12. Spike

• Possible reasons for a spike in the latency of SQL queries:
  • When the DB is trying to flush the dirty pages to hard disk
  • When the buffer pool is not enough
  • When the DB is free and tries to flush dirty pages
• Parameters related to flushing dirty pages:
  • innodb_io_capacity: the capacity of the disk, usually set to the IOPS of the hard disk
  • innodb_max_dirty_pages_pct: the percentage of maximum dirty pages
  • innodb_flush_neighbors: whether to flush neighbouring pages together with the current page