hi Lifei, This sounds to me like you need an OVER window aggregation. OVER is a standard SQL clause to compute aggregates for each row over a group of surrounding rows (defined by ordering and partitioning).
Check out the documentation [1]. The example only shows ROW based windows, but Flink also supports time-based RANGES, like 5 minutes. Best, Fabian [1] https://ci.apache.org/projects/flink/flink-docs-release-1.8/dev/table/sql.html#aggregations Am Di., 16. Apr. 2019 um 10:07 Uhr schrieb Lifei Chen <hust...@gmail.com>: > Hi, all: > > I have a `Order` table as follow: > > rowtime item price > ======= ======== ====== > 09:00 item1 10 > 09:01 item2 15 > 09:03 item1 20 > > > I want to calculate the moving average price in past 5 minutes, and emit > the result for every record. > how to do this using flink sql? > > > Regards > Lifei >
