SQLスライディングウィンドウ-間隔全体で最大値を見つける

SELECT  *,
        (
        SELECT  SUM(value)
        FROM    mytable mi
        WHERE   mi.tstamp BETWEEN m.tstamp - '5 minute'::INTERVAL AND m.tstamp
        ) AS maxvalue
FROM    mytable m
ORDER BY
        maxvalue DESC
LIMIT   1

PostgreSQL 11以降の場合：

SELECT  SUM(value) OVER (ORDER BY tstamp RANGE '5 minute' PRECEDING) AS maxvalue,
        *
FROM    mytable m
ORDER BY
        maxvalue DESC
LIMIT   1