ZRANGEBYLEX for lexicographic queries in Redis

Introduction

ZRANGEBYLEX helps you get items from a sorted list based on alphabetical order, not numbers.

You want to find all names starting with a certain letter in a list.

You need to get all words between 'apple' and 'banana' alphabetically.

You want to list all items that come after 'cat' but before 'dog' in a dictionary.

You want to filter usernames that start with letters between 'a' and 'm'.

Syntax

Redis

ZRANGEBYLEX key min max [LIMIT offset count]

min and max define the lexicographic range using special characters: '[' means inclusive, '(' means exclusive, '-' means minimum, '+' means maximum.

LIMIT is optional and helps you get a smaller part of the results by skipping some and limiting how many you get.

Examples

Gets all items from 'myset' starting at 'apple' and including 'banana'.

Redis

ZRANGEBYLEX myset [apple [banana

Gets all items from 'myset' after 'apple' but before 'banana', excluding both.

Redis

ZRANGEBYLEX myset (apple (banana

Gets all items from 'myset' in alphabetical order.

Redis

ZRANGEBYLEX myset - +

Gets the first 3 items from 'myset' between 'cat' and 'dog', including both.

Redis

ZRANGEBYLEX myset [cat [dog LIMIT 0 3

Sample Program

We add fruits with score 0 (score is ignored for lex queries). Then we get fruits from 'banana' to 'fig' inclusive, sorted alphabetically.

Redis

127.0.0.1:6379> ZADD fruits 0 apple 0 banana 0 cherry 0 date 0 fig 0 grape
(integer) 6
127.0.0.1:6379> ZRANGEBYLEX fruits [banana [fig
1) "banana"
2) "cherry"
3) "date"
4) "fig"

Important Notes

ZRANGEBYLEX only works on sorted sets where all scores are the same or ignored; it sorts by member name alphabetically.

Time complexity is O(log(N)+M) where N is total elements and M is returned elements.

Common mistake: Using ZRANGEBYLEX on sorted sets with different scores expecting numeric order; it sorts by member name, not score.

Use ZRANGEBYLEX when you want alphabetical range queries; use ZRANGE for numeric score ranges.

Summary

ZRANGEBYLEX gets items from a sorted set based on alphabetical order.

Use '[' for inclusive and '(' for exclusive range boundaries.

LIMIT helps control how many results you get and where to start.