peekAppend

peekAppend(engine, data)

在不更新流引擎状态且不向输出表写入结果的情况下，返回在引擎当前状态基础上加上指定数据后的即时计算结果。目前仅支持 TimeSeriesEngine 和ReactiveStateEngine 的部分算子，具体如下：

TimeSeriesEngine：设置 keyColumn 且未设置 useSystemTime、acceptedDelay、forceTriggerTime。

ReactiveStateEngine：cumavg、cumsum、cumstd、cumstdp、cumvar、cumvarp、cumprod、cumcount、mcount、msum、mavg、mstd、mstdp、mvar、mvarp 以及无状态算子（表达式，无状态函数等）。

engine 流引擎。

data 一个表或元组，表示要写入流数据引擎的消息。

返回一个表对象，即在引擎当前状态上加上 data 的即时计算结果。引擎状态不会更新，也不会有输出结果到 outputTable。

ReactiveStateEngine 示例

share streamTable(100:0, `sym`time`price, [STRING,DATETIME,DOUBLE]) as tickStream
share streamTable(1000:0, `sym`time`factor1, [STRING,DATETIME,DOUBLE]) as result
rse = createReactiveStateEngine(name="reactiveDemo", metrics =[<time>, <cumsum(price)>], dummyTable=tickStream, outputTable=result, keyColumn="sym")
data = table(take(["000001.SH","000002.SH","000003.SH"], 3) as sym, take(2021.02.08T09:31:00 + 1..3, 3) as time, take(100.0, 3) as price)
res = rse.peekAppend(data)
rse.append!(data)
//res和result一致

share streamTable(100:0, `sym`time`price, [STRING,DATETIME,DOUBLE]) as tickStream
share streamTable(1000:0, `sym`time`factor1, [STRING,DATETIME,DOUBLE]) as result
rse = createReactiveStateEngine(name="reactiveDemo", metrics =[<time>, <cumsum(price)>], dummyTable=tickStream, outputTable=result, keyColumn="sym")

data = table(take(["000001.SH"], 3) as sym, take(2021.02.08T09:31:00 + 1..3, 3) as time, 100 200 300 as price)
res2 = rse.peekAppend(data)

TimeSeriesEngine 示例

share streamTable(1000:0, `sym`time`volume, [STRING,DATETIME,INT]) as tickStream
share streamTable(1000:0, `time`sym`sumVolume, [DATETIME,STRING,INT]) as result
tse = createTimeSeriesEngine(name="tse", windowSize=60, step=60, metrics=<[sum(volume)]>, dummyTable=tickStream, outputTable=result, timeColumn="time", useSystemTime=false, keyColumn="sym")

insert into tse values([`"000001.SH", 2021.02.08T09:30:00, 100])
data = table(take(["000001.SH"], 3) as sym, take(2021.02.08T09:30:00 + 1..3, 3) as time, 100 200 300 as price)
res = tse.peekAppend(data)