MDEV-12580 Wrong query result in join when using an index (Version > "10.2.3")

JOIN_TAB::remove_redundant_bnl_scan_conds() removes select_cond
from a JOIN_TAB if join cache is enabled, and tab->cache_select->cond
is the equal to tab->select_cond.

But after 8d99166c the code to initialize join cache was moved
to happen much later than JOIN_TAB::remove_redundant_bnl_scan_conds(),
and that code might, under certain conditions, revert to *not* using
join cache (set_join_cache_denial()).

If JOIN_TAB::remove_redundant_bnl_scan_conds() removes the WHERE
condition from the JOIN_TAB and later set_join_cache_denial() disables
join cache, we end up with no WHERE condition at all.

Fix: move JOIN_TAB::remove_redundant_bnl_scan_conds() to happen
after all possible set_join_cache_denial() calls.

mysql-test/r/join_cache.result

@@ -5949,4 +5949,13 @@ id	select_type	table	type	possible_keys	key	key_len	ref	rows	Extra
 1	SIMPLE	PROFILING	ALL	NULL	NULL	NULL	NULL	NULL	Using where
 1	SIMPLE	user	hash_ALL	NULL	#hash#$hj	1	information_schema.PROFILING.PAGE_FAULTS_MINOR	4	Using where; Using join buffer (flat, BNLH join)
 set join_cache_level=default;
+create table t1 (c1 date not null, key (c1)) engine=innodb;
+insert t1 values ('2017-12-27');
+create table t2 (pk int, f1 int, f2 int);
+insert t2 values (4,1,1), (6,1,1);
+set join_buffer_size = 222222208;
+select f2 from t2,t1 where f2 = 0;
+f2
+drop table t1, t2;
+set join_buffer_size = default;
 set @@optimizer_switch=@save_optimizer_switch;

mysql-test/r/limit_rows_examined.result

@@ -749,22 +749,24 @@ FROM t1, t2 AS alias2, t2 AS alias3
 WHERE alias3.c IN ( SELECT 1 UNION SELECT 6 ) 
 GROUP BY field1, field2, field3, field4, field5
 LIMIT ROWS EXAMINED 120;
-ERROR HY000: Sort aborted: 
+field1	field2	field3	field4	field5
+Warnings:
+Warning	1931	Query execution was interrupted. The query examined at least 121 rows, which exceeds LIMIT ROWS EXAMINED (120). The query result may be incomplete
 SHOW STATUS LIKE 'Handler_read%';
 Variable_name	Value
 Handler_read_first	1
-Handler_read_key	5
+Handler_read_key	4
 Handler_read_last	0
-Handler_read_next	7
+Handler_read_next	4
 Handler_read_prev	0
 Handler_read_retry	0
 Handler_read_rnd	0
 Handler_read_rnd_deleted	0
-Handler_read_rnd_next	38
+Handler_read_rnd_next	46
 SHOW STATUS LIKE 'Handler_tmp%';
 Variable_name	Value
 Handler_tmp_update	0
-Handler_tmp_write	70
+Handler_tmp_write	66
 FLUSH STATUS;
 SELECT a AS field1, alias2.d AS field2, alias2.f AS field3, alias2.e AS field4, b AS field5
 FROM t1, t2 AS alias2, t2 AS alias3 
@@ -772,20 +774,20 @@ WHERE alias3.c IN ( SELECT 1 UNION SELECT 6 )
 GROUP BY field1, field2, field3, field4, field5
 LIMIT ROWS EXAMINED 124;
 field1	field2	field3	field4	field5
-00:21:38	06:07:10	a	2007-06-08 04:35:26	2007-05-28 00:00:00
 Warnings:
 Warning	1931	Query execution was interrupted. The query examined at least 125 rows, which exceeds LIMIT ROWS EXAMINED (124). The query result may be incomplete
+Warning	1931	Query execution was interrupted. The query examined at least 127 rows, which exceeds LIMIT ROWS EXAMINED (124). The query result may be incomplete
 SHOW STATUS LIKE 'Handler_read%';
 Variable_name	Value
 Handler_read_first	1
-Handler_read_key	5
+Handler_read_key	4
 Handler_read_last	0
-Handler_read_next	7
+Handler_read_next	4
 Handler_read_prev	0
 Handler_read_retry	0
-Handler_read_rnd	2
-Handler_read_rnd_deleted	1
-Handler_read_rnd_next	39
+Handler_read_rnd	0
+Handler_read_rnd_deleted	0
+Handler_read_rnd_next	48
 SHOW STATUS LIKE 'Handler_tmp%';
 Variable_name	Value
 Handler_tmp_update	0

mysql-test/t/join_cache.test

@@ -3900,6 +3900,18 @@ SELECT * FROM INFORMATION_SCHEMA.PROFILING, mysql.user WHERE password_expired =
 
 set join_cache_level=default;
 
+#
+# MDEV-12580 Wrong query result in join when using an index (Version > "10.2.3")
+#
+create table t1 (c1 date not null, key (c1)) engine=innodb;
+insert t1 values ('2017-12-27');
+create table t2 (pk int, f1 int, f2 int);
+insert t2 values (4,1,1), (6,1,1);
+set join_buffer_size = 222222208;
+select f2 from t2,t1 where f2 = 0;
+drop table t1, t2;
+set join_buffer_size = default;
+
 # The following command must be the last one the file 
 # this must be the last command in the file
 set @@optimizer_switch=@save_optimizer_switch;

mysql-test/t/limit_rows_examined.test

@@ -489,7 +489,6 @@ GROUP BY field1, field2, field3, field4, field5
 LIMIT ROWS EXAMINED 120;
 
 FLUSH STATUS;
---error 1028
 SELECT a AS field1, alias2.d AS field2, alias2.f AS field3, alias2.e AS field4, b AS field5
 FROM t1, t2 AS alias2, t2 AS alias3 
 WHERE alias3.c IN ( SELECT 1 UNION SELECT 6 ) 

sql/sql_select.cc

@@ -1138,6 +1138,8 @@ int JOIN::init_join_caches()
     }
     if (tab->cache && tab->cache->init(select_options & SELECT_DESCRIBE))
       revise_cache_usage(tab);
+    else
+      tab->remove_redundant_bnl_scan_conds();
   }
   return 0;
 }
@@ -11161,8 +11163,8 @@ void JOIN_TAB::remove_redundant_bnl_scan_conds()
     select->cond is not processed separately. This method assumes it is always
     the same as select_cond.
   */
-  DBUG_ASSERT(!select || !select->cond ||
-              (select->cond == select_cond));
+  if (select && select->cond != select_cond)
+    return;
 
   if (is_cond_and(select_cond))
   {
@@ -11472,7 +11474,6 @@ make_join_readinfo(JOIN *join, ulonglong options, uint no_jbuf_after)
       /* purecov: end */
     }
 
-    tab->remove_redundant_bnl_scan_conds();
     DBUG_EXECUTE("where",
                  char buff[256];
                  String str(buff,sizeof(buff),system_charset_info);