Fixed LP bug#694092.

In some cases the function make_cond_for_index() was mistaken
when detecting index only pushdown conditions for a table: 
a pushdown condition that was not index only could be marked
as such.
It happened because the procedure erroneously used the markers
for index only conditions that remained from the calls of
this function that extracted the index conditions for other 
tables.
Fixed by erasing index only markers as soon as they are need
anymore.

mysql-test/r/join_cache.result

@@ -6056,4 +6056,39 @@ a4	b5
 SET SESSION optimizer_switch = 'outer_join_with_cache=off';
 SET SESSION join_cache_level = DEFAULT;
 DROP TABLE t1,t2,t3,t4,t5;
+#
+# Bug #694092: incorrect detection of index only pushdown conditions
+#
+CREATE TABLE t1 (
+f1 varchar(10), f3 int(11), PRIMARY KEY (f3)
+);
+INSERT INTO t1 VALUES ('y',1),('or',5);
+CREATE TABLE t2 (
+f3 int(11), f2 varchar(1024), f4 varchar(10), PRIMARY KEY (f3)
+);
+INSERT INTO t2 VALUES (6,'RPOYT','y'),(10,'JINQE','m');
+SET SESSION join_cache_level = 1;
+SET SESSION optimizer_switch = 'index_condition_pushdown=off';
+EXPLAIN
+SELECT * FROM t1,t2
+WHERE t1.f1 = t2.f4 AND (t1.f3 = 1 AND t2.f3 = 4 OR t1.f3 = 2 AND t2.f3 = 6);
+id	select_type	table	type	possible_keys	key	key_len	ref	rows	Extra
+1	SIMPLE	t1	range	PRIMARY	PRIMARY	4	NULL	2	Using where; Using MRR
+1	SIMPLE	t2	range	PRIMARY	PRIMARY	4	NULL	2	Using where; Using MRR; Using join buffer (flat, BNL join)
+SELECT * FROM t1,t2
+WHERE t1.f1 = t2.f4 AND (t1.f3 = 1 AND t2.f3 = 4 OR t1.f3 = 2 AND t2.f3 = 6);
+f1	f3	f3	f2	f4
+SET SESSION optimizer_switch = 'index_condition_pushdown=on';
+EXPLAIN
+SELECT * FROM t1,t2
+WHERE t1.f1 = t2.f4 AND (t1.f3 = 1 AND t2.f3 = 4 OR t1.f3 = 2 AND t2.f3 = 6);
+id	select_type	table	type	possible_keys	key	key_len	ref	rows	Extra
+1	SIMPLE	t1	range	PRIMARY	PRIMARY	4	NULL	2	Using index condition; Using MRR
+1	SIMPLE	t2	range	PRIMARY	PRIMARY	4	NULL	2	Using index condition; Using where; Using MRR; Using join buffer (flat, BNL join)
+SELECT * FROM t1,t2
+WHERE t1.f1 = t2.f4 AND (t1.f3 = 1 AND t2.f3 = 4 OR t1.f3 = 2 AND t2.f3 = 6);
+f1	f3	f3	f2	f4
+SET SESSION join_cache_level = DEFAULT;
+SET SESSION optimizer_switch = DEFAULT;
+DROP TABLE t1,t2;
 set @@optimizer_switch=@save_optimizer_switch;

mysql-test/t/join_cache.test

@@ -2700,5 +2700,40 @@ SET SESSION join_cache_level = DEFAULT;
 
 DROP TABLE t1,t2,t3,t4,t5;
 
+--echo #
+--echo # Bug #694092: incorrect detection of index only pushdown conditions
+--echo #
+
+CREATE TABLE t1 (
+  f1 varchar(10), f3 int(11), PRIMARY KEY (f3)
+);
+INSERT INTO t1 VALUES ('y',1),('or',5);
+
+CREATE TABLE t2 (
+ f3 int(11), f2 varchar(1024), f4 varchar(10), PRIMARY KEY (f3)
+);
+INSERT INTO t2 VALUES (6,'RPOYT','y'),(10,'JINQE','m');
+
+SET SESSION join_cache_level = 1;
+
+SET SESSION optimizer_switch = 'index_condition_pushdown=off';
+EXPLAIN
+SELECT * FROM t1,t2
+  WHERE t1.f1 = t2.f4 AND (t1.f3 = 1 AND t2.f3 = 4 OR t1.f3 = 2 AND t2.f3 = 6);
+SELECT * FROM t1,t2
+  WHERE t1.f1 = t2.f4 AND (t1.f3 = 1 AND t2.f3 = 4 OR t1.f3 = 2 AND t2.f3 = 6);
+
+SET SESSION optimizer_switch = 'index_condition_pushdown=on';
+EXPLAIN
+SELECT * FROM t1,t2
+  WHERE t1.f1 = t2.f4 AND (t1.f3 = 1 AND t2.f3 = 4 OR t1.f3 = 2 AND t2.f3 = 6);
+SELECT * FROM t1,t2
+  WHERE t1.f1 = t2.f4 AND (t1.f3 = 1 AND t2.f3 = 4 OR t1.f3 = 2 AND t2.f3 = 6);
+
+SET SESSION join_cache_level = DEFAULT;
+SET SESSION optimizer_switch = DEFAULT;
+
+DROP TABLE t1,t2;
+
 # this must be the last command in the file
 set @@optimizer_switch=@save_optimizer_switch;

sql/opt_index_cond_pushdown.cc

@@ -155,7 +155,11 @@ Item *make_cond_for_index(Item *cond, TABLE *table, uint keyno,
 	  new_cond->argument_list()->push_back(fix);
           used_tables|= fix->used_tables();
         }
-        n_marked += test(item->marker == ICP_COND_USES_INDEX_ONLY);
+        if (test(item->marker == ICP_COND_USES_INDEX_ONLY))
+        {
+          n_marked++;
+          item->marker= 0;
+        } 
       }
       if (n_marked ==((Item_cond*)cond)->argument_list()->elements)
         cond->marker= ICP_COND_USES_INDEX_ONLY;
@@ -184,7 +188,11 @@ Item *make_cond_for_index(Item *cond, TABLE *table, uint keyno,
 	if (!fix)
 	  return (COND*) 0;
 	new_cond->argument_list()->push_back(fix);
-        n_marked += test(item->marker == ICP_COND_USES_INDEX_ONLY);
+        if (test(item->marker == ICP_COND_USES_INDEX_ONLY))
+        {
+          n_marked++;
+          item->marker= 0;
+        } 
       }
       if (n_marked ==((Item_cond*)cond)->argument_list()->elements)
         cond->marker= ICP_COND_USES_INDEX_ONLY;