... command, 567locking, 26 2 26 6deadlocks, 26 2 26 4exclusive locks, 26 2explicit locking, 26 4 26 6locking rows, 26 5 26 6locking tables, 26 6shared locks, 26 2LOG exception level, 29 0log filesappending ... 17 20 data types, 20 1 21 2ALTER TYPE, 555arrays, 21 0 21 2boolean data type, 20 2 20 4changing data type in SELECT, 86char data type, 40character data types, 20 4 20 6columns, choosing for, 21 converting ... rules, 24 6handling multi-user access, 26 transaction isolation levelschanging, 26 1PostgreSQL default, 26 1undesirable phenomena, 25 6transactions, 25 5 26 1ANSI isolation levels, 26 0 26 1changing...