Fix for bug#42944: partition not pruned correctly

Problem: we don't prune a LESS THAN partition if MAXVALUE is given and
given value is equal to a LESS THAN value.

Fix: prune partitions in such cases.

mysql-test/r/partition.result

@@ -1911,5 +1911,18 @@ select count(*) from t1;
 count(*)
 288
 drop table t1;
+#
+# Bug#42944: partition not pruned correctly
+#
+CREATE TABLE t1 (a int) PARTITION BY RANGE (a)
+(PARTITION p0 VALUES LESS THAN (100),
+PARTITION p1 VALUES LESS THAN (200),
+PARTITION p2 VALUES LESS THAN (300),
+PARTITION p3 VALUES LESS THAN MAXVALUE);
+INSERT INTO t1 VALUES (10), (100), (200), (300), (400);
+EXPLAIN PARTITIONS SELECT * FROM t1 WHERE a>=200;
+id	select_type	table	partitions	type	possible_keys	key	key_len	ref	rows	Extra
+1	SIMPLE	t1	p2,p3	ALL	NULL	NULL	NULL	NULL	3	Using where
+DROP TABLE t1;
 End of 5.1 tests
 SET @@global.general_log= @old_general_log;

mysql-test/t/partition.test

@@ -1922,6 +1922,19 @@ insert into t1 select s1 from t1 where s1=3;
 select count(*) from t1;
 drop table t1;
 
+
+--echo #
+--echo # Bug#42944: partition not pruned correctly
+--echo #
+CREATE TABLE t1 (a int) PARTITION BY RANGE (a)
+  (PARTITION p0 VALUES LESS THAN (100),
+   PARTITION p1 VALUES LESS THAN (200),
+   PARTITION p2 VALUES LESS THAN (300),
+   PARTITION p3 VALUES LESS THAN MAXVALUE);
+INSERT INTO t1 VALUES (10), (100), (200), (300), (400);
+EXPLAIN PARTITIONS SELECT * FROM t1 WHERE a>=200;
+DROP TABLE t1;
+
 --echo End of 5.1 tests
 
 

sql/sql_partition.cc

@@ -2937,7 +2937,8 @@ uint32 get_partition_id_range_for_endpoint(partition_info *part_info,
       the maximum value is in the current partition.
     */
     if (part_func_value > bound ||
-        (part_func_value == bound && !part_info->defined_max_value))
+        (part_func_value == bound &&
+         (!part_info->defined_max_value || loc_part_id < max_partition)))
       loc_part_id++;
   }
   else