> #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?
Yes that's 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? No. WAL journal mode still doesn't allow 2 concurrent writers. Pavel On Wed, Aug 18, 2010 at 11:10 AM, Black, Michael (IS) <michael.bla...@ngc.com> wrote: > 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 > _______________________________________________ sqlite-users mailing list sqlite-users@sqlite.org http://sqlite.org:8080/cgi-bin/mailman/listinfo/sqlite-users
