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Q: What are the different data types supported by Redis?

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Q: What is the difference between Redis and traditional relational databases?

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Q: Explain Redis persistence mechanisms.

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Q: What are the common use cases for Redis?

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Q: How does Redis handle memory management?

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Q: Explain Redis transactions and their limitations.

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Q: What is Redis Pub/Sub and how does it work?

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Q: Explain Redis Cluster and its benefits.

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Q: What is pipelining in Redis and when should you use it?

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Q: How does Redis replication work?

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What are the different data types supported by Redis?

beginner

Redis supports several data types:

String: Binary-safe strings up to 512MB
Hash: Field-value pairs, like objects
List: Ordered collection of strings
Set: Unordered collection of unique strings
Sorted Set (ZSet): Set ordered by a score
Bitmap: String treated as bit array
HyperLogLog: Probabilistic data structure for cardinality estimation
Geospatial: Longitude/latitude coordinates
Stream: Log-like data structure for message queues

SET mykey "hello"          # String
HSET user:1 name "John"    # Hash
LPUSH mylist "item1"       # List
SADD myset "member1"       # Set
ZADD myzset 1 "item1"      # Sorted Set

What is the difference between Redis and traditional relational databases?

beginner

Aspect	Redis	Relational Database
Storage	In-memory	Disk-based
Data Model	Key-value, NoSQL	Relational tables
Schema	Schema-less	Fixed schema
ACID	Limited ACID properties	Full ACID compliance
Performance	Extremely fast (microseconds)	Slower (milliseconds)
Persistence	Optional	Always persistent
Query Language	Commands	SQL
Relationships	No joins	Complex relationships
Use Cases	Caching, sessions, real-time	Complex business logic

Explain Redis persistence mechanisms.

beginner

Redis offers two persistence options:

RDB (Redis Database Backup):

Point-in-time snapshots
Compact binary format
Good for backups and disaster recovery
Can lose data between snapshots

AOF (Append Only File):

Logs every write operation
Better durability (can be configured for every operation)
Larger file size
Slower restart times

# RDB configuration
SAVE 900 1      # Save if at least 1 key changed in 900 seconds
SAVE 300 10     # Save if at least 10 keys changed in 300 seconds

# AOF configuration
appendonly yes
appendfsync everysec  # Options: always, everysec, no