Re: Missing comments/docs about custom scan path

From: Etsuro Fujita <etsuro(dot)fujita(at)gmail(dot)com>
To: Richard Guo <guofenglinux(at)gmail(dot)com>
Cc: Pg Hackers <pgsql-hackers(at)postgresql(dot)org>
Subject: Re: Missing comments/docs about custom scan path
Date: 2023-08-30 09:07:59
Message-ID: CAPmGK16M-Arhb4jhwtFe0vmqEn4dk8myN248T6d_e19ZWakO4A@mail.gmail.com
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Hi Richard,

On Wed, Aug 30, 2023 at 11:05 AM Richard Guo <guofenglinux(at)gmail(dot)com> wrote:
> On Tue, Aug 29, 2023 at 5:08 PM Etsuro Fujita <etsuro(dot)fujita(at)gmail(dot)com> wrote:
>> Another thing I would like to propose is minor adjustments to the docs
>> related to parallel query:
>>
>> A custom scan provider will typically add paths for a base relation by
>> setting the following hook, which is called after the core code has
>> generated all the access paths it can for the relation (except for
>> Gather paths, which are made after this call so that they can use
>> partial paths added by the hook):
>>
>> For clarity, I think "except for Gather paths" should be "except for
>> Gather and Gather Merge paths".
>>
>> Although this hook function can be used to examine, modify, or remove
>> paths generated by the core system, a custom scan provider will
>> typically confine itself to generating CustomPath objects and adding
>> them to rel using add_path.
>>
>> For clarity, I think "adding them to rel using add_path" should be eg,
>> "adding them to rel using add_path, or using add_partial_path if they
>> are partial paths".

> +1. I can see that this change makes the doc more consistent with the
> comments in set_rel_pathlist.

Agreed.

I have committed the patch. Thanks for taking a look!

Best regards,
Etsuro Fujita

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