database - ISOdate/POSIXct vs Milliseconds -
this more of thinking question. have been working around different time/date formats, , noticed seems preferred store date/time objects variables unique classes (like isodate or posixct) in databases (like mongo, mysql, postegen). i why 1 want convert such format when analyzing data, wondering what's advantage when store in format in data-base? do these formats tend take less space conventional numbers? can't seem find answer online. for arguments sake let's talk simple date type (just date, no time or time zone) - such date type in mysql. say stored string of 2014-12-31 . what's 1 day later? human, it's easy come answer 2015-01-01 , computer needs have algorithms programmed in. while these types might expose apis have algorithms dealing calendar math, under hood store information whole number of days since starting date (which called "epoch"). 2014-12-31 stored 16701 . computer can efficiently add 1 16702 next day. this make...