Jan Wieck schrieb:
On 12/2/2005 6:01 PM, Michael Riess wrote:
Hi,
thanks for your comments so far - I appreciate it. I'd like to narrow
down my problem a bit:
As I said in the other thread, I estimate that only 20% of the 15,000
tables are accessed regularly. So I don't think that vacuuming or the
number of file handles is a problem. Have a look at this:
What makes you think that? Have you at least tried to adjust your shared
buffers, freespace map settings and background writer options to values
that match your DB? How does increasing the kernel file desctriptor
limit (try the current limit times 5 or 10) affect your performance?
Of course I tried to tune these settings. You should take into account
that the majority of the tables are rarely ever modified, therefore I
don't think that I need a gigantic freespace map. And the background
writer never complained.
Shared memory ... I currently use 1500 buffers for 50 connections, and
performance really suffered when I used 3000 buffers. The problem is
that it is a 1GB machine, and Apache + Tomcat need about 400MB.
But thanks for your suggestions! I guess that I'll have to find a way to
reduce the number of tables. Unfortunately my application needs them, so
I'll have to find a way to delete rarely used tables and create them on
the fly when they're accessed again. But this will really make my
application much more complex and error-prone, and I had hoped that the
database system could take care of that. I still think that a database
system's performance should not suffer from the mere presence of unused
tables.
Mike
