Re: "Select * " on 12-18M row table from remote machine thru JDBC - Performance nose-dives after 10M-ish records

Try to run the software with -XX:+PrintGCDetails probably the Java app
is memory starved.

You can also try to run the java program with the Netbeans Profiler or
with VisualVM and check what's blocking the process.

Luis Flores

On Fri, Sep 28, 2012 at 3:05 PM, antthelimey <antthelimey(at)gmail(dot)com> wrote:
> On machine 1 - a table that contains between 12 and 18 million rows
> On machine 2 - a Java app that calls Select * on the table, and writes it
> into a Lucene index
>
> Originally had a fetchSize of 10,000 and would take around 38 minutes for 12
> million, 50 minutes for 16ish million to read it all & write it all back out
> as the lucene index
>
> One day it started taking 4 hours. If something changed, we dont know what
> it was
>
> We tracked it down to, after 10 million or so rows, the Fetch to get the
> next 10,000 rows from the DB goes from like 1 second to 30 seconds, and
> stays there
>
> After spending a week of two devs & DBA trying to solve this, we eventually
> "solved" it by upping the FetchRowSize in the JDBC call to 50,000
>
> It was performing well enough again for a few weeks
>
> then...one day... it started taking 4 hours again
>
> we tried upping the shared_buffer from 16GB to 20GB
>
> And last night... it took 7 hours
>
> does anyone have ANY ideas?!
>
> we are on postgres 9.1
>
> the Server merely shows an idle transaction, waiting to be asked for the
> next bunch of rows - not IO or CPU bound
>
> thanks much
>
>
>
>
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