Redis Lists: LTRIM

Redis LTRIM Command

Redis LTRIM command is used to trim an existing list so that it will contain only the specified range of elements specified. Both start and stop are zero-based indexes, where 0 is the first element of the list (the head), 1 the next element and so on.

Here are some common uses and scenarios for the "LTRIM" command:

• List Size Management: Limit the size of a list by keeping only a specified range of elements.
• Data Partitioning: Maintain efficient data partitioning by trimming unnecessary elements from lists.
• Task Queue Optimization: Optimize task queues by retaining only the most relevant tasks within a specified range.
• Event Handling: Manage event lists by trimming outdated or unnecessary events based on their position.
• Memory Efficiency: Improve memory usage by reducing the size of lists to essential elements.

Syntax:

redis 127.0.0.1:6379> LTRIM KEY_NAME START STOP

Available since

1.0.0.

Return Value

String reply, OK

Return Value Type

String

Example: Redis LTRIM: Delete your data outside the range specified by index

127.0.0.1:6379> LPUSH mycolor1 white black red blue
(integer) 4
127.0.0.1:6379> LRANGE mycolor1 0 -1
1) "blue"
2) "red"
3) "black"
4) "white"
127.0.0.1:6379> LTRIM mycolor1 1 2
OK
127.0.0.1:6379> LRANGE mycolor1 0 -1
1) "red"
2) "black"

Example: Redis LTRIM: Use negative

127.0.0.1:6379> LPUSH mycolor1 white black red blue
(integer) 4
127.0.0.1:6379> LTRIM mycolor1 -2 -1
OK
127.0.0.1:6379> LRANGE mycolor1 0 -1
1) "black"
2) "white"

Example: Redis LTRIM: Range Selection Caution

127.0.0.1:6379> LPUSH mycolor1 white black red blue
(integer) 4
127.0.0.1:6379> LTRIM mycolor1 10 10
OK
127.0.0.1:6379> LRANGE mycolor1 0 -1
(empty list or set)

Previous: LRANGE
Next: RPOP