Re: [ext] Re: Losing data because of problematic configuration? - Mailing list pgsql-general

From Holtgrewe, Manuel
Subject Re: [ext] Re: Losing data because of problematic configuration?
Date
Msg-id fabac0b6aff24e0d82e3871892f5b2cd@bih-charite.de
Whole thread Raw
In response to Re: Losing data because of problematic configuration?  (Tom Lane <tgl@sss.pgh.pa.us>)
Responses Re: [ext] Re: Losing data because of problematic configuration?
List 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?
 
"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


pgsql-general by date:

Previous
From: Jehan-Guillaume de Rorthais
Date:
Subject: Re: query issue
Next
From: AI Rumman
Date:
Subject: CONCAT function adding extra characters