DB write locks

[stwiname]

In order to guard against more than one node running for the same project and schema there should be a lock on the tables for the schema to stop this happening.

Requirements:

• Setup write lock on all tables in the schema. Query should look something like this LOCK TABLE schema_name.* IN ACCESS EXCLUSIVE MODE;
• Don't create write locks if the project is a multichain project
• It should update the locks with any schema migrations
• It should work with POI. This currently has another connection for a sync task.