Transactions and Isolation

Part of the PostgreSQL course

Two UPDATE statements move money from Alice to Bob. The first one runs, the connection drops, the second one never happens, and thirty pounds have simply ceased to exist. Nothing was buggy about either statement; the problem is that they were two separate events when they needed to be one.

Open the terminal, give this lesson a fresh database of its own, and connect to it as postgres (lesson 02 explains the sudo -u postgres) ...