bk commit into 4.1 tree (gkodinov:1.2537) BUG#21019

[kgeorge]

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4.1 repository of kgeorge. When kgeorge does a push these changes will
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ChangeSet@stripped, 2006-07-24 18:33:08+03:00, gkodinov@stripped +3 -0
  Bug #21019: First result of SELECT COUNT(*) different than consecutive runs
   When optimizing conditions like 'a = <some_val> OR a IS NULL' so that they're
   united into a single condition on the key and checked together it must check
   which value is the NULL value in a correct way : not only using ->is_null but
   also check if the expression doesn't depend on tables.

  mysql-test/r/select.result@stripped, 2006-07-24 18:32:59+03:00, gkodinov@stripped +26 -0
    Bug #21019: First result of SELECT COUNT(*) different than consecutive runs
     - test case

  mysql-test/t/select.test@stripped, 2006-07-24 18:33:00+03:00, gkodinov@stripped +15 -0
    Bug #21019: First result of SELECT COUNT(*) different than consecutive runs
     - test case

  sql/sql_select.cc@stripped, 2006-07-24 18:33:01+03:00, gkodinov@stripped +1 -1
    Bug #21019: First result of SELECT COUNT(*) different than consecutive runs
     - check whether a value is null in the correct way.

# This is a BitKeeper patch.  What follows are the unified diffs for the
# set of deltas contained in the patch.  The rest of the patch, the part
# that BitKeeper cares about, is below these diffs.
# User:	gkodinov
# Host:	macbook.gmz
# Root:	/Users/kgeorge/mysql/work/B21019-4.1-opt

--- 1.460/sql/sql_select.cc	2006-07-24 18:33:21 +03:00
+++ 1.461/sql/sql_select.cc	2006-07-24 18:33:21 +03:00
@@ -2144,7 +2144,7 @@ merge_key_fields(KEY_FIELD *start,KEY_FI
 	  old->level= and_level;
 	  old->optimize= KEY_OPTIMIZE_REF_OR_NULL;
 	  /* Remember the NOT NULL value */
-	  if (old->val->is_null())
+	  if (!old->val->used_tables() && old->val->is_null())
 	    old->val= new_fields->val;
           /* The referred expression can be NULL: */ 
           old->null_rejecting= 0;

--- 1.75/mysql-test/r/select.result	2006-07-24 18:33:21 +03:00
+++ 1.76/mysql-test/r/select.result	2006-07-24 18:33:21 +03:00
@@ -2744,3 +2744,29 @@ SELECT i='1e+01',i=1e+01, i in (1e+01), 
 i='1e+01'	i=1e+01	i in (1e+01)	i in ('1e+01')
 0	1	1	1
 DROP TABLE t1;
+CREATE TABLE t1 (a int, b int);
+INSERT INTO t1 VALUES (1,1), (2,1), (4,10);
+CREATE TABLE t2 (a int PRIMARY KEY, b int, KEY b (b));
+INSERT INTO t2 VALUES (1,NULL), (2,10);
+ALTER TABLE t1 ENABLE KEYS;
+EXPLAIN SELECT STRAIGHT_JOIN SQL_NO_CACHE COUNT(*) FROM t2, t1 WHERE t1.b = t2.b OR t2.b
IS NULL;
+id	select_type	table	type	possible_keys	key	key_len	ref	rows	Extra
+1	SIMPLE	t2	index	b	b	5	NULL	2	Using index
+1	SIMPLE	t1	ALL	NULL	NULL	NULL	NULL	3	Using where
+SELECT STRAIGHT_JOIN SQL_NO_CACHE * FROM t2, t1 WHERE t1.b = t2.b OR t2.b IS NULL;
+a	b	a	b
+1	NULL	1	1
+1	NULL	2	1
+1	NULL	4	10
+2	10	4	10
+EXPLAIN SELECT STRAIGHT_JOIN SQL_NO_CACHE COUNT(*) FROM t2, t1 WHERE t1.b = t2.b OR t2.b
IS NULL;
+id	select_type	table	type	possible_keys	key	key_len	ref	rows	Extra
+1	SIMPLE	t2	index	b	b	5	NULL	2	Using index
+1	SIMPLE	t1	ALL	NULL	NULL	NULL	NULL	3	Using where
+SELECT STRAIGHT_JOIN SQL_NO_CACHE * FROM t2, t1 WHERE t1.b = t2.b OR t2.b IS NULL;
+a	b	a	b
+1	NULL	1	1
+1	NULL	2	1
+1	NULL	4	10
+2	10	4	10
+DROP TABLE IF EXISTS t1,t2;

--- 1.58/mysql-test/t/select.test	2006-07-24 18:33:21 +03:00
+++ 1.59/mysql-test/t/select.test	2006-07-24 18:33:21 +03:00
@@ -2297,4 +2297,19 @@ INSERT INTO t1 VALUES (10);
 SELECT i='1e+01',i=1e+01, i in (1e+01), i in ('1e+01') FROM t1;
 DROP TABLE t1;
 
+#
+# Bug #21019: First result of SELECT COUNT(*) different than consecutive runs
+#
+CREATE TABLE t1 (a int, b int);
+INSERT INTO t1 VALUES (1,1), (2,1), (4,10);
+
+CREATE TABLE t2 (a int PRIMARY KEY, b int, KEY b (b));
+INSERT INTO t2 VALUES (1,NULL), (2,10);
+ALTER TABLE t1 ENABLE KEYS;
+
+EXPLAIN SELECT STRAIGHT_JOIN SQL_NO_CACHE COUNT(*) FROM t2, t1 WHERE t1.b = t2.b OR t2.b
IS NULL;
+SELECT STRAIGHT_JOIN SQL_NO_CACHE * FROM t2, t1 WHERE t1.b = t2.b OR t2.b IS NULL;
+EXPLAIN SELECT STRAIGHT_JOIN SQL_NO_CACHE COUNT(*) FROM t2, t1 WHERE t1.b = t2.b OR t2.b
IS NULL;
+SELECT STRAIGHT_JOIN SQL_NO_CACHE * FROM t2, t1 WHERE t1.b = t2.b OR t2.b IS NULL;
+DROP TABLE IF EXISTS t1,t2;
 # End of 4.1 tests