Redis Questions

Vikas Vimal (Vikki)

Score: 🔥 175

Beginner

Took 2 months

Databases

Redis

80%

Questions Attempted

15 / 15

Correct Answers

Incorrect Answers

Points Earned

🔥 12

Question 1

What is the correct way to set a key-value pair named 'mykey' with the value 'myvalue' using redis-py?

r.set('mykey', 'myvalue')
r.insert('mykey', 'myvalue')
r.put('mykey', 'myvalue')
r.assign('mykey', 'myvalue')

Explanation:

The r.set() method is used to store a value associated with a specific key in Redis. Assuming 'r' is your Redis connection object.

Question 2

What is the expected return value of 'EXISTS user' if the 'user' key is present in Redis?

True
1
0
False

Explanation:

The EXISTS command in Redis returns 1 if the key exists and 0 if it doesn't. It doesn't use boolean values.

Question 3

How do you set a key to expire after 20 seconds in Redis?

EXPIRE key 20
SETEX key 20 value
TIMEOUT key 20
PERSIST key 20

Explanation:

The EXPIRE command is used to set an expiration time (in seconds) for a key. In this case, EXPIRE key 20 would make the 'key' expire after 20 seconds.

Question 4

What is a potential drawback of using only RDB snapshots for persistence in Redis?

High memory usage
Slow write speeds
Potential data loss between snapshots
Complex configuration

Explanation:

If your Redis server crashes, you'll only recover data up to the last successful RDB snapshot. Any writes after the snapshot might be lost.

Question 5

What is the primary effect of renaming a key in Redis?

Changes the value associated with the key.
Changes the data type of the key.
Changes the expiration time of the key.
Changes how the key is referenced.

Explanation:

Renaming a key only affects how it is identified within Redis. The data type, value, and expiration time remain unchanged.

Question 6

What file extension is typically used for Redis's Append-Only File?

.rdb
.redis
.aof
.log

Explanation:

Redis AOF files, containing the write operation logs, are conventionally saved with the '.aof' extension.

Question 7

Which command is used to decrease the value of a key by 1 in Redis?

DECR
DECREMENT
SUB
MINUS

Explanation:

DECR is the command in Redis specifically designed to decrement the value of a key by 1.

Question 8

After installing Redis, what command is commonly used to start the Redis server?

redis-server
start redis
run redis
execute redis

Explanation:

The redis-server command is used to initiate the Redis server process, making it ready to accept connections and process commands.

Question 9

Which method is used to check if a key exists in a Redis database using redis-py?

r.exists('mykey')
r.check('mykey')
r.has_key('mykey')
r.contains('mykey')

Explanation:

The r.exists() method checks if the provided key exists within the Redis database, returning 1 if it does and 0 if not. 'r' is your Redis connection object.

Question 10

What is the correct syntax to set a key-value pair in Redis where the key is 'name' and the value is 'John'?

SET name John
STORE name John
PUT name John
CREATE name John

Explanation:

In Redis, the SET command is used to set a key-value pair. The syntax is SET key value.

Question 11

How does Redis differ from a traditional relational database like MySQL?

Redis is schema-less, while MySQL enforces a strict schema
Redis is primarily disk-based, while MySQL is in-memory
Redis is optimized for complex joins and queries, while MySQL is not
Redis is not suitable for storing persistent data, while MySQL is

Explanation:

Redis's flexibility shines in its schema-less nature, allowing you to store data without predefined structures. MySQL, as a relational database, requires a defined schema.

Question 12

How do you delete a key-value pair in Redis where the key is 'city'?

DELETE city
REMOVE city
ERASE city
DROP city

Explanation:

The DELETE command is used to remove key-value pairs from Redis. You specify the key you want to delete.

Question 13

You need to store a leaderboard with scores for players. Which Redis data type is most appropriate?

List
Set
Sorted Set
Hash

Explanation:

Sorted Sets are designed for storing elements with scores, allowing efficient retrieval of top scores or ranges.

Question 14

What is the result of executing 'INCR counter' if the 'counter' key does not exist in Redis?

Error: Key not found
0
1
Null

Explanation:

If the key doesn't exist, INCR treats it as if it had a value of 0 and increments it to 1.

Question 15

What is the purpose of the SADD command in Redis?

Adds an element to a sorted set.
Adds an element to a set only if it doesn't already exist.
Adds an element to the beginning of a list.
Retrieves a value from a hash.

Explanation:

SADD adds elements to a set. If the element already exists, the command does not have any effect.