suppose we have a sql query that will take 2 seconds.
We cache the results of this sql query to redis and set a 60-second timeout.
so when 60 seconds arrive, that is, two seconds from 60 to 62 seconds, hundreds of requests may miss the cache and query the database directly.
how can I prevent this from happening?
this is cached Avalanche: if the cache expires within a period of time, a large number of cache traverses occur, and all queries fall on the database
.Cache traversal refers to querying a data that must not exist. Because when the cache misses, it needs to be queried from the database, and if the data cannot be found, it is not written to the cache. This will cause the non-existent data to be queried to the database every time, resulting in cache penetration.
solution to caching Avalanche:
Source: https://blog.csdn.net/m0_3811.
estimate the maximum duration of cached data. 60 seconds is not set randomly, but according to the needs of the scene. Set a longer time. I really don't know any other way. I have paid attention to it and look forward to another answer
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