On 04/30/2015 01:57 PM, Robert Haas wrote:
>
> 2. There should be a compatibility GUC to restore the old behavior.
> The new behavior should be the default, because if we're not confident
> that the new behavior will be better for most people, we have no
> business installing it in the first place (plus few people will try
> it). But just in case it turns out to suck for some people, we should
> provide an escape hatch, at least for a few releases.
You can override the ndistinct estimate with ALTER TABLE. I think that's
enough for an escape hatch.
- Heikki