Re: [HACKERS] Autovacuum loose ends

From: Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us>
To: "Matthew T(dot) O'Connor" <matthew(at)zeut(dot)net>
Cc: Alvaro Herrera <alvherre(at)alvh(dot)no-ip(dot)org>, pgsql-patches(at)postgreSQL(dot)org
Subject: Re: [HACKERS] Autovacuum loose ends
Date: 2005-07-25 04:59:01
Message-ID: 19938.1122267541@sss.pgh.pa.us
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"Matthew T. O'Connor" <matthew(at)zeut(dot)net> writes:
> I don't know either, but this brings up another question. Stats
> wraparound. The n_tup_ins/upd/del columns in the stats system are
> defined as bigint, what happens when the total number of upd for example
> exceeds the capacity for bigint, or overflows to negative, anyone have
> any idea?

We'll all be safely dead, for one thing ;-)

At one update per nanosecond, it'd take approximately 300 years to wrap
a 64-bit counter. Somehow I don't have a problem with the idea that
Postgres would need to be rebooted that often. We'd want to fix the
32-bit nature of XIDs long before 64-bit stats counters get to be a
real-world issue ...

regards, tom lane

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