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Redis interview questions

Top Redis interview questions and answers

1. What is Redis?

Redis is an open source released under BSD licensed, in-memory data structure store, it can be used as a database, cache and message broker.

2. List the data structures supported by Redis.

Redis supports following Data Structures

  • Strings
  • Hashes
  • Lists
  • Sets
  • Sorted sets with range queries
  • bitmaps
  • Hyperloglogs
  • Geospatial indexes with radius queries

3. List some advantages of Redis?

Following are some advantages of Redis

  • Exceptionally Faster than others
  • Supports for rich data types like Hashes, Sets, bitmaps
  • Rich client-side library.
  • Support for server-side locking.
  • Operations are atomic.

4. List some commonly used Redis commands?

Some commonly used Redis commands list

Command NameDescription
APPENDAppend a value to a key
AUTHAuthenticate to the server
BGREWRITEAOFAsynchronously rewrite the append-only file
BGSAVEAsynchronously save the dataset to disk
BITCOUNTCount set bits in a string
CLIENT LISTGet the list of client connections
CLUSTER INFOProvides info about Redis Cluster node state

Read more from Redis Commands List

5. In which language Redis is written?

Redis is NoSql  based Key-value Database, which is written in ANSI C

6.List some Redis Clients supported by PHP?

Below are some Redis Clients supported by PHP Programming Language

  • amphp/redis
  • cheprasov/php-redis-client
  • Credis
  • PHP Redis implementation / wrapper
  • PHP Sentinel Client
  • phpredis

7. What is redis-cli.

redis-cli is the Redis command line interface, a simple program that allows to send commands to Redis, and read the replies sent by the server, directly from the terminal.

8. Explain REPL

REPL stands for Read Eval Print Loop. It an interactive mode where the user types commands and get replies.

9. List the programming languages supported by Redis?

Redis supports a wide range of programming language. Some major programming languages supported by Redis are PHP, Java, Python, Scala, Perl, Ruby, C#, and C++.