Re: HOT updates & REDIRECT line pointers

On Wed, Mar 21, 2012 at 8:44 PM, Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us> wrote:
> Oh, right.  So scratch that objection.  The other one is still fatal
> though ...

So, could we just decide that we don't care about preserving that
property any more, and document it as an incompatibility in whatever
release we break it in? It strikes me that it likely wouldn't be any
worse than, oh, say, flipping the default value of
standard_conforming_strings, and we could even have a backward
compatibility GUC if we were so inclined. I realize that the
standard_conforming_strings change was dictated by a desire to conform
to the SQL standards, and this isn't, but it seems awfully painful to
me to insist that this is a property that we can never give up.

I can remember one other proposal to which you raised this same
objection: the idea of an on-line tuple mover to handle the situation
where a user wishes to do an on-line reorganization of a bloated table
by incrementally moving tuples to lower-numbered pages. It's possible
that the idea with which I started this thread might turn out to be
horribly unsafe for one reason or another, but I think that there's
broad support for the tuple mover concept.

--
Robert Haas
EnterpriseDB: http://www.enterprisedb.com
The Enterprise PostgreSQL Company