How structured data is different from un structured data.
During a write operation, when a datanode writes in to the HDFS, it verifies a checksum for that data. This checksum helps in verifying the data corruptions during the data transmission.When the same data is read from the HDFS, the client verifies the checksum returned by the datanode against the checksum it calculates against the data to check the data corruption that might have caused by the data node that might have occurred during the storage of data in the data node.Therefore every datanode periodically runs a block scanner, to verify all the blocks that are stored in the data node. So this helps to identify and fix the corrupt data before a read operation. With the block scanner service, HDFS can prematurely identify and fix corruptions.
What is meant by JSON objects?
Answer: An object is defined as a set of key-value pairs. A JSON starts with a left brace "{" and ends with another right brace "}". Every key is followed by a colon “:” and the key-value pairs are separated from each other by using a comma ",". So, basically, the JSON object is a collection of keys along with their values arranged in a pre-specified JSON format.
Explain JSON syntax rules?
There are several rules that describe the structure of the JSON. These are:
Data inside a JSON is arranged in key-value pair. The left side represents the key and the data on the right side represents value. Both key and value are separated by a colon “:”.
Each set of key-value pair is separated from the other pair by using a comma “,”.
Curly braces define the JSON objects. Left curly brace “{“ represents the start of the object and right curly brace “}” represents the end of an object.
Arrays are defined inside a JSON object by using square brackets “[ ]”.
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