Re: unlogged tables

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(dot)ru(at)gmail(dot)com]
Enviado el: lunes, 14 de noviembre de 2011 07:39 a.m.
Para: Richard Huxton
CC: Stephen Frost; Anibal David Acosta; pgsql-performance(at)postgresql(dot)org
Asunto: Re: [PERFORM] unlogged tables

On 14 November 2011 14:17, Richard Huxton <dev(at)archonet(dot)com> wrote:
> On 14/11/11 10:08, Sergey Konoplev wrote:
>>
>> On 14 November 2011 12:58, Richard Huxton<dev(at)archonet(dot)com>  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

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