From: Tom Lane <tgl@sss.pgh.pa.us>
To: Aleksander Alekseev <aleksander@timescale.com>
Cc: pgsql-hackers@lists.postgresql.org, Chantal Keller <chantal.keller@universite-paris-saclay.fr>
Subject: Re: Improving EXPLAIN's display of SubPlan nodes
Date: Mon, 22 Jan 2024 12:07:23 -0500
Message-ID: <3791430.1705943243@sss.pgh.pa.us> (raw)
In-Reply-To: <CAJ7c6TMApZ62NOOk73_BmKkKtdhV+i=tyvXR52DAB-YVuFANDA@mail.gmail.com>
References: <2838538.1705692747@sss.pgh.pa.us>
<CAJ7c6TMApZ62NOOk73_BmKkKtdhV+i=tyvXR52DAB-YVuFANDA@mail.gmail.com>
Aleksander Alekseev <aleksander@timescale.com> writes:
> Although something like:
> ```
> + Filter: (ANY (base_tbl.a = $1) FROM SubPlan 1 (returns $1))
> + SubPlan 1 (returns $1)
> ```
> ... arguably doesn't give much more information to the user comparing
> to what we have now:
> ```
> - Filter: (SubPlan 1)
> - SubPlan 1
> ```
Yeah, I would probably not have thought to do this on my own; but
we had an actual user request for it. I think arguably the main
benefit is to confirm "yes, this is the sub-select you think it is".
The main thing that's still missing compared to what is in the plan
data structure is information about which Param is which. I think
we have the subplan output Params relatively well covered through
the expedient of listing them in the generated plan_name, but it's
still not apparent to me how we could shoehorn subplan input
Params into this (or whether it's worth doing).
regards, tom lane
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To: pgsql-hackers@postgresql.org
Cc: tgl@sss.pgh.pa.us, aleksander@timescale.com, chantal.keller@universite-paris-saclay.fr
Subject: Re: Improving EXPLAIN's display of SubPlan nodes
In-Reply-To: <3791430.1705943243@sss.pgh.pa.us>
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