Thread

Re: Add estimated hit ratio to Memoize in EXPLAIN to explain cost adjustment

Ilia Evdokimov <ilya.evdokimov@tantorlabs.com> — 2025-05-01T12:22:34Z

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.