Hi Clemens, There are various scenarios for decreased latency. 1. Kindly check the host entry if dbserver is internal and not communicating to Internet 2. Please traceroute/ use sniffer on forwarded port will give you exact route followed. Regards Amol Arakh On Tuesday 22 March 2011 07:05 PM, Clemens Eisserer wrote: > Hi, > > I experience a very strange problem, when using the jdbc driver with > ssh's local port forwarding: > ssh -v -L 4321:dbserver:5432 user@dbserver > > SELECT statements show about the same latency as without > port-forwarding (and even decreased latency when compression is > enabled), but sometimes UPDATE/DELETE statements take seconds to > complete. > The other time they are as fast as they should be. When I connect to > postgres without port-forwarding the update statements consistently > take only a few milliseconds. > > Any idea what the reason could be, I've tested it with two different > ssh clients (one java, and openssh) both show the same behaviour. > Could it be some buffering on the server side, to make data transfer > more efficient? > Could it be because selects usually send a lot of data back to the > client, buffering doesn't hurt - but for update/delete usually only a > acknoledgement is sent back and buffering starts to be an issue? > > Thank you in advance, Clemens > > > Btw the java-based client seems to be waiting for data while it > executes the statements: > > java.net.SocketInputStream.socketRead0(Native Method) > java.net.SocketInputStream.read(SocketInputStream.java:129) > org.postgresql.core.VisibleBufferedInputStream.readMore(VisibleBufferedInputStream.java:135) > org.postgresql.core.VisibleBufferedInputStream.ensureBytes(VisibleBufferedInputStream.java:104) > org.postgresql.core.VisibleBufferedInputStream.read(VisibleBufferedInputStream.java:73) > org.postgresql.core.PGStream.ReceiveChar(PGStream.java:259) > org.postgresql.core.v3.QueryExecutorImpl.processResults(QueryExecutorImpl.java:1620) > org.postgresql.core.v3.QueryExecutorImpl.execute(QueryExecutorImpl.java:257) > - locked org.postgresql.core.v3.QueryExecutorImpl@17b1683 >
