Re: Re: [COMMITTERS] pgsql: Properly set relpersistence for fake relcache entries.

On Sep 15, 2012, at 11:29 AM, Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us> wrote:
> Robert Haas <robertmhaas(at)gmail(dot)com> writes:
>> Definitions aside, I think it's a pretty scary issue. It basically means that if you have a recovery (crash or archive) during which you read a buffer into memory, the buffer won't be checkpointed. So if, before the buffer is next evicted, you have a crash, and if at least one checkpoint has intervened between the most recent WAL-logged operation on the buffer and the crash, you're hosed. That's not a terribly unlikely scenario.
>
> This is only an issue on standby slaves or when doing a PITR recovery, no?
> As far as I can tell from the discussion, it would *not* affect crash
> recovery, because we don't do restartpoints during crash recovery.

No, I think it does affect crash recovery. Whether or not restartspoints happen during recovery doesn't matter; what does matter is that after recovery there may be shared buffers that are erroneously not marked as permanent. Such buffers won't be checkpointed except at shutdown time, which is wrong.

...Robert