sql sliding window - finding max value over interval

Question

i have a sliding window problem. specifically, i do not know where my window should start and where it should end. i do know the size of my interval/window.

i need

Answer 1

SELECT  *,
        (
        SELECT  SUM(value)
        FROM    mytable mi
        WHERE   mi.tstamp BETWEEN m.tstamp - '2.5 minute'::INTERVAL AND m.tstamp + '2.5 minute'::INTERVAL
        ) AS maxvalue
FROM    mytable m
ORDER BY
        maxvalue DESC
LIMIT   1