If i have a metrics which step is 60 seconds, I want a result which have one point per 120 seconds, and every points is sum of before two points,
for example
(t1=t, v1), (t2 = t+60, v2), (t3 = t + 120, v3), (t4 = t+180, v4), (t5 = t+240, v5), (t6=t+300, v6)
I want result(t2 = t+60, v2+v1) ,(t4 = t+180, v4+v3), (t6 = t+300, v6+v5)
If I use promql like
sum_over_time(metric[2m]),
I will get (t1=t, v1+v0), (t2 = t+60, v2+v1), (t3 = t + 120, v3+v2), (t4 = t+180, v4+v3), (t5 = t+240, v5+v4), (t6=t+300, v6+v5)
I must sample the result with 120 second after sum_over_time , how should I write promql?