Message-ID: <32dc1fe9-175a-4894-b4c4-c6cdc6a76a16@gmail.com>
Date: Thu, 18 Sep 2025 09:55:57 +0200
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Subject: Re: Why isn't PG using an index-only scan?
To: David Rowley <dgrowleyml@gmail.com>,
 Jean-Christophe BOGGIO <postgresql@thefreecat.org>
Cc: "pgsql-performance@lists.postgresql.org"
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 <CAApHDvoUdvw68oHnfACQE=u8XPJ+Te49dZsfC2yW+DVfzdT2+Q@mail.gmail.com>
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From: Andrei Lepikhov <lepihov@gmail.com>
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On 18/9/2025 09:20, David Rowley wrote:
> On Thu, 18 Sept 2025 at 18:36, Jean-Christophe BOGGIO
> If it still takes a long time, you might try SET enable_mergejoin = 0;
> and run the EXPLAIN ANALYZE SELECT .. part.  That'll at least give us
> more accurate row counts of what we're actually working with.This appears to be a good example of a missing feature: the in-execution 
callback or hook.
Imagine if we had a hook within the ExecProcNode. In that scenario, we 
could create a trivial extension that would stop the query after, let's 
say, 10 minutes of execution and display the current state. This would 
give us more reliable data on estimation and the state of the plan tree.

What are your thoughts?

-- 
regards, Andrei Lepikhov