system-design-primer/resources/noat.cards/Write-behind (write-back).md

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Write-behind (write-back)

Introduction

Source: Scalability, availability, stability, patterns

In write-behind, tha application does the following:

• Add/update entry in cache
• Asynchronously write entry to the data store, improving write performance

Disadvantage(s) : write-behind

• There could be data loss if the cache goes down prior to its contents hitting the data store.
• It is more complex to implement write-behind than it is to implement cache-aside or write-through.