[OSM-dev] Further Database optimisation and data size

SteveC steve at asklater.com
Thu Apr 20 20:54:19 BST 2006


* @ 20/04/06 07:50:35 PM nick at nickhill.co.uk wrote:
> From these tests, using integers is much faster for database retrieval 
> on key columns.
> 
> Storing the data completely in memory can be helpful, but is not 
> necessarily overriding. Previous tests have shown that tripling the 
> available memory from 340Mb to 980Mb for 100million points as doubles 
> makes around 10% difference. That is on a 1.7Gb data set.
> 
> The ease by which the queries can be performed in terms of processing 
> power is perhaps of greatest importance. In addition, I plan to run an 
> optimisation which will put most groups of tiles within 4 hard drive 
> seeks of data retrieval for any table, without changing any SQL logic. 
> (I have  not yet finished tests on this).

I can't read perl well, does the test include converting the returned
data set rows back to lat/lon?

have fun,

SteveC steve at asklater.com http://www.asklater.com/steve/




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