From a98cf1277f25097d948667cbf084a28a4dc3cd92 Mon Sep 17 00:00:00 2001 From: Haojun Liao Date: Wed, 26 Apr 2023 16:33:23 +0800 Subject: [PATCH] Update 14-stream.md --- docs/en/12-taos-sql/14-stream.md | 34 ++++++++++++++++++++++++++++++-- 1 file changed, 32 insertions(+), 2 deletions(-) diff --git a/docs/en/12-taos-sql/14-stream.md b/docs/en/12-taos-sql/14-stream.md index b8f6c3a163..eed1713a3c 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) + -- GitLab