Master Redis Data Types and Commands: Strings, Hashes, Lists, Sets, Sorted Sets

Redis Data Types

General Operations

# Check if a key exists
EXISTS name            # returns (integer) 1
EXISTS name1           # returns (integer) 0

# Rename a key
RENAME name name2      # OK

# Get the data type of a key
TYPE name2             # string
TYPE PHPREDIS_SESSION:... # string

# Delete a key
DEL name2              # returns (integer) 1

# Get the TTL of a key (in seconds)
TTL age                # returns (integer) -1
TTL PHPREDIS_SESSION:... # returns (integer) 1212

# Set expiration (seconds)
EXPIRE aaa 100

# Set expiration (milliseconds)
PEXPIRE aaa 100

# Remove expiration
PERSIST aaa

String Operations (strings)

Add

# Set a key
SET name zls           # OK

# Set multiple keys
MSET name zls name1 huanglong name2 wuyangke   # OK

# Get multiple keys
MGET name name1 name2
1) "zls"
2) "huanglong"
3) "wuyangke"

# Get and set atomically
GETSET xxx 123        # (nil)
GET xxx               # "123"

# Set key with expiration (seconds)
SET book hongloumeng EX 100   # OK

# Set key with expiration (milliseconds)
SET book hongloumeng PX 100   # OK

# Increment
INCR zan               # returns (integer) 1
INCRBY fans 10000       # returns (integer) 10023
DECR fans               # returns (integer) 10012
DECRBY fans 1000        # returns (integer) 9012
INCRBYFLOAT zls 0.1    # returns "1.4"

Delete

DEL zls                # returns (integer) 1

Update

# Append to a string
APPEND name1 liquanyi  # returns (integer) 17
GET name1              # "huanglongliquanyi"

# Overwrite part of a string
SETRANGE name1 5 L    # returns (integer) 17
GET name1              # "huangLongliquanyi"

Query

# Get a single key
GET name1              # "huangLongliquanyi"

# Get multiple keys
MGET name1 name2
1) "huangLongliquanyi"
2) "wuyangke"

# Get string length
STRLEN name1          # returns (integer) 17
STRLEN name2          # returns (integer) 8

# Get TTL (seconds and milliseconds)
TTL name1              # returns (integer) 93
PTTL name1             # returns (integer) 91417

# Get substring
GETRANGE name1 0 4    # "huang"

Hash Operations (dictionary type)

Use case: Store partially mutable data such as user profiles or product information; the structure most closely resembles a table.

# Create or update fields
HSET keyname field value
HSET student_id_1 name zls
HSET student_id_1 name zls age 18 gender m
HMSET student_id_1 name zls age 18 gender m

# Retrieve fields
HGET keyname field
HGET student_id_1 name
HGETALL keyname
HGETALL student_id_1
HMGET student_id_1 name age

# Delete fields
HDEL student_id_1 age gender   # returns (integer) 2
DEL student_id_1               # delete the whole hash

# Update whole hash
HSET student_id_1 name zls age 18 gender m   # returns (integer) 3
HGETALL student_id_1

List Operations (list type)

Message queue analogy: A list can act as a simple FIFO queue where producers push items and consumers pop them.

# Push elements to the left (LPUSH)
LPUSH access_log '10.0.0.1 - - [03/Sep/2022:03:38:41 +0800] "POST /index.php HTTP/1.1" 200 1500 "-" "Mozilla/5.0 ..."'
LPUSH access_log '10.0.0.1 - - [03/Sep/2022:03:54:09 +0800] "POST /index.php HTTP/1.1" 200 1500 "-" "Mozilla/5.0 ..."'

# Push to the right (RPUSH)
RPUSH name1 hl
RPUSH name1 wyk
RPUSH name1 zls

# Insert after a specific element
LINSERT name2 AFTER hl hjx   # after: insert after; before: insert before

# Get a range of elements
LRANGE name1 0 2
1) "hl"
2) "wyk"
3) "zls"

# Pop from the left (LPOP)
LPOP name1   # "hl"
LPOP name1   # "wyk"
LPOP name1   # "zls"

# Get list length
LLEN name1

# Transfer element from one list to another (RPOPLPUSH)
RPOPLPUSH name1 name2   # moves the rightmost element of name1 to the left of name2

# Remove elements by value (LREM)
LREM name2 7 hl   # removes 7 occurrences of "hl"

# Trim list to keep only a range (LTRIM)
LTRIM name2 0 1   # keep first two elements

# Set element by index (LSET)
LSET name1 0 xwq   # replace element at index 0

# Get element by index (LINDEX)
LINDEX name1 1   # "hjx"
LINDEX name1 -1  # "hjx" (last element)

# Example: simulate a social feed
LPUSH wechat 'monday hl sb'
LPUSH wechat 'tiusiday hl yiran sb'
LPUSH wechat 'wensiday hl always sb'
LRANGE wechat 0 -1
1) "wensiday hl always sb"
2) "tiusiday hl yiran sb"
3) "monday hl sb"

Set Operations (set type)

# Create sets
SADD zls_fans wyk hl
SADD tly_fans mls gaofei wyk

# Membership test
SISMEMBER zls_fans hl   # returns (integer) 1
SISMEMBER zls_fans cls  # returns (integer) 0

# Get all members
SMEMBERS zls_fans
1) "hl"
2) "wyk"

# Cardinality
SCARD zls_fans   # returns (integer) 2
SCARD tly_fans   # returns (integer) 3

# Set difference
SDIFF hl_fans tly_fans zls_fans
# Set intersection (common friends)
SINTER hl_fans zls_fans
# Set union
SUNION hl_fans zls_fans

# Store difference in a new set
SDIFFSTORE result tly_fans hl_fans
SCARD result   # returns (integer) 2
SMEMBERS result
1) "wyk"
2) "gaofei"

# Random member
SRANDMEMBER zls_fans

# Move element between sets
SMOVE hl_fans zls_fans mls

# Remove element(s)
SPOP hl_fans   # removes and returns a random element
SREM zls_fans hl   # returns number of removed elements

# Add many numeric members (unordered)
SADD zls_fans 111 222 333 444 555 666

Sorted Set Operations (sorted‑set type)

Use case: Leaderboards where members are ordered by a score rather than insertion time.

# Add members with scores
ZADD myzset 1 "one" 2 "two" 3 "three"

# Retrieve members only
ZRANGE chengji 0 -1
1) "wyk"
2) "hl"
3) "zls"

# Retrieve members with scores
ZRANGE chengji 0 -1 WITHSCORES
1) "wyk"
2) "1"
3) "hl"
4) "38"
5) "zls"
6) "100"

# Get rank of a member
ZRANK chengji wyk   # 0
ZRANK chengji zls   # 2

# Cardinality
ZCARD chengji       # 3

# Count members with scores in a range
ZCOUNT chengji 30 40   # 1
ZCOUNT chengji 30 101  # 2

# Get score of a member
ZSCORE chengji wyk   # "1"
ZSCORE chengji zls   # "100"

# Get members by score range
ZRANGEBYSCORE chengji 30 40
1) "hl"

# Pagination with score range (using LIMIT)
ZRANGEBYSCORE chengji -inf +inf LIMIT 2 3
1) "hjx"
2) "xwq"
3) "zls"

# Delete members by score range
ZREMRANGEBYSCORE chengji 30 40   # returns number removed

# Delete members by rank range
ZREMRANGEBYRANK chengji 0 2   # removes first three members

# Reverse order (high to low)
ZREVRANGE chengji 0 -1 WITHSCORES
1) "zls"
2) "100"
3) "hjx"
4) "60"
5) "xwq"
6) "50"
7) "hl"
8) "38"
9) "wyk"
10) "1"

# Reverse range by score
ZREVRANGEBYSCORE chengji 101 30 WITHSCORES
1) "zls"
2) "100"
3) "hjx"
4) "60"
5) "xwq"
6) "50"
7) "hl"
8) "38"

# Reverse range with LIMIT
ZREVRANGEBYSCORE chengji 101 30 WITHSCORES LIMIT 1 2
1) "hjx"
2) "60"
3) "xwq"
4) "50"