Mysql 空间索引未使用

Question

我正在寻找能够找到从点到点的近似匹配的行（假设在 20 米内）。它可以工作，但不使用索引。

我正在尝试利用此表上的空间索引，但它似乎没有被使用（解释命令给我“possible_keys”= null）。

以下内容：

• mysql 5.7.17

• 表：

  CREATE TABLE `geoDirections` (
     `id` int(11) NOT NULL,
     `from` point NOT NULL,
     `to` point NOT NULL,
  ) ENGINE=InnoDB;
  ALTER TABLE `geoDirections`
      ADD PRIMARY KEY (`id`),
      ADD SPATIAL KEY `from` (`from`),
      ADD SPATIAL KEY `to` (`to`);
  

• 大约插入了 1000000 行

我尝试了什么：

• 使用 ST_Contains

  EXPLAIN SELECT 
     g.`from`
  FROM 
      geoDirections g
  WHERE
      ST_Contains(ST_Buffer(
            ST_GeomFromText('POINT(-2.00751 48.6547)', 4326), (0.00001*20)), g.`from`) = 1 
      AND
          ST_Contains(ST_Buffer(
            ST_GeomFromText('POINT(-2.05757 48.6338)', 4326), (0.00001*20)), g.`to`) = 1 
  

给我

    | id  |  select_type  |  table  |  partitions  |  type  |  possible_keys  |  key  |  key_len  |  ref  |  rows  |  filtered  |  Extra       |
    | 1   |  SIMPLE       |  g      |     null     |  ALL   |     null        |  null |    null   |  null | 994867 |  100.00    |  Using where |

• 使用计算距离

  EXPLAIN SELECT
      X(g.`from`),Y(g.`from`), g.*, (
        6373 * acos (
        cos ( radians( -2.00751 ) )
        * cos( radians( X(g.`from`) ) )
        * cos( radians( Y(g.`from`) ) - radians( 48.6547  ) )
        + sin ( radians( -2.00751 ) )
        * sin( radians( X(g.`from`) ) )
      )
  ) AS distanceFrom
  FROM geoDirections g
  HAVING distanceFrom < 0.02
  

给我

    | id  |  select_type  |  table  |  partitions  |  type  |  possible_keys  |  key  |  key_len  |  ref  |  rows  |  filtered  |  Extra  |
    | 1   |  SIMPLE       |  g      |     null     |  ALL   |     null        |  null |    null   |  null | 994867 |  100.00    |  null   |

• 即使是简单的事情

  EXPLAIN SELECT
      X(g.`from`),Y(g.`from`), g.*
  FROM geoDirections g
  WHERE X(g.`from`) = -2.00751
  

给我

    | id  |  select_type  |  table  |  partitions  |  type  |  possible_keys  |  key  |  key_len  |  ref  |  rows  |  filtered  |  Extra       |
    | 1   |  SIMPLE       |  g      |     null     |  ALL   |     null        |  null |    null   |  null | 994867 |  100.00    |  Using where |

• 尝试将 InnoDb 转换为 MyIsam（作为不应该支持空间索引的旧 InnoDb 版本）

我错过了什么？

Answer 1

Bug #76384 Spatial index not used when checking return values explicitly.

试试：

mysql> DROP TABLE IF EXISTS `geoDirections`;
Query OK, 0 rows affected (0.00 sec)

mysql> CREATE TABLE `geoDirections` (
    ->    `id` INT(11) NOT NULL,
    ->    `from` POINT NOT NULL,
    ->    `to` POINT NOT NULL
    -> ) ENGINE=InnoDB;
Query OK, 0 rows affected (0.01 sec)

mysql> ALTER TABLE `geoDirections`
    ->     ADD PRIMARY KEY (`id`),
    ->     ADD SPATIAL INDEX (`from`),
    ->     ADD SPATIAL INDEX (`to`);
Query OK, 0 rows affected (0.00 sec)
Records: 0  Duplicates: 0  Warnings: 0

mysql> EXPLAIN SELECT `g`.`from`
    -> FROM `geoDirections` `g`
    -> WHERE
    ->       ST_Contains(ST_Buffer(
    ->           ST_GeomFromText('POINT(-2.00751 48.6547)', 4326), (0.00001 * 20)), `g`.`from`) 
    ->       AND
    ->       ST_Contains(ST_Buffer(
    ->           ST_GeomFromText('POINT(-2.05757 48.6338)', 4326), (0.00001 * 20)), `g`.`to`)\G
*************************** 1. row ***************************
           id: 1
  select_type: SIMPLE
        table: g
   partitions: NULL
         type: ALL
possible_keys: from,to
          key: NULL
      key_len: NULL
          ref: NULL
         rows: 1
     filtered: 100.00
        Extra: Using where
1 row in set, 1 warning (0.00 sec)