| From: | Jesper Pedersen <jesper(dot)pedersen(at)redhat(dot)com> |
|---|---|
| To: | Peter Geoghegan <pg(at)bowt(dot)ie> |
| Cc: | Thomas Munro <thomas(dot)munro(at)enterprisedb(dot)com>, Bhushan Uparkar <bhushan(dot)uparkar(at)gmail(dot)com>, pgsql-hackers <pgsql-hackers(at)postgresql(dot)org>, Alexander Korotkov <a(dot)korotkov(at)postgrespro(dot)ru> |
| Subject: | Re: Index Skip Scan |
| Date: | 2018-08-17 17:15:46 |
| Message-ID: | 9f2a0339-7d4a-e632-2ad6-237b24a95fa6@redhat.com |
| Views: | Raw Message | Whole Thread | Download mbox | Resend email |
| Thread: | |
| Lists: | pgsql-hackers |
Hi Peter,
On 08/16/2018 03:48 PM, Peter Geoghegan wrote:
> On Wed, Aug 15, 2018 at 11:22 PM, Thomas Munro
> <thomas(dot)munro(at)enterprisedb(dot)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
| From | Date | Subject | |
|---|---|---|---|
| Next Message | Tomas Vondra | 2018-08-17 17:29:32 | Re: [PATCH] Improve geometric types |
| Previous Message | Emre Hasegeli | 2018-08-17 16:40:44 | Re: [PATCH] Improve geometric types |