| From: | "Pavan Deolasee" <pavan(dot)deolasee(at)gmail(dot)com> |
|---|---|
| To: | "Tom Lane" <tgl(at)sss(dot)pgh(dot)pa(dot)us> |
| Cc: | "Alvaro Herrera" <alvherre(at)commandprompt(dot)com>, pgsql-hackers(at)postgresql(dot)org |
| Subject: | Re: Interesting glitch in autovacuum |
| Date: | 2008-09-11 05:25:06 |
| Message-ID: | 2e78013d0809102225w7b0b6d83ue273b4786db1477c@mail.gmail.com |
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| Lists: | pgsql-hackers |
On Wed, Sep 10, 2008 at 9:22 PM, Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us> 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
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