zoukankan      html  css  js  c++  java
  • Creating Spatial Indexes(mysql 创建空间索引 The used table type doesn't support SPATIAL indexes)

    For MyISAM tables, MySQL can create spatial indexes using syntax similar to that for creating regular indexes, but extended with the SPATIAL keyword. Currently, columns in spatial indexes must be declared NOT NULL. The following examples demonstrate how to create spatial indexes:

    • With CREATE TABLE:

      CREATE TABLE geom (g GEOMETRY NOT NULL, SPATIAL INDEX(g)) ENGINE=MyISAM;
      
    • With ALTER TABLE:

      ALTER TABLE geom ADD SPATIAL INDEX(g);
      
    • With CREATE INDEX:

      CREATE SPATIAL INDEX sp_index ON geom (g);
      

    For MyISAM tables, SPATIAL INDEX creates an R-tree index. For storage engines that support nonspatial indexing of spatial columns, the engine creates a B-tree index. A B-tree index on spatial values will be useful for exact-value lookups, but not for range scans.

    For more information on indexing spatial columns, see Section 13.1.8, “CREATE INDEX Syntax”.

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

    Example: Suppose that a table geom contains more than 32,000 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> DESCRIBE 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
  • 相关阅读:
    UITableView多选全选
    iOS16进制设置颜色
    svg矢量图
    canvas 时钟案例
    canvas 方块旋转案例
    canvas万花筒案例
    swiper(轮播)组件
    canvas介绍(画布)
    scroll-view组件
    view组件
  • 原文地址:https://www.cnblogs.com/mfryf/p/3455276.html
Copyright © 2011-2022 走看看