ZRANGEBYSCORE for score-based queries in Redis - Practice Problems & Coding Challenges

Challenge - 5 Problems

❓ query_result

intermediate

Output of ZRANGEBYSCORE with inclusive range

Given a sorted set 'players' with scores: {"Alice": 50, "Bob": 70, "Charlie": 70, "Diana": 90}, what is the output of the command ZRANGEBYSCORE players 50 70?

A ["Alice", "Bob", "Charlie"]

B ["Alice", "Diana"]

C ["Bob", "Charlie"]

D ["Alice", "Bob"]

💡 Hint

ZRANGEBYSCORE includes elements with scores equal to the min and max by default.

ZRANGEBYSCORE returns all elements with scores between the min and max inclusive. Here, Alice (50), Bob (70), and Charlie (70) are included.

❓ query_result

intermediate

ZRANGEBYSCORE with exclusive min and max

What is the result of ZRANGEBYSCORE players (50 (90 on the same sorted set as before?

A ["Bob", "Charlie"]

B ["Alice", "Bob", "Charlie"]

C ["Diana"]

D []

💡 Hint

Parentheses before a score mean exclusive range boundary.

The command excludes scores equal to 50 and 90, so only Bob and Charlie with score 70 are returned.

📝 Syntax

advanced

Identify the syntax error in ZRANGEBYSCORE usage

Which option contains a syntax error when trying to get elements with scores between 10 and 20?

A ZRANGEBYSCORE myset 10 (20

B ZRANGEBYSCORE myset (10 20

C ZRANGEBYSCORE myset 10 20 (LIMIT 0 5)

D ZRANGEBYSCORE myset 10 20

💡 Hint

Check the syntax for LIMIT usage in ZRANGEBYSCORE.

The LIMIT option requires the keyword LIMIT before offset and count, not parentheses around it.

❓ optimization

advanced

Optimizing ZRANGEBYSCORE for large sorted sets

You want to retrieve only the first 3 elements with scores between 100 and 200 from a large sorted set. Which command is the most efficient?

A ZRANGEBYSCORE myset (100 (200 LIMIT 0 3

B ZRANGEBYSCORE myset 100 200 LIMIT 0 3

C ZRANGEBYSCORE myset 100 200

D ZRANGEBYSCORE myset 100 200 LIMIT 3 0

💡 Hint

LIMIT offset count syntax helps reduce data transferred.

Using LIMIT 0 3 returns only the first 3 matching elements, reducing memory and network usage.

🧠 Conceptual

expert

Understanding ZRANGEBYSCORE with negative and positive infinity

What is the output of ZRANGEBYSCORE myset -inf +inf on a sorted set with elements {"a": 1, "b": 2, "c": 3}?

A ["a"]

B []

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

D ["a", "b", "c"]

💡 Hint

Negative and positive infinity include all scores.

Using -inf and +inf as min and max returns all elements in ascending score order.