On 09/01/2019 22:01, Daniel Verite wrote: >> I don't see anything wrong here. The collation says that both values >> are equal, so which one is returned is implementation-dependent. > Is it, but it's impractical if the product of seemingly the same GROUP BY > flip-flops between its different valid results. If it can't be avoided, then > okay. If it can be avoided at little cost, then it would be better to do it.
But there is no concept of which one of these is the preferred variant, so I don't see how the system is supposed to pick one and then stick to it across separate query invocations. -- Peter Eisentraut http://www.2ndQuadrant.com/ PostgreSQL Development, 24x7 Support, Remote DBA, Training & Services
