From: Florian Weimer <fweimer@bfk.de>
To: pgsql-hackers@postgresql.org
Subject: Large number of open(2) calls with bulk INSERT into empty table
Date: Sun, 27 Nov 2011 15:24:34 +0000
Message-ID: <82ipm51tcd.fsf@mid.bfk.de> (raw)
I noticed that a bulk INSERT into an empty table (which has been
TRUNCATEd in the same transaction, for good measure) results in a
curious number of open(2) calls for the FSM resource fork:
open("base/657862/16554373_fsm", O_RDWR) = -1 ENOENT (No such file or directory)
lseek(17, 0, SEEK_END) = 407584768
write(17, "\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0"..., 8192) = 8192
lseek(18, 0, SEEK_END) = 333119488
write(18, "\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0"..., 8192) = 8192
lseek(18, 0, SEEK_END) = 333127680
write(18, "\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0"..., 8192) = 8192
open("base/657862/16554373_fsm", O_RDWR) = -1 ENOENT (No such file or directory)
lseek(17, 0, SEEK_END) = 407592960
write(17, "\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0"..., 8192) = 8192
lseek(18, 0, SEEK_END) = 333135872
write(18, "\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0"..., 8192) = 8192
open("base/657862/16554373_fsm", O_RDWR) = -1 ENOENT (No such file or directory)
lseek(17, 0, SEEK_END) = 407601152
write(17, "\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0"..., 8192) = 8192
lseek(18, 0, SEEK_END) = 333144064
write(18, "\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0"..., 8192) = 8192
lseek(18, 0, SEEK_END) = 333152256
write(18, "\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0"..., 8192) = 8192
open("base/657862/16554373_fsm", O_RDWR) = -1 ENOENT (No such file or directory)
I'm not sure if this result in a significant performance hit on Linux
(because the dentry cache covers negative lookups, too), but I suspect
that it could be an issue with other systems.
This happens with PostgreSQL 9.1.0.
--
Florian Weimer <fweimer@bfk.de>
BFK edv-consulting GmbH http://www.bfk.de/
Kriegsstraße 100 tel: +49-721-96201-1
D-76133 Karlsruhe fax: +49-721-96201-99
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: fweimer@bfk.de
Subject: Re: Large number of open(2) calls with bulk INSERT into empty table
In-Reply-To: <82ipm51tcd.fsf@mid.bfk.de>
* 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