Converting to columnar formats

Your Amazon Athena query performance improves if you convert your data into open source columnar formats, such as Apache parquet or ORC.

Options for easily converting source data such as JSON or CSV into a columnar format include using CREATE TABLE AS queries or running jobs in AWS Glue.

• You can use CREATE TABLE AS (CTAS) queries to convert data into Parquet or ORC in one step. For an example, see Example: Writing query results to a different format on the Examples of CTAS queries page.

• For information about running an AWS Glue job to transform CSV data to Parquet, see the section "Transform the data from CSV to Parquet format" in the AWS Big Data blog post Build a data lake foundation with AWS Glue and Amazon S3. AWS Glue supports using the same technique to convert CSV data to ORC, or JSON data to either Parquet or ORC.