Re: Increasing row retrieving speed via net8 - SOLVED
Date: Tue, 17 Apr 2012 21:08:40 +0300
There was a reason why I stated "fetch more rows at a time" as the #1 item to fix.... The TCP buffer and SDU size tweaking does not help much when your main wait event is "SQL*Net message from client". The TCP buffer and SDU size tweaking would help to reduce the "SQL*Net more data to client" waits though, assuming that your link still has bandwidth left. If it doesn't no need to bother...
On Tue, Apr 17, 2012 at 6:39 PM, GG <grzegorzof_at_interia.pl> wrote:
> W dniu 2012-04-16 20:13, Tanel Poder pisze:
>> And if you're wondering, how come it's possible that 10 x application
>> connections can retrieve 10 x more than a single application connection -
>> this is why I listed the Bandwidth Delay Product as #2 in the list. If you
>> have too small TCP buffer sizes for your network latency (delay) and link
>> max theoretical throughput (bandwidth) then this buffer size ends up
>> throttling your TCP connection throughput. The reason - TCP is a reliable
>> protocol, thus a TCP packet can not be discarded from the TCP send buffer
>> before an ACK has arrived for at least that packet sequence number (or
>> higher). So, the higher the network latency (time to get ACK) and the lower
>> the TCP buffer size, the lower your connection's throughput will be
>> throttled to.
>> With 10 x connections however, each connection have their own TCP
>> send/receive buffers, thus the aggregate throughput for all the connections
>> is 10 x higher.
> Well , it was about buffers but not tcp at least not in that moment :).
> Informatica got its own buffers:
> *DTM Buffer Cache and DTM Buffer Block size
> and default values are not optimal for large (270 columns) row sources.
> Looks like with that buffers You can scale fetch size and with 200MB
> buffer I was having 400k fetch size :) .
> Now I can saturated 100Mbit with 1 connection :)
> So now its time to play with tcp/ip stack / sdu buffers when we finished
> with application .
> Still dont know how strace looks like now , probably get root tomorrow :).