Redis | Fresco Play

Question 1: Redis is single threaded.

Answer: True

Question 2: Redis can be configured to meet different requirements by editing the configuration settings in __.

Answer: redis.conf

Question 3: Which configuration setting specifies the file to which RDB snapshot dump is saved to _?

Answer: dbfilename

Question 4: Which of the following is not a Key Value database?

Answer: MongoDB

Question 5: _ is the number of sentinels that need to agree the fact that the master is not reachable and make a failover procedure promoting slave to master.

Answer: Quorum

Question 6: When using Pipelining, will the additional memory used be high?

Answer: Yes

Question 7: Redis is widely used as a secondary database for ___.

Answer: Caching

Question 8: Which is the default persistence mode in Redis?

Answer: RDB

Question 9: Which is the best way for persistence in Redis?

Answer: AOF

Question 10: Redis provides multi-state architecture during replication where every instance can both read and write.

Answer: False

Question 11: Which one is a difference between Memcached and Redis?

Answer: Single threaded

Question 12: ___ returns the number of elements in a set

Answer: SCARD

Question 13: Given is a code snippet : 127.0.0.1:6379> lpush numbers 4 127.0.0.1:6379> lpush numbers 3 127.0.0.1:6379> lpush numbers 7 127.0.0.1:6379> rpush numbers 10 127.0.0.1:6379> rpush numbers 15 127.0.0.1:6379> lpush numbers 12. Which of the following will be the output for the given code?

Answer: 12,7,3,4,10,15

Question 14: Which among the following does Redis Hashes stores?

Answer: Key value pairs

Question 15: ___ command will add elements to the set.

Answer: SADD

Question 16: Consider "a" as a shared key among two processes A and B. Process A : set a 10, INCRBY a 2, get a. Process B : INCR a, get a. Which of the following will be the final value for a?

Answer: 13

Question 17: _ sets the key to expire within the given number of seconds.

Answer: EXPIRE

Question 18: Which among the following are the data structures that are commonly used in Redis?

Answer: Sets

Question 19: The _ command is used to remove the expiration from a key.

Answer: Persist

Question 20: Sets are unordered collection of strings

Answer: True

Question 21: _ returns an array of values.

Answer: HGET

Question 22: Which one of the following set command removes and returns members of a set?

Answer: SPOP

Question 23: _ sets the key to expire within the given number of seconds.

Answer: EXPIRE

Question 24: _ configuration setting allows you set a hard upper bound on the amount of memory that is available to a running Redis instance.

Answer: maxmemory

Question 25: In a Redis transaction, we can use command to enter into the transaction and queue the transaction commands instead of executing them.

Answer: Multi

Question 26: _ returns an array of values.

Answer: HGET

Question 27: Which among the following does Redis Hashes stores?

Answer: Key value pairs

Question 28: Which is the type of locking where the data is not actually locked but the users are notified and their changes are cancelled if another user is already modifying the data?

Answer: Optimistic locking

Question 29: gives the total number of bytes allocated by Redis.

Answer: used_memory

Question 30: _ is used to flush the transaction queue and exit from the transaction.

Answer: Discard

Question 31: ZSCORE command returns the range of members in a sorted set, by score

Answer: False

Question 32: The _ command is used to remove the expiration from a key.

Answer: Persist

Question 33: _ is a type of lock that allows you to limit the number of processes that can concurrently access a resource to some fixed number.

Answer: Counting semaphore

Question 34: Which is the short structure that Redis provides for the compact representation of Sets?

Answer: intset

Question 35: Which among the following factors helps in calculating the number of shards in Redis?

Answer: number of keys in single shard

Question 36: =---- implies the maximum allowed size of each individual element in the data structure to be encoded to ziplist short structure.

Answer: max-ziplist-value

Question 37: Which file is configured to change persistence mode?

Answer: redis.conf

Question 38: __ is required in distributed backend systems where cache state needs to be maintained uniformly across the systems.

Answer: Centralized cache

Question 39: ___ is the technique of breaking down data into multiple parts.

Answer: Sharding

Question 40: In Redis context, senders are named as _ and receivers are named as Subscribers.

Answer: Publishers

Question 41: _ are used to store, retrieve and update data.

Answer: Commands

Question 42: _ is an implementation of partitioning where you can send your query to a random instance and the instance will forward your query to the right node.

Answer: Query routing

Question 43: __ is the number of sentinels that need to agree the fact that the master is not reachable and make a failover procedure promoting slave to master.

Answer: Quorum

Question 44: __ is the memory eviction policy where keys are evicted by removing the less recently used keys first, but only among keys that have an expires set, inorder to make space for the newly added data.

Answer: Volatile-lru

Question 45: In-Memory database stores data in memory.

Answer: True

Question 46: Lists is a sequence of ___.

Answer: Ordered element

Question 47: __ command provides a check-and-set behavior to Redis commands.

Answer: WATCH

Question 48: The command is used to set a lock in string dataset.

Answer: SETNX

Question 49: Persistent server should be the _ once the whole environment is started.

Answer: master Server

Question 50: Twemproxy is a proxy developed at Twitter for Redis protocol for automatic partitioning among multiple redis instances and optional ejection of node if it is not available

Answer: True

Question 51: How many commands can be send to a server in pipelining?

Answer: Multiple

Question 52: Consider an example, where a range of users from 0 to 10000 goes to a redis instance R0 and another range of users 10001 to 20000 goes to R1. This is _ partitioning.

Answer: Range partitioning

Question 53: In-Memory database stores data in memory.

Answer: True

Question 54: _ is the configuration setting that tells the maximum number of items allowed in a Hash table for ziplist encoding.

Answer: hash-max-ziplist-entries

Question 55: Which configuration setting is used to specify the memory eviction policy in Redis?

Answer: maxmemory-policy

Question 56: The configuration setting in redis.conf that could be configured to the number of samples of keys to be checked, to evict keys with the oldest access time.

Answer: maxmemory

Question 57: Which among the following is a benefit of Pipelining?

Answer: 1. Data as batches 2. Primary memory

Question 58: Redis provides the output of all commands in ____________.

Answer: Single Step

Question 59: In a key-value pair, _____ is represented by a string.

Answer: key

Question 60: Redis string cannot hold any value beyond a length. Choose the length from the following :

Answer: 512 MB

Question 61: ____ ____ refers to an undesirable state when a system attempts to perform two or more operations, which should, otherwise, be done in a proper sequence to be executed correctly.

Answer: Race condition

Question 62: ________ is used for failover process when a master is not working, promoting slave to master.

Answer: Sentinel

Question 63: _________ is the memory policy that returns errors when the memory limit is reached and the client is trying to execute commands that result in more memory usage.

Answer: noeviction

Question 64: redis.conf is configured for changing __________ to connect to Redis server.

Answer: 1. memory 2. Key

Question 65: The environment continues working even, if a slave fails!

Answer: True

Question 66: Which is the mechanism to enforce limits on the access of a resource when multiple threads are executed?

Answer: 1. PERSIST 2. EXPIRE

Question 67: The environment continues working even, if a slave fails!

Answer: True