| From: | Ilia Evdokimov <ilya(dot)evdokimov(at)tantorlabs(dot)com> |
|---|---|
| To: | Andrei Lepikhov <lepihov(at)gmail(dot)com>, David Rowley <dgrowleyml(at)gmail(dot)com> |
| Cc: | Robert Haas <robertmhaas(at)gmail(dot)com>, Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us>, Lukas Fittl <lukas(at)fittl(dot)com>, Daniel Gustafsson <daniel(at)yesql(dot)se>, PostgreSQL Hackers <pgsql-hackers(at)lists(dot)postgresql(dot)org>, Nikolay Samokhvalov <samokhvalov(at)gmail(dot)com> |
| Subject: | Re: Add estimated hit ratio to Memoize in EXPLAIN to explain cost adjustment |
| Date: | 2025-05-01 19:10:56 |
| Message-ID: | 14a42b49-f733-41ba-9cde-8669984116e6@tantorlabs.com |
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| Lists: | pgsql-hackers |
On 01.05.2025 16:37, Andrei Lepikhov wrote:
> I still think that two meaningful digits are enough for an EXPLAIN. We
> usually need to estimate the tuple set's size, not a precise number of
> tuples or groups. And definitely, not an arbitrarily chosen two digits
> after the point. So, IMO, good examples may look like the following:
> 50%, 5.0%, 0.00051%.
>
The idea is not bad. But I think it might be better to raise this in a
new thread, because this is not the only place [0] where we might want
to output numbers like that. We could also discuss there what else might
benefit from such formatting.
[0]:
https://www.postgresql.org/message-id/3365160.1739385615%40sss.pgh.pa.us
--
Best regards,
Ilia Evdokimov,
Tantor Labs LLC.
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