在加入与范围的标准表的MySQL优化(MySQL optimization on join tabl

我将通过使用在一个表中的范围中的另一表中的单个位置（由两列表示）加入两个表。

但是，性能是太慢了，大约是20分钟。我曾尝试添加索引表或更改查询。但表现依然不佳。

所以，我要求接合速度的优化。

以下是查询到MySQL。

mysql> SELECT `inVar`.chrom, `inVar`.pos, `openChrom_K562`.score
    -> FROM `inVar`
    -> LEFT JOIN `openChrom_K562`
    -> ON (
    -> `inVar`.chrom=`openChrom_K562`.chrom AND
    -> `inVar`.pos BETWEEN `openChrom_K562`.chromStart AND `openChrom_K562`.chromEnd
    -> );

inVar和openChrom_K562是我使用的表。

inVar存储每行中的单个位置。

openChrom_K562存储由所指示的范围信息chromStart和chromEnd 。

inVar包含57902行和openChrom_K562各自有137373行。

上表中的字段。

mysql> DESCRIBE inVar;
+-------+-------------+------+-----+---------+-------+
| Field | Type        | Null | Key | Default | Extra |
+-------+-------------+------+-----+---------+-------+
| chrom | varchar(31) | NO   | PRI | NULL    |       |
| pos   | int(10)     | NO   | PRI | NULL    |       |
+-------+-------------+------+-----+---------+-------+

mysql> DESCRIBE openChrom_K562;
+------------+-------------+------+-----+---------+-------+
| Field      | Type        | Null | Key | Default | Extra |
+------------+-------------+------+-----+---------+-------+
| chrom      | varchar(31) | NO   | MUL | NULL    |       |
| chromStart | int(10)     | NO   | MUL | NULL    |       |
| chromEnd   | int(10)     | NO   |     | NULL    |       |
| score      | int(10)     | NO   |     | NULL    |       |
+------------+-------------+------+-----+---------+-------+

建索引表中

mysql> SHOW INDEX FROM inVar;
+-------+------------+----------+--------------+-------------+-----------+-------------+----------+--------+------+------------+---------+
| Table | Non_unique | Key_name | Seq_in_index | Column_name | Collation | Cardinality | Sub_part | Packed | Null | Index_type | Comment |
+-------+------------+----------+--------------+-------------+-----------+-------------+----------+--------+------+------------+---------+
| inVar |          0 | PRIMARY  |            1 | chrom       | A         |        NULL |     NULL | NULL   |      | BTREE      |         |
| inVar |          0 | PRIMARY  |            2 | pos         | A         |       57902 |     NULL | NULL   |      | BTREE      |         |
+-------+------------+----------+--------------+-------------+-----------+-------------+----------+--------+------+------------+---------+

mysql> SHOW INDEX FROM openChrom_K562;
+----------------+------------+-------------+--------------+-------------+-----------+-------------+----------+--------+------+------------+---------+
| Table          | Non_unique | Key_name    | Seq_in_index | Column_name | Collation | Cardinality | Sub_part | Packed | Null | Index_type | Comment |
+----------------+------------+-------------+--------------+-------------+-----------+-------------+----------+--------+------+------------+---------+
| openChrom_K562 |          1 | start_end   |            1 | chromStart  | A         |      137373 |     NULL | NULL   |      | BTREE      |         |
| openChrom_K562 |          1 | start_end   |            2 | chromEnd    | A         |      137373 |     NULL | NULL   |      | BTREE      |         |
| openChrom_K562 |          1 | chrom_only  |            1 | chrom       | A         |          22 |     NULL | NULL   |      | BTREE      |         |
| openChrom_K562 |          1 | chrom_start |            1 | chrom       | A         |          22 |     NULL | NULL   |      | BTREE      |         |
| openChrom_K562 |          1 | chrom_start |            2 | chromStart  | A         |      137373 |     NULL | NULL   |      | BTREE      |         |
| openChrom_K562 |          1 | chrom_end   |            1 | chrom       | A         |          22 |     NULL | NULL   |      | BTREE      |         |
| openChrom_K562 |          1 | chrom_end   |            2 | chromEnd    | A         |      137373 |     NULL | NULL   |      | BTREE      |         |
+----------------+------------+-------------+--------------+-------------+-----------+-------------+----------+--------+------+------------+---------+

MySQL的执行计划

mysql> EXPLAIN SELECT `inVar`.chrom, `inVar`.pos, score  FROM `inVar`  LEFT JOIN `openChrom_K562`  ON ( inVar.chrom=openChrom_K562.chrom AND  `inVar`.pos BETWEEN chromStart AND chromEnd );
+----+-------------+----------------+-------+--------------------------------------------+------------+---------+-----------------+-------+-------------+
| id | select_type | table          | type  | possible_keys                              | key        | key_len | ref             | rows  | Extra       |
+----+-------------+----------------+-------+--------------------------------------------+------------+---------+-----------------+-------+-------------+
|  1 | SIMPLE      | inVar          | index | NULL                                       | PRIMARY    | 37      | NULL            | 57902 | Using index |
|  1 | SIMPLE      | openChrom_K562 | ref   | start_end,chrom_only,chrom_start,chrom_end | chrom_only | 33      | tmp.inVar.chrom |  5973 |             |
+----+-------------+----------------+-------+--------------------------------------------+------------+---------+-----------------+-------+-------------+

现在看来，这只能通过寻找优化chrom在两个表。然后做蛮力表中比较。

有没有办法做到像索引上的位置进一步优化？

（这是我第一次发布的问题，遗憾的发布质量较差。）

chrom_only很可能是一个坏的索引选择你的加入，你只有CHROM 22个值。

如果我已经解释这一权利的查询应该是如果使用的更快start_end

SELECT `inVar`.chrom, `inVar`.pos, `openChrom_K562`.score
FROM `inVar`
LEFT JOIN `openChrom_K562`
USE INDEX (`start_end`)
ON (
`inVar`.chrom=`openChrom_K562`.chrom AND
`inVar`.pos BETWEEN `openChrom_K562`.chromStart AND `openChrom_K562`.chromEnd
)