Free Indexes, queries and scale lessonsIndexes, queries and scale · Stage 3 · Scaling out · Step 2
Caching and the CAP trade-off
Cache patterns and their staleness, and what CAP actually forces you to choose when the network splits. About 14 minutes.
A product catalogue is read by millions and updated by editors. A cache holds each product page for 60 seconds. What does that choice accept?
- AReaders may see a change up to 60 seconds late, in exchange for far fewer database reads
- BEdits may be lost
- CEvery reader always sees the latest edit
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Readers may see a change up to 60 seconds late, in exchange for far fewer database reads. A TTL bounds the staleness.
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