Range in form tbl.key >= const doesn't work in reverse column family

[spetrunia]

This is a continuation of issue #16.

Run this

create table t0 (a int);
insert into t0 values (0),(1),(2),(3),(4),(5),(6),(7),(8),(9);
create table t1(a int);
insert into t1 select A.a + B.a* 10 + C.a * 100 from t0 A, t0 B, t0 C;

create table t2 (
  pk int not null,
  a  int not null,
  b  int not null,
  primary key(pk),
  key(a) comment 'rev:cf1'
) engine=rocksdb;
insert into t2 select A.a, FLOOR(A.a/10), A.a from t1 A;

The problem query:

MySQL [test]> explain select * from t2 force index (a) where a>=0;
+----+-------------+-------+-------+---------------+------+---------+------+------+-------------+
| id | select_type | table | type  | possible_keys | key  | key_len | ref  | rows | Extra       |
+----+-------------+-------+-------+---------------+------+---------+------+------+-------------+
|  1 | SIMPLE      | t2    | range | a             | a    | 4       | NULL |   10 | Using where |
+----+-------------+-------+-------+---------------+------+---------+------+------+-------------+
1 row in set (0.01 sec)

MySQL [test]> select * from t2 force index (a) where a>=0;
Empty set (0.01 sec)

The correct result is

MySQL [test]> select * from t2 ignore index (a) where a>=0;
+-----+----+-----+
| pk  | a  | b   |
+-----+----+-----+
|   0 |  0 |   0 |
|   1 |  0 |   1 |
|   2 |  0 |   2 |
|   3 |  0 |   3 |
|   4 |  0 |   4 |
|   5 |  0 |   5 |
.. (total 1000 rows)

[spetrunia]

https://reviews.facebook.net/D34647