So....to clarify...this is a completely safe operation in 3.7.0.1.??? #1 WAL COMMIT will not corrupt current reading thread (even if deletes occur, changes/adds are not visible either). #2 Next SELECT transaction will pick up the new data. Correct? Dangerous thing would be two threads writing if either one is using a currect SELECT for it's updatable dataset. Is this even possible? Michael D. Black Senior Scientist Advanced Analytics Directorate Northrop Grumman Information Systems
________________________________ From: sqlite-users-boun...@sqlite.org on behalf of Pavel Ivanov Sent: Wed 8/18/2010 9:57 AM To: General Discussion of SQLite Database Subject: EXTERNAL:Re: [sqlite] multiple conections for the same database > Which means the read works on old data until you COMMIT? > Is that true? So that COMMIT will allow you to query the changed/new data > from the other thread? AFAIK, no. Of course until you COMMIT no reader will see your data. But after you commit all already started reading transactions won't see your changes. Reading transaction should be started after COMMIT to see changes. Pavel On Wed, Aug 18, 2010 at 10:50 AM, Black, Michael (IS) <michael.bla...@ngc.com> wrote: > Which means the read works on old data until you COMMIT? > Is that true? So that COMMIT will allow you to query the changed/new data > from the other thread? > > Michael D. Black > Senior Scientist > Advanced Analytics Directorate > Northrop Grumman Information Systems > > > ________________________________ > > From: sqlite-users-boun...@sqlite.org on behalf of Pavel Ivanov > Sent: Wed 8/18/2010 9:15 AM > To: General Discussion of SQLite Database > Subject: EXTERNAL:Re: [sqlite] multiple conections for the same database > > > >> SQLite allows multiple readers, or exactly one wrier, accessing the database >> at the same time. You can't read and write simultaneously, you must arrange >> for your connections to take turns. SQLITE_BUSY error is a signal for you to >> back off, wait a little, then try again. See also >> http://sqlite.org/c3ref/busy_timeout.html > > A little correction to this: in latest version (3.7.0.1) with WAL > journal mode SQLite can read old data while another connection > writing. So things could be a little easier for you. > > > Pavel > > On Wed, Aug 18, 2010 at 8:11 AM, Igor Tandetnik <itandet...@mvps.org> wrote: >> andres felipe tamayo cortes <andrewt12...@hotmail.com> wrote: >>> i have one application who reads a database, it run well without problems, >>> but when i tried to load this dabase from other >>> program (while its still running the first application), appearsme database >>> blocked, isnt it possible to load one database from >>> more than one programm at time? >>> >>> what i am tring to do its that one program reads the database while other >>> program writes so the first program has to see what the >>> second programs write. >> >> SQLite allows multiple readers, or exactly one wrier, accessing the database >> at the same time. You can't read and write simultaneously, you must arrange >> for your connections to take turns. SQLITE_BUSY error is a signal for you to >> back off, wait a little, then try again. See also >> http://sqlite.org/c3ref/busy_timeout.html >> -- >> Igor Tandetnik >> >> _______________________________________________ >> 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 > > > > _______________________________________________ > 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 _______________________________________________ sqlite-users mailing list sqlite-users@sqlite.org http://sqlite.org:8080/cgi-bin/mailman/listinfo/sqlite-users
