Thanks, I'll check it out. Fabian Hueske <fhue...@gmail.com> 于2019年4月16日周二 下午6:37写道：
> 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 >> >
