Python SQLite: database is locked

Question

I'm trying this code:

import sqlite  connection = sqlite.connect('cache.db') cur = connection.cursor() cur.execute('''create table item   (id integer primary key, itemno text unique,         scancode text, descr text, price real)''')  connection.commit() cur.close() 

I'm catching this exception:

Traceback (most recent call last):   File "cache_storage.py", line 7, in <module>     scancode text, descr text, price real)''')   File "/usr/lib/python2.6/dist-packages/sqlite/main.py", line 237, in execute     self.con._begin()   File "/usr/lib/python2.6/dist-packages/sqlite/main.py", line 503, in _begin     self.db.execute("BEGIN") _sqlite.OperationalError: database is locked 

Permissions for cache.db are ok. Any ideas?

Answer 1

I'm presuming you are actually using sqlite3 even though your code says otherwise. Here are some things to check:

1. That you don't have a hung process sitting on the file (unix: $ fuser cache.db should say nothing)
2. There isn't a cache.db-journal file in the directory with cache.db; this would indicate a crashed session that hasn't been cleaned up properly.
3. Ask the database shell to check itself: $ sqlite3 cache.db "pragma integrity_check;"
4. Backup the database $ sqlite3 cache.db ".backup cache.db.bak"
5. Remove cache.db as you probably have nothing in it (if you are just learning) and try your code again
6. See if the backup works $ sqlite3 cache.db.bak ".schema"

Failing that, read Things That Can Go Wrong and How to Corrupt Your Database Files