| From: | Ilia Evdokimov <ilya(dot)evdokimov(at)tantorlabs(dot)com> |
|---|---|
| To: | 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>, Andrei Lepikhov <lepihov(at)gmail(dot)com> |
| Subject: | Re: Add estimated hit ratio to Memoize in EXPLAIN to explain cost adjustment |
| Date: | 2025-05-01 12:22:34 |
| Message-ID: | 15e0422a-31ec-4e82-b0cf-0839f636b185@tantorlabs.com |
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| Lists: | pgsql-hackers |
On 27.04.2025 22:58, Ilia Evdokimov wrote:
> Therefore, I think it is better to report percentages directly. Since
> non-text EXPLAIN formats do not display units, I propose to rename the
> field to "hit_percent" in all formats, including the text format. This
> way, the meaning of the value remains clear without needing additional
> context. What do you think about this approach?
I attached updated v9 patch with the suggested changes. The updated line
in the EXPLAIN looks like this:
Text format:
Estimates: capacity=1 distinct keys=1 lookups=2 hit percent=50.00%
Non-text format:
Estimated Capacity: 1
Estimated Distinct Lookup Keys: 1
Estimated Lookups: 2
Estimated Hit Percent: 50.00
Any suggestions?
--
Best regards,
Ilia Evdokimov,
Tantor Labs LLC.
| Attachment | Content-Type | Size |
|---|---|---|
| v9-0001-Expose-cache-hit-statistics-in-Memoize-node-EXPLAIN.patch | text/x-patch | 7.3 KB |
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