I just heard that Oracle has a feature called External Table that allows to access a flat file (for example a CSV file in the file system) from the database.
I just want to know if there is something similar in DB2 for LUW.
The closest thing I could see is to implement a Table function (written in Java, for example) that will read the file, and return a table with the data from the file. However, this procedure takes a long time (create the Java code, compile the Java and create the function in DB2 associating the Java class) and the implementation is not dynamic for different files with different quantity of columns (table function returns a predefined set of columns).
Here the documentation of Oracle External Tables: http://docs.oracle.com/cd/B28359_01/server.111/b28319/et_concepts.htm
Yes, IBM offers this as part of their InfoSphere Federation Server, which basically allows you to define nicknames inside a database to various data sources. Supported data sources