Thanks for the explanation. The journal mode was OFF which means there is
no journal file created. So why is it the check still performed ?
On Wed, Aug 10, 2011 at 10:24 PM, Richard Hipp <d...@sqlite.org> wrote:
> On Wed, Aug 10, 2011 at 12:40 PM, Sreekumar TP <sreekumar...@gmail.com
> >wrote:
>
> > The 179148 failures on 'access' system call is due to access check of
> two
> > files - the journal file and the wal-file.
> > The journal mode was OFF as also WAL mode.
> > Why is sqlite checking access permissions for this file 179140 times?
> > Removing or optimising this will make it faster by 20% atleast!
> >
>
>
> SQLite must check for the existence of hot journals that were left behind
> by
> other processes that were writing to the database but crashed before they
> finished. If SQLite did not check for these, and if other processes did
> crash in the middle of a transaction, the database file would go corrupt.
>
> If your process is the only one accessing the database file, you can
> disable
> the journal-checks by doing:
>
> PRAGMA locking_mode=EXCLUSIVE;
>
>
>
>
> >
> >
> > access("/dev/shm/test.db-journal", F_OK) = -1 ENOENT (No such file or
> > directory)
> >
> > access("/dev/shm/test.db-wal", F_OK) = -1 ENOENT (No such file or
> > directory)
> >
> > -Sreekumar
> > On Wed, Aug 10, 2011 at 5:28 PM, Sreekumar TP <sreekumar...@gmail.com
> > >wrote:
> >
> > > Hi,
> > >
> > > I have the results from the tests (below). Alot of the time is spent
> in
> > > checking file permissions and locking the file (40 %).
> > >
> > >
> > > Inmem
> > >
> > > % time seconds usecs/call calls errors syscall
> > >
> > > ------ ----------- ----------- --------- --------- ----------------
> > >
> > > 28.53 0.124727 1 118524 write
> > >
> > > 23.42 0.102382 0 414624 gettimeofday
> > >
> > > 20.78 0.090840 1 76513 read
> > >
> > > 13.72 0.059977 0 191255 _llseek
> > >
> > >
> > >
> > > Db in tmpfs
> > >
> > > % time seconds usecs/call calls errors syscall
> > >
> > > ------ ----------- ----------- --------- --------- ----------------
> > >
> > > 21.83 0.257073 1 263306 write
> > >
> > > 21.18 0.249488 1 179148 179148 access
> > >
> > > 20.61 0.242725 0 509292 fcntl64
> > >
> > > 13.04 0.153551 0 448720 _llseek
> > >
> > > 9.44 0.111194 1 189370 read
> > >
> > > 8.16 0.096124 0 414624 gettimeofday
> > > 2.55 0.030000 3750 8 fdatasync
> > >
> > > On Tue, Aug 9, 2011 at 7:34 PM, Pavel Ivanov <paiva...@gmail.com>
> > wrote:
> > >
> > >> > Journal mode is WAL
> > >>
> > >> I believe in-memory database can't have journal mode WAL. So you
> > >> compare completely different settings.
> > >>
> > >>
> > >> Pavel
> > >>
> > >>
> > >> On Tue, Aug 9, 2011 at 5:15 AM, <sreekumar...@gmail.com> wrote:
> > >> >
> > >> > Journal mode is WAL
> > >> >
> > >> >
> > >> > ------Original Message------
> > >> > From: Roger Binns
> > >> > Sender: sqlite-users-boun...@sqlite.org
> > >> > To: General Discussion of SQLite Database
> > >> > ReplyTo: General Discussion of SQLite Database
> > >> > Subject: Re: [sqlite] In memory v/s tmpfs
> > >> > Sent: Aug 9, 2011 2:42 PM
> > >> >
> > >> > -----BEGIN PGP SIGNED MESSAGE-----
> > >> > Hash: SHA1
> > >> >
> > >> > On 08/08/2011 06:34 PM, sreekumar...@gmail.com wrote:
> > >> >> From the point of view of performance, I expected similar
> performance
> > ,
> > >> tmpfs being a little slower due to filesystem overhead. However, the
> > >> operations on tmpfs was much slower than expected.
> > >> >
> > >> > Using tmpfs requires many kernel calls which is considerably more
> > effort
> > >> > than the occasional malloc call. Additionally files have to be
> > locked,
> > >> > journals made etc (you didn't mention your journal setting).
> > >> >
> > >> > Roger
> > >> > -----BEGIN PGP SIGNATURE-----
> > >> > Version: GnuPG v1.4.11 (GNU/Linux)
> > >> > Comment: Using GnuPG with Mozilla - http://enigmail.mozdev.org/
> > >> >
> > >> > iEYEARECAAYFAk5A+g0ACgkQmOOfHg372QTR8ACgqNeeuOxHRy7+hMH5RY/OAyV2
> > >> > Wq0AoMaSRtoFN4obCgmgHlpHthd9z5Zp
> > >> > =pkJt
> > >> > -----END PGP SIGNATURE-----
> > >> > _______________________________________________
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> > >> > http://sqlite.org:8080/cgi-bin/mailman/listinfo/sqlite-users
> > >> >
> > >> >
> > >> > Sent from BlackBerry® on Airtel
> > >> > _______________________________________________
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> > >> >
> > >>
> > >
> > >
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>
>
>
> --
> D. Richard Hipp
> d...@sqlite.org
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