From: | Andy Fan <zhihuifan1213(at)163(dot)com> |
---|---|
To: | Nikita Malakhov <hukutoc(at)gmail(dot)com> |
Cc: | Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us>, PostgreSQL Hackers <pgsql-hackers(at)postgresql(dot)org>, David Rowley <dgrowley(at)gmail(dot)com>, Tomas Vondra <tomas(at)vondra(dot)me> |
Subject: | Re: detoast datum into the given buffer as a optimization. |
Date: | 2024-10-29 23:47:06 |
Message-ID: | 87o7328oat.fsf@163.com |
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Lists: | pgsql-hackers |
Nikita Malakhov <hukutoc(at)gmail(dot)com> writes:
> Hi!
>
> Sorry for misguiding you, I've overlooked va_rawsize with va_extinfo.
> You're right, va_rawsize holds uncompressed size, and extinfo actual
> storage size. This was not intentional.
That's OK, so we are in the same page here.
> I'd better not count on caller's do know detoasted data length,
> and much more the buffer is correctly initialized, because we cannot
> check that inside and must rely on the caller, which would for sure
> lead to unexpected segfaults, I agree with Tom Lane's proposal above.
> Other options seem to be more crude and error-prone here. This is
> an internal data fetching function and it should not generate new kinds
> of errors, I think.
Tom'sreply depends on the fact I was going to changing the "detoast_attr"
to "detoast_attr_buffer", as I have expalined in my previous post. I
don't think a [new] user provided buffer function is so harmful. What
do you think about function "text_to_string_buffer"? This is also a
part in my previous reply, but is ignored by your reply?
> In case you're playing with this part of the code - I was always
> confused with detoast_attr and detoast_external_attr functions
> both marked as entry points of retrieving toasted data and both
> look a lot the same. Have you ever thought of making a single
> entry point by slightly redesigning this part?
You can check [1] for a indepent improvements for this topic.
[1] https://www.postgresql.org/message-id/874j4vcspl.fsf%40163.com
--
Best Regards
Andy Fan
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