"Raymond O'Donnell" <rod@iol.ie> writes:
> Is it just me? :-) from time to time I get repeat broadcasts from
> various PG mailing lists - posts that I've already received several days
> previously are sent again.
There are people on the lists with broken mail software that resubmits
old traffic back to the list. The listserv has some defenses against
that --- it's supposed to reject message-ids that it's seen before ---
but count on Microsoft to mangle mail messages badly enough to get
around that.
The latest example, which I too just got, looks on inspection of the
headers to be blamable on <wavey@intercom.net>. The time delay suggests
it was held for moderation, so maybe the software *did* recognize it as
a dup and it was moderator error to let it through.
regards, tom lane
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Date: Tue, 14 Aug 2007 13:59:43 -0500
From: "Scott Marlowe" <scott.marlowe@gmail.com>
To: RPK <rpk.general@gmail.com>
Subject: Re: [GENERAL] MVCC cons
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On 8/14/07, RPK <rpk.general@gmail.com> wrote:
>
> I want to know whether MVCC has cons also. Is it heavy on resources? How
> PGSQL MVCC relates with SQL Server 2005 new Snapshot Isolation.
Of course it does. There ain't no such thing as a free lunch, after all.
PostgreSQL's mvcc implementation means that a row that gets updated a
lot may have many dead rows in the database, and if you don't run
vacuum often enough, or have enough space allocated in your free space
map, your tables can become bloated.
In a worst case scenario, a highly updated table may get so big that
normal vacuuming cannot salvage it and you would have to either
reindex or perform a vacuum full on it.
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