Error: database disk image is malformed

classic Classic list List threaded Threaded
2 messages Options
Reply | Threaded
Open this post in threaded view
|

Error: database disk image is malformed

Tal Tabakman-2
Hi Simon

thanks for your prompt reply

answers for the below

1. The database is written by a single process who has an EXCLUSIVE LOCK

2. Only AFTER all data is being written, costumer can access it (read mode)

3. potentially, it is a single writer followed by multiple readers kind of flow

4. For the problem described we had also a single reader.

5. hence, I hardly think that this is a concurrency issue

6. the OS is linux in 64 bits mode

7. file system is NFS.

8. so, user launches an execution via local DRM (LSF i think) and from
a remote machine is a DB is generated, after DB is generated another
execution is launched and another remote machine access it in a read
mode and some "SELECT..." queries are used, then the corruption error
appears...


>* Answering your question below,*>* *>* yes , I believe  that the costumer is using network*
You can read section 6.0 of

<http://www.sqlite.org/lockingv3.html>

to learn some of the problems involved.  If you need any further help
from us then I'm sorry but we have more questions:

Which network file protocol is being used.  NFS ?  SMB ?

What OS are all the computers involved running ?

Are all accesses across a network or is one app accessing the file as
a local file and the other accessing it across the network ?
_______________________________________________
sqlite-users mailing list
[hidden email]
http://sqlite.org:8080/cgi-bin/mailman/listinfo/sqlite-users
Reply | Threaded
Open this post in threaded view
|

Re: Error: database disk image is malformed

Richard Hipp-3
On Fri, Aug 17, 2012 at 8:08 AM, Tal Tabakman <[hidden email]>wrote:

>
> 7. file system is NFS.
>

Consider using the "unix-dotfile" VFS instead of the standard "unix" VFS.
(Add the string "unix-dotfile" as the 4th argument to sqlite3_open_v2().)

The unix-dotfile VFS will use dot-file locking instead of posix advisory
locking.  The unix-dotfile VFS will usually work better on NFS.

The down side of unix-dotfile is that will cut concurrency, but it sounds
like you are not using concurrency anyhow.  Also, if a process crashes, it
might leave a stale dot-file lock that you'll need to clear manually.


--
D. Richard Hipp
[hidden email]
_______________________________________________
sqlite-users mailing list
[hidden email]
http://sqlite.org:8080/cgi-bin/mailman/listinfo/sqlite-users