从本地数据库逆向GeoCode

Question

We are using SQL Server 2008 web edition. We have a table named "tbl_geodata" which has address and latitude and longitude values. We also have a "History" table which has only latitude and longitude values including other information. What we need is like following...

We get a set of records based on a query from "History" (lat long values), say 5000 records

Now we are using the following formula to calculate address from the "tbl_geodata" for each row (5000 rows).

SELECT top 1 geo_street,geo_town,geo_country,( 3959 acos( cos( radians(History.lat) ) cos( radians( gps_latitude ) ) cos( radians( gps_longitude ) - radians(History.long) ) + sin( radians(History.lat) ) sin( radians( gps_latitude ) ) ) ) AS distance FROM tbl_geodata ORDER BY distance

Currently we are seeing high cpu utilisation and performance issue. Can anyone please suggest the improvement steps?

Answer 1

You need a spatial index. See CREATE SPATIAL INDEX , and Spatial Indexes overview . Spatial indexes were introduced in SQL Server 2008, and Web Edition should allow them.