system-design-primer/resources/noat.cards/14-6 Refresh-ahead.md

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# Refresh-ahead
## Introduction
![](https://camo.githubusercontent.com/49dcb54307763b4f56d61a4a1369826e2e7d52e4/687474703a2f2f692e696d6775722e636f6d2f6b78746a7167452e706e67)
[Source: From cache to in-memory data grid](http://www.slideshare.net/tmatyashovsky/from-cache-to-in-memory-data-grid-introduction-to-hazelcast)
You can configure the cache to automatically refresh any recently accessed cache entry prior to its expiration.
Refresh-ahead can result in reduced latency vs read-through if the cache can accurately predict which items are likely to be needed in the future.
## Disadvantage(s) : refresh-ahead
- Not accurately predicting which items are likely to be needed in the future can result in reduced performance than without refresh-ahead.