Re: [HACKERS] Storing rows bigger than one block

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От Vadim B. Mikheev
Тема Re: [HACKERS] Storing rows bigger than one block
Дата
Msg-id 34BB2BB1.50AA6127@sable.krasnoyarsk.su
обсуждение исходный текст
Ответ на Re: [HACKERS] varchar/char size  (darrenk@insightdist.com (Darren King))
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Mattias Kregert wrote:
>
> Darren King wrote:
>
> > There is a var in the tuple header, t_chain, 6.2.1 that has since been
> > removed for 6.3.  I think its original purpose was with time-travel,
> > _but_, if we go with a ROWID instead of an oid in the future, this could
> > be put back in the header and would be the actual address of the next
> > block in the chain.

No, this is not for time-travel. Look at implementation guide.

> >
> > Oracle has this concept of chained rows.  It is how they implement all
> > of their LONG* types and also handle rows of normal types that are
> > larger than the block size.
>
> Yes! I can't see why PostgreSQL should not be able to store rows bigger
> than one block? I have seen people referring to this limitation every
> now and then, but I don't understand why it has to be that way?
> Is this something fundamental to PostgreSQL?
                    ^^^^^^^^^^^
It seems that answeer is "No". Just - not implemented feature.
Personally, I would like multi-representation feature more than that.
And easy to implement.

Vadim

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