Re: How many views... - Mailing list pgsql-general

From Holger Klawitter
Subject Re: How many views...
Date
Msg-id 200411290915.29686.lists@klawitter.de
Whole thread Raw
In response to Re: How many views...  ("Uwe C. Schroeder" <uwe@oss4u.com>)
List pgsql-general
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Hi,

> .... where sqrt(pow((lat1 - lat2),2) + pow((long1 - long2),2)) >= 50

I assume that you dont want to deal with distances > 1000km?!

> of the records that aren't in question anyways. How do you come to the
> lat/long values for the max difference? Is there a general formula for
> that?

You can problably resort to simplified formulas like this:

latitude: 1 degree ~~ 111km
longitude: 1 degree ~~ 111km * cos( reference latitude )

> (I hated math all my life ;-) )

The whole thing is likely to get tough for you then ;-)

Mit freundlichem Gruß / With kind regards
    Holger Klawitter
- --
lists <at> klawitter <dot> de
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