常量字符串前声明了 binary 后，会在列上加 cast，导致无法抽取 query range

code = BINARY 'XS2504'

CREATE TABLE test (code VARCHAR(20));
CREATE INDEX idx_code ON test(code);

obclient [test]> explain SELECT * FROM test WHERE  code = BINARY 'XS2504';
+----------------------------------------------------------------------------------------------------------------------+
| Query Plan                                                                                                           |
+----------------------------------------------------------------------------------------------------------------------+
| =====================================================                                                                |
| |ID|OPERATOR             |NAME|EST.ROWS|EST.TIME(us)|                                                                |
| -----------------------------------------------------                                                                |
| |0 |EXCHANGE IN REMOTE   |    |1       |5           |                                                                |
| |1 |└─EXCHANGE OUT REMOTE|    |1       |5           |                                                                |
| |2 |  └─TABLE FULL SCAN  |test|1       |4           |                                                                |
| =====================================================                                                                |
| Outputs & filters:                                                                                                   |
| -------------------------------------                                                                                |
|   0 - output([test.code]), filter(nil)                                                                               |
|   1 - output([test.code]), filter(nil)                                                                               |
|   2 - output([test.code]), filter([cast(test.code, VARCHAR(1048576)) = cast('XS2504', VARCHAR(1048576))]), rowset=16 |
|       access([test.code]), partitions(p0)                                                                            |
|       is_index_back=false, is_global_index=false, filter_before_indexback[false],                                    |
|       range_key([test.__pk_increment]), range(MIN ; MAX)always true                                                  |
+----------------------------------------------------------------------------------------------------------------------+
15 rows in set (0.013 sec)