Classes implementing InputFormat frequently

Question

Which is the base class for all file-based InputFormats? And which are the most frequent use Input Formats?

Answer 1

FileInputFormat : Base class for all file-based InputFormats

Other frequently used Input Formats are:

KeyValueTextInputFormat : An InputFormat for plain text files. Files are broken into lines. Either line feed or carriage-return are used to signal end of line. Each line is divided into key and value parts by a separator byte. If no such a byte exists, the key will be the entire line and value will be empty.

TextInputFormat : An InputFormat for plain text files. Files are broken into lines. Either linefeed or carriage-return are used to signal end of line. Keys are the position in the file, and values are the line of text..

NLineInputFormat : NLineInputFormat which splits N lines of input as one split. In many "pleasantly" parallel applications, each process/mapper processes the same input file (s), but with computations are controlled by different parameters.

SequenceFileInputFormat : An InputFormat for SequenceFiles.

Regarding second query, get the files from remote servers first and use appropriate InputFileFormat depending on contents in file. Hadoop works best for data locality.