BUG#30573: Ordered range scan over partitioned tables returns some rows twice

The problem: ha_partition::read_range_first() could return a record that is 
outside of the scanned range. If that record happened to be in the next 
subsequent range, it would satisfy the WHERE and appear in the output twice.
(we would get it the second time when scanning the next subsequent range)

Fix: 
Made ha_partition::read_range_first() check if the returned recod is within
the scanned range, like other read_range_first() implementations do.

mysql-test/r/partition_range.result

-drop table if exists t1;
+drop table if exists t1, t2;
 create table t1 (a int unsigned)
 partition by range (a)
 (partition pnull values less than (0),
@@ -709,3 +709,23 @@ WHERE (a >= '2004-07-01' AND a <= '2004-09-30') OR
 id	select_type	table	partitions	type	possible_keys	key	key_len	ref	rows	Extra
 1	SIMPLE	t1	p407,p408,p409,p507,p508,p509	ALL	NULL	NULL	NULL	NULL	18	Using where
 DROP TABLE t1;
+create table t1 (a int);
+insert into t1 values (0),(1),(2),(3),(4),(5),(6),(7),(8),(9);
+CREATE TABLE t2 (
+defid int(10) unsigned NOT NULL,
+day int(10) unsigned NOT NULL,
+count int(10) unsigned NOT NULL,
+filler char(200),
+KEY (defid,day)
+) 
+PARTITION BY RANGE (day) (
+PARTITION p7 VALUES LESS THAN (20070401) , 
+PARTITION p8 VALUES LESS THAN (20070501));
+insert into t2 select 20, 20070311, 1, 'filler' from t1 A, t1 B;
+insert into t2 select 20, 20070411, 1, 'filler' from t1 A, t1 B;
+insert into t2 values(52, 20070321, 123, 'filler') ;
+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;
+sum(count)
+579
+drop table t1, t2;

mysql-test/t/partition_range.test

@@ -6,7 +6,7 @@
 -- source include/have_partition.inc
 
 --disable_warnings
-drop table if exists t1;
+drop table if exists t1, t2;
 --enable_warnings
 
 #
@@ -757,3 +757,29 @@ DROP TABLE t1;
 #                       a = "C2345678901234567890";
 #select * from t1 where a = "12345678901234567890";
 #drop table t1;
+
+
+#
+# BUG#30573: get wrong result with "group by" on PARTITIONed table
+#
+create table t1 (a int);
+insert into t1 values (0),(1),(2),(3),(4),(5),(6),(7),(8),(9);
+CREATE TABLE t2 (
+  defid int(10) unsigned NOT NULL,
+  day int(10) unsigned NOT NULL,
+  count int(10) unsigned NOT NULL,
+  filler char(200),
+  KEY (defid,day)
+) 
+PARTITION BY RANGE (day) (
+  PARTITION p7 VALUES LESS THAN (20070401) , 
+  PARTITION p8 VALUES LESS THAN (20070501));
+
+insert into t2 select 20, 20070311, 1, 'filler' from t1 A, t1 B;
+insert into t2 select 20, 20070411, 1, 'filler' from t1 A, t1 B;
+insert into t2 values(52, 20070321, 123, 'filler') ;
+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;
+

sql/ha_partition.cc

@@ -3838,7 +3838,7 @@ int ha_partition::read_range_first(const key_range *start_key,
 			     start_key->key,
                              start_key->keypart_map, start_key->flag);
   }
-  DBUG_RETURN(error);
+  DBUG_RETURN (error? error: compare_key(end_range) <= 0 ? 0 : HA_ERR_END_OF_FILE);
 }