Why does the type has a number following it?

`min` int(11) NULL COMMENT "",
  `batch_id` bigint(20) NULL COMMENT "",

What do

int(11)

and

bigint(20)

mean?

Summary: Its an archaic leftover that used to indicate how many digits should display on the end user interface. It is no longer used by anybody and they can all be removed to avoid the perception of being confused with an array like AccountNum int[11] IMHO.