1. What is Hive Metastore?

Ans : Hive metastore is a database that stores metadata about your Hive tables (eg. table name, column names and types, table location, storage handler being used, number of buckets in the table, sorting columns if any, partition columns if any, etc.). When you create a table, this metastore gets updated with the information related to the new table which gets queried when you issue queries on that table.

2. Wherever (Different Directory) I run hive query, it creates new metastore_db, please explain the reason for it? Ans: Whenever you run the hive in embedded mode, it creates the local metastore. And before creating the metastore it looks whether metastore already exist or not. This property is defined in configuration file hive-site.xml. Property is “javax.jdo.option.ConnectionURL” with default value “jdbc:derby:;databaseName=metastore_db;create=true”. So to change the behavior change the location to absolute path, so metastore will be used from that location.

3. Is it possible to use same metastore by multiple users, in case of embedded hive? Ans: No, it is not possible to use metastore in sharing mode. It is recommended to use standalone “real” database like MySQL or PostGresSQL.

4. Is multiline comment supported in Hive Script ?

Ans: No.

5. If you run hive as a server, what are the available mechanism for connecting it from application?

Ans: There are following ways by which you can connect with the Hive Server: 1. Thrift Client: Using thrift you can call hive commands from a various programming languages e.g. C++, Java, PHP, Python and Ruby. 2. JDBC Driver : It supports the Type 4 (pure Java) JDBC Driver 3. ODBC Driver: It supports ODBC protocol.