I ran into some odd behavior from older versions of SQLite, and I wonder if anyone can add some details and help me find a good workaround.
The details are at http://trac.buildbot.net/ticket/1810. With apologies for boiling this down to Python: import os import sqlite3 print "sqlite.py:", sqlite3.version print "sqlite itself:", sqlite3.sqlite_version if os.path.exists("/tmp/my.db"): os.unlink("/tmp/my.db") def combined(): conn1 = sqlite3.connect("/tmp/my.db") curs1 = conn1.cursor() print "1: pragma" ## B curs1.execute("PRAGMA table_info('foo')") conn2 = sqlite3.connect("/tmp/my.db") curs2 = conn2.cursor() print "2: create" curs2.execute("CREATE TABLE foo ( a integer )") conn2.commit() conn2.close() ## C print "1: select" # curs1.execute("SELECT * from sqlite_master") ## A curs1.execute("SELECT * from foo") combined() This script fails for sqlite-3.6.12 and earlier, and works for sqlite-3.6.17 and higher. If I add a query of sqlite_master (A), things work. Remove the PRAGMA (B) and things work. Adding or removing the close() (C) makes no difference. This is a part of Buildbot (http://buildbot.net), and older versions of SQLite are still present on lots of common systems, so I can't substantially change the required version of SQLite without alienating a lot of users. My workaround is to run the above at startup, and if I get an OperationalError, run 'SELECT * from sqlite_master' before each real query. Obviously, that's not great for performance, but I don't understand the underlying problem well enough to invent something better. I'd love to have a pointer to the bug that was solved here (I had a look through the tracker, but didn't see anything related) as well as the version in which it was solved. I'd also love to know what's going on - per-connection caching of schema metadata? Finally, any suggestions for a better workaround would be great. TIA! Dustin _______________________________________________ sqlite-users mailing list sqlite-users@sqlite.org http://sqlite.org:8080/cgi-bin/mailman/listinfo/sqlite-users
