Consider the following rules and guidelines when you configure a Sqoop source in a mapping:
If you create a password file to access a database, to run the mapping successfully, you must ensure that the password file exists on HDFS.
To override the default query in a mapping with an advanced query, you must define a mapping parameter and set its value to $CONDITIONS. You must then include $CONDITIONS in the WHERE clause of the custom query.
If you define a custom query, you must verify that the metadata of the custom query matches the metadata of the source object. Otherwise, Sqoop might write blank values to the target.
If you specify a sort condition in a mapping, the Data Integration Service ignores the Order By condition.
You cannot sort columns in a Sqoop source.
You cannot read distinct rows from a Sqoop source.