types in redis

Redis supports several different data types that allow you to store a variety of data structures. As of the latest Redis versions, the primary data types include:

1. Strings:

   • The simplest type, storing text or binary data up to 512 MB in size.
   • Examples: "Hello, World!", "12345", "\x00\x01\x02"

2. Lists:

   • Ordered collections of strings.
   • Implemented as linked lists, allowing operations like LPUSH, RPUSH, LPOP, RPOP, and LRANGE.
   • Example: ["apple", "banana", "cherry"]

3. Sets:

   • Unordered collections of unique strings.
   • Support operations like SADD, SREM, SPOP, SMEMBERS, and set operations like SINTER, SUNION, SDIFF.
   • Example: {"apple", "banana", "cherry"}

4. Sorted Sets (ZSets):

   • Similar to Sets but with an associated score for each member, allowing the members to be ordered.
   • Support operations like ZADD, ZREM, ZRANGE, ZRANGEBYSCORE, ZINCRBY.
   • Example: {("apple", 1), ("banana", 2), ("cherry", 3)}

5. Hashes:

   • Maps of fields and values, similar to dictionaries or hash tables.
   • Useful for storing objects.
   • Support operations like HSET, HGET, HMSET, HGETALL.
   • Example: {"name": "Alice", "age": "30", "city": "Wonderland"}

6. Bitmaps:

   • Strings that can be used as bit arrays.
   • Allow bit-level operations.
   • Support operations like SETBIT, GETBIT, BITCOUNT.

7. HyperLogLogs:

   • Probabilistic data structure used for counting unique items with high efficiency.
   • Support operations like PFADD, PFCOUNT, PFMERGE.
   • Useful for approximate distinct counting.

8. Geospatial Indexes:

   • Specialized form of sorted sets for storing geospatial data.
   • Support operations like GEOADD, GEORADIUS, GEODIST, GEOPOS.
   • Example: Store locations with latitude and longitude.

9. Streams:

   • Log-based data structure for storing an append-only series of messages.
   • Support operations like XADD, XRANGE, XREAD, XGROUP.
   • Useful for real-time data processing and message brokering.

Additional Features and Data Structures

• Modules:

  • Redis can be extended with custom modules that provide new data types and functionalities.

• Keys and Keyspace Notifications:

  • Although not a data type, Redis provides notifications for events related to keys.

Example Commands for Each Type

• String: SET key "value", GET key
• List: LPUSH mylist "world", RPUSH mylist "hello", LRANGE mylist 0 -1
• Set: SADD myset "hello", SADD myset "world", SMEMBERS myset
• Sorted Set: ZADD myzset 1 "one", ZADD myzset 2 "two", ZRANGE myzset 0 -1 WITHSCORES
• Hash: HSET myhash field1 "foo", HSET myhash field2 "bar", HGETALL myhash
• Bitmap: SETBIT mybitkey 7 1, GETBIT mybitkey 7, BITCOUNT mybitkey
• HyperLogLog: PFADD myhll "foo" "bar" "baz", PFCOUNT myhll
• Geospatial: GEOADD mygeo 13.361389 38.115556 "Palermo", GEORADIUS mygeo 15 37 200 km
• Stream: XADD mystream * name Alice, XRANGE mystream - +

Redis's diverse data types make it a versatile tool for various use cases, from simple caching to complex data structures and real-time data processing.