A Skewed tables is a special type of table in which some values in a column appear more often. Due to this the distribution in skewed. In Hive, when we specify a table as SKEWED during creation, then skewed values are written into separate files and remaining values go to another file.
E.g. CREATE TABLE tableName (column1 STRING, column2 STRING) SKEWED BY (column1) on (‘value1’)
During queries, we get better performance in Hive with SKEWED tables.Read the full book at www.amazon.com