Based on the link you provide, it looks like I need unix-none VFS and specify it as:
ATTACH 'file:demo2.db?vfs=unix-none' AS demo2; FLoM will be ensuring sequential access. The journaling, as I understand, is independent of locking and will still work. That is robustness to crashes will remain. unix-none just disables file lock requests, which are the cause of the overhead. Is this correct? Roman ________________________________________ From: sqlite-users [sqlite-users-boun...@mailinglists.sqlite.org] on behalf of Keith Medcalf [kmedc...@dessus.com] Sent: Friday, September 27, 2019 11:50 PM To: SQLite mailing list Subject: Re: [sqlite] disable file locking mechanism over the network Yeah, WAL mode cannot work over a remote connection as the WAL index is a shared memory file -- which can only be accessed by processes on a single computer. If you are using FLoM to co-ordinate your "application" use of SQLite3, then maybe you want to look at using the dotfile VFS which uses dotfiles to co-ordinate multi-access rather than file locks. https://nam02.safelinks.protection.outlook.com/?url=https%3A%2F%2Fsqlite.org%2Fsearch%3Fs%3Dd%26q%3Ddotfile&data=02%7C01%7Croman.fleysher%40einstein.yu.edu%7C07b8076c03944d262b0808d743c6f9a6%7C04c70eb48f2648079934e02e89266ad0%7C1%7C1%7C637052394192099402&sdata=Jkew%2B%2FZJkF2GZbtfYYtHfbFsXJiv%2FMUHfwveVXYdvxI%3D&reserved=0 >-----Original Message----- >From: sqlite-users <sqlite-users-boun...@mailinglists.sqlite.org> On >Behalf Of Roman Fleysher >Sent: Friday, 27 September, 2019 21:43 >To: SQLite mailing list <sqlite-users@mailinglists.sqlite.org> >Subject: Re: [sqlite] disable file locking mechanism over the network > >The timeout is set to 50min ! > >The database is used to synchronize / manage tasks. A kind of job >manager. Thus each access is a quick search with small update or delete. > >I looked at the WALL mode. I do not exactly understand how it works, but >SQLite developers warn not to use WALL over network in item 2 of the link >you mention. > >I was not aware of the various synch option. I will study them. > >Thank you, > >Roman > >________________________________________ >From: sqlite-users [sqlite-users-boun...@mailinglists.sqlite.org] on >behalf of Simon Slavin [slav...@bigfraud.org] >Sent: Friday, September 27, 2019 7:53 PM >To: SQLite mailing list >Subject: Re: [sqlite] disable file locking mechanism over the network > >On 27 Sep 2019, at 11:59pm, Roman Fleysher ><roman.fleys...@einstein.yu.edu> wrote: > >> From experience, it seems that because SQLite still requests file >locks, the performance increase is not that big. I wonder if there is a >way to disable SQLite's internal file locking mechanism. I know this >seems strange to ask. But FLoM should be able to do it faster over many >compute nodes. > >What busy_timeout did you set ? > >Do you process multiple operations inside a transaction, or do you let >SQLite create its own transactions automatically ? > >SQLite always locks the entire database. It does not implement table or >row locking. > >SQLite has two (main) journalling modes. The journalling made influences >which operations lock out other operations. The biggest change in >lockouts occurs whether you do or do not have writes from multiple >connections at once. You might want to try executing this command just >once: > > PRAGMA journal_mode = WAL > >This makes a change to the database so that all connections which open it >know it's in WAL mode. You don't have to change your software. It might >speed things up. (You can do > > PRAGMA journal_mode = DELETE > >to set it back.) > >There are other other things you can do to disable various parts of the >locking system, but you should try the above first. You might want to >play around with > ><https://nam02.safelinks.protection.outlook.com/?url=https%3A%2F%2Fsqlite >.org%2Fpragma.html%23pragma_synchronous&data=02%7C01%7Croman.fleysher >%40einstein.yu.edu%7C26f5036ca2bc4f75ac5008d743a5f596%7C04c70eb48f2648079 >934e02e89266ad0%7C1%7C0%7C637052252378056899&sdata=a%2FTb%2Fr7kdca1Q4 >%2F1Le1azbaXR0jdmkDKm042RRMgNYM%3D&reserved=0> > >Refs: > ><https://nam02.safelinks.protection.outlook.com/?url=https%3A%2F%2Fsqlite >.org%2Fpragma.html%23pragma_journal_mode&data=02%7C01%7Croman.fleyshe >r%40einstein.yu.edu%7C26f5036ca2bc4f75ac5008d743a5f596%7C04c70eb48f264807 >9934e02e89266ad0%7C1%7C0%7C637052252378056899&sdata=MuvGgmedEKY7QBfx3 >03DUcH4iWkpnRL1D3ADV51LeEg%3D&reserved=0> ><https://nam02.safelinks.protection.outlook.com/?url=https%3A%2F%2Fsqlite >.org%2Fwal.html&data=02%7C01%7Croman.fleysher%40einstein.yu.edu%7C26f >5036ca2bc4f75ac5008d743a5f596%7C04c70eb48f2648079934e02e89266ad0%7C1%7C0% >7C637052252378056899&sdata=svGLhgL5mQkQfQ%2B7UwsKzaJ4krn8%2F%2FgnHTm3 >LG3UEPA%3D&reserved=0> >_______________________________________________ >sqlite-users mailing list >sqlite-users@mailinglists.sqlite.org >https://nam02.safelinks.protection.outlook.com/?url=http%3A%2F%2Fmailingl >ists.sqlite.org%2Fcgi-bin%2Fmailman%2Flistinfo%2Fsqlite- >users&data=02%7C01%7Croman.fleysher%40einstein.yu.edu%7C26f5036ca2bc4 >f75ac5008d743a5f596%7C04c70eb48f2648079934e02e89266ad0%7C1%7C0%7C63705225 >2378056899&sdata=MV%2FomDHw0jFta70BSSxaKIzUP3mSqhdx%2BH3WY64UCZo%3D&a >mp;reserved=0 >_______________________________________________ >sqlite-users mailing list >sqlite-users@mailinglists.sqlite.org >https://nam02.safelinks.protection.outlook.com/?url=http%3A%2F%2Fmailinglists.sqlite.org%2Fcgi-bin%2Fmailman%2Flistinfo%2Fsqlite-users&data=02%7C01%7Croman.fleysher%40einstein.yu.edu%7C07b8076c03944d262b0808d743c6f9a6%7C04c70eb48f2648079934e02e89266ad0%7C1%7C1%7C637052394192099402&sdata=OhldMpwWIrIVdPdGgltmiR0ucyw3TUCSlbVOiG7kwGM%3D&reserved=0 _______________________________________________ sqlite-users mailing list sqlite-users@mailinglists.sqlite.org https://nam02.safelinks.protection.outlook.com/?url=http%3A%2F%2Fmailinglists.sqlite.org%2Fcgi-bin%2Fmailman%2Flistinfo%2Fsqlite-users&data=02%7C01%7Croman.fleysher%40einstein.yu.edu%7C07b8076c03944d262b0808d743c6f9a6%7C04c70eb48f2648079934e02e89266ad0%7C1%7C1%7C637052394192099402&sdata=OhldMpwWIrIVdPdGgltmiR0ucyw3TUCSlbVOiG7kwGM%3D&reserved=0 _______________________________________________ sqlite-users mailing list sqlite-users@mailinglists.sqlite.org http://mailinglists.sqlite.org/cgi-bin/mailman/listinfo/sqlite-users
