[英]Which PostGIS SRID is most efficient for a spatial index?
I have a PostGIS-enabled database with a table called locations
that stores latitude-longitude points (SRID 4326) in a column called coordinates
. 我有一个支持PostGIS的数据库,其中有一个名为
locations
的表,它将纬度 - 经度点(SRID 4326)存储在名为coordinates
的列中。 However, all of my lookups on that table convert the points to a metric projection (SRID 26986) mainly to do distance comparisons. 但是,我在该表上的所有查找都将点转换为度量投影(SRID 26986),主要用于进行距离比较。
Obviously I'd like to create a spatial index on the coordinates
column. 显然我想在
coordinates
列上创建一个空间索引。 My question is, which is the best (most computationally efficient) SRID to use in the coordinates
spatial index in this case? 我的问题是,在这种情况下,哪个是
coordinates
空间索引中使用的最佳( 计算效率最高)SRID?
I can either index using SRID 4326... 我可以使用SRID 4326进行索引...
CREATE INDEX locations_coordinates_gist
ON locations
USING GIST (coordinates);
Or using SRID 26986... 或者使用SRID 26986 ......
CREATE INDEX locations_coordinates_gist
ON locations
USING GIST (ST_Transform(coordinates, 26986));
I discovered this helpful information reading the PostGIS documentation on the ST_Transform
function... 我发现了这个有用的信息,在
ST_Transform
函数上阅读PostGIS文档......
If using more than one transformation, it is useful to have a functional index on the commonly used transformations to take advantage of index usage.
如果使用多个转换,则在常用转换上使用功能索引以利用索引使用是很有用的。
So it seems the answer is, use both! 所以似乎答案是,使用两者! I have created two indices, one with each SRID.
我创建了两个索引,每个SRID一个。
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