Set reindex period.
time is in the form 'xxxA[yyyB[zzzC]]'
(Spaces are allowed between xxx and A and yyy and so on)
there xxx, yyy, zzz are numbers (can be negative!)
A, B, C can be one of the following:
s - second
M - minute
h - hour
d - day
m - month
y - year
(these letters are the same as in strptime/strftime functions)
If you specify only number without any character, it is assumed
that time is given in seconds.
Can be set many times before "Server" command and
takes effect till the end of config file or till next Period command.