Re: [GENERAL] problems with memory

* Dean Browett <dbrowett(at)bizonline(dot)net> [000218 15:55] wrote:
> Hi,
>
> We are running postgres-6.5.3 on a dual pentium 300 machine, 0.5Gb RAM under
> Linux Redhat 6.0 (kernel 2.2.14). The machine we are using sits on a 100Mb
> network and the nics are 3com3c590's. We are also using a DPT Raid
> controller in a raid5 configuration set up as 1 logical drive.
>
> We are try to insert a large amount of data into the database. What happens
> is that when we first start loading data everything is fine. Over a period
> of time (1.5hrs) there is a marked decrease in performance in terms of both
> memory and cpu usage. At this time cpu usage has crept up to 45-50% and
> memory usage is 100Mb and rising slowly and there is only one connection to
> the database.
>
> All the statistics are gleaned from using 'top'.
>
>
> Consequently, the database gets slower and slower until it loads at the rate
> of <3KBps at which point it becomes more exciting to watch paint dry 8-)).
>
> Postgres is the only program running (except for normal system programs)
> that uses a significant amount of memory.
>
> Is Postgres known to leak memory? What causes the high cpu usage?
>
> Any ideas would be greatly appreciated.

You really haven't given very much information on the rules and constraints
in your tables, one problem that I had was that a constraint on a table
of mine caused extreme slowdown because each row inserted needed to be
validated through a constraint, as the table grew the amount of data that
needed to be scanned for each insert grew exponentially.

hope this helps,
-Alfred