11.6.1 Creating Spatial Indexes

MySQL can create spatial indexes using syntax similar to that for creating regular indexes, but extended with the SPATIAL keyword. Spatial columns that are indexed currently must be declared NOT NULL. The following examples demonstrate how to create spatial indexes.

• With CREATE TABLE:

  mysql> CREATE TABLE geom (g GEOMETRY NOT NULL, SPATIAL INDEX(g));
  

• With ALTER TABLE:

  mysql> ALTER TABLE geom ADD SPATIAL INDEX(g);
  

• With CREATE INDEX:

  mysql> CREATE SPATIAL INDEX sp_index ON geom (g);
  

To drop spatial indexes, use ALTER TABLE or DROP INDEX:

• With ALTER TABLE:

  mysql> ALTER TABLE geom DROP INDEX g;
  

• With DROP INDEX:

  mysql> DROP INDEX sp_index ON geom;
  

Example: Suppose that a table geom contains more than 32000 geometries, which are stored in the column g of type GEOMETRY. The table also has an AUTO_INCREMENT column fid for storing object ID values.

mysql> SHOW FIELDS FROM geom;
+-------+----------+------+-----+---------+----------------+
| Field | Type     | Null | Key | Default | Extra          |
+-------+----------+------+-----+---------+----------------+
| fid   | int(11)  |      | PRI | NULL    | auto_increment |
| g     | geometry |      |     |         |                |
+-------+----------+------+-----+---------+----------------+
2 rows in set (0.00 sec)

mysql> SELECT COUNT(*) FROM geom;
+----------+
| count(*) |
+----------+
|    32376 |
+----------+
1 row in set (0.00 sec)

To add a spatial index on the column g, use this statement:

mysql> ALTER TABLE geom ADD SPATIAL INDEX(g);
Query OK, 32376 rows affected (4.05 sec)
Records: 32376  Duplicates: 0  Warnings: 0

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