From: | Shridhar Daithankar <shridhar_daithankar(at)persistent(dot)co(dot)in> |
---|---|
To: | Alvaro Herrera <alvherre(at)dcc(dot)uchile(dot)cl> |
Cc: | pgsql-hackers(at)postgresql(dot)org |
Subject: | Re: Some thoughts about i/o priorities and throttling vacuum |
Date: | 2003-10-17 14:25:44 |
Message-ID: | 3F8FFBE8.2090007@persistent.co.in |
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Lists: | pgsql-hackers |
Alvaro Herrera wrote:
> On Fri, Oct 17, 2003 at 07:41:38PM +0530, Shridhar Daithankar wrote:
>
>>Alvaro Herrera wrote:
>>
>>
>>>On Fri, Oct 17, 2003 at 07:04:45PM +0530, Shridhar Daithankar wrote:
>
>
>>>The database can suffer XID wraparound anyway if there's at least one
>>>table without updates, because the autovacuum daemon will never vacuum
>>>it (correct me if I'm wrong).
>>
>>If a table is never updated and hence not vacuumed at all, why would it be
>>involved in a transaction that would have xid wrap around?
>
>
> Because the tuples on it were involved in some insert operation at some
> time (else the table would not have any tuples). So it _has_ to be
> vacuumed, else you run the risk of losing the tuples when the wraparound
> happens. (Sorry, I don't know how to explain this better.)
OK. So here is what I understand. I have a table which contains 100 rows which
appeated there due to some insert operation. Then I vacuum it. And sit there for
internity for rest of the database to approach the singularity(the xid
wraparound..:-) Nice term, isn't it?).
So this static table is vulnerable to xid wraparound? I doubt.
Did I miss something?
Shridhar
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