Hive storage handler implementation to query databases over JDBC
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README.md

Hive JDBC Storage Handler

Provides support for creating read-only Hive external tables that can read the results of a query run on an RDBMS such as MySQL.

Usage

  • Clone the git project and run mvn clean package to produce the storage handler JAR.

  • Start hive and add the JAR file to the classpath:

    ADD JAR /path/to/hive-jdbc-storage-handler-1.1.1-cdh4.3.0-SNAPSHOT-dist.jar;
    
  • Create an external table in Hive:

    CREATE EXTERNAL TABLE mysql_test
    (
        id STRING,
        part_name STRING,
        warehouse_id STRING,
        created STRING
    )
    STORED BY 'com.qubitproducts.hive.storage.jdbc.JdbcStorageHandler' 
    TBLPROPERTIES (
        "qubit.sql.database.type" = "MYSQL",
        "qubit.sql.jdbc.url" = "jdbc:mysql://localhost:3306/qubit?user=qubit&password=qubit",
        "qubit.sql.jdbc.driver" = "com.mysql.jdbc.Driver",
        "qubit.sql.query" = "SELECT part_id, part_name, warehouse_id, created_datetime FROM parts",
        "qubit.sql.column.mapping" = "id=part_id, created=created_datetime:date"
    );
    

Configuration

Table Creation

Required Table Properties
  • qubit.sql.database.type - Currently only supports MYSQL, H2 and DERBY.
  • qubit.sql.jdbc.url - Full JDBC connection URL.
  • qubit.sql.jdbc.driver - JDBC driver class name.
  • qubit.sql.query - Query to run against the database. The Storage handler is intelligent enough to determine the correct conditions to apply to the database query based on the hive query being executed. As such, please ensure that there are no WHERE clauses defined here. If column names differ between the hive table and the query, use the qubit.sql.column.mapping property to define the mappings.
Optional Table Properties
  • qubit.sql.column.mapping - If the Hive column names are different from the corresponding table column, use this property to indicate it. Format is: hiveColumnName=dbColumnName[:type] separated by commas. Currently the only accepted type is date. Sample usage: "qubit.sql.column.mapping" = "id=part_id, created=created_datetime:date". Only the columns that differ need to be specified.
  • qubit.sql.jdbc.fetch.size - Resultset fetch size. Default value is 1000.
  • Connections to the database are made through a DBCP connection pool. Specify any DBCP configuration options by prefixing them with qubit.sql.dbcp.. Eg: qubit.sql.dbcp.maxActive=5

Querying

The Storage handler is intelligent enough to determine the correct conditions to apply to the database query based on the hive query being executed. Therefore no additional steps need to be performed while querying.

Resultset fetch size can be changed at query time:

SET qubit.sql.jdbc.fetch.size=500;