diff --git a/docs/en/12-taos-sql/14-stream.md b/docs/en/12-taos-sql/14-stream.md index b8f6c3a163e1c2fa37e437725652eabb1a71dbe6..eed1713a3cea1d92a25da13356c19786567195c0 100644 --- a/docs/en/12-taos-sql/14-stream.md +++ b/docs/en/12-taos-sql/14-stream.md @@ -13,8 +13,11 @@ Because stream processing is built in to TDengine, you are no longer reliant on ```sql CREATE STREAM [IF NOT EXISTS] stream_name [stream_options] INTO stb_name SUBTABLE(expression) AS subquery stream_options: { - TRIGGER [AT_ONCE | WINDOW_CLOSE | MAX_DELAY time] - WATERMARK time + TRIGGER [AT_ONCE | WINDOW_CLOSE | MAX_DELAY time] + WATERMARK time + IGNORE EXPIRED [0|1] + DELETE_MARK time + FILL_HISTORY [0|1] } ``` @@ -141,3 +144,30 @@ The data in expired windows is tagged as expired. TDengine stream processing pro 2. Recalculate the data. In this method, all data in the window is reobtained from the database and recalculated. The latest results are then returned. In both of these methods, configuring the watermark is essential for obtaining accurate results (if expired data is dropped) and avoiding repeated triggers that affect system performance (if expired data is recalculated). + +## Supported functions + +All scalar functions are available in stream processing. +All System Information Functions are not available for stream processing. +All aggregate and selection functions are available in stream processing, except following functions + +- [leastsquares](../function/#leastsquares) +- [percentile](../function/#percentile) +- [top](../function/#leastsquares) +- [bottom](../function/#top) +- [elapsed](../function/#leastsquares) +- [interp](../function/#elapsed) +- [derivative](../function/#derivative) +- [irate](../function/#irate) +- [twa](../function/#twa) +- [histogram](../function/#histogram) +- [diff](../function/#diff) +- [statecount](../function/#statecount) +- [stateduration](../function/#stateduration) +- [csum](../function/#csum) +- [mavg](../function/#mavg) +- [sample](../function/#sample) +- [tail](../function/#tail) +- [unique](../function/#unique) +- [mode](../function/#mode) +