RE: [HACKERS] Re: ALTER TABLE DROP COLUMN

> -----Original Message-----
> From: owner-pgsql-hackers(at)postgreSQL(dot)org
> [mailto:owner-pgsql-hackers(at)postgreSQL(dot)org]On Behalf Of Bruce Momjian
>
> [Charset ISO-8859-1 unsupported, filtering to ASCII...]
> > Bruce Momjian writes:
> >
> > > You can exclusively lock the table, then do a heap_getnext() scan over
> > > the entire table, remove the dropped column, do a
> heap_insert(), then a
> > > heap_delete() on the current tuple,
> >
> > Wow, that almost seems to easy to be true. I never thought that having
> > tuples of different structures in the table at the same time would be
> > possible. If so then I don't see a reason why this would be too hard to
> > do.
>
> If the transaction is not committed, I don't think anything actually
> reads the tuple columns, so you are safe.
>

Hmm,tuples of multiple version in a table ?
This is neither clean nor easy for me.
There's no such stuff which takes the case into account,AFAIK.

Seems no one but me object to it. I'm tired of this issue and it's
painful for me to continue discussion further in my poor English.
I may be able to provide another implementation on trial and it
may be easier than only objecting to your proposal.
Is it OK ?

Regards.

Hiroshi Inoue
Inoue(at)tpf(dot)co(dot)jp