Data Engineering Associate with Databricks Practice Exam

Which of the following functions is atomic and allows reading the table while processing?

1. INSERT OVERWRITE

2. INSERT INTO

3. MERGE INTO

4. COPY INTO

The correct answer is: INSERT OVERWRITE

The function that is atomic and allows reading the table while processing is indeed correctly identified with the option given. The atomic property ensures that the operation either completes successfully in its entirety or does not complete at all, maintaining the integrity of the data. In this context, the `INSERT OVERWRITE` command is designed to replace existing data in a table with new data while allowing readers to access the table during the operation. This feature is crucial for maintaining data availability and consistency, especially in environments where real-time data access is necessary. When `INSERT OVERWRITE` is executed, it first makes a copy of the existing data before it replaces it, which allows any ongoing queries or reads from the table to retrieve the data that was present prior to the overwrite. This capability is fundamental for data systems that prioritize high availability and need to manage concurrent read and write operations effectively. In contrast, other options like `INSERT INTO`, `MERGE INTO`, and `COPY INTO` may not support concurrent reading in the same way while they are processing, as they could lock the data or change the state of the table in a manner that affects ongoing reads. Understanding the implications of atomicity and read consistency is key when selecting appropriate data manipulation strategies in data engineering.