Re: Reduce heap tuple header size - Mailing list pgsql-patches

From Bruce Momjian
Subject Re: Reduce heap tuple header size
Date
Msg-id 200206211645.g5LGjmH28312@candle.pha.pa.us
Whole thread Raw
In response to Re: Reduce heap tuple header size  (Tom Lane <tgl@sss.pgh.pa.us>)
Responses Re: Reduce heap tuple header size II  (Manfred Koizar <mkoi-pg@aon.at>)
List pgsql-patches
Tom Lane wrote:
> Bruce Momjian <pgman@candle.pha.pa.us> writes:
> > Tom Lane wrote:
> >> Some of these may never happen (I'm not even in favor of all of them)
> >> but it's certain that we will want to do some of them.  I don't want to
> >> take the same hit over and over when some intelligent project management
> >> would let us take it just once or twice.
>
> > Yes, there are some good ones there, but the idea that somehow they are
> > all going to hit in the same release seems unlikely.  I say let's do
> > some now, some later, and move ahead.
>
> I think it's very likely that P-I-T recovery and replication will hit
> in the 7.4 release cycle.  I would prefer to see us plan ahead to do
> these other changes for 7.4 as well, and get as many of them done in
> that cycle as we can.
>
> Basically my point is that there are costs and benefits to this sort
> of change, and many of the costs are quantized --- it doesn't cost
> more to make three incompatible disk-format changes than one, *as long
> as they're in the same release*.  So we should try to do some actual
> management of such changes, not accept them willy-nilly whenever someone
> feels like doing one.
>
> This patch is unlikely to suffer significant bit-rot if we hold it for
> 7.4, and that's what I think we should do with it.

Well, that is a different argument than initially.  So, it is a valid
patch, but we have to decide when to apply it.

We can easily hold it until we near release of 7.3.  If pg_upgrade is in
good shape _and_ no other format changes are required, we can  hold it
for 7.4.  What happens if 7.4 doesn't have any format changes?

However, if we have other changes or pg_upgrade isn't going to work, we
can apply it in August.

(Manfred, you can be sure I will not lose this patch.)

However, we have been very bad at predicting what features/changes are
coming in future releases.  Also, I don't think replication will require
tuple format changes.  I will check with the group but I haven't heard
anything about that.

So, we have to decide if we apply it now or delay it for later in 7.3,
or for >=7.4.

My personal vote is that we apply it now, and perhaps try some of the
other format changes we were going to make.  Tom's vote is to hold it, I
assume. Let's see what others say.


--
  Bruce Momjian                        |  http://candle.pha.pa.us
  pgman@candle.pha.pa.us               |  (610) 853-3000
  +  If your life is a hard drive,     |  830 Blythe Avenue
  +  Christ can be your backup.        |  Drexel Hill, Pennsylvania 19026

pgsql-patches by date:

Previous
From: Tom Lane
Date:
Subject: Re: Reduce heap tuple header size
Next
From: Ron Snyder
Date:
Subject: script to check consistency between guc.h and postgresql.conf.sample