Re: ALTER TABLE lock strength reduction patch is unsafe

On 27 January 2014 20:35, Peter Geoghegan <pg(at)heroku(dot)com> wrote:
> On Mon, Jan 27, 2014 at 12:25 PM, Robert Haas <robertmhaas(at)gmail(dot)com> wrote:
>> I haven't reviewed the patch, but -1 for adding a GUC.
>
> I'm pretty surprised that it's been suggested that some people might
> prefer AccessExclusiveLocks. Why would anyone prefer that?

Nobody has said "prefer". I said...

> Some people may be surprised
> that their programs don't wait in the same places they used to. We
> hope that is a positive and useful behaviour, but it may not always be
> so.

We get the new behaviour by default and I expect we'll be very happy with it.

A second thought is that if we have problems of some kind in the field
as a result of the new lock modes then we will be able to turn them
off. I'm happy to fix any problems that occur, but that doesn't mean
there won't be any. If everybody is confident that we've foreseen
every bug, then no problem, lets remove it. I recall being asked to
add hot_standby = on | off for similar reasons.

--
Simon Riggs http://www.2ndQuadrant.com/
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