Re: [BUG] Failed Assertion in ReorderBufferChangeMemoryUpdate()

From: Amit Kapila <amit(dot)kapila16(at)gmail(dot)com>
To: Dilip Kumar <dilipbalaut(at)gmail(dot)com>
Cc: "Drouvot, Bertrand" <bdrouvot(at)amazon(dot)com>, PostgreSQL Hackers <pgsql-hackers(at)lists(dot)postgresql(dot)org>
Subject: Re: [BUG] Failed Assertion in ReorderBufferChangeMemoryUpdate()
Date: 2021-09-07 03:08:47
Message-ID: CAA4eK1KDYWp4mtCOpGymMHXd1oi_Wqy+LS7X-NwpF=pp2MSJSg@mail.gmail.com
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On Mon, Sep 6, 2021 at 9:14 PM Dilip Kumar <dilipbalaut(at)gmail(dot)com> wrote:
>
> On Mon, Sep 6, 2021 at 8:54 PM Drouvot, Bertrand <bdrouvot(at)amazon(dot)com> wrote:
>>
>> Thanks for your feedback!
>>
>> That seems indeed more logical, so I see 3 options to do so:
>>
>> 1) Add a new API say ReorderBufferChangeMemorySubstractSize() (with a Size as one parameter) and make use of it in ReorderBufferToastReplace()
>>
>> 2) Add a new "Size" parameter to ReorderBufferChangeMemoryUpdate(), so that if this parameter is > 0 then it would be used instead of "sz = ReorderBufferChangeSize(change)"
>>
>> 3) Do the substraction directly into ReorderBufferToastReplace() without any API
>>
>> I'm inclined to go for option 2), what do you think?
>

Isn't it better if we use option 2) at all places as then we won't
need any special check inside ReorderBufferChangeMemoryUpdate()?

> Yet another option could be to create a new API say ReorderBufferReplaceChangeMemoryUpdate(), which takes, 2 parameters, oldchange, and newchange as inputs, it will compute the difference and add/subtract that size. Logically, that is what we are actually trying to do right? i.e. replacing old change with the new change.
>

Note that in ReorderBufferToastReplace(), the new tuple is replaced in
change so by the time we want to do this computation oldchange won't
be preserved.

--
With Regards,
Amit Kapila.

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