1) Dynamo is a NoSQL database developed by amazon. Which of the following about

Question

1) Dynamo is a NoSQL database developed by amazon. Which of the following about Dynamo is correct?

Select one or more

a) Dynamo provides simple read and write operations to a data item than can be uniquley identified by a key

b) Dynamo uses the shared everything architecture and can scale out to improve performance

c) To achieve high availbility and durability. it replicates its data on mutliple machines

d) Dynamo runs on a commodity hardware infrastructure

2) Which of the following is/are correct?

Select one or more

a) In Bigtable, the row range for a big table is dynamically partinioned according to the lexicographic order

b) Bigtable cannot be used with MapReduce for running large scale parallel computations

c) Bigtable cannot manage versioned data

d) Dynamo uses consistent hashing to achieve incremental scalability.

Explanation / Answer

#1

Option a is correct because this is defined by Dynamo's query model

Option b is correct because

Dynamo is incrementally scalable and allows service owners to scale up and down based on their current request load.

Each of the background tasks uses this controllers to access the resource (e.g. database), shared across all background tasks. Hence everything is shared

Option c is also true, because dynamo creates multiple replicas to make databases available and to give performance along with durability, each storage node maintains an object buffer in its main memory. Each write operation is stored in the buffer and gets periodically written to storage by a writer thread. In this scheme, read operations first check if the requested key is present in the buffer. If so, the object is read from the buffer instead of the storage engine.

Option d is correct

For better efficiency Dynamo has commodity hardware infrastructure. Services must be able to configure Dynamo such that they consistently achieve their latency and throughput requirements.

#2

Option a is correct, Bigtable maintains data in lexicographic order by row key

Option b is incorrect, MapReduce is a framework designed for running large scale parallel computations developed at Google

Option c is incorrect, Bigtable supports per column settings, which helps garbage collector of BigTable to maintain versions. One can specify number of versions of a cell to be kept

Option d is correct. Dynamo’s partitioning scheme uses consistent hashing to distribute the load between multiple storage hosts

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