Mysql空间索引未使用

Question

我正在寻找能够找到近似匹配（假设在20米范围内）从给定点到点的行。它可以工作，但不使用索引。

我想利用这个表上的空间索引，但它似乎并没有被使用（解释命令给我“possible_keys”= null）。

下列要求：

• 的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`); 
  

• 以防万一百万行插入

我试了一下：

• 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 
  

使用计算出的距离使我

| 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 | 

• 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 | 

• 甚至一些如

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

简单给我

| 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 | 

• 试图转换的InnoDB在MyISAM（较旧版本的InnoDB应该wheren't支持空间索引）

我缺少什么？

Answer 1

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

尝试：

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)