Re: explain analyze rows=%.0f - Mailing list pgsql-hackers

From Andrey Lepikhov
Subject Re: explain analyze rows=%.0f
Date
Msg-id a9393107-6bb9-c835-50b7-c0f453a514b8@postgrespro.ru
Whole thread Raw
In response to Re: explain analyze rows=%.0f  (Amit Kapila <amit.kapila16@gmail.com>)
List pgsql-hackers
On 22/7/2022 16:47, Amit Kapila wrote:
> I feel the discussion has slightly deviated which makes it unclear
> whether this patch is required or not?

After quick review I want to express my thoughts.
At first, We have been waiting for this feature for years. Often clients 
give an explain to us where we see something like:
"rows=0, loops=1000000".
Without verbose mode, I can't even understand whether this node produces 
any rows or not.
So, I think this feature is useful for parameterized plans mostly.
Also, printing two decimal digits or even three isn't meaningful - 
sometimes we have a plan where number of loops is about 1E6 or even 1E7, 
but number of real rows is equal 100 or 1000.
To overcome this issue, I see two options:
1. Show the exact number of tuples without division by loops (fair case 
but invasive and bad for automation tools).
2. Show rows in scientific format like X.XXEXX.
I vote for second option.

-- 
regards,
Andrey Lepikhov
Postgres Professional




pgsql-hackers by date:

Previous
From: Amit Kapila
Date:
Subject: Re: Perform streaming logical transactions by background workers and parallel apply
Next
From: Masahiko Sawada
Date:
Subject: Re: Perform streaming logical transactions by background workers and parallel apply