- a/src/backend/optimizer/path/pathkeys.c +++ b/src/backend/optimizer/path/pathkeys.c @@ -7,7 +7,7 @@ * * * IDENTIFICATION - * $Header: /cvsroot/pgsql/src/backend/optimizer/path/pathkeys.c,v 1.9 1999/05/17 00:26:33 tgl Exp $ + * $Header: /cvsroot/pgsql/src/backend/optimizer/path/pathkeys.c,v 1.10 1999/05/25 16:09:28 momjian Exp $ * *------------------------------------------------------------------------- */ @@ -26,9 +26,9 @@ #include "optimizer/ordering.h" static int match_pathkey_joinkeys(List *pathkey, List *joinkeys, - int outer_or_inner); + int outer_or_inner); static List *new_join_pathkey(List *pathkeys, List *join_rel_tlist, - List *joinclauses); + List *joinclauses); /*-------------------- @@ -41,7 +41,7 @@ static List *new_join_pathkey(List *pathkeys, List *join_rel_tlist, * of generating the relation and the resulting ordering of the tuples. * Sequential scan Paths have NIL pathkeys, indicating no known ordering. * Index scans have Path.pathkeys that represent the chosen index. - * A single-key index pathkeys would be { {tab1_indexkey1} }. For a + * A single-key index pathkeys would be { {tab1_indexkey1} }. For a * multi-key index pathkeys would be { {tab1_indexkey1}, {tab1_indexkey2} }, * indicating major sort by indexkey1 and minor sort by indexkey2. * @@ -70,12 +70,12 @@ static List *new_join_pathkey(List *pathkeys, List *join_rel_tlist, * executor might have to split the join into multiple batches. * * NestJoin does not perform sorting, and allows non-equijoins, so it does - * not allow useful pathkeys. (But couldn't we use the outer path's order?) + * not allow useful pathkeys. (But couldn't we use the outer path's order?) * * -- bjm *-------------------- */ - + /**************************************************************************** * KEY COMPARISONS ****************************************************************************/ @@ -111,11 +111,11 @@ static List *new_join_pathkey(List *pathkeys, List *join_rel_tlist, */ bool order_joinkeys_by_pathkeys(List *pathkeys, - List *joinkeys, - List *joinclauses, - int outer_or_inner, - List **matchedJoinKeysPtr, - List **matchedJoinClausesPtr) + List *joinkeys, + List *joinclauses, + int outer_or_inner, + List **matchedJoinKeysPtr, + List **matchedJoinClausesPtr) { List *matched_joinkeys = NIL; List *matched_joinclauses = NIL; @@ -123,9 +123,10 @@ order_joinkeys_by_pathkeys(List *pathkeys, List *i = NIL; int matched_joinkey_index = -1; int matched_keys = 0; + /* - * Reorder the joinkeys by picking out one that matches each pathkey, - * and create a new joinkey/joinclause list in pathkey order + * Reorder the joinkeys by picking out one that matches each pathkey, + * and create a new joinkey/joinclause list in pathkey order */ foreach(i, pathkeys) { @@ -138,34 +139,36 @@ order_joinkeys_by_pathkeys(List *pathkeys, matched_keys++; if (matchedJoinKeysPtr) { - JoinKey *joinkey = nth(matched_joinkey_index, joinkeys); + JoinKey *joinkey = nth(matched_joinkey_index, joinkeys); + matched_joinkeys = lappend(matched_joinkeys, joinkey); } - + if (matchedJoinClausesPtr) { Expr *joinclause = nth(matched_joinkey_index, joinclauses); + Assert(joinclauses); matched_joinclauses = lappend(matched_joinclauses, joinclause); } } else - /* A pathkey could not be matched. */ + /* A pathkey could not be matched. */ break; } /* - * Did we fail to match all the joinkeys? - * Extra pathkeys are no problem. + * Did we fail to match all the joinkeys? Extra pathkeys are no + * problem. */ if (matched_keys != length(joinkeys)) { - if (matchedJoinKeysPtr) - *matchedJoinKeysPtr = NIL; - if (matchedJoinClausesPtr) - *matchedJoinClausesPtr = NIL; - return false; + if (matchedJoinKeysPtr) + *matchedJoinKeysPtr = NIL; + if (matchedJoinClausesPtr) + *matchedJoinClausesPtr = NIL; + return false; } if (matchedJoinKeysPtr) @@ -190,7 +193,8 @@ match_pathkey_joinkeys(List *pathkey, { Var *key; int pos; - List *i, *x; + List *i, + *x; JoinKey *jk; foreach(i, pathkey) @@ -232,9 +236,9 @@ match_pathkey_joinkeys(List *pathkey, */ Path * get_cheapest_path_for_joinkeys(List *joinkeys, - PathOrder *ordering, - List *paths, - int outer_or_inner) + PathOrder *ordering, + List *paths, + int outer_or_inner) { Path *matched_path = NULL; List *i; @@ -243,7 +247,7 @@ get_cheapest_path_for_joinkeys(List *joinkeys, { Path *path = (Path *) lfirst(i); int better_sort; - + if (order_joinkeys_by_pathkeys(path->pathkeys, joinkeys, NIL, outer_or_inner, NULL, NULL) && pathorder_match(ordering, path->pathorder, &better_sort) && @@ -274,8 +278,8 @@ get_cheapest_path_for_joinkeys(List *joinkeys, */ List * make_pathkeys_from_joinkeys(List *joinkeys, - List *tlist, - int outer_or_inner) + List *tlist, + int outer_or_inner) { List *pathkeys = NIL; List *jk; @@ -284,7 +288,8 @@ make_pathkeys_from_joinkeys(List *joinkeys, { JoinKey *jkey = (JoinKey *) lfirst(jk); Var *key; - List *p, *p2; + List *p, + *p2; bool found = false; key = (Var *) extract_join_key(jkey, outer_or_inner); @@ -292,17 +297,19 @@ make_pathkeys_from_joinkeys(List *joinkeys, /* check to see if it is in the target list */ if (matching_tlist_var(key, tlist)) { + /* - * Include it in the pathkeys list if we haven't already done so + * Include it in the pathkeys list if we haven't already done + * so */ foreach(p, pathkeys) { List *pathkey = lfirst(p); - + foreach(p2, pathkey) { Var *pkey = lfirst(p2); - + if (equal(key, pkey)) { found = true; @@ -371,7 +378,7 @@ new_join_pathkeys(List *outer_pathkeys, * * Note that each returned pathkey is the var node found in * 'join_rel_tlist' rather than the joinclause var node. - * (Is this important?) Also, we return a fully copied list + * (Is this important?) Also, we return a fully copied list * that does not share any subnodes with existing data structures. * (Is that important, either?) * @@ -393,7 +400,7 @@ new_join_pathkey(List *pathkey, Expr *tlist_key; Assert(key); - + tlist_key = matching_tlist_var(key, join_rel_tlist); if (tlist_key && !member(tlist_key, new_pathkey)) new_pathkey = lcons(copyObject(tlist_key), new_pathkey); @@ -404,8 +411,8 @@ new_join_pathkey(List *pathkey, Expr *tlist_other_var; tlist_other_var = matching_tlist_var( - other_join_clause_var(key, joinclause), - join_rel_tlist); + other_join_clause_var(key, joinclause), + join_rel_tlist); if (tlist_other_var && !member(tlist_other_var, new_pathkey)) new_pathkey = lcons(copyObject(tlist_other_var), new_pathkey); } |