Hi everyone, I've been playing around recently at home with mysql databases on my smb share. In my tests I only used select-statements on Windows 10 using the C# ADO.NET wrapper with the latest nuget package.
I've opened the database and selected a few records on my workstation, subsequent select's were very fast. Then on antoher workstation I did the same. After moving back to my workstation I found that the same statement was much slower. My investigation showed that the first client is granted an smb-oplock and the client caches the whole database locally. That's why subsequent select's are super fast. When another client select's data, the smb server sends an oplock break request to the first client, and it removes the cached db to load it again over the network. I was interested why smb breaks the oplock and found that every time I execute my command: SQLiteDataReader reader = command.ExecuteReader(); // C# code wireshark shows me 3 lock requests/responses to/from smb: 1. exclusive lock, fail immediately 2. shared lock, fail immediately 3. unlock I wonder if SQLite needs an exclusive lock (which obviously is an exclusive lock in smb language, maybe not in ntfs/fat language) for select's on the database, or if the translation of file-locks is broken within windows' smb protocol implementation. Interesting fact: I only see those lock requests when a second user is connected to the db (another smb detail I guess). It's not that there's any problem here, I just want to understand what's going on, as I've been assuming that a read only file access will not break an smb oplock. Maybe anyone can clarify it or is also interested in this topic. Best Regards, Wolfgang _______________________________________________ sqlite-users mailing list sqlite-users@mailinglists.sqlite.org http://mailinglists.sqlite.org/cgi-bin/mailman/listinfo/sqlite-users
