pg.ddx.io pgsql-hackers@postgresql.org mailing list archive help / color / mirror / Atom feed From: Andy Fan <zhihuifan1213@163.com>
To: Tomas Vondra <tomas.vondra@enterprisedb.com>
Cc: Nikita Malakhov <hukutoc@gmail.com>
Cc: Michael Zhilin <m.zhilin@postgrespro.ru>
Cc: Peter Smith <smithpb2250@gmail.com>
Cc: vignesh C <vignesh21@gmail.com>
Cc: Matthias van de Meent <boekewurm+postgres@gmail.com>
Cc: pgsql-hackers@lists.postgresql.org
Subject: Re: Shared detoast Datum proposal
Date: Mon, 04 Mar 2024 09:29:53 +0800
Message-ID: <87v862dbht.fsf@163.com> (raw )
In-Reply-To: <d2e3ef5c-ac09-4b10-a99f-4c964b490f8c@enterprisedb.com >
References: <87il4jrk1l.fsf@163.com >
<87wmskm9qu.fsf@163.com >
<CAHut+PsehMtwQ4uE9VS2C7jB1yT0SZVOPU22u1=ma1K7dKFUow@mail.gmail.com >
<87v87kvboq.fsf@163.com >
<71321d83-391b-473b-aaf6-618c7f682b96@postgrespro.ru >
<87r0i7vos3.fsf@163.com >
<874je3hcwn.fsf@163.com >
<c066e988-38b9-460f-9e9d-aedd2482bff2@enterprisedb.com >
<8734tmg88e.fsf@163.com >
<7f4c8673-4c5d-4dbf-b8e5-0ec11cd2fba0@enterprisedb.com >
<87h6i2djf9.fsf@163.com >
<87jzms0xza.fsf@163.com >
<CAN-LCVMU_AzYNDQ-MgX3xc5qCnhTgO1LWKUCygOu3neBM-y94g@mail.gmail.com >
<87frxf1gld.fsf@163.com >
<fea81484-09b5-499d-80d0-acb8df43d047@enterprisedb.com >
<CAN-LCVPv1f0DKk9UvpJ_OnY6CcpNvo7M-RkZVfLi7xRGdBNjqQ@mail.gmail.com >
<871q8z19ux.fsf@163.com >
<CAN-LCVON0vAr6tyiK4jsLmkCPd6PxkfxzXDyG8rjM9t3jOVM6g@mail.gmail.com >
<87msrgdq93.fsf@163.com >
<87frx7et1j.fsf@163.com >
<d2e3ef5c-ac09-4b10-a99f-4c964b490f8c@enterprisedb.com >
Tomas Vondra <tomas.vondra@enterprisedb.com> writes:
> On 3/3/24 07:10, Andy Fan wrote:
>>
>> Hi,
>>
>> Here is a updated version, the main changes are:
>>
>> 1. an shared_detoast_datum.org file which shows the latest desgin and
>> pending items during discussion.
>> 2. I removed the slot->pre_detoast_attrs totally.
>> 3. handle some pg_detoast_datum_slice use case.
>> 4. Some implementation improvement.
>>
>
> I only very briefly skimmed the patch, and I guess most of my earlier
> comments still apply.
Yes, the overall design is not changed.
> But I'm a bit surprised the patch needs to pass a
> MemoryContext to so many places as a function argument - that seems to
> go against how we work with memory contexts. Doubly so because it seems
> to only ever pass CurrentMemoryContext anyway. So what's that about?
I think you are talking about the argument like this:
/* ----------
- * detoast_attr -
+ * detoast_attr_ext -
*
* Public entry point to get back a toasted value from compression
* or external storage. The result is always non-extended varlena form.
*
+ * ctx: The memory context which the final value belongs to.
+ *
* Note some callers assume that if the input is an EXTERNAL or COMPRESSED
* datum, the result will be a pfree'able chunk.
* ----------
*/
+extern struct varlena *
+detoast_attr_ext(struct varlena *attr, MemoryContext ctx)
This is mainly because 'detoast_attr' will apply more memory than the
"final detoast datum" , for example the code to scan toast relation
needs some memory as well, and what I want is just keeping the memory
for the final detoast datum so that other memory can be released sooner,
so I added the function argument for that.
--
Best Regards
Andy Fan
view thread (53+ messages) latest in thread
Message-ID: <87v862dbht.fsf@163.com>
Permalink: ../87v862dbht.fsf@163.com/
Also on: postgresql.org/message-id/87v862dbht.fsf@163.com
copy link · copy postgr.es
reply Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Reply to all the recipients using the --to and --cc options:
reply via email
To: pgsql-hackers@postgresql.org
Cc: zhihuifan1213@163.com, tomas.vondra@enterprisedb.com, hukutoc@gmail.com, m.zhilin@postgrespro.ru, smithpb2250@gmail.com, vignesh21@gmail.com, boekewurm+postgres@gmail.com, pgsql-hackers@lists.postgresql.org
Subject: Re: Shared detoast Datum proposal
In-Reply-To: <87v862dbht.fsf@163.com>
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
This inbox is served by DDX for PostgreSQL; see mirroring instructions
for how to clone and mirror all data and code used for this inbox