Re: Reduce heap tuple header size

Tom Lane wrote:
> Bruce Momjian <pgman(at)candle(dot)pha(dot)pa(dot)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.

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