On 09/12/2010 15:51, tv@fuzzy.cz wrote:
>> Hi, Im using Postgres 8.3 on a Macbook Pro Labtop.
>> I using the database with just one db connection to build a lucene
>> search index from some of the data, and Im trying to improve
>> performance. The key thing is that I'm only a single user but
>> manipulating large amounts of data , i.e processing tables with upto 10
>> million rows in them, so I think want to configure Postgres so that it
>> can create large temporary tables in memory
> I'm not sure what exactly you mean by "manipulating data" - does that mean
> reading or writing?
>
> I'd definitely increase shared_buffers, work_mem (don't be afraid to set
> work_mem to say 32MB or 64MB - this should be safe with a single
> connection, although it depends on the queries). To improve writes,
> increase checkpoint_segments etc.
>
> If you really don't need extra safety - e.g. if you have all the data
> backed up and just need to run some ad-hoc analysis (and it does not
> matter if it crashes as you can recover it from backup), you can disable
> fsync. This will make writes much faster, but it won't be safe in case of
> crash.
>
> DON'T DO THIS IF YOU NEED TO KEEP YOUR DATA SAFE!
>
> But as you're runninng the app on your laptop, I guess you can live with
> frync=off. You'll loose the consistency but you'll get better performance.
>
Hi ( sorry for the double posting, thought Id use the wrong email
address but both have been posted anyway).
As far as the db is concerned Im just reading data then writing the data
to a lucene search index (which is outside of the database) , but my
labtop is jut a test machine I want to run the same code on production.
Why would work_mem not be safe at 64MB if I have 2GB of memory - what
have I got to be careful of.
Paul