| From: | KONDO Mitsumasa <kondo(dot)mitsumasa(at)lab(dot)ntt(dot)co(dot)jp> |
|---|---|
| To: | Florian Weimer <fweimer(at)redhat(dot)com> |
| Cc: | pgsql-general(at)postgresql(dot)org |
| Subject: | Re: Bottlenecks with large number of relation segment files |
| Date: | 2013-08-06 10:28:57 |
| Message-ID: | 5200CFE9.1060001@lab.ntt.co.jp |
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| Lists: | pgsql-general pgsql-hackers |
(2013/08/05 20:38), Florian Weimer wrote:
> On 08/05/2013 10:42 AM, John R Pierce wrote:
>> On 8/5/2013 1:01 AM, KONDO Mitsumasa wrote:
>>> When we open file, ext3 or ext4 file system seems to sequential search
>>> inode for opening file in file directory.
>>
>> no, ext3/4 uses H-tree structures to search directories over 1 block
>> long quite efficiently.
>
> And the Linux dentry cache is rather aggressive, so most of the time, only the
> in-memory hash table will be consulted. (The dentry cache only gets flushed on
> severe memory pressure.)
Are you really? When I put large number of files in same directory and open,
it is very very slow. But open directory is not.
So I think it's only directory search. Not file search in same directory. And I
heard before it.
Regards,
--
Mitsumasa KONDO
NTT Open Source Software Center
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