3.2 Read-Through, Write-Through, Write-Behind

A profile update shows the difference between the strategies in this lesson. A user changes a display name, and the question is when the database learns about it and what happens if something fails in between. In cache-aside, the application talks to both the cache and the database and keeps them consistent itself. The three strategies here move that responsibility into the cache layer, so the application talks only to the cache, and the cache layer loads from and writes to the database.