[ADMIN] Sequence "self" change - possible?

[Lukasz Brodziak]

Hello,

Is it possible for sequence to decrement its value by itself? Or is it
possible to see wether it was changed by someone. The thing is that on one
of our clinet's DB sequence rolled back to the state from 8 months ago.

[Szymon Guz]

Post by Lukasz Brodziak
Hello,
Is it possible for sequence to decrement its value by itself? Or is it
possible to see wether it was changed by someone. The thing is that on one
of our clinet's DB sequence rolled back to the state from 8 months ago.
--
Łukasz Brodziak

Hi Łukasz,

you can have set the sequence as cycled (
http://www.postgresql.org/docs/current/static/sql-createsequence.html) so
it can set automatically to minvalue when reaching maxvalue.

Show us the definition of that sequence.

regards
Szymon

[Oliveiros d'Azevedo Cristina]

Can it be that it wrapped around?

Best,
Oliveiros
----- Original Message -----
From: Lukasz Brodziak
To: pgsql-***@postgresql.org
Sent: Monday, November 28, 2011 2:04 PM
Subject: [ADMIN] Sequence "self" change - possible?


Hello,


Is it possible for sequence to decrement its value by itself? Or is it possible to see wether it was changed by someone. The thing is that on one of our clinet's DB sequence rolled back to the state from 8 months ago.



--
Łukasz Brodziak

[Craig Ringer]

Post by Lukasz Brodziak
Hello,
Is it possible for sequence to decrement its value by itself? Or is it
possible to see wether it was changed by someone. The thing is that on
one of our clinet's DB sequence rolled back to the state from 8 months ago.

It shouldn't generally be possible, no. It'd have to be changed by a
call to nextval(), setval() or the like, or a direct UPDATE to the
underlying sequence pseudo-table.

Could someone have tried to restore a backup from 8 months ago? That'd
result in a setval(...) call when pg_restore or psql (depending on
backup format) tried to set the sequence position.

In your case, though, your next post mentions possible database
corruption, so I'm wondering if this is related. If something's been
scribbling over the database files, someone's half-restored an old
file-level backup, or something similarly horrible then anything could
happen.

--
Craig Ringer