database creation getting hung up on a NFS mount path

(1) By anonymous on 2021-10-27 15:03:47 [link]

I am trying to create create database on a NFS mount point
I create a db connection using sqlite3_open call.. As per the documentation the default VFS using on unix OS is 'unix.'  
The execution gets stuck at the function sqlite3_exec

Now, if I register any other VFS like unix-excl using  sqlite3_open_v2 call.. then it works fine. 

The NFS s/c version used is 3.

I have few questions around this:

- Why does VFS 'unix' not work for NFS? Is it version dependent?
- The process just gets hung up on the sqlite3_exec. Can there be a way to exit from this situation?

(2) By Simon Slavin (slavin) on 2021-10-27 15:35:07 in reply to 1 [link]

I can't answer your specific question because I'm not familiar enough with NFS.  However before considering using NFS for a SQLite database you should read this:

<https://www.sqlite.org/howtocorrupt.html#_filesystems_with_broken_or_missing_lock_implementations>

Having said that, there's now a lock-testing suite for NFS4:

<https://sourceforge.net/projects/locktests/>

which looks useful, but I don't know enough to understand the results.

(3) By Keith Medcalf (kmedcalf) on 2021-10-28 06:03:37 in reply to 1

> Now, if I register any other VFS like unix-excl using sqlite3_open_v2 call.. then it works fine. 

This would indicate that the POSIX locking used when using the normal VFS is not implemented sufficiently correctly when the database file is on a remote NFS filesystem.

This is documented and expected.