Data types

aki speaks Redis on the wire, so the data types are the Redis data types. Strings, bitmaps, lists, sets, sorted sets, hashes, streams, HyperLogLog, and geo all work the way your Redis client expects. This page walks through each one with a small example you can paste into redis-cli.

Every command runs through the same paged engine and write-ahead log, so a write here is durable the moment it returns, not the next time something snapshots memory.

Strings

Strings are the basic type: a key holds a sequence of bytes. SET and GET take options like EX/PX for a TTL, NX/XX to set only if the key is missing or present, and GET to return the old value while setting the new one.

redis-cli SET greeting "hello" EX 60 NX
redis-cli GET greeting
redis-cli SET greeting "hi" GET

Strings that hold numbers can be incremented and decremented atomically.

redis-cli SET counter 10
redis-cli INCR counter
redis-cli INCRBY counter 5
redis-cli DECR counter
redis-cli INCRBYFLOAT counter 0.5

You can append to a string, read or write a substring by offset, and batch multiple keys at once.

redis-cli APPEND greeting " there"
redis-cli GETRANGE greeting 0 4
redis-cli SETRANGE greeting 0 "HI"
redis-cli MSET a 1 b 2 c 3
redis-cli MGET a b c

LCS finds the longest common subsequence of two string values, with LEN and IDX for the length and the matched ranges.

redis-cli SET key1 "ohmytext"
redis-cli SET key2 "mynewtext"
redis-cli LCS key1 key2
redis-cli LCS key1 key2 LEN

Bitmaps

A bitmap is a string treated as a bit array. You set and read individual bits, count the set bits, find the first 0 or 1, and combine bitmaps with boolean operations.

redis-cli SETBIT visits 7 1
redis-cli GETBIT visits 7
redis-cli BITCOUNT visits
redis-cli BITPOS visits 1
redis-cli BITOP AND dest visits other

BITFIELD packs several integers of arbitrary width into one string and operates on them in a single call.

redis-cli BITFIELD mykey SET u8 0 255 GET u8 0 INCRBY u8 0 10

Lists

Lists are ordered sequences you push and pop from either end. LRANGE reads a window, LMOVE shifts an element from one list to another, and LMPOP pops from the first non-empty list in a set of keys.

redis-cli RPUSH tasks a b c
redis-cli LPUSH tasks start
redis-cli LRANGE tasks 0 -1
redis-cli LPOP tasks
redis-cli RPOP tasks
redis-cli LMOVE tasks done LEFT RIGHT
redis-cli LMPOP 2 tasks done LEFT

The blocking variants wait for an element to arrive instead of returning nil on an empty list, which is how you build a simple queue.

redis-cli BLPOP tasks 5
redis-cli BRPOP tasks 5
redis-cli BLMOVE tasks done LEFT RIGHT 5

Sets

A set is an unordered collection of unique members. You add members, list them, test membership, and compute intersections, unions, and differences across sets.

redis-cli SADD tags go redis db
redis-cli SMEMBERS tags
redis-cli SISMEMBER tags go
redis-cli SADD other go rust
redis-cli SINTER tags other
redis-cli SUNION tags other
redis-cli SDIFF tags other
redis-cli SSCAN tags 0

Sorted sets

A sorted set keeps unique members ordered by a floating-point score. You can range by rank, by score, or by lexical order, look up a member's rank, bump a score, and pop the lowest or highest scoring member.

redis-cli ZADD board 100 alice 200 bob 150 carol
redis-cli ZRANGE board 0 -1 WITHSCORES
redis-cli ZRANGEBYSCORE board 120 250
redis-cli ZRANGEBYLEX board "[a" "[c"
redis-cli ZRANK board bob
redis-cli ZINCRBY board 25 alice
redis-cli ZPOPMIN board
redis-cli ZPOPMAX board

ZADD takes GT, LT, NX, and XX so you can update a score only when the new one is greater, lesser, or only when the member is new or already present.

redis-cli ZADD board GT 250 alice
redis-cli ZADD board NX 50 dave

Hashes

A hash maps fields to values inside one key, like a small record. You set and get fields, fetch the whole hash, delete fields, increment numeric fields, and scan large hashes incrementally.

redis-cli HSET user:1 name alice age 30
redis-cli HGET user:1 name
redis-cli HGETALL user:1
redis-cli HINCRBY user:1 age 1
redis-cli HDEL user:1 age
redis-cli HSCAN user:1 0

Fields can carry their own TTL. HEXPIRE sets a per-field expiry, HTTL reads it, and HPERSIST removes it, so one field can expire while the rest of the hash stays.

redis-cli HEXPIRE user:1 60 FIELDS 1 name
redis-cli HTTL user:1 FIELDS 1 name
redis-cli HPERSIST user:1 FIELDS 1 name

Streams

A stream is an append-only log of entries, each with an ID and a set of field-value pairs. XADD appends, XRANGE and XLEN read, and XREAD follows the stream from a given ID.

redis-cli XADD events '*' type login user alice
redis-cli XLEN events
redis-cli XRANGE events - +
redis-cli XREAD COUNT 10 STREAMS events 0

Consumer groups let several workers split the entries and track what has been processed. XGROUP creates a group, XREADGROUP hands out entries, XACK marks them done, and XAUTOCLAIM reassigns entries from a worker that went away.

redis-cli XGROUP CREATE events workers 0
redis-cli XREADGROUP GROUP workers w1 COUNT 5 STREAMS events '>'
redis-cli XACK events workers 1700000000000-0
redis-cli XAUTOCLAIM events workers w2 60000 0

HyperLogLog

A HyperLogLog estimates how many distinct items it has seen using a tiny, fixed amount of space. You add items, count the approximate cardinality, and merge several into one. The trade is a small error rate in exchange for not storing every member.

redis-cli PFADD visitors alice bob carol
redis-cli PFCOUNT visitors
redis-cli PFADD visitors2 carol dave
redis-cli PFMERGE total visitors visitors2
redis-cli PFCOUNT total

Geo

Geo commands store longitude and latitude points in a sorted set and query them by distance. GEOADD stores points, GEOSEARCH finds points within a radius or box, and the rest read back distance, position, and geohash.

redis-cli GEOADD places -122.27 37.80 oakland -122.42 37.77 sf
redis-cli GEOSEARCH places FROMMEMBER sf BYRADIUS 50 km ASC
redis-cli GEODIST places sf oakland km
redis-cli GEOPOS places sf
redis-cli GEOHASH places sf

Generic key commands

These work across every type. You delete keys, test existence, set and read TTLs, ask a key's type, list or scan keys, rename, copy, serialize, and sort.

redis-cli DEL greeting
redis-cli EXISTS user:1
redis-cli EXPIRE user:1 120
redis-cli TTL user:1
redis-cli PERSIST user:1
redis-cli TYPE board
redis-cli SCAN 0 MATCH 'user:*' COUNT 100
redis-cli RENAME user:1 user:one
redis-cli COPY user:one user:two
redis-cli SORT tasks ALPHA

DUMP and RESTORE serialize a single key to and from the Redis dump format, which is handy for moving one key between servers.

redis-cli DUMP user:one
redis-cli RESTORE user:copy 0 "<serialized bytes>"

For the exact arguments, return values, and edge cases of every command, see the full command reference.