Dropping Tables and Databases¶

Let us understand how to DROP Spark Metastore Tables as well as Databases.

Let us start spark context for this Notebook so that we can execute the code provided. You can sign up for our 10 node state of the art cluster/labs to learn Spark SQL using our unique integrated LMS.

val username = System.getProperty("user.name")

import org.apache.spark.sql.SparkSession

val username = System.getProperty("user.name")
val spark = SparkSession.
    builder.
    config("spark.ui.port", "0").
    config("spark.sql.warehouse.dir", s"/user/${username}/warehouse").
    enableHiveSupport.
    appName(s"${username} | Spark SQL - Managing Tables - Basic DDL and DML").
    master("yarn").
    getOrCreate

If you are going to use CLIs, you can use Spark SQL using one of the 3 approaches.

Using Spark SQL

spark2-sql \
    --master yarn \
    --conf spark.ui.port=0 \
    --conf spark.sql.warehouse.dir=/user/${USER}/warehouse

Using Scala

spark2-shell \
    --master yarn \
    --conf spark.ui.port=0 \
    --conf spark.sql.warehouse.dir=/user/${USER}/warehouse

Using Pyspark

pyspark2 \
    --master yarn \
    --conf spark.ui.port=0 \
    --conf spark.sql.warehouse.dir=/user/${USER}/warehouse

We can use DROP TABLE command to drop the table.. Let us drop orders table

%%sql

CREATE DATABASE IF NOT EXISTS itversity_retail

%%sql

USE itversity_retail

%%sql

SHOW tables

%%sql

CREATE TABLE IF NOT EXISTS orders (
  order_id INT,
  order_date STRING,
  order_customer_id INT,
  order_status STRING
) ROW FORMAT DELIMITED FIELDS TERMINATED BY ','

%%sql

DROP TABLE orders

%%sql

DROP TABLE IF EXISTS orders

DROP TABLE on managed table will delete both metadata in metastore as well as data in HDFS, while DROP TABLE on external table will only delete metadata in metastore.
We can drop database by using DROP DATABASE Command. However we need to drop all the tables in the database first.
Here is the example to drop the database itversity_retail - DROP DATABASE itversity_retail
We can also drop all the tables and databases by adding CASCADE.

%%sql

DROP DATABASE itversity_retail

%%sql

DROP DATABASE IF EXISTS itversity_retail CASCADE

Apache Spark using SQL

Dropping Tables and Databases¶