From: | Dimitri <dimitrik(dot)fr(at)gmail(dot)com> |
---|---|
To: | Kevin Grittner <Kevin(dot)Grittner(at)wicourts(dot)gov> |
Cc: | Alexandre de Arruda Paes <adaldeia(at)gmail(dot)com>, pgsql-performance(at)postgresql(dot)org |
Subject: | Re: Fwd: Vacuum Full + Cluster + Vacuum full = non removable dead rows |
Date: | 2010-08-21 08:25:45 |
Message-ID: | AANLkTinpa+932QM7c8SxhkAY4Gr7RHFb_F_HHX+T3J64@mail.gmail.com |
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Lists: | pgsql-performance |
So, does it mean that VACUUM will never clean dead rows if you have a
non-stop transactional activity in your PG database???... (24/7 OLTP
for ex.)
Rgds,
-Dimitri
On 8/19/10, Kevin Grittner <Kevin(dot)Grittner(at)wicourts(dot)gov> wrote:
> Alexandre de Arruda Paes <adaldeia(at)gmail(dot)com> wrote:
>> 2010/8/18 Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us>
>
>>> There's an open transaction somewhere that VACUUM is preserving
>>> the tuples for. This transaction need not ever have touched the
>>> table, or ever intend to touch the table --- but VACUUM cannot
>>> know that, so it saves any tuples that the transaction might be
>>> entitled to see if it looked.
>>>
>>> > carmen=# select * from vlocks where relname='tp93t'; select *
>>> > from pg_stat_activity where usename='webpa';
>>>
>>> You keep on showing us only subsets of pg_stat_activity :-(
>
>> select * from pg_stat_activity where usename='webpa';
>
> You keep on showing us only subsets of pg_stat_activity :-(
>
> *ANY* open transaction, including "idle in transaction" including
> transactions by other users in other databases will prevent vacuum
> from cleaning up rows, for the reasons Tom already gave you.
>
> What do you get from?:
>
> select * from pg_stat_activity where current_query <> '<IDLE>'
> order by xact_start limit 10;
>
> -Kevin
>
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