On Thu, 2007-09-27 at 10:17 +0200, Zeugswetter Andreas ADI SD wrote: > > > Attached is a modified version to implement both of these. I also > bailed > > > out if there was surplus input. I tried an optimization of > allocating a > > > separate buffer for outputting the zeros, to avoid repeated memset > calls. > > > It didn't seem to make a very big difference; do you think it's > worth > > > cluttering the code with that? > > > > Would it work to just ftruncate the file? > > We would need to teach recovery to accept a short file if the last > record is a > valid switch log XLOG record. RestoreArchivedFile currently bails out if > the file > size is not XLogSegSize.
We also need to check in pg_standby to see whether the file is still being copied or is complete. Currently, we check the filesize and wait for it to be 16M. There would need to be another way for pg_standby to assess whether the file has completed transfer before copying into the data directory of the standby node. > We need to make exact checks though, or this would reduce reliability. > (e.g. a short file must have records up to the very end) > > The probably useful next step would be to pass the current length to the > archive_command, > so it can write the filled part of the file without the need for a > filter. It's certainly possible to pass file metadata as well as the file. I'd be worried that would significantly complicate the mechanism, which at the moment is clean and simple; so this isn't gonna happen for 8.3 AFAICS. Changing that would require people to redesign their HA configs, which doesn't sound that great to me. The next step for me is to stream the records, not to fuss too much with the existing file level copying. Streaming provides what we really want: a shorter delay in data transfer between primary and standby, without additional overhead. -- Simon Riggs 2ndQuadrant http://www.2ndQuadrant.com ---------------------------(end of broadcast)--------------------------- TIP 1: if posting/reading through Usenet, please send an appropriate subscribe-nomail command to [EMAIL PROTECTED] so that your message can get through to the mailing list cleanly
