Avoiding exclusive schema lock error with ArcPy?

Question

I have a script for updating some features on my database every night (just for copying and replacing some features). This features are "read-only". My problem is that I can't avoid that these features are opened by users, and my script can show the following error:

ExecuteError: ERROR 000464: Cannot get exclusive schema lock. 
              Either being edited or in use by another application.

Can I force the phyton script, via some command, copying the files, even been opened by some user? Can I take down all the connections on my database before running the script?

Answer 1

I suppose that you are working with SDE.

You should kill all connections using sdemon command-line tool.

1. If there is an ArcSDE installed on PC where you a running the script then you can execute sdemon -o kill locally to kill all connections. Take a look at this help topic. I am not sure is it killing direct-connections on 10.0. I remember that it was a kind of a problem on 9.3 and that it is definitely killing direct-connections on 10.1.
2. If you don't have ArcSDE installed and it is running only on a separate server then you can execute this command remotely from Python. There is some discussion in this topic.

Answer 2

Another possibility since you said you are using SDE is to delete shared locks from the layer_locks and table_locks tables using SQL, PL/SQL, T-SQL, etc. e.g.:

DELETE FROM TABLE_LOCKS WHERE SDE_ID = :b1 AND REGISTRATION_ID = :b2

I would definitely not recommend this approach on a versioned geodatabase. See also: How are the various lock mechanisms implemented in ArcSDE and the geodatabase?

Answer 3

If the preference is to remove specific SDE user locks, there is a way to do this via arcpy. I prefer this approach because it doesn't require that you jump onto the database server to perform an sde command. I can disconnect any unwanted locks, then perform data updates all in one script/process.

Example from the above link is very useful:

import arcpy

admin_workspace = "Database Connections/[email protected]"
arcpy.env.workspace = admin_workspace
user_name = "GDB"

# Look through the users in the connected user list and get the SDE ID.
# Use the SDE ID to disconnect the user that matches the username variable
users = arcpy.ListUsers() # The environment is set, no workspace is needed.
for item in users:
    if item.Name == user_name:
        arcpy.DisconnectUser(admin_workspace, item.ID)

Answer 4

I'm not very familiar with postgresql but I think this post can lead you to the right direction:

https://stackoverflow.com/questions/5108876/kill-a-postgresql-session-connection