compute using previous rows

[Kenji]

I would like to compute weighted sum between 1 previous row and current row.

value = "value from current row" * weight + "value from previous row" * (1 - weight)

The below gets cyclic aliases error but conceptually this is what I want to achieve.

CREATE TABLE tbl (

  timestamp DateTime,

  value     Float64

)

SELECT

    timestamp,
    neighbor(weighted_value, -1) AS prev_value,

    value * 0.7 + prev_value * 0.3 AS weighted_value
FROM tbl

WHERE timestamp >= now() - toIntervalMinute(5)

ORDER BY timestamp

This query is stateful similar to moving average.  Maybe window functions can help?

The number of rows are up to 300.  Maybe array can help but I can't figure it out so far.