value field in prebuilt. This field tracks the last value in an autoincrement
interval. We use this value to check whether we need to update a table's
AUTOINC counter, if the value written to a table is less than this value
then we avoid updating the table's AUTOINC value in order to reduce
mutex contention. If it's not reset (e.g., after a DELETE statement) then
there is the possibility of missing updates to the table's AUTOINC counter
resulting in a subsequent duplicate row error message under certain 
conditions (see the test case for details).

Bug #38839 - auto increment does not work properly with InnoDB after update