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From: Ilia Evdokimov <[email protected]>
To: Andrei Lepikhov <[email protected]>
To: David Rowley <[email protected]>
Cc: Robert Haas <[email protected]>
Cc: Tom Lane <[email protected]>
Cc: Lukas Fittl <[email protected]>
Cc: Daniel Gustafsson <[email protected]>
Cc: PostgreSQL Hackers <[email protected]>
Cc: Nikolay Samokhvalov <[email protected]>
Subject: Re: Add estimated hit ratio to Memoize in EXPLAIN to explain cost adjustment
Date: Thu, 1 May 2025 22:10:56 +0300
Message-ID: <[email protected]> (raw)
In-Reply-To: <[email protected]>
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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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