ZRANGEBYSCORE for score-based queries in Redis - Cheat Sheet & Quick Revision

Recall & Review

beginner

What does the Redis command ZRANGEBYSCORE do?

It returns all the members in a sorted set with scores within a given range, ordered from lowest to highest score.

intermediate

How do you specify the score range in ZRANGEBYSCORE?

You provide two arguments: the minimum score and the maximum score. You can use parentheses to exclude a boundary (e.g., (5 means greater than 5).

beginner

What does the syntax ZRANGEBYSCORE key min max WITHSCORES return?

It returns the members with scores between min and max along with their scores.

intermediate

How can you limit the number of results returned by ZRANGEBYSCORE?

By adding the LIMIT offset count option after the score range to return a subset of matching members.

beginner

Why is ZRANGEBYSCORE useful in real-life applications?

It helps retrieve items like top scores, events in a time range, or ranked data efficiently based on numeric scores.

What does ZRANGEBYSCORE myset 10 20 return?

A All members regardless of score

B Members with scores between 10 and 20 inclusive

C Members with scores less than 10 or greater than 20

D Members with scores exactly 10 or 20 only

ZRANGEBYSCORE returns members with scores between the min and max values, including both boundaries by default.

How do you exclude the minimum score 5 in ZRANGEBYSCORE?

A Use (5

B Use 5

C Use [5

D Use >5

Using (5 means scores strictly greater than 5, excluding 5 itself.

Which option returns scores along with members?

A SCORES

B LIMIT

C WITHSCORES

D INCLUDE

WITHSCORES tells Redis to return each member's score along with the member.

What does LIMIT 0 3 do in ZRANGEBYSCORE?

A Limits scores to 0 or 3 only

B Skips the first 3 members

C Returns members with scores 0 to 3

D Returns the first 3 matching members

LIMIT offset count returns count members starting from offset 0, so first 3 members.

Which data structure does ZRANGEBYSCORE work on?

A Sorted Sets

B Lists

C Hashes

D Strings

ZRANGEBYSCORE works on sorted sets, which store members with scores.

Explain how to use ZRANGEBYSCORE to get members with scores between 50 and 100, including how to exclude the lower bound.

Think about how to write the min argument to exclude 50.

Describe a real-life scenario where ZRANGEBYSCORE would be helpful and how you would use it.

Consider a game or event timeline.

Practice

1. What does the Redis command ZRANGEBYSCORE do?

easy

A. It returns the rank of a member in a sorted set.

B. It deletes members from a sorted set by score.

C. It adds a member with a score to a sorted set.

D. It returns members in a sorted set within a given score range.

Solution

1. Step 1: Understand the command purpose

   ZRANGEBYSCORE is used to get members from a sorted set based on their scores.

2. Step 2: Compare options with command behavior

   Only It returns members in a sorted set within a given score range. correctly describes returning members within a score range.

3. Final Answer:

   It returns members in a sorted set within a given score range. -> Option D

4. Quick Check:

   ZRANGEBYSCORE = returns members by score range [OK]

Hint: ZRANGEBYSCORE fetches by score range, not by rank or deletion [OK]

Common Mistakes:

• Confusing ZRANGEBYSCORE with ZREM (deletion)
• Thinking it returns rank instead of members
• Mixing it up with ZADD (adding members)

2. Which of the following is the correct syntax to get members with scores between 10 and 20 from sorted set myzset including their scores?

easy

A. ZRANGEBYSCORE myzset 10 20 INCLSCORES

B. ZRANGEBYSCORE myzset 10 20 WITHSCORE

C. ZRANGEBYSCORE myzset 10 20 WITHSCORES

D. ZRANGEBYSCORE myzset 10 20 SCORES

Solution

1. Step 1: Recall correct option for including scores

   The correct keyword to include scores in output is WITHSCORES.

2. Step 2: Check syntax correctness

   ZRANGEBYSCORE myzset 10 20 WITHSCORES uses the exact correct syntax: ZRANGEBYSCORE myzset 10 20 WITHSCORES.

3. Final Answer:

   ZRANGEBYSCORE myzset 10 20 WITHSCORES -> Option C

4. Quick Check:

   WITHSCORES keyword includes scores [OK]

Hint: Use WITHSCORES exactly to get scores with members [OK]

Common Mistakes:

• Misspelling WITHSCORES
• Using WITHSCORE or SCORES instead
• Omitting WITHSCORES when scores are needed

3. Given the sorted set myzset with members and scores:
"a"=5, "b"=10, "c"=15, "d"=20, "e"=25
What is the result of ZRANGEBYSCORE myzset 10 20 LIMIT 1 2?

medium

A. ["c", "d"]

B. ["b", "c", "d"]

C. ["b", "c"]

D. ["a", "b"]

Solution

1. Step 1: Identify members in score range 10 to 20

   Members with scores 10, 15, 20 are "b", "c", "d".

2. Step 2: Apply LIMIT 1 2

   LIMIT 1 2 means skip 1 member, then return next 2 members. Skipping "b", next two are "c", "d".

3. Final Answer:

   ["c", "d"] -> Option A

4. Quick Check:

   LIMIT skips then returns count [OK]

Hint: LIMIT offset count skips offset, returns count members [OK]

Common Mistakes:

• Ignoring LIMIT offset and returning from start
• Confusing score range with member count
• Including members outside score range

4. You run the command ZRANGEBYSCORE myzset (10 20 but get an error. What is the likely cause?

medium

A. Syntax error due to missing closing parenthesis after 20.

B. Incorrect use of parentheses for exclusive range; missing closing parenthesis.

C. Command is missing the key name.

D. Missing closing parenthesis for exclusive range syntax.

Solution

1. Step 1: Analyze the command syntax

   The command uses (10 to indicate exclusive minimum score 10, which is correct syntax.

2. Step 2: Identify the error

   The command ends with 20 without closing parenthesis or space, causing syntax error.

3. Final Answer:

   Syntax error due to missing closing parenthesis after 20. -> Option A

4. Quick Check:

   Exclusive range needs parentheses on score values [OK]

Hint: Check parentheses carefully for exclusive score ranges [OK]

Common Mistakes:

• Forgetting parentheses for exclusive ranges
• Missing spaces between arguments
• Using parentheses incorrectly around scores

5. You want to get the top 3 members with scores between 0 and 100 from sorted set myzset, including their scores, but only if their score is greater than 50. Which command achieves this?

hard

A. ZRANGEBYSCORE myzset 50 100 WITHSCORES LIMIT 0 3

B. ZRANGEBYSCORE myzset (50 100 WITHSCORES LIMIT 0 3

C. ZRANGEBYSCORE myzset [50 100 WITHSCORES LIMIT 0 3

D. ZRANGEBYSCORE myzset (50 100 LIMIT 3 WITHSCORES

Solution

1. Step 1: Define score range with exclusive lower bound

   To get scores greater than 50, use (50 for exclusive minimum.

2. Step 2: Include scores and limit results

   Use WITHSCORES to include scores and LIMIT 0 3 to get top 3 members.

3. Step 3: Verify command syntax

   ZRANGEBYSCORE myzset (50 100 WITHSCORES LIMIT 0 3 correctly uses ZRANGEBYSCORE myzset (50 100 WITHSCORES LIMIT 0 3.

4. Final Answer:

   ZRANGEBYSCORE myzset (50 100 WITHSCORES LIMIT 0 3 -> Option B

5. Quick Check:

   Exclusive range + WITHSCORES + LIMIT = correct command [OK]

Hint: Use (score for exclusive, WITHSCORES, then LIMIT offset count [OK]

Common Mistakes:

• Using inclusive 50 instead of exclusive
• Placing LIMIT before WITHSCORES
• Using wrong bracket types for exclusive range