What Is Derby in Hive

Derby is a open source relational database management system. It is developed by Apache Software Foundation in 1997. It is written and implemented completely in the Java programming language. The primary database model of Derby is Relational DBMS. All OS with a Java VM are server operating system.

Why Derby is required for Hive?

Hive in embedded mode has a limitation of one active user at a time. You may want to run Derby as a Network Server, this way multiple users can access it simultaneously from different systems. See Metadata Store and Embedded Metastore for more information.

What is the limitation of using Derby as the Metastore DB in Hive?

But, this mode also has limitation that, as only one embedded Derby database can access the database files on disk at any one time, so only one Hive session could be open at a time. If we try to start the second session it produces an error when it attempts to open a connection to the metastore.