ST_DWithin以度为参数，而不是以米为单位，为什么?

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问题描述

ST_DWithin 文件说，第三个参数(距离)以米为单位.但是，当我执行一些查询时，似乎将第三个参数作为学位"?

The ST_DWithin document says , the third parameter(distance) is in meters. But when I execute some query , it seems it takes the 3rd parameter as 'degree' ?

这是我的简化表结构:

> \d+ theuser;
                         Table "public.theuser"
  Column  |          Type          | Modifiers | Storage  | Description
----------+------------------------+-----------+----------+-------------
 id       | bigint                 | not null  | plain    |
 point    | geometry               |           | main     |
Indexes:
    "theuser_pkey" PRIMARY KEY, btree (id)
    "point_index" gist (point)
Referenced by:
    ...
Has OIDs: no

所有点都以SRID = 4326存储.

All points are stored with SRID=4326.

这是查询:

> select * from theuser where ST_DWithin(point , ST_GeomFromText('POINT(120.9982 24.788)',4326) , 100 );

它将第三个参数(100)作为'degree'，因此它返回所有数据，我必须缩小到0.001才能找到附近的点.

It takes the 3rd parameter (100) as 'degree' , so it returns all data , I have to narrow down to 0.001 to find nearby points.

但是我如何直接将电表作为第三个参数(我不想进行电表/度数转换)?我的查询出了什么问题?为什么postgreSQL不能将其视为文档所说的计量器?

But how do I directly pass meters as 3rd parameter (I don't want to do meter/degree transformation ) ? What's wrong with my query ? why postgreSQL doesn't take it as meters as document says ?

环境:

> select version();
                                                  version
-----------------------------------------------------------------------------------------------------------
 PostgreSQL 8.4.9 on i486-pc-linux-gnu, compiled by GCC gcc-4.4.real (Ubuntu 4.4.3-4ubuntu5) 4.4.3, 32-bit

> SELECT postgis_lib_version();
 postgis_lib_version
---------------------
 1.4.0

如果是导致此问题的SRID，则哪个SRID直接使用表"作为单位? (我尝试过转换为SRID = 2163，但仍在度数上).

If it is the SRID that causes this problem , what SRID directly makes use of 'meter' as the unit ? (I tried transforming to SRID=2163 , but still in degree) Thanks.

meters

ST_DWithin以度为参数，而不是以米为单位，为什么?

问题描述

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