In Hadoop, the two basic data types are:
WritableComparable is the base interface for keys, and
Writable is the base class interface for values.
Classes implementing the above two interfaces provide your basic primitives:
byte ----------------- ByteWritable
int ----------------- IntWritable
long ----------------- LongWritable
float ----------------- FloatWritable
boolean ----------------- BooleanWritable
You can use the following built-in data types as key and value.
Text :This class stores text using standard UTF8 encoding.
ByteWritable : This stores a sequence of bytes.
VIntWritable and VLongWritable : WritableComparable for integer and long values stored in variable-length format.
Nullwritable:This is zero-length Writable type that can be used when you don’t want to use a key or value type.
The following hadoop built-in collection data types can only be used as value types
ArrayWritable:This stores an array of values belonging to a Writable type.
TwoDArrayWritable:This stores a matrix of values belonging to the same Writable type.
MapWritable:This stores a map of key-value pairs.keys and values should be of the writable datatypes (Map<Writable,Writable>).
SortedMapwritable:This stores a sorte map of key-value pairs.Keys should implement the WritableComparable interface ( SortedMap<WritableComparable,Writable> ).
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WritableComparable is the base interface for keys, and
Writable is the base class interface for values.
Classes implementing the above two interfaces provide your basic primitives:
byte ----------------- ByteWritable
int ----------------- IntWritable
long ----------------- LongWritable
float ----------------- FloatWritable
boolean ----------------- BooleanWritable
You can use the following built-in data types as key and value.
Text :This class stores text using standard UTF8 encoding.
ByteWritable : This stores a sequence of bytes.
VIntWritable and VLongWritable : WritableComparable for integer and long values stored in variable-length format.
Nullwritable:This is zero-length Writable type that can be used when you don’t want to use a key or value type.
The following hadoop built-in collection data types can only be used as value types
ArrayWritable:This stores an array of values belonging to a Writable type.
TwoDArrayWritable:This stores a matrix of values belonging to the same Writable type.
MapWritable:This stores a map of key-value pairs.keys and values should be of the writable datatypes (Map<Writable,Writable>).
SortedMapwritable:This stores a sorte map of key-value pairs.Keys should implement the WritableComparable interface ( SortedMap<WritableComparable,Writable> ).
What is Big Data- Know More about BIG Data-Click here
If you know anyone who has started learning Hadoop, why not help them out! Just share this post with them. Thanks for studying today!...
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