Re: [sqlite] WAL and local UNC filenames
On Mon, Nov 7, 2011 at 5:48 PM, Jean-Christophe Deschamps j...@antichoc.net wrote: Pavel, This is not a local file. Even if you use your hostname as netname file is still retrieved through network stack. And I guess SAMBA doesn't work well with memory mapped files (in addition to all problems with locking). True but why did I get no error? Since MMF don't cope with network it would be good to get a no-no somewhere. I really don't know which layer should bark however. I can't answer this question. Maybe it's something like all operations are successful but memory mapping is not actually shared between processes. So every process sees its own copy and assumes that no other process works with database, thus database can be corrupted in many possible ways. Pavel ___ sqlite-users mailing list sqlite-users@sqlite.org http://sqlite.org:8080/cgi-bin/mailman/listinfo/sqlite-users
Re: [sqlite] WAL and local UNC filenames
What I've seen is that windows makes a local copy of the memory mapped file. Perhaps in swap. If you watch your application using ProcMon you can see all the disk IO. That's how I noticed the copy. For my usage, only one process opens the DB so, maybe it's a non-issue. C Tuesday, November 8, 2011, 10:05:17 PM, you wrote: PI On Mon, Nov 7, 2011 at 5:48 PM, Jean-Christophe Deschamps PI j...@antichoc.net wrote: Pavel, This is not a local file. Even if you use your hostname as netname file is still retrieved through network stack. And I guess SAMBA doesn't work well with memory mapped files (in addition to all problems with locking). True but why did I get no error? Since MMF don't cope with network it would be good to get a no-no somewhere. I really don't know which layer should bark however. PI I can't answer this question. Maybe it's something like all operations PI are successful but memory mapping is not actually shared between PI processes. So every process sees its own copy and assumes that no PI other process works with database, thus database can be corrupted in PI many possible ways. PI Pavel PI ___ PI sqlite-users mailing list PI sqlite-users@sqlite.org PI http://sqlite.org:8080/cgi-bin/mailman/listinfo/sqlite-users -- Best regards, Tegmailto:t...@djii.com ___ sqlite-users mailing list sqlite-users@sqlite.org http://sqlite.org:8080/cgi-bin/mailman/listinfo/sqlite-users
Re: [sqlite] WAL and local UNC filenames
Hi Pavel, I can't answer this question. Maybe it's something like all operations are successful but memory mapping is not actually shared between processes. So every process sees its own copy and assumes that no other process works with database, thus database can be corrupted in many possible ways Probably something like this. In fact it did bite me but without too much consequence. Back in 2008 (before WAL birth) I parametrized the root of my data files tree so that all files in the tree are relative to this root where the DB lies, and all individual file relative paths are stored in a Paths table in the DB itself. To make things more flexible I specified the root as an UNC path, so I could move the whole tree around without change, provided the target machine has the required netname. Changing \\machine\dbPath\ to D:\dbPath\ fixed it. ___ sqlite-users mailing list sqlite-users@sqlite.org http://sqlite.org:8080/cgi-bin/mailman/listinfo/sqlite-users
Re: [sqlite] WAL and local UNC filenames
Does your path begin with 'file:' ? No, simply \\netname\share\path\test.db This is not a local file. Even if you use your hostname as netname file is still retrieved through network stack. And I guess SAMBA doesn't work well with memory mapped files (in addition to all problems with locking). Pavel On Sun, Nov 6, 2011 at 10:04 PM, Jean-Christophe Deschamps j...@antichoc.net wrote: Does your path begin with 'file:' ? No, simply \\netname\share\path\test.db ___ sqlite-users mailing list sqlite-users@sqlite.org http://sqlite.org:8080/cgi-bin/mailman/listinfo/sqlite-users ___ sqlite-users mailing list sqlite-users@sqlite.org http://sqlite.org:8080/cgi-bin/mailman/listinfo/sqlite-users
Re: [sqlite] WAL and local UNC filenames
Pavel, This is not a local file. Even if you use your hostname as netname file is still retrieved through network stack. And I guess SAMBA doesn't work well with memory mapped files (in addition to all problems with locking). True but why did I get no error? Since MMF don't cope with network it would be good to get a no-no somewhere. I really don't know which layer should bark however. ___ sqlite-users mailing list sqlite-users@sqlite.org http://sqlite.org:8080/cgi-bin/mailman/listinfo/sqlite-users
[sqlite] WAL and local UNC filenames
Dear List, If a DB in WAL mode is opened using a UNC path refering to a _local_ drive, weird things happen until the DB gets corrupted but AFAIK no error code is thrown. Windows doesn't seem to open the memory mapped file if it has a UNC path. Can someone confirm? I don't know if this qualifies as bug or library misuse. Obviously using a UNC path in WAL mode is a bad idea but still... ___ sqlite-users mailing list sqlite-users@sqlite.org http://sqlite.org:8080/cgi-bin/mailman/listinfo/sqlite-users
Re: [sqlite] WAL and local UNC filenames
On 7 Nov 2011, at 2:02am, Jean-Christophe Deschamps wrote: If a DB in WAL mode is opened using a UNC path refering to a _local_ drive, weird things happen until the DB gets corrupted but AFAIK no error code is thrown. Does your path begin with 'file:' ? Simon. ___ sqlite-users mailing list sqlite-users@sqlite.org http://sqlite.org:8080/cgi-bin/mailman/listinfo/sqlite-users
Re: [sqlite] WAL and local UNC filenames
Does your path begin with 'file:' ? No, simply \\netname\share\path\test.db ___ sqlite-users mailing list sqlite-users@sqlite.org http://sqlite.org:8080/cgi-bin/mailman/listinfo/sqlite-users
