How to free space of temp files in RDS Postgres

Hello, to free up space from temporary files in Amazon RDS for PostgreSQL, you can follow these steps:

Monitor Temporary File Usage
    Enable the "temp_bytes" and "temp_files" metrics in the Performance Insights dashboard.
    Use these metrics to identify queries that are creating large temporary files.

Adjust PostgreSQL Parameters
    Modify the "work_mem" parameter to allocate more memory for complex operations, potentially reducing the need for temporary files.
    Set the "temp_file_limit" parameter to cancel queries that exceed a specified size limit for temporary files.

Optimize Queries
    Analyze queries that frequently create large temporary files.
    Consider rewriting these queries or creating appropriate indexes to improve performance and reduce temporary file usage.

Use pg_ls_tmpdir Function
    For PostgreSQL 13 and above, use the pg_ls_tmpdir() function to view current temporary file usage.
    This can help identify specific queries or operations causing excessive temporary file creation.

Implement Regular Maintenance
    Schedule regular VACUUM and ANALYZE operations to optimize table statistics and free up space.
    Consider using VACUUM FULL for more aggressive space reclamation, but be aware of the potential performance impact.

Consider RDS Optimized Reads
    If your workload involves multiple concurrent queries that increase temporary file usage, consider using Amazon RDS Optimized Read instances.
    These instances use local NVMe-based SSDs for temporary file storage, which can improve performance.

Monitor Free Storage Space
    Keep an eye on the FreeStorageSpace metric in CloudWatch to ensure your DB instance has sufficient free storage.

Review and Adjust Storage Configuration
    If temporary file usage consistently causes storage issues, consider increasing your allocated storage or upgrading to a larger instance type.

By implementing these steps, you can effectively manage and reduce temporary file usage in your RDS PostgreSQL instance, helping to free up space and improve overall performance. Remember to test any changes in a non-production environment first and consult AWS documentation for the most up-to-date information on best practices and available features.

Additional Resources:

https://docs.aws.amazon.com/AmazonRDS/latest/UserGuide/PostgreSQL.ManagingTempFiles.html

https://docs.aws.amazon.com/AmazonRDS/latest/UserGuide/Appendix.Oracle.CommonDBATasks.using-tempfiles.html

https://docs.aws.amazon.com/AmazonRDS/latest/UserGuide/SQLServer.TempDB.Shrinking.html

Best of luck and thank you for using AWS!

Brian