Re: A long-running transaction

On Fri, Apr 13, 2007 at 12:42:36PM -0400, Joe wrote:
>
> Just curious: is there a way to defeat MVCC?

No. That is,

> i.e., if you can lock the
> database exclusively, there won't be any readers or writers?

while this is true, it doesn't shut off the way writes go through the
system. MVCC is rather close to the central guts of PostgreSQL.

If you want to understand more about why this is the case, what the
trade-off considerations are, &c., then I stronly advise you to troll
through the -hackers archives. Approximately once every 8-10 months
someone comes along with an idea for a change that disables MVCC in
just this or that case. Most of the time, the actual effects of this
are different than people think they will be -- concurrency is hard,
and making changes so that it's impossible to get into a race is
tricky. This is why the in-place storage management that
EnterpriseDB contributed was both somewhat controversial and somewhat
limited in its application.

A

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