Re: pg_ctl stop -m immediate on the primary server inflates sequences - Mailing list pgsql-hackers

From Martijn van Oosterhout
Subject Re: pg_ctl stop -m immediate on the primary server inflates sequences
Date
Msg-id 20100410200215.GC6944@svana.org
Whole thread Raw
In response to Re: pg_ctl stop -m immediate on the primary server inflates sequences  (Boszormenyi Zoltan <zb@cybertec.at>)
Responses Re: pg_ctl stop -m immediate on the primary server inflates sequences  (Boszormenyi Zoltan <zb@cybertec.at>)
List pgsql-hackers
On Sat, Apr 10, 2010 at 02:36:41PM +0200, Boszormenyi Zoltan wrote:
> >> The above is quite reproducable, "pg_ctl stop -m immediate"
> >> "usually" inflated my serial sequence, but I had two occasions
> >> when not. The 69 -> 70 was one. The inflated increase is always 33:
> >
> > AFAIKS sequences are pre-logged with 32 values to WAL to avoid
> > overhead. I suspect this is why you are seeing those gaps.
>
> Then it should happen all the time, even with "-m fast" or "-m smart", no?

Nope, because on a normal shutdown it writes out the actual value. When
you say "immediate" you mean "right now, don't bother with anything not
important", like for example gaps in sequences. You're essentially
crashing the DB.

Have a ncie day,
--
Martijn van Oosterhout   <kleptog@svana.org>   http://svana.org/kleptog/
> Patriotism is when love of your own people comes first; nationalism,
> when hate for people other than your own comes first.
>                                       - Charles de Gaulle

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