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From: Japin Li <[email protected]>
To: Chao Li <[email protected]>
Cc: PostgreSQL Hackers <[email protected]>
Subject: Re: Use SMgrRelation instead of SMgrRelationData * in pgaio_io_set_target_smgr()
Date: Mon, 16 Mar 2026 10:31:23 +0800
Message-ID: <SY7PR01MB10921042E8A0C0EAD8310D0EAB640A@SY7PR01MB10921.ausprd01.prod.outlook.com> (raw)
In-Reply-To: <[email protected]>
References: <SY7PR01MB10921D0F6F3C2682570D6C31BB645A@SY7PR01MB10921.ausprd01.prod.outlook.com>
	<[email protected]>
	<SY7PR01MB10921122C8059E98C4923FE1CB642A@SY7PR01MB10921.ausprd01.prod.outlook.com>
	<[email protected]>

On Mon, 16 Mar 2026 at 08:50, Chao Li <[email protected]> wrote:
>> On Mar 14, 2026, at 11:07, Japin Li <[email protected]> wrote:
>> 
>> 
>> Hi, Chao
>> 
>> On Fri, 13 Mar 2026 at 15:29, Chao Li <[email protected]> wrote:
>>>> On Mar 13, 2026, at 15:05, Japin Li <[email protected]> wrote:
>>>> 
>>>> 
>>>> Hi, hackers
>>>> 
>>>> While reading smgr.h, I noticed an inconsistent type usage in
>>>> pgaio_io_set_target_smgr(). Currently the function is declared as:
>>>> 
>>>>   extern void pgaio_io_set_target_smgr(PgAioHandle *ioh,
>>>>                                        SMgrRelationData *smgr,
>>>>                                        ForkNumber forknum,
>>>>                                        BlockNumber blocknum,
>>>>                                        int nblocks,
>>>> 
>>>> However, SMgrRelation is defined as "typedef SMgrRelationData * SMgrRelation;",
>>>> and all other functions in the smgr subsystem use SMgrRelation as the parameter
>>>> type.
>>>> 
>>>> To keep the code consistent with the rest of the smgr API, this patch changes
>>>> the parameter from SMgrRelationData * to SMgrRelation in both the definition
>>>> and declaration.
>>>> 
>>>> This is purely a style/consistency cleanup with no functional change.
>>>> 
>>>> Thoughts? Is this change acceptable?
>>>> 
>>>> -- 
>>>> Regards,
>>>> Japin Li
>>>> ChengDu WenWu Information Technology Co., Ltd.
>>>> 
>>>> <v1-0001-Use-SMgrRelation-instead-of-SMgrRelationData-in-p.patch>
>>> 
>>> pgaio_io_set_target_smgr doesn’t update smgr, so, instead of “SMgrRelation”,  I think it’s better to change the type to "const SMgrRelationData *”.
>> 
>> Thanks for the review! Makes sense — I've updated the patch to v2.
>> 
>> -- 
>> Regards,
>> Japin Li
>> ChengDu WenWu Information Technology Co., Ltd.
>> 
>> <v2-0001-Use-SMgrRelation-instead-of-SMgrRelationData-in-p.patch>
>
> “const SMgrRelation *” will not work as you expected, you have to do “const SMgrRelationData *”. We want to protect the data the pointer pointing to from changing but the pointer itself.

Thanks for pointing that out!  I hadn't noticed the difference before.
Updated as you suggested.

>
> Best regards,
> --
> Chao Li (Evan)
> HighGo Software Co., Ltd.
> https://www.highgo.com/

-- 
Regards,
Japin Li
ChengDu WenWu Information Technology Co., Ltd.

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