Re: Interesting glitch in autovacuum

On Wed, Sep 10, 2008 at 9:22 PM, Tom Lane  wrote:

>
> On reflection I'm not even sure that this is strictly an autovacuum
> bug.  It can be cast more generically as "RecentGlobalXmin getting
> used without ever having been set", and it sure looks to me like the
> HOT patch may have introduced a few risks of that sort.
>

ISTM that HOT may be safe here because even if RecentGlobalXmin is not
set and has the boot time value of FirstNormalTransactionId, the
heap_page_prune_opt() would just return without doing any real work.
This is OK except in VACUUM where we anyways use OldestXmin. So I
don't see a real problem here. But its good to fix the larger problem
as per the suggestion.

Thanks,
Pavan

-- 
Pavan Deolasee
EnterpriseDB http://www.enterprisedb.com