Added readme.

Author: jberkus

locks/README.rst

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+Lock-Logging Scripts
+====================
+
+Since the amount of information you can usefully get out of log_lock_waits is limited, these 
+scripts add a way to log complex information to PostgreSQL tables.
+
+1. Run table_locks_setup.sql and transaction_locks_setup.sql against the target database
+   This will create 2 tables and 2 functions for logging.
+
+2. Add a cron job to execute log_locks.sh every 1 to 10 minutes.  
+
+Note that, under pathological conditions, querying the locks tables can have significant overhead,
+and the lock logging query itself can become blocked or bog down.  For that reason, we recommend
+discretion on how frequently you run the cron job.