Re: Remove xmin and cmin from frozen tuples - Mailing list pgsql-hackers

From Alvaro Herrera
Subject Re: Remove xmin and cmin from frozen tuples
Date
Msg-id 20050902213533.GB30425@surnet.cl
Whole thread Raw
In response to Re: Remove xmin and cmin from frozen tuples  (Tom Lane <tgl@sss.pgh.pa.us>)
Responses Re: Remove xmin and cmin from frozen tuples
List pgsql-hackers
On Fri, Sep 02, 2005 at 05:18:09PM -0400, Tom Lane wrote:
> Bruce Momjian <pgman@candle.pha.pa.us> writes:
> > Updated TODO:
> 
> >         o Allow COPY on a newly-created table to skip WAL logging
> 
> >           On crash recovery, the table involved in the COPY would
> >           have its heap and index files truncated.  One issue is
> >           that no other backend should be able to add to the table
> >           at the same time, which is something that is currently
> >           allowed.
> 
> This is simply wrong.  (1) a table created in the current transaction
> isn't visible to anyone else, (2) the correct rollback state is for
> it not to be there, rather than be there and empty.

As a related note:

I remember somebody mentioned some time ago that if you create a table
and then crash before ending the transaction, the tuple in pg_class is
no longer valid, but the file remains.  I think this will be a much
worse problem if we allow a table that's being COPY'ed to remain after a
crash.

-- 
Alvaro Herrera -- Valdivia, Chile         Architect, www.EnterpriseDB.com
Oh, oh, las chicas galacianas, lo harán por las perlas,
¡Y las de Arrakis por el agua! Pero si buscas damas
Que se consuman como llamas, ¡Prueba una hija de Caladan! (Gurney Halleck)


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