"fast_order_limit" breaks results with offset（Mroongaの同値でのfast_order_limitでoffsetの結果が壊れる）

[piroor]

原因および対処法の案： https://ja.osdn.net/projects/groonga/lists/archive/dev/2017-January/004255.html

[kenhys]

まだ状況は同じ。MySQL 5.7.27+Mroonga 9.05

MySQL [test]> CREATE TABLE m_fol_test (
    ->   id int primary key auto_increment,
    ->   title varchar(255) not null,
    ->   price int unsigned not null,
    ->   FULLTEXT KEY(title) COMMENT 'tokenizer "TokenBigramSplitSymbolAlphaDigit"',
    ->   KEY (price)
    -> ) ENGINE=Mroonga;
Query OK, 0 rows affected (0.037 sec)

MySQL [test]> INSERT INTO m_fol_test (title, price) VALUES
    -> ('mroonga01', 500),
    -> ('mroonga02', 500),
    -> ('mroonga03', 500),
    -> ('mroonga04', 500),
    -> ('mroonga05', 500),
    -> ('mroonga06', 500),
    -> ('mroonga07', 500),
    -> ('mroonga08', 500),
    -> ('mroonga09', 500),
    -> ('mroonga10', 500);
Query OK, 10 rows affected (0.004 sec)
Records: 10  Duplicates: 0  Warnings: 0

MySQL [test]> select id from m_fol_test where match(title) against('+mroonga' IN BOOLEAN MODE) order by price asc limit 0, 10; 
+----+
| id |
+----+
|  1 |
|  2 |
|  3 |
|  4 |
|  5 |
|  6 |
|  7 |
|  8 |
|  9 |
| 10 |
+----+
10 rows in set (0.042 sec)

MySQL [test]> select id from m_fol_test where match(title) against('+mroonga' IN BOOLEAN MODE) order by price asc limit 0, 5;
+----+
| id |
+----+
|  1 |
|  3 |
|  4 |
|  5 |
| 10 |
+----+
5 rows in set (0.003 sec)

MySQL [test]> select id from m_fol_test where match(title) against('+mroonga' IN BOOLEAN MODE) order by price asc limit 5, 5;
+----+
| id |
+----+
|  6 |
|  7 |
|  8 |
|  9 |
| 10 |
+----+
5 rows in set (0.003 sec)

MySQL [test]> SHOW STATUS LIKE 'Mroonga_fast_order_limit';
+--------------------------+-------+
| Variable_name            | Value |
+--------------------------+-------+
| Mroonga_fast_order_limit | 3     |
+--------------------------+-------+
1 row in set (0.003 sec)