Can PostgreSQL UPDATEs in autocommit mode deadlock?
That is certainly possible if the update affects more than a single table row.
This can come to pass in two ways:

The query modifies more than a single row in the target table.

The updated table has a foreign key constraint to another table. In that case, you may end up with a FOR KEY SHARE lock on the referenced table.


The deadlock can happen if your statement successfully locks a couple of rows and then blocks on a lock on some other row.