Sqlite python sqlite3.OperationalError: database is locked

Question

I have written the following code, which is showing the sqlite3.OperationalError: database is locked error. Any help to debug would be much appreciated.

Answer 1

cursor2 = conn.cursor()
cursor3 = conn.cursor()
cursor4 = conn.cursor()

I think you have to close the connection which you have opened,may be the error is because of that cause you have opened multiple connections.

cursor2 = conn.cursor()
"""EDIT YOUR DATABASE USING CODE AND CLOSE THE CONNECTION"""
connection.close()

cursor3 = conn.cursor()
"""EDIT YOUR DATABASE USING CODE AND CLOSE THE CONNECTION"""
connection.close()

cursor4 = conn.cursor()
"""EDIT YOUR DATABASE USING CODE AND CLOSE THE CONNECTION"""
connection.close()

Answer 2

"Database is locked" means that some other connection has an active connection.

Use PRAGMA busy_timeout to wait some time for the other transaction to finish:

conn.execute("PRAGMA busy_timeout = 30000")   # 30 s

However, if that other application deliberately keeps an open transaction to keep the database locked, there is nothing you can do.

Answer 3

I'm not sure if this will help anyone, but I figured out a solution to my own Locked Database problem.

I use PyCharm and found that several instances of the script I was working on were all running. This was usually due to errors in the code I was testing, but it stayed active (and therefore the connection to the db was still active). Close out of those (stop all the processes) and try again - it has worked every time for me!

If anyone knows a way to make it timeout after a little while, please comment this solution. I tried cur.execute("PRAGMA busy_timeout = 30000") (found from another thread on a similar question) but it didn't seem to do anything.

Answer 4

I had the same issue but it was resolved when I used the following to close the concurrent connections.

conn.close()

So, if your program begins like this:

import sqlite3

conn = sqlite3.connect('pg_example.db', timeout=10)
c = conn.cursor()

Make sure that you're including the conn.close() after each SQL statement

t = ('RHAT',)
c.execute('SELECT * FROM stocks WHERE symbol=?', t)
conn.commit()
conn.close() #This is the one you need