| From: | Andres Freund <andres(at)anarazel(dot)de> |
|---|---|
| To: | Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us> |
| Cc: | Robert Haas <robertmhaas(at)gmail(dot)com>, Daniel Gustafsson <daniel(at)yesql(dot)se>, Kyotaro Horiguchi <horikyota(dot)ntt(at)gmail(dot)com>, deniel1495(at)mail(dot)ru, Ibrar Ahmed <ibrar(dot)ahmad(at)gmail(dot)com>, tejeswarm(at)hotmail(dot)com, hlinnaka <hlinnaka(at)iki(dot)fi>, Masahiko Sawada <masahiko(dot)sawada(at)2ndquadrant(dot)com>, "pgsql-hackers(at)postgresql(dot)org" <pgsql-hackers(at)postgresql(dot)org>, Daniel Wood <hexexpert(at)comcast(dot)net> |
| Subject: | Re: Corruption during WAL replay |
| Date: | 2022-03-25 06:07:37 |
| Message-ID: | 20220325060737.iayq5cs36jktqlag@alap3.anarazel.de |
| Views: | Raw Message | Whole Thread | Download mbox | Resend email |
| Thread: | |
| Lists: | pgsql-hackers |
Hi,
On 2022-03-25 01:38:45 -0400, Tom Lane wrote:
> Andres Freund <andres(at)anarazel(dot)de> writes:
> > Not sure what to do here... I guess we can just change the value we overwrite
> > the page with and hope to not hit this again? But that feels deeply deeply
> > unsatisfying.
>
> AFAICS, this strategy of whacking a predetermined chunk of the page with
> a predetermined value is going to fail 1-out-of-64K times.
Yea. I suspect that the way the modifications and checksumming are done are
actually higher chance than 1/64k. But even it actually is 1/64k, it's not
great to wait for (#animals * #catalog-changes) to approach a decent
percentage of 1/64k.
I'm was curious whether there have been similar issues in the past. Querying
the buildfarm logs suggests not, at least not in the pg_checksums test.
> We have to change the test so that it's guaranteed to produce an invalid
> checksum. Inverting just the checksum field, without doing anything else,
> would do that ... but that feels pretty unsatisfying too.
We really ought to find a way to get to wider checksums :/
Greetings,
Andres Freund
| From | Date | Subject | |
|---|---|---|---|
| Next Message | Masahiko Sawada | 2022-03-25 06:19:12 | Re: Logical replication timeout problem |
| Previous Message | Tom Lane | 2022-03-25 05:38:45 | Re: Corruption during WAL replay |