Subject: RE: DB Performance issues
From: Ruprecht, Chris (cruprech@compucom.com)
Date: Fri Aug 24 2001 - 06:59:26 MDT
Yep, I noticed the Macs seem to be limited to 1.5GB. My old 9600, even
with its 12 memory slots, has a max of 1.5 GB, unless somebody is making
FPM DIMMs with more than 128 MB each.
About the data: once a record is more than 6 months old, it's no longer
of any interest to anybody. It gets removed from the database all
together. We could move this age up to 3 months, but some times,
somebody would need the historical data to do some comparisons.
We can not dump data into a history table and delete it from the main
table, because you can not run a query to include data from both tables,
the run time would be terrible.
There is a fair amount of fixed data which doesn't change all that much,
which surely should be cached. I'm not sure, how Postgres handels these
issues but I have seen things growing a bit out of proportion. One of
the Postgres developers helped me track down a bug the other day where a
process would use up all physical RAM (768 MB) plua all swap space (1
GB) and then crash. The bug will be fixed in the next major release
(7.2) of Postgres but I have a work-around for now.
With the right parameters, however, one should be able to use the
available RAM efficiently. I'm not sure if Linux itself does such a good
job in deciding what, and what not to keep in RAM. I see that my Linux
box always uses all memory, but I have no idea what it puts in there...
Best regards,
Chris
> -----Original Message-----
> From: Christopher Murtagh [mailto:christopher.murtagh@mcgill.ca]
> Sent: Thursday, August 23, 2001 4:24 PM
> To: yellowdog-general@lists.yellowdoglinux.com
> Subject: Re: Michael: printing+reformatting hda13 from ext2 to hfs
>
>
> On Thu, 23 Aug 2001, Ruprecht, Chris wrote:
> >I'm not sure how much RAM the current Macs can take, but
> surely, Memory
> >is not really a subject any more - my PB Pismo memory went
> down to $49
> >for a 512 MB (2-2-2 memory) module. 256 MB PC133, I saw for $25...
>
> AFAIK, the bluish-grey G4s had a physical limit that maxed out at
> 1.5GB. I'm not sure about the latest line though, maybe this
> has improved
> now that Apple is working with a more serious OS. So, if you can get a
> machine with 4GB of RAM it will still out-do any Mac.
>
> Also, what I might do if I were you is move your older data
> (the stuff
> you said that was not likely to be accessed much) into
> different tables
> than the current data (maybe as a batch job at night as the
> data becomes
> 'old'). This might make it easier for the current stuff to be
> cached and
> speed up performance. This is just a guess though, not quite sure how
> PostgreSQL would handle it.
>
> Cheers,
>
> Chris
>
> --
>
> Christopher Murtagh
> Webmaster / Sysadmin
> Web Communications Group
> McGill University
> Montreal, Quebec
> Canada
>
>
>
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