Re: nested-xacts cursors (was Re: Performance with new

From: Oliver Jowett <oliver(at)opencloud(dot)com>
To: Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us>
Cc: Alvaro Herrera <alvherre(at)dcc(dot)uchile(dot)cl>, pgsql-hackers(at)postgresql(dot)org
Subject: Re: nested-xacts cursors (was Re: Performance with new
Date: 2004-07-05 08:35:47
Message-ID: 40E912E3.9000103@opencloud.com
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Tom Lane wrote:

> BTW, I've been more or less ignoring the nearby debate about whether
> cursors ought to roll back at subxact abort or not, because right now
> I don't know how to implement *either* behavior. Unless we have
> credible theories about how to implement both, it's a bit useless to
> debate which is better.

If/when you have a choice -- the JDBC driver code gets easier if you
don't roll back at abort. If rollback of cursor state can happen, then
the driver will need to preserve client-side state associated with each
cursor (i.e. the driver's idea of its position) at the start of each
subtransaction so it can restore it on rollback -- or always use FETCH
ABSOLUTE (which I think needs SCROLL cursors?)

-O

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