Mysql big data table update is slow to solve

Mysql big tree data table update is slow Solution Problem description: tens of millions of data tables, update where gid = "adadadfadsfasdf", returned results show analysis between 70 ms to 1 s: The table is large, so update, it may be necessary to retrieve the index first and then the page, but even if it is a disk operation, each disk operation takes 5 ms, which may take 20 or 30 ms, so the time must be spent on io wait. Iostat-x-d 1 3 is used to display the waiting time for dozens of milliseconds, so the time is indeed spent on io wait. Solution: reduce io and increase mysql memory, which is 10 Gb, now 50 GB