ZRANGEBYLEX for lexicographic queries in Redis - Practice Problems & Coding Challenges

Challenge - 5 Problems

❓ query_result

intermediate

What is the output of this ZRANGEBYLEX query?

Given a sorted set myzset with members a, b, c, d, and e, what does the command ZRANGEBYLEX myzset [b [d return?

Redis

ZRANGEBYLEX myzset [b [d

A ["b", "c", "d"]

B ["c", "d"]

C ["a", "b", "c", "d"]

D ["b", "c"]

💡 Hint

Remember that square brackets mean inclusive range in lexicographic queries.

The command returns all members from 'b' to 'd' inclusive, so it includes 'b', 'c', and 'd'.

📝 Syntax

intermediate

Which ZRANGEBYLEX command is syntactically correct?

Choose the syntactically valid ZRANGEBYLEX command to get members lexicographically between 'a' (exclusive) and 'c' (inclusive).

A ZRANGEBYLEX myzset [a [c

B ZRANGEBYLEX myzset [a (c

C ZRANGEBYLEX myzset (a (c

D ZRANGEBYLEX myzset (a [c

💡 Hint

Parentheses mean exclusive, square brackets mean inclusive in ZRANGEBYLEX.

Option D correctly uses (a for exclusive start and [c for inclusive end, matching the requirement.

❓ optimization

advanced

How to optimize a ZRANGEBYLEX query for large sorted sets?

You want to retrieve members lexicographically between 'm' and 'z' from a very large sorted set. Which approach optimizes performance best?

A Use ZRANGEBYLEX with a small range and LIMIT option to paginate results.

B Use ZRANGEBYSCORE instead with scores converted from lexicographic values.

C Use ZRANGEBYLEX with exclusive ranges to reduce returned members.

D Use ZRANGEBYLEX without LIMIT to get all results at once.

💡 Hint

Fetching large ranges at once can be slow; pagination helps.

Using LIMIT with ZRANGEBYLEX paginates results, reducing memory and network load.

🔧 Debug

advanced

Why does this ZRANGEBYLEX command return an empty list?

Given a sorted set with members 'apple', 'banana', 'cherry', 'date', why does ZRANGEBYLEX myzset (banana (cherry return an empty list?

A Because the sorted set is empty.

B Because the command syntax is invalid and causes an error.

C Because the range excludes both 'banana' and 'cherry', and no members lie strictly between them.

D Because the range should use square brackets instead of parentheses.

💡 Hint

Parentheses exclude the boundary members.

The range excludes 'banana' and 'cherry' and no other members are lexicographically between them.

🧠 Conceptual

expert

What is the difference between ZRANGEBYLEX and ZRANGEBYSCORE?

Which statement best describes the difference between ZRANGEBYLEX and ZRANGEBYSCORE commands in Redis sorted sets?

A ZRANGEBYLEX queries by numeric score values, ZRANGEBYSCORE queries by lexicographic order.

B ZRANGEBYLEX queries members by their lexicographic order ignoring scores, while ZRANGEBYSCORE queries by numeric score values.

C Both commands query by score but ZRANGEBYLEX is faster.

D ZRANGEBYLEX only works on sets with string scores, ZRANGEBYSCORE only on numeric members.

💡 Hint

Think about what 'lex' and 'score' mean.

ZRANGEBYLEX uses the member strings' lexicographic order ignoring scores; ZRANGEBYSCORE uses numeric scores.