Re: [HACKERS] Patch: Write Amplification Reduction Method (WARM)

On Tue, Mar 21, 2017 at 04:56:16PM -0300, Alvaro Herrera wrote:
> Bruce Momjian wrote:
> > On Tue, Mar 21, 2017 at 04:43:58PM -0300, Alvaro Herrera wrote:
> > > Bruce Momjian wrote:
> > > 
> > > > I don't think it makes sense to try and save bits and add complexity
> > > > when we have no idea if we will ever use them,
> > > 
> > > If we find ourselves in dire need of additional bits, there is a known
> > > mechanism to get back 2 bits from old-style VACUUM FULL.  I assume that
> > > the reason nobody has bothered to write the code for that is that
> > > there's no *that* much interest.
> > 
> > We have no way of tracking if users still have pages that used the bits
> > via pg_upgrade before they were removed.
> 
> Yes, that's exactly the code that needs to be written.

Yes, but once it is written it will take years before those bits can be
used on most installations.

--  Bruce Momjian  <bruce@momjian.us>        http://momjian.us EnterpriseDB
http://enterprisedb.com

+ As you are, so once was I.  As I am, so you will be. +
+                      Ancient Roman grave inscription +