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Redis cache hit rate

2022-04-22 16:03:00 【a10534126】

What are the factors that affect the cache hit rate

Update strategy

The smaller the granularity of the cache , Low update frequency , The higher the percentage of hits .

Give a practical example to illustrate ： When caching a single object （ For example, single user information ）, Only when the data corresponding to the object changes , You need to update or remove the cache .

And when you cache a collection （ For example, all user data ）, When the data corresponding to any of these objects changes , Need to update or remove the cache .

Clear strategy

For a continuously running server , The server needs to check and organize its resources and status regularly , Clean up useless cache , The proportion of garbage is also a factor affecting the hit rate of cache .

The three removal strategies are as follows ：
（1） Clean up immediately . When setting the expiration time of the key , Create a callback event , When the expiration time reaches , Key deletion is performed automatically by the time processor .

（2） Inert cleaning . The key is out of date , No matter . When reading / Write an expired key when , Will trigger lazy delete policy , Delete this expiration directly key

（3） Regular clearance . Every once in a while , Yes expires Dictionary check , Delete the expiration key inside .

Business scenario

Cache fit “ Read more and write less ” Business scenario of , On the contrary, using cache makes little sense , The hit rate will be very low .

The longer the cache time is , The lower the timeliness requirement , The more suitable for caching .

Cache capacity

The capacity of the cache is limited , It is easy to cause cache invalidation and elimination .

Cache failure

Cache node failure , It will also cause cache invalidation , A typical practice in the industry is through consistency Hash Algorithm , Or use node redundancy .