Re: Aggressive freezing in lazy-vacuum

ITAGAKI Takahiro <itagaki(dot)takahiro(at)oss(dot)ntt(dot)co(dot)jp> writes:
> Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us> wrote:
>> I think it's a really bad idea to freeze that aggressively under any
>> circumstances except being told to (ie, VACUUM FREEZE). When you
>> freeze, you lose history information that might be needed later --- for
>> forensic purposes if nothing else.

> I don't think we can supply such a historical database functionality here,
> because we can guarantee it just only for INSERTed tuples even if we pay
> attention. We've already enabled autovacuum as default, so that we cannot
> predict when the next vacuum starts and recently UPDATEd and DELETEd tuples
> are removed at random times.

I said nothing about expired tuples. The point of not freezing is to
preserve information about the insertion time of live tuples. And your
test case is unconvincing, because no sane DBA would run with such a
small value of vacuum_freeze_min_age.

regards, tom lane