Optimization problem


The ES version I 'm using is 14.3 and found some issues are displayed

Day 1 :I had ported the data and the indexing is completed . I had
also optimized the database manually.

Day 2 : We were working in the data and made some searches , the
database was working fine .

Suddenly the optimization tooks place without any intimation .On
that time the database was closed and we weren't able to get DB
access .

Day 3 : After optimization process , the same database was working

Question 1 : Is there any method, that we need to configure to get the
information when the optimization is going to start for that
particular DB ?
Question 2 : Is there any settings to schedule the time for this
process to be happened ?
Question 3 : Is there any predefined rule for optimization?
Question 4 : Why the index are getting optimized very often?