Hi Peter,
On 08/16/2018 03:48 PM, Peter Geoghegan wrote:
> On Wed, Aug 15, 2018 at 11:22 PM, Thomas Munro
> <thomas.munro@enterprisedb.com> wrote:
>> * groups and certain aggregates (MIN() and MAX() of suffix index
>> columns within each group)
>> * index scans where the scan key doesn't include the leading columns
>> (but you expect there to be sufficiently few values)
>> * merge joins (possibly the trickiest and maybe out of range)
>
> FWIW, I suspect that we're going to have the biggest problems in the
> optimizer. It's not as if ndistinct is in any way reliable. That may
> matter more on average than it has with other path types.
>
Thanks for sharing this; it is very useful to know.
Best regards,
Jesper
