Big Data is thriving, and so are the technologies associated with it. Cassandra and Hadoop are a few of the popular technologies, which are used for, in simple terms, data analysis. Though there are many overlapping factors, the key differences between the two have been discussed below. These factors will help you select the best one based on your needs.
Difference Between Cassandra and Hadoop
Hadoop is a Big Data processing framework, while Cassandra is the distributed NoSQL database made to process a large amount of data. They may appear similar, but they are two different entities serving different purposes.
While Hadoop goes with batch processing, Cassandra is famous for real-time processing. Furthermore, both are PRO in the analysis of data generated through the online mode, like mobile or web, and can address online requests instantly.
Must Read: Hadoop Tutorial for Beginners
Consistency, Availability, and Partition Tolerance (CAP)
Hadoop focuses on CP, i.e., Consistency and Partition Tolerance while Cassandra follows AP or Availability with Partition Tolerance.
Casandra and Hadoop support all the formats, i.e., structured, semi-structured, unstructured, and images except, Cassandra does not support images.
The key difference lies in architecture, which affects the performance and speed. While Hadoop is famous for master-slave architectural design (Name Node is the master and Data Node is the slave), Cassandra works on distributed architectural design. In the cluster, each node has the same role, unlike Hadoop, and the communication among those is in a peer-to-peer fashion.
Tolerance to Fault
As mentioned prior, architectural design is highly responsible for the performance, and so are faults and failures. Cassandra is always the first choice if the probability of fault occurrence is required to be low. In master-slave design, a slight fault can bring down the whole system while in distributed design, other nodes will take care of all the requests.
Data Compression and Protection
At most, Hadoop can compress the data up to 15% while Cassandra can compress it up to 80%. That is a lot of compression at no cost!
If we draw our attention to data protection, then both technologies are best in their ways. While Hadoop provides audit and access control, Cassandra has a commit log design that provides functions like backup and restores.
Data Flow and Storage Model
Hadoop data is directly written in the data note, whereas Cassandra is first written in memory, and then in the disk. It is written in the memory structure format, which is also called mem-table.
Considering the storage model for Hadoop the term Hadoop Distributed File System or HDFS is coined where huge files are broken and replicated in many nodes. A different strategy is followed in Cassandra. The Keys Space Column strategy is followed, where primary and secondary indexing is done.
Learn about: Top Hadoop Tools
Logical Data Model
If we talk about the logical data model of Cassandra and Hadoop (refer to the images), we will find that in Hadoop, data is partitioned by a 1-column row key while in Cassandra data is partitioned by a multi-column primary key. It has been found that the data logic arrangement in Cassandra is more convenient as compared to the lexicographical order followed by Hadoop.
Replication factors are the unit that defines the number of data replicas that have been stored on multiple nodes to ensure fault tolerance and reliability. For Hadoop, the replication factor is constant (3 by default); however, in Cassandra, it is the number of nodes in the data centre.
Data is stored in key-value pair fashion, which makes indexing very simple in Cassandra as compared to Hadoop.
With almost similar processing and other attributes, there is always confusion while choosing the ‘best’ out of Cassandra and Hadoop. There have been instances where technology leaders claim that Cassandra delivers more as compared to Hadoop like in the case of architecture; it has an easier setup and less requirement along with an easier and flexible development environment. Nevertheless, Cassandra lacks data consistency.
The best choice depends on the requirement, as there is no tug-of-war of Cassandra vs Hadoop. For example, if performance is the major focus, then Cassandra is the best option, as it provides high availability, scalability, and low latency. It works wonders with real-time data analysis, unlike Hadoop.
Hadoop, on the other hand, is suggested when voluminous data needs to be searched, reported, stored, or analysed. As Big Data grows, so does the functionality of each technology. It depends on us how wisely we use it.
It has been rightly said that data is the fuel and it will drive technology and gradually the whole world. Small enterprises or giant organisations both deal with data. From data elicitation to processing, each step requires predictive analysis skills and strong fundamental knowledge. This knowledge will not only help you grow professionally but also increase the probability of career success.
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