The write that happened twice
Every sale goes in the register and must also reach the warehouse. The app crashes now and then. Which design lets the two disagree?
Read the lesson behind this The write that has to happen twice (CDC and the outbox)Preparing for interviews? The ten-week plan puts this in order with DSA and the design rounds.
A clerk writes each sale in the register and must also tell the warehouse. Written twice, a crash between the two leaves one side wrong, in either order. Carbon paper writes the sale and its slip in one stroke, and a courier carries the slips, sometimes twice. Watch what goes missing, what is made up, and what arrives twice.
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the lesson The write that has to happen twice (CDC and the outbox)
The whole idea this lab came from, told start to finish.
on the path Module 2 of 29 in System Design: When the stalls must agree
The lessons, boards and videos around this lab, in reading order.
Board: The Ledger Everyone Reads