From 0ff27333555ad98ad3380b9b15e99e2e6c8bea0d Mon Sep 17 00:00:00 2001
From: Bruce Momjian <bruce@momjian.us>
Date: Sat, 20 Feb 1999 18:01:02 +0000
Subject: [PATCH] Update pathkeys comparison function.
---
src/backend/optimizer/path/pathkeys.c | 4 +-
src/backend/optimizer/util/keys.c | 76 +++++++++++++++------------
src/backend/optimizer/util/pathnode.c | 26 ++++-----
3 files changed, 57 insertions(+), 49 deletions(-)
diff --git a/src/backend/optimizer/path/pathkeys.c b/src/backend/optimizer/path/pathkeys.c
index e19eeec01ff..f1ea6cbae68 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 1.3 1999/02/20 16:32:35 momjian Exp $
+ * $Header: /cvsroot/pgsql/src/backend/optimizer/path/pathkeys.c,v 1.4 1999/02/20 18:01:01 momjian Exp $
*
*-------------------------------------------------------------------------
*/
@@ -54,7 +54,7 @@ static List *new_matching_subkeys(Var *subkey, List *considered_subkeys,
* { {tab1.col1, tab2.col1} }. This allows future joins to use either Var
* as a pre-sorted key to prevent Mergejoins from having to re-sort the Path.
* They are equal, so they are both primary sort keys. This is why pathkeys
- * is a List of Lists.
+ * is a List of Lists. -- bjm
*/
/****************************************************************************
diff --git a/src/backend/optimizer/util/keys.c b/src/backend/optimizer/util/keys.c
index 123b6dc4cb4..c921c24c0d1 100644
--- a/src/backend/optimizer/util/keys.c
+++ b/src/backend/optimizer/util/keys.c
@@ -7,7 +7,7 @@
*
*
* IDENTIFICATION
- * $Header: /cvsroot/pgsql/src/backend/optimizer/util/Attic/keys.c,v 1.18 1999/02/19 02:05:16 momjian Exp $
+ * $Header: /cvsroot/pgsql/src/backend/optimizer/util/Attic/keys.c,v 1.19 1999/02/20 18:01:02 momjian Exp $
*
*-------------------------------------------------------------------------
*/
@@ -110,62 +110,70 @@ extract_join_key(JoinKey *jk, int outer_or_inner)
* Returns t iff two sets of path keys are equivalent. They are
* equivalent if the first Var nodes match the second Var nodes.
*
- * XXX It isn't necessary to check that each sublist exactly contain
- * the same elements because if the routine that built these
- * sublists together is correct, having one element in common
- * implies having all elements in common.
- * Huh? bjm
+ * See the top of optimizer/path/pathkeys.c for a description of pathkeys.
+ * Each pathkey is ordered by its join order, so they not pre-ordered to
+ * match. We must search them ourselves.
*
+ * This gets called a lot, so it is optimized.
*/
bool
pathkeys_match(List *keys1, List *keys2, int *better_key)
{
List *key1,
- *key2,
- *key1a,
- *key2a;
+ *key2;
+ bool key1_subsetof_key2 = true,
+ key2_subsetof_key1 = true;
for (key1 = keys1, key2 = keys2;
key1 != NIL && key2 != NIL;
key1 = lnext(key1), key2 = lnext(key2))
{
- for (key1a = lfirst(key1), key2a = lfirst(key2);
- key1a != NIL && key2a != NIL;
- key1a = lnext(key1a), key2a = lnext(key2a))
- if (!equal(lfirst(key1a), lfirst(key2a)))
+ List *i;
+
+ if (key1_subsetof_key2)
+ foreach(i, lfirst(key1))
{
- *better_key = 0;
- return false;
+ Var *subkey = lfirst(i);
+ if (!member(subkey, lfirst(key2)))
+ {
+ key1_subsetof_key2 = false;
+ break;
+ }
}
- if (key1a != NIL && key2a == NIL)
- {
- *better_key = 1;
- return true;
- }
- if (key1a == NIL && key2a != NIL)
- {
- *better_key = 2;
- return true;
- }
+
+ if (key2_subsetof_key1)
+ foreach(i, lfirst(key2))
+ {
+ Var *subkey = lfirst(i);
+ if (!member(subkey, lfirst(key1)))
+ {
+ key2_subsetof_key1 = false;
+ break;
+ }
+ }
+ if (!key1_subsetof_key2 && !key2_subsetof_key1)
+ break; /* no need to continue comparisons. */
}
- /* Now the result should be true if list keys2 has at least as many
- * entries as keys1, ie, we did not fall off the end of keys2 first.
- * If key1 is now NIL then we hit the end of keys1 before or at the
- * same time as the end of keys2.
- */
- if (key1 != NIL && key2 == NIL)
+ if (!key1_subsetof_key2 && !key2_subsetof_key1)
{
- *better_key = 1;
- return true;
+ *better_key = 0;
+ return false;
}
- if (key1 == NIL && key2 != NIL)
+ if (key1_subsetof_key2 && !key2_subsetof_key1)
{
*better_key = 2;
return true;
}
+ if (!key1_subsetof_key2 && key2_subsetof_key1)
+ {
+ *better_key = 1;
+ return true;
+ }
+
*better_key = 0;
return true;
+
}
/*
diff --git a/src/backend/optimizer/util/pathnode.c b/src/backend/optimizer/util/pathnode.c
index 9041a9fe9b7..d94e124193e 100644
--- a/src/backend/optimizer/util/pathnode.c
+++ b/src/backend/optimizer/util/pathnode.c
@@ -7,7 +7,7 @@
*
*
* IDENTIFICATION
- * $Header: /cvsroot/pgsql/src/backend/optimizer/util/pathnode.c,v 1.37 1999/02/18 00:49:38 momjian Exp $
+ * $Header: /cvsroot/pgsql/src/backend/optimizer/util/pathnode.c,v 1.38 1999/02/20 18:01:02 momjian Exp $
*
*-------------------------------------------------------------------------
*/
@@ -172,15 +172,15 @@ better_path(Path *new_path, List *unique_paths, bool *is_new)
{
path = (Path *) lfirst(temp);
-#if 0
-/*def OPTDUP_DEBUG*/
+#ifdef OPTDUP_DEBUG
if (!pathkeys_match(new_path->pathkeys, path->pathkeys, &better_key) ||
better_key != 0)
{
- printf("oldpath\n");
- pprint(path->pathkeys);
+ printf("betterkey = %d\n", better_key);
printf("newpath\n");
pprint(new_path->pathkeys);
+ printf("oldpath\n");
+ pprint(path->pathkeys);
if (path->pathkeys && new_path->pathkeys &&
length(lfirst(path->pathkeys)) >= 2/* &&
length(lfirst(path->pathkeys)) <
@@ -191,10 +191,10 @@ better_path(Path *new_path, List *unique_paths, bool *is_new)
&better_sort) ||
better_sort != 0)
{
- printf("oldord\n");
- pprint(path->pathorder);
printf("neword\n");
pprint(new_path->pathorder);
+ printf("oldord\n");
+ pprint(path->pathorder);
}
#endif
@@ -204,8 +204,8 @@ better_path(Path *new_path, List *unique_paths, bool *is_new)
&better_sort))
{
/*
- * Replace pathkeys that match exactly, (1,2), (1,2).
- * Replace pathkeys (1,2) with (1,2,3) if the latter is not
+ * Replace pathkeys that match exactly, {{1,2}}, {{1,2}}
+ * Replace pathkeys {{1,2}}with {{1,2,3}}} if the latter is not
* more expensive and replace unordered path with ordered
* path if it is not more expensive. Favor sorted keys
* over unsorted keys in the same way.
@@ -221,10 +221,10 @@ better_path(Path *new_path, List *unique_paths, bool *is_new)
{
#ifdef OPTDUP_DEBUG
printf("replace with new %p old %p better key %d better sort %d\n", &new_path, &path, better_key, better_sort);
- printf("old\n");
- pprint(path);
printf("new\n");
pprint(new_path);
+ printf("old\n");
+ pprint(path);
#endif
*is_new = false;
return path;
@@ -241,10 +241,10 @@ better_path(Path *new_path, List *unique_paths, bool *is_new)
{
#ifdef OPTDUP_DEBUG
printf("skip new %p old %p better key %d better sort %d\n", &new_path, &path, better_key, better_sort);
- printf("old\n");
- pprint(path);
printf("new\n");
pprint(new_path);
+ printf("old\n");
+ pprint(path);
#endif
*is_new = false;
return NULL;
--
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