Re: Commits 8de72b and 5457a1 (COPY FREEZE)

On 8 December 2012 22:18, Stephen Frost <sfrost(at)snowman(dot)net> wrote:

>> So the committed feature does address the visibility issue.
>
> Not hardly. It lets a user completely violate the basic rules of the
> overall database. The *correct* solution to this problem is to actually
> *fix* it, by setting it up such that tables created after a particular
> transaction starts aren't visible and similar.

Agreed, but that is also be a silent change of current behaviour.

But the above will only work for CREATE TABLE, not for TRUNCATE.

I've invested a lot of time in trying to improve the situation and
investigated many routes forwards, none of them very satisfying. Until
someone comes up with a better plan, FREEZE is a pragmatic way
forwards that improves things now rather than waiting for the perfect
solution. And if we want checksums anytime soon we need ways to
ameliorate the effect of hints on checksums, which this does,
soemwhat. Better plans, with code, welcome.

--
Simon Riggs http://www.2ndQuadrant.com/
PostgreSQL Development, 24x7 Support, Training & Services