Reading an External Hive Table on S3 in Another Airflow Job

I created an external table with airflow on s3, now I need to read this table in other airflow job, can you help me draft a hive sql statement to do this?

Certainly! If you have created an external table in Hive using Airflow and stored the data on S3, you can read this table in another Airflow job by writing a Hive SQL statement. Below is an example of how you can draft a Hive SQL statement to read from an external table.

Assuming your external table is named my_external_table, here is a basic Hive SQL statement to read data from it:

SELECT * FROM my_external_table;

If you need to perform more complex operations, such as filtering or aggregating the data, you can modify the SQL statement accordingly. Here are a few examples:

1. Filtering Data:

   SELECT * FROM my_external_table
   WHERE some_column = 'some_value';
   

2. Aggregating Data:

   SELECT some_column, COUNT(*)
   FROM my_external_table
   GROUP BY some_column;
   

3. Joining with Another Table:

   SELECT a.*, b.other_column
   FROM my_external_table a
   JOIN another_table b ON a.id = b.id;
   

To execute this Hive SQL statement in an Airflow job, you can use the HiveOperator. Below is an example of how you can define an Airflow task to run the Hive SQL statement:

from airflow import DAG
from airflow.providers.apache.hive.operators.hive import HiveOperator
from datetime import datetime

default_args = {
    'owner': 'airflow',
    'start_date': datetime(2023, 1, 1),
    'retries': 1,
}

dag = DAG(
    'read_hive_table',
    default_args=default_args,
    schedule_interval='@daily',
)

read_hive_table = HiveOperator(
    task_id='read_hive_table',
    hql='SELECT * FROM my_external_table;',
    hive_cli_conn_id='your_hive_connection_id',
    dag=dag,
)

read_hive_table

In this example:

• Replace 'your_hive_connection_id' with the actual connection ID configured in Airflow for your Hive connection.
• The hql parameter contains the Hive SQL statement to be executed.

Make sure that the Airflow environment has the necessary permissions and configurations to access the Hive metastore and the S3 bucket where your external table data is stored.

This should help you read the external table created on S3 in another Airflow job using Hive