| From: | Thomas Munro <thomas(dot)munro(at)gmail(dot)com> |
|---|---|
| To: | Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us> |
| Cc: | Andres Freund <andres(at)anarazel(dot)de>, Andrew Dunstan <andrew(at)dunslane(dot)net>, Heikki Linnakangas <hlinnaka(at)iki(dot)fi>, Noah Misch <noah(at)leadboat(dot)com>, Bharath Rupireddy <bharath(dot)rupireddyforpostgres(at)gmail(dot)com>, Justin Pryzby <pryzby(at)telsasoft(dot)com>, pgsql-hackers(at)postgresql(dot)org |
| Subject: | Re: Direct I/O |
| Date: | 2023-04-09 23:46:16 |
| Message-ID: | CA+hUKG+7ywdJbi+5BgVarapASYYqp9qBPWzRuVzVzhuQ3-dccg@mail.gmail.com |
| Views: | Raw Message | Whole Thread | Download mbox | Resend email |
| Thread: | |
| Lists: | pgsql-hackers |
On Mon, Apr 10, 2023 at 8:43 AM Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us> wrote:
> Boy, it's hard to look at that trace and not call it a filesystem bug.
Agreed.
> Given the apparent dependency on COW, I wonder if this has something
> to do with getting confused about which copy is current?
Yeah, I suppose it would require bogus old page versions (or I guess
alternatively completely mixed up page offsets) rather than bogus
zeroed pages to explain the too-high count observed in one of crake's
failed runs: I guess it counted some pre-updated tuples that were
supposed to be deleted and then counted the post-updated tuples on
later pages (insert joke about the Easter variant of the Halloween
problem). It's just that in the runs I've managed to observe and
analyse, the previous version always happened to be zeros.
| From | Date | Subject | |
|---|---|---|---|
| Next Message | Michael Paquier | 2023-04-09 23:46:31 | Re: Commitfest 2023-03 starting tomorrow! |
| Previous Message | Noah Misch | 2023-04-09 23:40:54 | Re: Direct I/O |