Content-Type: multipart/mixed; boundary="------------IpLq4Sds0k0Tk5RJsMrwVk3d"
Message-ID: <908b63e1-4b79-2889-98d1-1909cac39785@postgrespro.ru>
Date: Sun, 8 Dec 2024 18:00:25 +0300
MIME-Version: 1.0
User-Agent: Mozilla/5.0 (Macintosh; Intel Mac OS X 10.15; rv:91.0)
 Gecko/20100101 Thunderbird/91.9.1
Subject: Re: Parallel index build for BRIN
Content-Language: en-US
From: Egor Rogov <e.rogov@postgrespro.ru>
To: pgsql-docs@lists.postgresql.org
References: <114e2d5d-125e-07d8-94aa-5ad175fb7443@postgrespro.ru>
 <009f4101-29a2-850e-6767-72a9104ec89a@postgrespro.ru>
In-Reply-To: <009f4101-29a2-850e-6767-72a9104ec89a@postgrespro.ru>
Archived-At: 
 <https://www.postgresql.org/message-id/908b63e1-4b79-2889-98d1-1909cac39785%40postgrespro.ru>
Precedence: bulk

This is a multi-part message in MIME format.
--------------IpLq4Sds0k0Tk5RJsMrwVk3d
Content-Type: text/plain; charset=UTF-8; format=flowed
Content-Transfer-Encoding: 8bit

Hi,


On 17.11.2024 11:28, Egor Rogov wrote:
> Hi everyone,
>
> This thread doesn't seem to have attracted attention, so let me try 
> again. Two documentation pages claim that B-tree is the only access 
> method that supports parallel building, which is no longer true. I 
> propose to fix it in a way like this:
>
> diff --git a/doc/src/sgml/config.sgml b/doc/src/sgml/config.sgml
> index d54f9049569..b5b1580dee7 100644
> --- a/doc/src/sgml/config.sgml
> +++ b/doc/src/sgml/config.sgml
> @@ -2835,7 +2835,7 @@ include_dir 'conf.d'
>           Sets the maximum number of parallel workers that can be
>           started by a single utility command.  Currently, the parallel
>           utility commands that support the use of parallel workers are
> -         <command>CREATE INDEX</command> only when building a B-tree 
> index,
> +         <command>CREATE INDEX</command> when building a B-tree or 
> BRIN index,
>           and <command>VACUUM</command> without <literal>FULL</literal>
>           option.  Parallel workers are taken from the pool of processes
>           established by <xref linkend="guc-max-worker-processes"/>, 
> limited
> diff --git a/doc/src/sgml/ref/create_index.sgml 
> b/doc/src/sgml/ref/create_index.sgml
> index 621bc0e253c..208389e8006 100644
> --- a/doc/src/sgml/ref/create_index.sgml
> +++ b/doc/src/sgml/ref/create_index.sgml
> @@ -808,7 +808,7 @@ Indexes:
>     leveraging multiple CPUs in order to process the table rows faster.
>     This feature is known as <firstterm>parallel index
>     build</firstterm>.  For index methods that support building indexes
> -   in parallel (currently, only B-tree),
> +   in parallel (currently, B-tree and BRIN),
>     <varname>maintenance_work_mem</varname> specifies the maximum
>     amount of memory that can be used by each index build operation as
>     a whole, regardless of how many worker processes were started.


I've spotted another mention of B-tree being the only AM that supports 
parallel builds: comment in src/backend/catalog/index.c. As this mention 
is not visible to the users, I'd propose removing it altogether rather 
than fixing it. Updated patch is attached.


>
> Thanks,
> Egor
>
>
> On 05.11.2024 12:12, Egor Rogov wrote:
>> Hi,
>>
>> Commit b4375717 introduced parallel CREATE INDEX for BRIN. I've 
>> noticed that a couple of documentation pages need to be updated 
>> accordingly. A small patch is attached.
>>
>> Thanks,
>> Egor
--------------IpLq4Sds0k0Tk5RJsMrwVk3d
Content-Type: text/plain; charset=UTF-8;
 name="0001-Doc-and-comment-parallel-CREATE-INDEX-is-allowed-for.patch"
Content-Disposition: attachment;
 filename*0="0001-Doc-and-comment-parallel-CREATE-INDEX-is-allowed-for.pa";
 filename*1="tch"
Content-Transfer-Encoding: base64
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--------------IpLq4Sds0k0Tk5RJsMrwVk3d--