How to fine-tune PostgreSQL fill factor

Fine tuning and optimizing the fill factor in PostgreSQL can significantly impact the performance of your database. The fill factor is a parameter that determines the percentage of a data page to be filled with rows, leaving space for future updates to minimize page splits and improve performance on frequently updated tables. By adjusting the fill factor, you can optimize storage efficiency and reduce the overhead of page splits.

To fine-tune the fillfactor for tables and indexes, consider the following:

1. Analyze Your Workload:
   • If the table experiences frequent updates, consider lowering the table fillfactor from 100 to around 70-80% to leave room for updates and minimize page splits.
   • For indexes, a fill factor of 90 is generally a good starting point. However, if the indexed columns are updated frequently, you might lower it further.
2. Monitor Performance:
   • Use PostgreSQL’s built-in tools (e.g., pg_stat_user_tables, pg_stat_user_indexes) to monitor the number of page splits and the overall performance impact.
   • Adjust the fillfactor based on observed performance.
3. Test and Iterate:
   • Test different fillfactors in a staging environment before applying them to production. This helps in identifying the optimal settings.
   • Consider Storage and Update Patterns:
4. Highly updated tables and indexes benefit from lower fillfactors to accommodate changes without needing frequent reorganization.
   • If updates are infrequent, higher fillfactors maximize storage efficiency.
   • Ultimately, the best fillfactor settings depend on your specific workload and performance goals. Regular monitoring and adjustments based on performance metrics will help you achieve the optimal configuration.