Broadridge Financial Solutions Lead Data Engineer Interview Questions, Process, and Tips

A datawarehouse is a centralized repository that stores integrated and structured data from multiple sources for analysis and reporting.

• Datawarehouse stores historical data for analysis

• It is used for decision-making and business intelligence

• Data is extracted, transformed, and loaded (ETL) into the datawarehouse

• Examples: Amazon Redshift, Snowflake, Google BigQuery

To open multiple sessions in PostgreSQL, you can use multiple connections from different clients.

• Use different client applications to connect to the PostgreSQL database with different credentials

• Each client connection will create a separate session in PostgreSQL

• You can also use connection pooling to manage multiple sessions efficiently

Flattening JSON involves converting nested JSON structures into a flat key-value format.

• Use a programming language with built-in functions for flattening JSON, such as Python's json_normalize() function.

• Recursively iterate through the JSON structure to extract all nested key-value pairs.

• Map each nested key to a flat key by joining the parent keys with a separator, such as a dot.

• Handle arrays by creating separate keys f

Use the xmltodict library in Python to flatten XML data structures.

• Install the xmltodict library using pip install xmltodict

• Use xmltodict.parse() to convert XML data to a Python dictionary

• Use json.dumps() to convert the dictionary to a JSON string for a flattened structure

Self join is used to join a table with itself to compare rows within the same table.

• Use the same table name for both instances in the query

• Specify aliases for each instance of the table to differentiate them

• Use a join condition to specify how the rows should be matched