Pierre,
> I added a field in PageHeader which contains :
> - 0 to indicate a non-compressed page
> - length of compressed data if compressed
>
> If compression gains nothing (ie gains less than 4K), the page is
> stored raw.
>
> It seems that only pages having a PageHeader are handled by md.c, so
> it should work (am I mistaken ?)
Well, there's the issue of upgradability; this would require us to have
an incompatible upgrade of on-disk formats. So we don't want to go
further down this route unless we're sure it's worthwhile.
--
Josh Berkus
PostgreSQL Experts Inc.
www.pgexperts.com
