Maybe an option like "Recover from file " will be useful So, for example, daily some process do a COPY of entire table to a file In case of crash postgres recover content from the file. :) -----Mensaje original----- De: Sergey Konoplev [mailto:gray.ru@xxxxxxxxx] Enviado el: lunes, 14 de noviembre de 2011 07:39 a.m. Para: Richard Huxton CC: Stephen Frost; Anibal David Acosta; pgsql-performance@xxxxxxxxxxxxxx Asunto: Re: unlogged tables On 14 November 2011 14:17, Richard Huxton <dev@xxxxxxxxxxxx> wrote: > On 14/11/11 10:08, Sergey Konoplev wrote: >> >> On 14 November 2011 12:58, Richard Huxton<dev@xxxxxxxxxxxx> wrote: > Let's say you were doing something like "UPDATE unlogged_table SET x=1 > WHERE y=2". If a crash occurs during this command, there's no > guarantee that the affected disk pages were all updated. Worse, a > single page might be partially updated or even have rubbish in it > (depending on the nature of the crash). > > Without the WAL there's no way to check whether the table is good or > not, or even to know what the last updates were. So - the only safe > thing to do is truncate the unlogged tables. > > In the event of a normal shutdown, we can flush all the writes to disk > so we know all the data has been written, so there is no need to truncate. Thank you for the explanation. Now I understand it. > > -- > Richard Huxton > Archonet Ltd > -- Sergey Konoplev Blog: http://gray-hemp.blogspot.com LinkedIn: http://ru.linkedin.com/in/grayhemp JID/GTalk: gray.ru@xxxxxxxxx Skype: gray-hemp -- Sent via pgsql-performance mailing list (pgsql-performance@xxxxxxxxxxxxxx) To make changes to your subscription: http://www.postgresql.org/mailpref/pgsql-performance
