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From: Chao Li <[email protected]>
To: Japin 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 11:14:57 +0800
Message-ID: <[email protected]> (raw)
In-Reply-To: <SY7PR01MB10921042E8A0C0EAD8310D0EAB640A@SY7PR01MB10921.ausprd01.prod.outlook.com>
References: <SY7PR01MB10921D0F6F3C2682570D6C31BB645A@SY7PR01MB10921.ausprd01.prod.outlook.com>
	<[email protected]>
	<SY7PR01MB10921122C8059E98C4923FE1CB642A@SY7PR01MB10921.ausprd01.prod.outlook.com>
	<[email protected]>
	<SY7PR01MB10921042E8A0C0EAD8310D0EAB640A@SY7PR01MB10921.ausprd01.prod.outlook.com>



> On Mar 16, 2026, at 10:31, Japin Li <[email protected]> wrote:
> 
> 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.
> 
> <v3-0001-Add-the-const-qualifier-to-the-SMgrRelationData-p.patch>

V3 LGTM.

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

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