時間範囲内で5分の間隔にグループ化

これはすべての間隔で機能します。

PostgreSQL

SELECT
    TIMESTAMP WITH TIME ZONE 'epoch' +
    INTERVAL '1 second' * round(extract('epoch' from timestamp) / 300) * 300 as timestamp,
    name,
    count(b.name)
FROM time a, id 
WHERE …
GROUP BY 
round(extract('epoch' from timestamp) / 300), name

MySQL

SELECT
    timestamp,  -- not sure about that
    name,
    count(b.name)
FROM time a, id 
WHERE …
GROUP BY 
UNIX_TIMESTAMP(timestamp) DIV 300, name