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From: Mark Kirkwood <[email protected]>
To: David Rowley <[email protected]>
Cc: [email protected]
Subject: Re: Unexpected planner choice in simple JOIN
Date: Thu, 8 Jan 2026 17:03:01 +1300
Message-ID: <[email protected]> (raw)
In-Reply-To: <CAApHDvqLR27kZkK5zaK2-6LQo_RB_wnVg8DHfHj17cTbr+RHtQ@mail.gmail.com>
References: <[email protected]>
	<[email protected]>
	<CAApHDvqLR27kZkK5zaK2-6LQo_RB_wnVg8DHfHj17cTbr+RHtQ@mail.gmail.com>

I don't think so - while the case I posted used a hash index on the 
child table, exactly the sane behaviour happens if it is a btree (I 
probably should have mentioned that sorry). Background is I discovered 
this while playing about with hash indexes...which I must say - someone 
has done excellent work on as in this *particular cases* they are 
getting me better query performance!

regards

Mark

On 08/01/2026 16:56, David Rowley wrote:
> On Thu, 8 Jan 2026 at 16:34, Mark Kirkwood <[email protected]> wrote:
>> This does seem to be related to parallel planning:
> Isn't it just a case of hash indexes not allowing parallel scans?
>
> David

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