Re: [Gnumed-devel] postgresql considerations

[Dave Cramer]

On Thu, Jun 14, 2012 at 9:58 AM, Karsten Hilbert
<address@hidden> wrote:
>> I was wondering what influences GNUmed's performance with regards
>> to database performance most.
>
> The proper answer to this question can really only be found by actual
> investigation.
>
> Possible reasons are:
>
> - network latency
> - many small queries in a use case which would benefit from fewer
>  larger queries
> - one large queries in a use case which would benefit from many
>  smaller queries
> - server capability (RAM, disk throughput)
> - dark buffers

What are dark buffers ?

> - wire transmit capacity
> - connection setup time (we only ever use one read-only connection
>  per thread during app instance lifetime, though, so that would
>  only affect write queries)
> - missing indices in the database
> - unfortunate joins on behalf of the query planner
> - unfortunate table layout
> - bad statistics of data distribution in the database
>
>> Second questions deals with harddrive performance. I noticed that when
>> running
>> Postgresql off an USB thumbdrive that its performance is far worse then an
>> old
>> harddrive. I know that USB thumbdrives have poor i/o performance. Is there
>> anything to counter this (e.g. getting large chunks of data in one go) ?
>>
>> Any explaination is appreciated.
>
> - use a system which makes good use of RAM for write caching
> - configure PostgreSQL to not use fsync (but you'll lose ACID)

This is your medical data, why would you ever not want to have ACID ?

>
> Karsten
>
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