Re: Keepalive for max_standby_delay

On Sun, 2010-05-16 at 17:11 +0100, Simon Riggs wrote:

> New version, with some other cleanup of wait processing.
> 
> New logic is that when Startup asks for next applychunk of WAL it saves
> the lastChunkTimestamp. That is then the base time used by
> WaitExceedsMaxStandbyDelay(), except when latestXLogTime is later.
> Since multiple receivechunks can arrive from primary before Startup asks
> for next applychunk we use the oldest receivechunk timestamp, not the
> latest. Doing it this way means the lastChunkTimestamp doesn't change
> when new keepalives arrive, so we have a stable and reasonably accurate
> recordSendTimestamp for each WAL record.
> 
> The keepalive is sent as the first part of a new message, if any. So
> partial chunks of data always have an accurate timestamp, even if that
> is slightly older as a result. Doesn't make much difference except with
> very large chunks.
> 
> I think that addresses the points raised on this thread and others.

Was about to post v3 after your last commit, but just found a minor bug
in my v2->v3 changes, even though they were fairly light. Too tired to
fix now. The general thinking underlying this patch is still the same
though and is worth discussing over next few days.

-- Simon Riggs           www.2ndQuadrant.com