| From: | Andrei Lepikhov <lepihov(at)gmail(dot)com> |
|---|---|
| To: | David Rowley <dgrowleyml(at)gmail(dot)com> |
| Cc: | pgsql-hackers(at)postgresql(dot)org, tomas(at)vondra(dot)me |
| Subject: | Re: Incremental Sort Cost Estimation Instability |
| Date: | 2024-11-11 14:10:47 |
| Message-ID: | a75528f4-6d5b-406a-8352-fbcdcff0418e@gmail.com |
| Views: | Raw Message | Whole Thread | Download mbox | Resend email |
| Thread: | |
| Lists: | pgsql-hackers |
Hi,
Revising the patch I found out that it may make sense to teach
estimate_num_groups to process a PathKey node inside the presortedExprs
list.
In this case it can pass through the EquivalenceClass members and choose
correct number of distinct values.
Here is a sketch of the solution (see in attachment).
--
regards, Andrei Lepikhov
| Attachment | Content-Type | Size |
|---|---|---|
| 0001-Improve-group-number-estimation.patch | text/x-patch | 11.4 KB |
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