04 Try it yourself Interactive
The same transfer, run twice. A holds 1,000 and B holds 500, so the bank’s books read 1,500 before the transfer and must read 1,500 after it. Commits runs it to the end. Crashes halfway cuts the power after the debit and before the credit, and then lets the recovery manager read the log at startup. The five nodes are the state diagram from section 02, with the current state marked. Both balances are on the stat row at every step, so you can watch the invariant break and be restored, and the label above the console names the letter of ACID on show at that moment. Nothing plays on its own: Next, Back and Reset, or the arrow keys.