Import control commands are used to import RDBMS data
Append: Append data to an existing dataset in HDFS. --append
Columns: columns to import from the table. --columns
• Where: where clause to use during import. --
where The common large objects are Blog and Clob.Suppose the object is less than 16 MB, it is stored inline with the rest of the data. If there are big objects, they are temporarily stored in a subdirectory with the name _lob. Those data are then materialized in memory for processing. If we set lob limit as ZERO (0) then it is stored in external memory.