Use DataBase Hive

Apache Hive is a data warehouse infrastructure and query language for Hadoop that allows you to query and analyze large datasets stored in Hadoop’s HDFS (Hadoop Distributed File System). It provides a SQL-like language called HiveQL, which makes it easier for users who are familiar with SQL to work with Hadoop data. Here are the general steps to use Hive:

1. Setup and Configuration:

   • First, ensure that you have Hadoop and Hive installed and configured on your Hadoop cluster. You can use a pre-built distribution like Cloudera CDH, Hortonworks HDP, or Apache Hive standalone.

2. Start Hive:

   • To start using Hive, open a terminal on your Hadoop cluster or a client machine with Hive installed, and enter the following command to start the Hive shell:
   bashCopy code

   hive

   This will launch the Hive interactive shell, where you can run HiveQL queries.

3. Create a Database:

   • You can create a database to organize your data. Hive databases are like namespaces for tables. Use the CREATE DATABASE command:
   sqlCopy code

   CREATE DATABASE mydatabase;

4. Switch to a Database:

   • You can switch to a specific database using the USE command:
   sqlCopy code

   USE mydatabase;

5. Create Tables:

   • Define tables in Hive to structure your data. You can create tables using HiveQL or load data from existing HDFS files.
   sqlCopy code

   CREATE TABLE mytable ( id INT, name STRING, age INT ) ROW FORMAT DELIMITED FIELDS TERMINATED BY ',';

6. Load Data:

   • You can load data into Hive tables using the LOAD DATA INPATH command or by inserting data from another table or query result.
   sqlCopy code

   LOAD DATA INPATH '/path/to/datafile' INTO TABLE mytable;

7. Query Data:

   • Run HiveQL queries to retrieve and analyze your data. Hive translates these queries into MapReduce or Tez jobs to process the data.
   sqlCopy code

   SELECT * FROM mytable WHERE age > 30;

8. Store Results:

   • You can store query results in another Hive table or export them to an external file or storage system.
   sqlCopy code

   INSERT OVERWRITE TABLE result_table SELECT * FROM mytable WHERE age > 30;

9. Exit Hive:

   • To exit the Hive shell, simply type quit or exit.

10. Hive Metastore:

    • Hive maintains a metastore that stores metadata about tables, columns, and their locations. You should configure a database for the Hive metastore to store this metadata.