Keys
Redis keys are binary-safe. It means you can use any binary sequence as a key, from a string ‘foo’ to the content of a JPEG file. The empty string “” is also a valid key.
- Very long keys are not a good idea. They take more memory, and more time in the lookup with costly key-comparison.
- Very short keys are often not a good idea. They harm readability and added space is often minor.
- Try to stick with a schema. For instance, “object-type:id” (”user:1000”). Dots (.) or dashes (-) are often used for multi-word fields, as in “comment:431:reply.to” or “comment:4321:reply-to”.
- The maximum allowed key size is 512 MB.
Data Types
- Strings: most basic and simplest data type
- can be used for atomic counters
- Lists: ordered list of strings
LPUSH,RPUSH
- Sets: unrepeated, unordered collection of Strings
- Hashes: maps between String fields and String values
- Sorted Sets: not repeating collection of Strings, each member associated with a
score, used to keep the Sorted Set in order from smallest to greatest score. - Bitmaps and HyperLogLogs: data types based on String base type, with their own semantics
- Streams: data structure that acts like an append-only log. useful for recording events in the order they occur.
- Geospatial Indexes: useful for finding locations within a given geographic radius.