Intelligent Nosql Assessment Test

Explanation
Replication refers to the process of creating an identical copy or duplicate of data. It involves copying the same data and distributing it to multiple locations or systems. This ensures data availability, reliability, and fault tolerance. Replication is commonly used in database systems, where data is replicated across multiple servers to enhance performance, provide backup, and support high availability.

Explanation
A Cassandra write is only considered successful when both commits are completed. This means that the data being written is successfully committed to both the commit log on disk and the memtable in memory. Only when both of these commits are completed can it be ensured that the write operation has been successfully executed and the data is durable and available for reading.

Explanation
The given options are all related to the concepts of Cassandra data models. However, "Row" is not a concept of Cassandra data models. In Cassandra, data is organized in a distributed manner using key spaces, which contain multiple rows. Each row consists of columns, and they are grouped together in clusters. Therefore, the correct answer is "Row" as it is not a concept of Cassandra data models.

Explanation
Flume supports three modes of operation. These modes are:
1. Standalone mode: In this mode, Flume runs as a single JVM process.
2. Agent mode: In this mode, Flume agents are used to collect, aggregate, and move data from various sources to a destination.
3. Embedded mode: In this mode, Flume is embedded within another application, allowing it to be used as a library.

Explanation
The correct answer is "Double node" because Flume does not have a specific mode of operation called "Double node". Flume supports four modes of operation: Single node, Pseudo distributed, Fully distributed, and Multinode.

Explanation
JAQL is a query language that is specifically designed for querying and manipulating data in Hadoop. It is primarily used in conjunction with Hadoop MapReduce jobs to process and analyze large datasets. JAQL provides a high-level interface for writing complex data transformations and is well-suited for tasks such as data extraction, transformation, and loading in Hadoop environments. Therefore, JAQL is the correct answer as it is commonly used to translate into Hadoop MapReduce jobs.

Explanation
A high-level consulting executive who is engaged in life-saving manual data entry is called a data wizard. This term implies that the executive possesses exceptional skills and expertise in handling data and can efficiently manipulate and analyze it to extract valuable insights. The term "wizard" suggests a level of mastery and proficiency in the field of data management, making it a fitting description for someone in this role.

Explanation
Cassandra was written in Java. Java is a widely used programming language known for its platform independence and object-oriented approach. Java's robustness and scalability make it a suitable choice for developing a distributed database system like Cassandra.

Explanation
Cassandra writes are first written to the commit log on disk for durability. This means that the data is securely stored and can be recovered even in the event of a system failure or crash. By writing the data to the commit log, Cassandra ensures that the data is not lost and can be retrieved later. This is an important feature for maintaining data integrity and reliability in distributed systems like Cassandra.

Explanation
Memtables and SStables are created per the column family. In Apache Cassandra, data is organized into column families, which are similar to tables in a relational database. Each column family contains multiple columns and rows, and it is the unit of data storage and retrieval in Cassandra. Memtables are in-memory data structures that temporarily hold data before flushing it to disk as SStables (sorted string tables). SStables are immutable files on disk that store data permanently. Therefore, both memtables and SStables are created and managed at the column family level.