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docs: clarify L1 backfill after L2 hit #2897

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docs: clarify L1 backfill after L2 hit #2897

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2 changes: 1 addition & 1 deletion docs/database/redis/cache-basics.md
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Expand Up @@ -169,7 +169,7 @@ Memcached 是分布式缓存最开始兴起的那会，比较常用的。后来

![多级缓存](https://oss.javaguide.cn/javaguide/database/redis/multilevel-cache.png)

读取缓存数据的时候，我们先从 L1 中读取，读取不到的时候再去 L2 读取。这样可以降低 L2 的压力，减少 L2 的读次数。如果 L2 也没有此数据的话，再去数据库查询，数据查询成功后再将数据写入到 L1 和 L2 中。
读取缓存数据的时候，我们先从 L1 中读取，命中后直接返回；L1 未命中时再去 L2 读取。如果 L2 命中，应先将数据回填到当前实例的 L1，再返回结果，避免后续每次 L1 未命中都重复访问 L2。如果 L2 也没有此数据，再去数据库查询，查询成功后将数据写入到 L1 和 L2 中。这样可以减少 L2 的读次数，降低 L2 的压力。

多级缓存开源实现推荐：

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