Amazon Athena produces cache files with every query, in the folder specified in S3StagingDirectory . CleanQueryResults specifies whether these files should be deleted once the connection is closed.
Amazon Athena stores the results of every query you execute as a CSV file in S3StagingDirectory. These CSV files can quickly rack up a lot of space in Amazon S3.
You can use CleanQueryResults, enabled by default, to clean these files for every query executed. Note that this behavior will add a minor performance hit when you disconnect the last connection in a process.
See Fine-Tuning Data Access for more information on configuring Athena's query caching.