Re: Shared row locking, revisited

From: Qingqing Zhou
Subject: Re: Shared row locking, revisited
Date: ,
Msg-id: d32kcd$1lh7$1@news.hub.org
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In response to: Shared row locking, revisited  (Alvaro Herrera)
Responses: Re: Shared row locking, revisited  (Alvaro Herrera)
List: pgsql-hackers

"Alvaro Herrera" <> writes
> Because we can't reuse MultiXactIds at system crash (else we risk taking
> an Id which is already stored in some tuple), we need to XLog it.  Not
> at the locking operation, because we don't want to log that one (too
> expensive.)  We can log the current value of MultiXactId counter once in
> a while; say, one each (say) 1000 acquisitions.  Following a crash, the
> value is restored to the last one logged + 1000.  (I think this can be a
> problem if we log one acquisition, then write some tuples, and then
> crash, without flushing the acquisition logged.  Maybe a solution is to
> force a flush after logging an acquisition.)
>

Does Oid have a similar problem?

Regards,
Qingqing





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