From: Shinya Okano <btokanosn@oss.nttdata.com>
To: Fujii Masao <masao.fujii@oss.nttdata.com>
To: Kasahara Tatsuhito <kasahara.tatsuhito@gmail.com>
Cc: pgsql-hackers <pgsql-hackers@postgresql.org>
Subject: Re: Add a description to the documentation that toast_tuple_target affects "Main"
Date: Wed, 14 Oct 2020 16:21:37 +0900
Message-ID: <cfe3c1f5f0987c70ddde187d411739e3@oss.nttdata.com> (raw)
In-Reply-To: <a4941ace-b898-3bd4-270f-2ccc1dc2af07@oss.nttdata.com>
References: <93f46e311a67422e89e770d236059817@oss.nttdata.com>
<CAP0=ZVJ9Wh2RnphL4nB6PuhODCxeMBBkzg3=5oSu+1FMOaNK6Q@mail.gmail.com>
<a4941ace-b898-3bd4-270f-2ccc1dc2af07@oss.nttdata.com>
On 2020-10-14 01:30, Fujii Masao wrote:
> On 2020/10/13 10:40, Kasahara Tatsuhito wrote:
>> On Fri, Oct 9, 2020 at 5:44 PM Shinya Okano
>> <btokanosn@oss.nttdata.com> wrote:
>>> Regarding the toast_tuple_target parameter of CREATE TABLE, the
>>> documentation says that it only affects External or Extended, but it
>>> actually affects the compression of Main as well.
>>>
>>> The attached patch modifies the document to match the actual
>>> behavior.
>> +1
>
> +1
>
> + we try to compress long column values or to move into TOAST
> tables, and
>
> "we try to compress and/or move long column values into TOAST tables,
> and" is better?
Thank you everyone for reviews.
I attached the new version of the patch.
Regards,
--
Shinya Okano
Attachments:V2-Add-Main-to-the-toast_tuple_target-doc.patch (text/x-diff, 1.3K) downloaddiff --git a/doc/src/sgml/ref/create_table.sgml b/doc/src/sgml/ref/create_table.sgmlindex 28f844071b..fd6777ae01 100644--- a/doc/src/sgml/ref/create_table.sgml+++ b/doc/src/sgml/ref/create_table.sgml@@ -1359,10 +1359,11 @@ WITH ( MODULUS <replaceable class="parameter">numeric_literal</replaceable>, REM
<listitem>
<para>
The toast_tuple_target specifies the minimum tuple length required before
- we try to move long column values into TOAST tables, and is also the- target length we try to reduce the length below once toasting begins.- This only affects columns marked as either External or Extended- and applies only to new tuples; there is no effect on existing rows.+ we try to compress and/or move long column values into TOAST tables, and+ is also the target length we try to reduce the length below once toasting+ begins. This affects columns marked as External (for move),+ Main (for compression), or Extended (for both) and applies only to new+ tuples. There is no effect on existing rows.
By default this parameter is set to allow at least 4 tuples per block,
which with the default block size will be 2040 bytes. Valid values are
between 128 bytes and the (block size - header), by default 8160 bytes.
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To: pgsql-hackers@postgresql.org
Cc: btokanosn@oss.nttdata.com, masao.fujii@oss.nttdata.com, kasahara.tatsuhito@gmail.com
Subject: Re: Add a description to the documentation that toast_tuple_target affects "Main"
In-Reply-To: <cfe3c1f5f0987c70ddde187d411739e3@oss.nttdata.com>
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