Most of the popular databases have connectors, using which data can be extracted and loaded onto the Hadoop filesystem. For example, if your RDBMS is Oracle, Oracle provides a suite of products which integrate the Oracle database with Apache Hadoop. The figure below (Figure 09) shows the full suite of Oracle Big Data connector products and what they do (details taken from www.oracle.com).
Figure 25: Oracle Big Data connector suite of products
Similar to Oracle, MySQL RDBMS has MySQL Applier, which is the native big data connector which can be used to load data from MySQL to Hadoop filesystem. MySQL Applier is also capable of incremental data transfer (real-time) as against the traditional batch by Sqoop. The following figure (Figure 10) shows the MySQL native connector to transfer data to HDFS.
Figure 26: MySQL Applier for Hadoop