Executed at must be an integer

[goetas]

Q	A
Type	bug
BC Break	-
Fixed issues

Summary

• executed_at must be an integer

[goetas]

I have reworked this PR. Now internally the executed time is a float (number of seconds+microtime), but when that value gets saved to the database, it gets converted in an integer (multiplied for 1000).
In this way at DB level is an integer (better compatibility with different databases). When saving the execution time, we loose the microseconds part, but I think that having milliseconds is enough.