Re: More stable query plans via more predictable column statistics

On Mon, Mar 7, 2016 at 6:02 PM, Jeff Janes <jeff(dot)janes(at)gmail(dot)com> wrote:

> On Mon, Mar 7, 2016 at 3:17 AM, Shulgin, Oleksandr
> <oleksandr(dot)shulgin(at)zalando(dot)de> wrote:
> >
> > They might get that different plan when they upgrade to the latest major
> > version anyway. Is it set somewhere that minor version upgrades should
> > never affect the planner? I doubt so.
>
> People with meticulous standards are expected to re-validate their
> application, including plans and performance, before doing major
> version updates into production. They can continue to use a *fully
> patched* server from a previous major release while they do that.
>
> This is not the case for minor version updates. We do not want to put
> people in the position where getting a security or corruption-risk
> update forces them to also accept changes which may destroy the
> performance of their system.
>
> I don't know if it is set out somewhere else, but there are many
> examples in this list of us declining to back-patch performance bug
> fixes which might negatively impact some users. The only times we
> have done it that I can think of are when there is almost no
> conceivable way it could have a meaningful negative effect, or if the
> bug was tied in with security or stability bugs that needed to be
> fixed anyway and couldn't be separated.
>

The necessity to perform security upgrades is indeed a valid argument
against back-patching this, since this is not a bug that causes incorrect
results or data corruption, etc.

Thank you all for the thoughtful replies!
--
Alex