I am using redis as centralized cache for distributed system. Currently i am using jedis to connect to redis cluster, where i am storing the value as byte[] instead of string. My question is does storing plain string or byte [] has impact on getting the data. In my application i serialize my java pojo object and convert to byte [] and then store, where as i can convert it to json and store so while getting it from redis i can readily use the object instead of deserialize. I have tried both but the only difference i can see is the extra step of deserialize
1 Answers
8
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In Redis, everything is a byte[]. What redis calls as strings are actually byte[] in programming languages.
When you store JSON, you still need to serialize it to byte[] before saving to redis, and do the reverse when you read back. This is no different from serializing a java object. In other words, you always have to pay the cost of serialization and deserialization.
That said, different libraries have different serialization costs. Java serialization is know to be slow and inefficient. JSON is likely to be better than java serialization - but wastes memory in redis because it is a text based. You can choose a better serialization library.
Kryo is a faster replacement for the java serializer. Message Pack is like JSON but faster. Protocol Buffers / Flat Buffers are even better, but require you to declare a schema upfront. There are other serialization formats as well, each with their tradeoffs.
The general recommendation - try to use the hash datatype. It is efficient, and lets you request specific fields instead of the whole object. Only if hash does not work for you, pick something else based on your needs.
P.S. If you are into benchmarks, this website has several - https://github.com/eishay/jvm-serializers/wiki
