Learn about the advantages of creating external tables from Parquet files rather than CSV when using CREATE TABLE AS SELECT in Databricks. Discover how Parquet enables optimized querying.
Table of Contents
Question
What is a benefit of creating an external table from Parquet rather than CSV when using a CREATE TABLE AS SELECT statement?
A. Parquet files can be partitioned
B. Parquet files will become Delta tables
C. Parquet files have a well-defined schema
D. Parquet files have the ability to be optimized
Answer
C. Parquet files have a well-defined schema
Explanation
The key benefit of creating an external table from Parquet files rather than CSV when using a CREATE TABLE AS SELECT statement in Databricks is that Parquet files have a well-defined schema.
Parquet is a columnar storage format that embeds the schema metadata within the file itself. This means that when you create an external table from Parquet files, the schema is automatically inferred and enforced. Having a well-defined schema provides several advantages:
- Schema validation: Data written to the Parquet table is validated against the schema, ensuring data integrity and consistency.
- Optimized querying: Parquet’s columnar structure allows for efficient querying and predicate pushdown. Queries can skip over irrelevant data and only read the required columns, improving performance.
- Compatibility with analytics tools: Many analytics and BI tools can directly read Parquet files and leverage the embedded schema, enabling seamless integration and analysis.
In contrast, CSV files do not have a built-in schema. When creating an external table from CSV, you need to manually specify the schema, which can be error-prone and requires additional effort. CSV files also lack the optimizations and efficient querying capabilities provided by Parquet’s columnar format.
While Parquet files do support partitioning (option A), this is not the primary benefit in the context of the question. Options B and D are incorrect as they do not accurately describe the benefits of using Parquet over CSV for external tables.
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