| From: | Masahiko Sawada <sawada(dot)mshk(at)gmail(dot)com> |
|---|---|
| To: | Andres Freund <andres(at)anarazel(dot)de> |
| Cc: | Robert Haas <robertmhaas(at)gmail(dot)com>, Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us>, Thomas Munro <thomas(dot)munro(at)enterprisedb(dot)com>, Amit Kapila <amit(dot)kapila16(at)gmail(dot)com>, PostgreSQL-development <pgsql-hackers(at)postgresql(dot)org> |
| Subject: | Re: [HACKERS] Moving relation extension locks out of heavyweight lock manager |
| Date: | 2017-12-13 08:57:42 |
| Message-ID: | CAD21AoBz3Yd7RYUZh0WEdXXisNKGxOJWauamwR_U1HfQ-W-tLA@mail.gmail.com |
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| Lists: | pgsql-hackers |
On Wed, Dec 13, 2017 at 4:30 PM, Andres Freund <andres(at)anarazel(dot)de> wrote:
> On 2017-12-13 16:02:45 +0900, Masahiko Sawada wrote:
>> When we add extra blocks on a relation do we access to the disk? I
>> guess we just call lseek and write and don't access to the disk. If so
>> the performance degradation regression might not be much.
>
> Usually changes in the file size require the filesystem to perform
> metadata operations, which in turn requires journaling on most
> FSs. Which'll often result in synchronous disk writes.
>
Thank you. I understood the reason why this measurement should use two
different filesystems.
Regards,
--
Masahiko Sawada
NIPPON TELEGRAPH AND TELEPHONE CORPORATION
NTT Open Source Software Center
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