Does anyone have any idea what the root cause of my issue is? I appreciate any insight. As I said, hash collisions can be rules out, sadly.
Well, you could set log_statement to 'all' for a bit to see *exactly* what each of the deadlocking processes are doing. Alternatively, perhaps you can write a hashextendedkey() function that outputs arguments and results to a log and/or a table.
keysToLock is a text[] parameter which is pre-sorted in our application
Would not hurt to triple-check this part as well. Could show us the app code? Maybe put in some sort of global assert in the app to verify that things are indeed sorted as you think they are.
