Different result with different join_cache_level and/or join_cache options in maria-5.3-mwl128

Test case with varying optimizer_switch:

CREATE TABLE `C` (
  `pk` int(11) NOT NULL AUTO_INCREMENT,
  `col_int_key` int(11) NOT NULL,
  `col_varchar_key` varchar(1) NOT NULL,
  PRIMARY KEY (`pk`),
  KEY `col_int_key` (`col_int_key`),
  KEY `col_varchar_key` (`col_varchar_key`,`col_int_key`)
) ENGINE=MARIA AUTO_INCREMENT=21 DEFAULT CHARSET=latin1 PAGE_CHECKSUM=1;
INSERT INTO `C` VALUES (1,9,'x');
INSERT INTO `C` VALUES (2,5,'g');
INSERT INTO `C` VALUES (3,1,'o');
INSERT INTO `C` VALUES (4,0,'g');
INSERT INTO `C` VALUES (5,1,'v');
INSERT INTO `C` VALUES (6,190,'m');
INSERT INTO `C` VALUES (7,6,'x');
INSERT INTO `C` VALUES (8,3,'c');
INSERT INTO `C` VALUES (9,4,'z');
INSERT INTO `C` VALUES (10,3,'i');
INSERT INTO `C` VALUES (11,186,'x');
INSERT INTO `C` VALUES (12,1,'g');
INSERT INTO `C` VALUES (13,8,'q');
INSERT INTO `C` VALUES (14,226,'m');
INSERT INTO `C` VALUES (15,133,'p');
INSERT INTO `C` VALUES (16,6,'e');
INSERT INTO `C` VALUES (17,3,'t');
INSERT INTO `C` VALUES (18,8,'j');
INSERT INTO `C` VALUES (19,5,'h');
INSERT INTO `C` VALUES (20,7,'w');

SELECT COUNT(table1 .`col_varchar_key`) FROM C table1 STRAIGHT_JOIN ( C table2 STRAIGHT_JOIN C table3 ON table3 .`col_varchar_key` = table2 .`col_varchar_key` AND table3 .`col_int_key` < table2 .`col_int_key` ) ON table3 .`pk` ;
EXPLAIN SELECT COUNT(table1 .`col_varchar_key`) FROM C table1 STRAIGHT_JOIN ( C table2 STRAIGHT_JOIN C table3 ON table3 .`col_varchar_key` = table2 .`col_varchar_key` AND table3 .`col_int_key` < table2 .`col_int_key` ) ON table3 .`pk` ;

SET SESSION join_cache_level = 6;
SELECT COUNT(table1 .`col_varchar_key`) FROM C table1 STRAIGHT_JOIN ( C table2 STRAIGHT_JOIN C table3 ON table3 .`col_varchar_key` = table2 .`col_varchar_key` AND table3 .`col_int_key` < table2 .`col_int_key` ) ON table3 .`pk` ;
EXPLAIN SELECT COUNT(table1 .`col_varchar_key`) FROM C table1 STRAIGHT_JOIN ( C table2 STRAIGHT_JOIN C table3 ON table3 .`col_varchar_key` = table2 .`col_varchar_key` AND table3 .`col_int_key` < table2 .`col_int_key` ) ON table3 .`pk` ;

SET SESSION optimizer_switch='join_cache_incremental=off';
SELECT COUNT(table1 .`col_varchar_key`) FROM C table1 STRAIGHT_JOIN ( C table2 STRAIGHT_JOIN C table3 ON table3 .`col_varchar_key` = table2 .`col_varchar_key` AND table3 .`col_int_key` < table2 .`col_int_key` ) ON table3 .`pk` ;
EXPLAIN SELECT COUNT(table1 .`col_varchar_key`) FROM C table1 STRAIGHT_JOIN ( C table2 STRAIGHT_JOIN C table3 ON table3 .`col_varchar_key` = table2 .`col_varchar_key` AND table3 .`col_int_key` < table2 .`col_int_key` ) ON table3 .`pk` ;

SET SESSION optimizer_switch='join_cache_bka=off';
SELECT COUNT(table1 .`col_varchar_key`) FROM C table1 STRAIGHT_JOIN ( C table2 STRAIGHT_JOIN C table3 ON table3 .`col_varchar_key` = table2 .`col_varchar_key` AND table3 .`col_int_key` < table2 .`col_int_key` ) ON table3 .`pk` ;
EXPLAIN SELECT COUNT(table1 .`col_varchar_key`) FROM C table1 STRAIGHT_JOIN ( C table2 STRAIGHT_JOIN C table3 ON table3 .`col_varchar_key` = table2 .`col_varchar_key` AND table3 .`col_int_key` < table2 .`col_int_key` ) ON table3 .`pk` ;

SET SESSION optimizer_switch='join_cache_h...

Test case with different join_cache_levels

CREATE TABLE `C` (
  `pk` int(11) NOT NULL AUTO_INCREMENT,
  `col_int_key` int(11) NOT NULL,
  `col_varchar_key` varchar(1) NOT NULL,
  PRIMARY KEY (`pk`),
  KEY `col_int_key` (`col_int_key`),
  KEY `col_varchar_key` (`col_varchar_key`,`col_int_key`)
) ENGINE=MARIA AUTO_INCREMENT=21 DEFAULT CHARSET=latin1 PAGE_CHECKSUM=1;
INSERT INTO `C` VALUES (1,9,'x');
INSERT INTO `C` VALUES (2,5,'g');
INSERT INTO `C` VALUES (3,1,'o');
INSERT INTO `C` VALUES (4,0,'g');
INSERT INTO `C` VALUES (5,1,'v');
INSERT INTO `C` VALUES (6,190,'m');
INSERT INTO `C` VALUES (7,6,'x');
INSERT INTO `C` VALUES (8,3,'c');
INSERT INTO `C` VALUES (9,4,'z');
INSERT INTO `C` VALUES (10,3,'i');
INSERT INTO `C` VALUES (11,186,'x');
INSERT INTO `C` VALUES (12,1,'g');
INSERT INTO `C` VALUES (13,8,'q');
INSERT INTO `C` VALUES (14,226,'m');
INSERT INTO `C` VALUES (15,133,'p');
INSERT INTO `C` VALUES (16,6,'e');
INSERT INTO `C` VALUES (17,3,'t');
INSERT INTO `C` VALUES (18,8,'j');
INSERT INTO `C` VALUES (19,5,'h');
INSERT INTO `C` VALUES (20,7,'w');

SELECT COUNT(table1 .`col_varchar_key`) FROM C table1 STRAIGHT_JOIN ( C table2 STRAIGHT_JOIN C table3 ON table3 .`col_varchar_key` = table2 .`col_varchar_key` AND table3 .`col_int_key` < table2 .`col_int_key` ) ON table3 .`pk` ;
EXPLAIN SELECT COUNT(table1 .`col_varchar_key`) FROM C table1 STRAIGHT_JOIN ( C table2 STRAIGHT_JOIN C table3 ON table3 .`col_varchar_key` = table2 .`col_varchar_key` AND table3 .`col_int_key` < table2 .`col_int_key` ) ON table3 .`pk` ;

SET SESSION join_cache_level = 1;
SELECT COUNT(table1 .`col_varchar_key`) FROM C table1 STRAIGHT_JOIN ( C table2 STRAIGHT_JOIN C table3 ON table3 .`col_varchar_key` = table2 .`col_varchar_key` AND table3 .`col_int_key` < table2 .`col_int_key` ) ON table3 .`pk` ;
EXPLAIN SELECT COUNT(table1 .`col_varchar_key`) FROM C table1 STRAIGHT_JOIN ( C table2 STRAIGHT_JOIN C table3 ON table3 .`col_varchar_key` = table2 .`col_varchar_key` AND table3 .`col_int_key` < table2 .`col_int_key` ) ON table3 .`pk` ;

SET SESSION join_cache_level = 2;
SELECT COUNT(table1 .`col_varchar_key`) FROM C table1 STRAIGHT_JOIN ( C table2 STRAIGHT_JOIN C table3 ON table3 .`col_varchar_key` = table2 .`col_varchar_key` AND table3 .`col_int_key` < table2 .`col_int_key` ) ON table3 .`pk` ;
EXPLAIN SELECT COUNT(table1 .`col_varchar_key`) FROM C table1 STRAIGHT_JOIN ( C table2 STRAIGHT_JOIN C table3 ON table3 .`col_varchar_key` = table2 .`col_varchar_key` AND table3 .`col_int_key` < table2 .`col_int_key` ) ON table3 .`pk` ;

SET SESSION join_cache_level = 3;
SELECT COUNT(table1 .`col_varchar_key`) FROM C table1 STRAIGHT_JOIN ( C table2 STRAIGHT_JOIN C table3 ON table3 .`col_varchar_key` = table2 .`col_varchar_key` AND table3 .`col_int_key` < table2 .`col_int_key` ) ON table3 .`pk` ;
EXPLAIN SELECT COUNT(table1 .`col_varchar_key`) FROM C table1 STRAIGHT_JOIN ( C table2 STRAIGHT_JOIN C table3 ON table3 .`col_varchar_key` = table2 .`col_varchar_key` AND table3 .`col_int_key` < table2 .`col_int_key` ) ON table3 .`pk` ;

SET SESSION join_cache_level = 4;
SELECT COUNT(table1 .`col_varchar_key`) FROM C t...

The problem is reproducible for the 5.3 tree.
The fix has been pushed into this tree.