I would start with an existing VFS implementation and modify it to use the primitives available to you. I started with the OS_WIN and modified it. That will probably be easier than starting from scratch.
You can switch VFSs with each open. You can use a different one for each DB open if you like. (I do that now.) I don't think you can switch the VFS for a given DB handle once it is opened. You will probably have to close it and reopen. Note that you can also, via #define values, exclude the pre-defined VFS implementations and just use your own. Brown, Daniel wrote: > Thanks for the pointers Roger and the example tests. > > Is it possible to change the VFS SQLite is using while SQLite is > running? I'm looking at creating two different VFS implementations and > it would be great to be able to switch between implementations as > required, I'd be looking to switch VFS during program start-up and > before any databases are loaded or used. > > -----Original Message----- > From: [EMAIL PROTECTED] > [mailto:[EMAIL PROTECTED] On Behalf Of Roger Binns > Sent: Tuesday, November 04, 2008 12:39 PM > To: General Discussion of SQLite Database > Subject: Re: [sqlite] VFS implementation guidance > > -----BEGIN PGP SIGNED MESSAGE----- > Hash: SHA1 > > Brown, Daniel wrote: > >> Are there any guides to implementing a VFS (sqlite3_vfs) for SQLite? >> > A > >> good practices guide would be as useful. I already have an existing >> file system API/library for the target system so I guess it is mostly >> just matching up the API with the VFS implementation via some wrapper >> functions? >> > > Pretty much just implement the functions as documented. One gotcha is > that xRandomness is only called once and is only called on the default > VFS which makes testing it fun. > > Another is that xGetLastError is never called so you don't need to > implement it. http://www.sqlite.org/cvstrac/tktview?tn=3337 > > You then need to run queries that exercise all parts of the VFS. If you > want some guidance, this is what I use: > > http://code.google.com/p/apsw/source/browse/apsw/trunk/tests.py#4759 > > Roger > -----BEGIN PGP SIGNATURE----- > Version: GnuPG v1.4.9 (GNU/Linux) > > iEYEARECAAYFAkkQssUACgkQmOOfHg372QTuLwCgygTWzPSW3CCHnQONXiEcKXf7 > 5XEAnR7DYzMf+hvXCORi/I/hpWgWF/t3 > =3tEY > -----END PGP SIGNATURE----- > _______________________________________________ > sqlite-users mailing list > [email protected] > http://sqlite.org:8080/cgi-bin/mailman/listinfo/sqlite-users > _______________________________________________ > sqlite-users mailing list > [email protected] > http://sqlite.org:8080/cgi-bin/mailman/listinfo/sqlite-users > > _______________________________________________ sqlite-users mailing list [email protected] http://sqlite.org:8080/cgi-bin/mailman/listinfo/sqlite-users
