Master Redis Lists: Commands, Encoding, and QUICKLIST Explained

What is Redis List?

Redis List is a collection of linked strings.

Limitations

Maximum number of elements is 2^32‑1 (4,294,967,295).

Use Cases

Lists serve as low‑level data structures for tasks such as storing queues of jobs or messages.

Common Operations

Operations focus on create, read, update, and delete.

Write Commands

LPUSH

Syntax: LPUSH key value [value ...] Adds elements to the head of the list and returns the list length.

127.0.0.1:6379> LPUSH listniuniu s1 s2 s3
(integer) 3
127.0.0.1:6379> LPUSH listniuniu s4
(integer) 4

RPUSH

Syntax: RPUSH key value [value ...] Adds elements to the tail and returns the list length.

127.0.0.1:6379> RPUSH listniuniu s5
(integer) 5

LPOP

Syntax: LPOP key Removes and returns the first element.

127.0.0.1:6379> LPOP listniuniu
"s4"

RPOP

Syntax: RPOP key Removes and returns the last element.

127.0.0.1:6379> RPOP listniuniu
"s5"

DEL

Syntax: DEL key [key ...] Deletes the key and returns the number of keys removed.

127.0.0.1:6379> DEL listniuniu
(integer) 1

Read Commands

LLEN

Syntax: LLEN key Returns the length of the list.

127.0.0.1:6379> LLEN listniuniu
(integer) 3

LRANGE

Syntax: LRANGE key start stop Returns elements between start and stop indices. Negative indices count from the end.

127.0.0.1:6379> LRANGE listniuniu 0 1
1) "s3"
2) "s2"
127.0.0.1:6379> LRANGE listniuniu -2 -1
1) "s2"
2) "s1"

Underlying Implementation

Encoding Types (pre‑3.2)

Lists were encoded as either ZIPLIST (compact) or LINKEDLIST.

ZIPLIST is used when all strings are less than 64 bytes and the list has fewer than 512 elements.

If those conditions are not met, LINKEDLIST is used, storing each element as a separate node.

QUICKLIST (since 3.2)

QUICKLIST combines ZIPLIST and LINKEDLIST: each node of a linked list holds a ZIPLIST, giving the memory efficiency of ZIPLIST and the flexibility of LINKEDLIST.

ZIPLIST Optimizations

From Redis 7.0, ZIPLIST is replaced by LISTPACK, a more efficient compressed list representation.

Summary

Redis List is a double‑ended list data structure whose internal encoding switches between ZIPLIST, LINKEDLIST, and QUICKLIST to balance memory usage and performance.