Truncating TablesΒΆ
Let us understand how to truncate tables.
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
TRUNCATE works only for managed tables. Only data will be deleted, structure will be retained.
Launch Spark SQL
%%sql
CREATE DATABASE IF NOT EXISTS itversity_retail
%%sql
SHOW tables
%%sql
DROP TABLE IF EXISTS orders
%%sql
CREATE TABLE orders (
order_id INT,
order_date STRING,
order_customer_id INT,
order_status STRING
) ROW FORMAT DELIMITED FIELDS TERMINATED BY ','
%%sql
LOAD DATA LOCAL INPATH '/data/retail_db/orders'
INTO TABLE orders
%%sql
SELECT * FROM orders LIMIT 10
%%sql
TRUNCATE TABLE orders
%%sql
SELECT * FROM orders LIMIT 10
%%sql
DROP TABLE IF EXISTS orders
%%sql
CREATE EXTERNAL TABLE orders (
order_id INT,
order_date STRING,
order_customer_id INT,
order_status STRING
) ROW FORMAT DELIMITED FIELDS TERMINATED BY ','
LOCATION '/user/itversity/external/retail_db/orders'
%%sql
LOAD DATA LOCAL INPATH '/data/retail_db/orders'
OVERWRITE INTO TABLE orders
%%sql
SELECT * FROM orders LIMIT 10
%%sql
TRUNCATE TABLE orders