MySQL 5.7 under InnoDB for COUNT (*) optimization

In MySQL 5.7 COUNT () selects a clustered index and makes an internal handler function call to get the total number of tables quickly

Execution plan display: Extra:select tables optimized away

In previous versions of 5.7, the count () request was usually: Scan the normal index to get this total.
6. Execution Plan display: Extra:using index

If the clustered index is large (or the size of the table data is large) and is not fully loaded into buffer pool, MySQL 5.7 query may be slower, rather than the original way (MySQL 5.6)
WORKAROUND: Force the normal index, but still need to add the where condition, or not.
Select COUNT () from Stock Force index (IDX_STOCK) where ID >0;
Extra:using where,using Index

MySQL 5.7 under InnoDB for COUNT (*) optimization