| From: | Andrei Lepikhov <lepihov(at)gmail(dot)com> |
|---|---|
| To: | Alena Rybakina <a(dot)rybakina(at)postgrespro(dot)ru> |
| Cc: | Kirill Reshke <reshkekirill(at)gmail(dot)com>, PostgreSQL Hackers <pgsql-hackers(at)lists(dot)postgresql(dot)org>, David Rowley <dgrowleyml(at)gmail(dot)com> |
| Subject: | Re: Consider the number of columns in the sort cost model |
| Date: | 2024-11-01 01:49:34 |
| Message-ID: | 86bd6d3c-c541-4047-924a-c883443c3d3f@gmail.com |
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| Lists: | pgsql-hackers |
On 10/31/24 21:00, Alena Rybakina wrote:
> On 29.10.2024 05:47, Andrei Lepikhov wrote:
> I played around with the examples a bit and couldn't figure out
> something. When I added the same values to different columns - firstly
> in a, later in b, the order of the columns for sort operation doesn't
> change. Isn't this a mistake?
This feature implements a cost-based approach to choosing the grouping
clauses' order. What kind of 'mistake' do you see here? Is there
something wrong with the costs, or do you see a bug in the cost
calculation code? Please specify your request.
--
regards, Andrei Lepikhov
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