1 files changed, 41 insertions, 0 deletions
diff --git a/mysql-test/t/partition_range.test b/mysql-test/t/partition_range.test
index 4d011ddc468..f386fac4998 100644
--- a/mysql-test/t/partition_range.test
+++ b/mysql-test/t/partition_range.test
@@ -846,3 +846,44 @@ insert into t2 values(52, 20070322, 456, 'filler') ;
 select sum(count) from t2 ch where ch.defid in (50,52) and ch.day between 20070320 and 20070401 group by defid;
 drop table t1, t2;
 
+
+--echo #
+--echo # Bug#50939: Loose Index Scan unduly relies on engine to remember range 
+--echo # endpoints
+--echo #
+CREATE TABLE t1 (
+ a INT,
+ b INT,
+ KEY ( a, b )
+) PARTITION BY HASH (a) PARTITIONS 1;
+
+CREATE TABLE t2 (
+ a INT,
+ b INT,
+ KEY ( a, b )
+);
+
+INSERT INTO t1 VALUES (1, 1), (2, 2), (3, 3), (4, 4), (5, 5);
+
+INSERT INTO t1 SELECT a +  5, b +  5 FROM t1;
+INSERT INTO t1 SELECT a + 10, b + 10 FROM t1;
+INSERT INTO t1 SELECT a + 20, b + 20 FROM t1;
+INSERT INTO t1 SELECT a + 40, b + 40 FROM t1;
+
+INSERT INTO t2 SELECT * FROM t1;
+
+--echo # plans should be identical
+EXPLAIN SELECT a, MAX(b) FROM t1 WHERE a IN (10,100) GROUP BY a;
+EXPLAIN SELECT a, MAX(b) FROM t2 WHERE a IN (10,100) GROUP BY a;
+
+FLUSH status;
+SELECT a, MAX(b) FROM t1 WHERE a IN (10, 100) GROUP BY a;
+--echo # Should be no more than 4 reads.
+SHOW status LIKE 'handler_read_key';
+
+FLUSH status;
+SELECT a, MAX(b) FROM t2 WHERE a IN (10, 100) GROUP BY a;
+--echo # Should be no more than 4 reads.
+SHOW status LIKE 'handler_read_key';
+
+DROP TABLE t1, t2;