Re: Improving compressibility of WAL files

>>> Greg Smith <gsmith@gregsmith.com> wrote: 
> I thought at one point that the direction this was going toward was
to 
> provide the size of the WAL file as a parameter you can use in the 
> archive_command:  %p provides the path, %f the file name, and now %l
the 
> length.  That makes an example archive command something like:
> 
> head -c "%l" "%p" | gzip > /mnt/server/archivedir/"%f"
Hard to beat for performance.  I thought there was some technical
snag.
> Expanding it back to always be 16MB on the other side might require
some 
> trivial script, can't think of a standard UNIX tool suitable for that
but 
> it's easy enough to write.
Untested, but it seems like something close to this would work:
cat $p $( dd if=/dev/null blocks=1 ibs=$(( (16 * 1024 * 1024) - $(stat
-c%s $p) )) )
-Kevin