| From: | Laurenz Albe <laurenz(dot)albe(at)cybertec(dot)at> |
|---|---|
| To: | Jialun Zhang <reatank(at)gmail(dot)com>, Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us> |
| Cc: | pgsql-novice(at)lists(dot)postgresql(dot)org |
| Subject: | Re: What's the best practice to compare the transaction with the checkpoint? |
| Date: | 2020-07-07 09:41:46 |
| Message-ID: | 96e63393bffdf23b4ea853a9ddebed1ed0acc670.camel@cybertec.at |
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| Thread: | |
| Lists: | pgsql-novice |
On Mon, 2020-07-06 at 17:50 -0400, Jialun Zhang wrote:
> > The replay of step 4 would need to perform something like "delete the file
> > for V if it exists, but don't complain if it does not", since we couldn't
> > be sure which state we'll find on-disk.
>
> What I am actually asking is that, is it possible that the replay depends
> on a deleted value, which has been physically removed by a VACUUM.
> Bear with my very basic knowledge in Postgres.
The WAL records that affect your out-of-line stored file would be written
by you, so you'd have to make sure that replaying such WAL records works
whether the file is present or not.
Yours,
Laurenz Albe
--
Cybertec | https://www.cybertec-postgresql.com
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