Vacuum

• 释放空间
• 维护统计信息
• 重新组织表
• 提速
  • 增加 maintenance_work_mem
  • parallel
  • analyze 慢但做额外统计
  • 考虑 pg_repack
  • 有大量删除考虑 vacuum full
• pg_stat_progress_analyze
• https://www.postgresql.org/docs/current/sql-vacuum.html

select * from pg_stat_progress_vacuum;

• phase
  • initializing
  • scanning heap - heap_blks_scanned
  • vacuuming indexes
  • vacuuming heap - heap_blks_vacuumed
  • cleaning up indexes
  • truncating heap
  • performing final cleanup

When to vacuum

• 进行了大量的表修改
• 感觉查询有性能问题