Enhance HOT update checklist script with additional output details an…

[gmartinez-dbai]

This pull request improves the usability and accuracy of the hot_update_optimization_checklist_json.sql script for analyzing PostgreSQL HOT update efficiency. The changes enhance output formatting for automation, add more detailed recommendations, and improve the accuracy of fillfactor reporting.

Usability and output improvements:

• Added example usage with psql and jq, clarified recommended flags, and documented optional dependencies for easier downstream automation.
• Enabled strict JSON output by setting QUIET, disabling the pager, and turning off the footer in the script.

Data accuracy and reporting enhancements:

• Improved the base_stats CTE to:
  • Use explicit table aliases for clarity,
  • Accurately extract the current fillfactor from pg_class.reloptions (defaulting to 100 if unset),
  • Use relid for size lookups,
  • Only include tables with sufficient updates, and
  • Refactor join logic for better reliability.
• Added current_fillfactor to the JSON output for each table, making it easier to correlate recommendations with the present configuration.
• Enhanced recommendations to include a clear issue description, the action SQL statement with a context-aware fillfactor value, and the current_fillfactor for transparency.…d examples