Re: [ext] Re: Losing data because of problematic configuration?
| От | Holtgrewe, Manuel |
|---|---|
| Тема | Re: [ext] Re: Losing data because of problematic configuration? |
| Дата | |
| Msg-id | fabac0b6aff24e0d82e3871892f5b2cd@bih-charite.de обсуждение исходный текст |
| Ответ на | Re: Losing data because of problematic configuration? (Tom Lane <tgl@sss.pgh.pa.us>) |
| Ответы |
Re: [ext] Re: Losing data because of problematic configuration?
|
| Список | pgsql-general |
>> < 2021-06-15 12:33:04.537 CEST > DEBUG: resetting unlogged relations: cleanup 1 init 0
>
> Are you perhaps keeping your data in an UNLOGGED table? If so, resetting
> it to empty after a crash is exactly what's supposed to happen. The
> entire point of UNLOGGED is that the performance benefits come at the
> cost of losing the data on crash.
D'oh!
Yes, that is the case. I once used this but I was convinced that I took this back in some version. It is not in my main deployment, though. Now I have to find out (a) why I have diverging deployment and (b) how that bug came about to be.
Thanks a lot!
From: Tom Lane <tgl@sss.pgh.pa.us>
Sent: Tuesday, June 15, 2021 3:39:31 PM
To: Holtgrewe, Manuel
Cc: pgsql-general@lists.postgresql.org
Subject: [ext] Re: Losing data because of problematic configuration?
Sent: Tuesday, June 15, 2021 3:39:31 PM
To: Holtgrewe, Manuel
Cc: pgsql-general@lists.postgresql.org
Subject: [ext] Re: Losing data because of problematic configuration?
"Holtgrewe, Manuel" <manuel.holtgrewe@bih-charite.de> writes:
> So it looks as if the database jumps back "half an hour" to ensure consistent data. Everything in between is lost.
Postgres does not lose committed data --- if it did, we'd consider that a
fairly serious bug. (Well, there are caveats of course. But most of them
have to do with operating-system crashes or power loss, neither of which
are at stake here.)
I am wondering about this though:
> < 2021-06-15 12:33:04.537 CEST > DEBUG: resetting unlogged relations: cleanup 1 init 0
Are you perhaps keeping your data in an UNLOGGED table? If so, resetting
it to empty after a crash is exactly what's supposed to happen. The
entire point of UNLOGGED is that the performance benefits come at the
cost of losing the data on crash.
regards, tom lane
> So it looks as if the database jumps back "half an hour" to ensure consistent data. Everything in between is lost.
Postgres does not lose committed data --- if it did, we'd consider that a
fairly serious bug. (Well, there are caveats of course. But most of them
have to do with operating-system crashes or power loss, neither of which
are at stake here.)
I am wondering about this though:
> < 2021-06-15 12:33:04.537 CEST > DEBUG: resetting unlogged relations: cleanup 1 init 0
Are you perhaps keeping your data in an UNLOGGED table? If so, resetting
it to empty after a crash is exactly what's supposed to happen. The
entire point of UNLOGGED is that the performance benefits come at the
cost of losing the data on crash.
regards, tom lane
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