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From:Ben Clewett Date:January 10 2006 5:13pm
Subject:Re: Geogrphic Advise
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Jigal,

Thanks, I'll give this a go...

Ben

Jigal van Hemert wrote:
> Ben Clewett wrote:
> 
>> But the index does not seem nearly as fast as liner (normal) indexes. 
>> Hence using a less effective liner index may be better...
>>
>> After this method I still need select a radius within these data 
>> points, more effort.
> 
> 
> This could be an excellent case for using HAVING <expr>
> 
> The WHERE can use an index and be very fast selecting the records that 
> might fall within the circle. The HAVING clause will be executed after 
> the record set is built and remove the records outside the circle, but 
> within the square. If the number of records you select is pretty limited 
> (a few hundred or so) the POW() calculations will not ask too much from 
> the server, but the full table scan is avoided...
> 
> Regards, Jigal.

Thread
temporary table issueXiaobo Chen10 Jan
  • Re: temporary table issueJigal van Hemert10 Jan
    • Re: temporary table issueXiaobo Chen10 Jan
    • Re: temporary table issueBen Clewett10 Jan
      • Re: temporary table issueJigal van Hemert10 Jan
        • Re: Geogrphic AdviseBen Clewett10 Jan
  • Re: temporary table issueBill Dodson10 Jan