Many Thanks Ken for your guidelines. Following your suggestions I found that indeed there was a silly mistake in the querying thread (I was using a 2-D array of queries, and I missed a comma :-( ).
After correcting this mistake, the two threads ran fine when run one at a time. When run together, I did not get any error message in the query thread. However, I did receive the "SQL logic error or missing database" message (error code 1) during an insertion after a random number of successful insertions and queries. This was accompanied by a seg fault. After many futile tries, I replaced the call to sqlite_prepare by sqlite_prepare_v2. And it seems to work! The program is running for 10 minutes now. What could have gone wrong with prepare? Another question, should I wrap each individual query (not inserts) within a transaction too? Thanks again for all the help. dbikash ken-33 wrote: > > I think you should consider running the program with one thread at a time. > > This will help you isolate if this is a problem within a thread or is an > interaction among the threads. > > I'll assume its both. After you fix all of the localized issues. > > I'd suggest recompiling sqlite with thread safe turned on. > > Allow each thread to create its own connection. > > Then Wrap each transaction with a begin immediate. That way you can > acquire a lock when needed. Use a loop around the begin immediate testing > for success. If you fail with sqlite busy. Simply sleep a short while > (hint usleep) loop and try again. > > HTH > Ken > > > > --- On Fri, 10/31/08, dbikash <[EMAIL PROTECTED]> wrote: > >> From: dbikash <[EMAIL PROTECTED]> >> Subject: Re: [sqlite] "SQL logic error or missing database" with >> multithreaded program >> To: sqlite-users@sqlite.org >> Date: Friday, October 31, 2008, 10:24 AM >> I use both int sqlite3_errcode() and sqlite3_errmsg(). Here >> is what they >> return (I get 3 different types of errors in different >> runs): >> 1, SQL logic error or missing database. >> 1, unrecognized token "" (there's a non >> printable character like a rectangle >> within the quotes). >> 1, SQL logic error or missing database, sqlite3_get_table() >> called with two >> or more incompatible queries (this last print is obtained >> from zErrMsg >> returned when the return value from sqlite3_get_table() is >> not SQLITE_OK) >> >> Also, the program is written to print an error and then >> continue in the >> infinite loop. I can find a few errors in query execution, >> but it is after >> an error in insertion (sqlite3_step() != SQLITE_DONE) that >> the program quits >> by itself. >> >> >> D. Richard Hipp wrote: >> > >> > >> > On Oct 31, 2008, at 9:46 AM, dbikash wrote: >> >> >> >> I get a SQLite error 1 (SQL logic error >> >> or missing database). What could be the problem? >> > >> > Is that the error message text that SQLite returns: >> "SQL logic error >> > or missing database"? Or is that just the >> meaning of SQLITE_ERROR >> > that you looked up? What error message does >> sqlite3_errmsg(db) return? >> > >> > D. Richard Hipp >> > [EMAIL PROTECTED] >> > >> > >> > >> > _______________________________________________ >> > sqlite-users mailing list >> > sqlite-users@sqlite.org >> > >> http://sqlite.org:8080/cgi-bin/mailman/listinfo/sqlite-users >> > >> > >> >> -- >> View this message in context: >> http://www.nabble.com/%22SQL-logic-error-or-missing-database%22-with-multithreaded-program-tp20266281p20268213.html >> Sent from the SQLite mailing list archive at Nabble.com. >> >> _______________________________________________ >> 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 > > -- View this message in context: http://www.nabble.com/%22SQL-logic-error-or-missing-database%22-with-multithreaded-program-tp20266281p20302902.html Sent from the SQLite mailing list archive at Nabble.com. _______________________________________________ sqlite-users mailing list sqlite-users@sqlite.org http://sqlite.org:8080/cgi-bin/mailman/listinfo/sqlite-users
