Period defines reindex period.
time parameter understands this format:
are numbers (negative numbers are allowed), and A
are interval specifier characters
s - second
M - minute
h - hour
d - day
m - month
y - year
The specifier characters are similar to format characters
used by the
time value is put into single or double quotes,
spaces are allowed between xxx, A and
yyy, and so on.
If you specify only a number without any characters, it is assumed
time is given in seconds.
The default value is 7d (one week).