On Thu, Jul 8, 2010 at 10:23, Fujii Masao <masao.fu...@gmail.com> wrote: > On Thu, Jul 8, 2010 at 4:57 PM, Pavel Golub <pa...@microolap.com> wrote: >> Sounds good for me. My customer proposed such a scenario: >> >> I have opened connection to database server (ver 8.4.3) through the >> SSH tunnel. This tunnel is created by external program "PUTTY". My PC >> running Application >> is connected to the ETH switch and server is connected to another port of >> the switch. So, when >> I disconnect server from the switch, my PC is still online (I mean ETH port >> have the link). So, my >> local side of the SSH tunnel is still alive, but remote side is down... So >> no connection to server >> is possible at this moment. But in this scenario, when I do something like >> this: >> >> PQExec(...); >> >> Application stay locked on this command. Looks like client is still waiting >> answer from the server in >> the case the TCP connection is still alive, even if Server is not accessible. >> >> The question is: Can this situation be solved with keealives? > > AFAIK, keepalive works only if there is no un-Acked data pending. > If network goes down before sending query to server (i.e., calling > PQexec), the ACK for the query doesn't arrive, so you cannot detect > the disconnection via keepalive while waiting for the result of the > query. OTOH, if network goes down after sending query, keepalive > would make you detect the disconnection.
In this scenario, wouldn't it work if the *ssh connection* had keepalives enabled though? Then that one should tear down, which in turn would send a clear signal to libpq the connection is gone. -- Magnus Hagander Me: http://www.hagander.net/ Work: http://www.redpill-linpro.com/ -- Sent via pgsql-hackers mailing list (pgsql-hackers@postgresql.org) To make changes to your subscription: http://www.postgresql.org/mailpref/pgsql-hackers
