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Tighten coding in samekeys(). Pretty braindead change,

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but it saves almost 10% of the runtime in Charles Hornberger's optimizer
example, so what the heck ...
This commit is contained in:
Tom Lane 1999-02-01 04:20:50 +00:00
parent 6ca2bf6534
commit 757f403451
1 changed files with 8 additions and 4 deletions
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12
src/backend/optimizer/util/keys.c
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@ -7,7 +7,7 @@
*
*
* IDENTIFICATION
* $Header: /cvsroot/pgsql/src/backend/optimizer/util/Attic/keys.c,v 1.9 1998/09/01 04:30:07 momjian Exp $
* $Header: /cvsroot/pgsql/src/backend/optimizer/util/Attic/keys.c,v 1.10 1999/02/01 04:20:50 tgl Exp $
*
*-------------------------------------------------------------------------
*/
@ -120,16 +120,20 @@ extract_subkey(JoinKey *jk, int which_subkey)
bool
samekeys(List *keys1, List *keys2)
{
bool allmember = true;
List *key1,
*key2;
for (key1 = keys1, key2 = keys2; key1 != NIL && key2 != NIL;
key1 = lnext(key1), key2 = lnext(key2))
if (!member(lfirst(key1), lfirst(key2)))
allmember = false;
return false;
if ((length(keys2) >= length(keys1)) && allmember)
/* 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)
return true;
else
return false;