Re: Improving compressibility of WAL files

On Fri, 2009-01-09 at 13:22 -0500, Tom Lane wrote:
> Simon Riggs <simon@2ndQuadrant.com> writes:
> > Yes, we could make the archiver do this, but I see no big advantage over
> > having it done externally. It's not faster, safer, easier. Not easier
> > because we would want a parameter to turn it off when not wanted.
> 
> And the other question to ask is how much effort and code should we be
> putting into the concept anyway.  AFAICS, file-at-a-time WAL shipping
> is a stopgap implementation that will be dead as a doornail once the
> current efforts towards realtime replication are finished.  There will
> still be some use for forced log switches in connection with backups,
> but that's not going to occur often enough to be important to optimize.

Agreed.

Half-filled WAL files were necessary to honour archive_timeout. With
continuous streaming all WAL files will be 100% full before we switch,
for most purposes.

-- Simon Riggs           www.2ndQuadrant.comPostgreSQL Training, Services and Support