Merge pull request #29731 from taosdata/doc/stream_ly
doc(srtream):supplement stream doc
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Shengliang Guan
GitHub
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e9f8745af8
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@ -26,7 +26,7 @@ CREATE STREAM [IF NOT EXISTS] stream_name [stream_options] INTO stb_name
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SUBTABLE(expression) AS subquery
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stream_options: {
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TRIGGER [AT_ONCE | WINDOW_CLOSE | MAX_DELAY time]
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TRIGGER [AT_ONCE | WINDOW_CLOSE | MAX_DELAY time | FORCE_WINDOW_CLOSE]
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WATERMARK time
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IGNORE EXPIRED [0|1]
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DELETE_MARK time
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@ -56,13 +56,17 @@ window_clause: {
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}
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```
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The subquery supports session windows, state windows, and sliding windows. When used with supertables, session windows and state windows must be used together with `partition by tbname`.
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The subquery supports session windows, state windows, time windows, event windows, and count windows. When used with supertables, state windows, event windows, and count windows must be used together with `partition by tbname`.
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1. SESSION is a session window, where tol_val is the maximum range of the time interval. All data within the tol_val time interval belong to the same window. If the time interval between two consecutive data points exceeds tol_val, the next window automatically starts.
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2. EVENT_WINDOW is an event window, defined by start and end conditions. The window starts when the start_trigger_condition is met and closes when the end_trigger_condition is met. start_trigger_condition and end_trigger_condition can be any condition expressions supported by TDengine and can include different columns.
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2. STATE_WINDOW is a state window. The col is used to identify the state value. Values with the same state value belong to the same state window. When the value of col changes, the current window ends and the next window is automatically opened.
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3. COUNT_WINDOW is a counting window, divided by a fixed number of data rows. count_val is a constant, a positive integer, and must be at least 2 and less than 2147483648. count_val represents the maximum number of data rows in each COUNT_WINDOW. If the total number of data rows cannot be evenly divided by count_val, the last window will have fewer rows than count_val. sliding_val is a constant, representing the number of rows the window slides, similar to the SLIDING in INTERVAL.
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3. INTERVAL is a time window, which can be further divided into sliding time windows and tumbling time windows.The INTERVAL clause is used to specify the equal time period of the window, and the SLIDING clause is used to specify the time by which the window slides forward. When the value of interval_val is equal to the value of sliding_val, the time window is a tumbling time window; otherwise, it is a sliding time window. Note: The value of sliding_val must be less than or equal to the value of interval_val.
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4. EVENT_WINDOW is an event window, defined by start and end conditions. The window starts when the start_trigger_condition is met and closes when the end_trigger_condition is met. start_trigger_condition and end_trigger_condition can be any condition expressions supported by TDengine and can include different columns.
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5. COUNT_WINDOW is a counting window, divided by a fixed number of data rows. count_val is a constant, a positive integer, and must be at least 2 and less than 2147483648. count_val represents the maximum number of data rows in each COUNT_WINDOW. If the total number of data rows cannot be evenly divided by count_val, the last window will have fewer rows than count_val. sliding_val is a constant, representing the number of rows the window slides, similar to the SLIDING in INTERVAL.
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The definition of a window is exactly the same as in the time-series data window query, for details refer to the TDengine window functions section.
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@ -11,7 +11,7 @@ import imgStream from './assets/stream-processing-01.png';
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```sql
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CREATE STREAM [IF NOT EXISTS] stream_name [stream_options] INTO stb_name[(field1_name, field2_name [PRIMARY KEY], ...)] [TAGS (create_definition [, create_definition] ...)] SUBTABLE(expression) AS subquery
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stream_options: {
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TRIGGER [AT_ONCE | WINDOW_CLOSE | MAX_DELAY time]
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TRIGGER [AT_ONCE | WINDOW_CLOSE | MAX_DELAY time | FORCE_WINDOW_CLOSE]
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WATERMARK time
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IGNORE EXPIRED [0|1]
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DELETE_MARK time
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@ -58,6 +58,10 @@ window_clause: {
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Where SESSION is a session window, tol_val is the maximum range of the time interval. All data within the tol_val time interval belong to the same window. If the time between two consecutive data points exceeds tol_val, the next window automatically starts. The window's_wend equals the last data point's time plus tol_val.
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STATE_WINDOW is a state window. The col is used to identify the state value. Values with the same state value belong to the same state window. When the value of col changes, the current window ends and the next window is automatically opened.
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INTERVAL is a time window, which can be further divided into sliding time windows and tumbling time windows.The INTERVAL clause is used to specify the equal time period of the window, and the SLIDING clause is used to specify the time by which the window slides forward. When the value of interval_val is equal to the value of sliding_val, the time window is a tumbling time window; otherwise, it is a sliding time window. Note: The value of sliding_val must be less than or equal to the value of interval_val.
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EVENT_WINDOW is an event window, defined by start and end conditions. The window starts when the start_trigger_condition is met and closes when the end_trigger_condition is met. start_trigger_condition and end_trigger_condition can be any condition expression supported by TDengine and can include different columns.
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COUNT_WINDOW is a count window, dividing the window by a fixed number of data rows. count_val is a constant, a positive integer, must be at least 2 and less than 2147483648. count_val represents the maximum number of data rows each COUNT_WINDOW contains. If the total number of data rows is not divisible by count_val, the last window will have fewer rows than count_val. sliding_val is a constant, representing the number of rows the window slides, similar to the SLIDING in INTERVAL.
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@ -23,7 +23,7 @@ CREATE STREAM [IF NOT EXISTS] stream_name [stream_options] INTO stb_name
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SUBTABLE(expression) AS subquery
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stream_options: {
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TRIGGER [AT_ONCE | WINDOW_CLOSE | MAX_DELAY time]
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TRIGGER [AT_ONCE | WINDOW_CLOSE | MAX_DELAY time | FORCE_WINDOW_CLOSE]
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WATERMARK time
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IGNORE EXPIRED [0|1]
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DELETE_MARK time
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@ -52,13 +52,17 @@ window_cluse: {
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}
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```
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subquery 支持会话窗口、状态窗口与滑动窗口。其中，会话窗口与状态窗口搭配超级表时必须与 partition by tbname 一起使用。
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subquery 支持会话窗口、状态窗口、时间窗口、事件窗口与计数窗口。其中，状态窗口、事件窗口与计数窗口搭配超级表时必须与 partition by tbname 一起使用。
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1. 其中，SESSION 是会话窗口，tol_val 是时间间隔的最大范围。在 tol_val 时间间隔范围内的数据都属于同一个窗口，如果连续的两条数据的时间间隔超过 tol_val，则自动开启下一个窗口。
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2. EVENT_WINDOW 是事件窗口，根据开始条件和结束条件来划定窗口。当 start_trigger_condition 满足时则窗口开始，直到 end_trigger_condition 满足时窗口关闭。 start_trigger_condition 和 end_trigger_condition 可以是任意 TDengine 支持的条件表达式，且可以包含不同的列。
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2. STATE_WINDOW 是状态窗口，col 用来标识状态量，相同的状态量数值则归属于同一个状态窗口，col 数值改变后则当前窗口结束，自动开启下一个窗口。
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3. COUNT_WINDOW 是计数窗口，按固定的数据行数来划分窗口。 count_val 是常量，是正整数，必须大于等于 2，小于 2147483648。 count_val 表示每个 COUNT_WINDOW 包含的最大数据行数，总数据行数不能整除 count_val 时，最后一个窗口的行数会小于 count_val 。 sliding_val 是常量，表示窗口滑动的数量，类似于 INTERVAL 的 SLIDING 。
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3. INTERVAL 是时间窗口，又可分为滑动时间窗口和翻转时间窗口。INTERVAL 子句用于指定窗口相等时间周期，SLIDING 字句用于指定窗口向前滑动的时间。当 interval_val 与 sliding_val 相等的时候，时间窗口即为翻转时间窗口，否则为滑动时间窗口，注意：sliding_val 必须小于等于 interval_val。
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4. EVENT_WINDOW 是事件窗口，根据开始条件和结束条件来划定窗口。当 start_trigger_condition 满足时则窗口开始，直到 end_trigger_condition 满足时窗口关闭。 start_trigger_condition 和 end_trigger_condition 可以是任意 TDengine 支持的条件表达式，且可以包含不同的列。
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5. COUNT_WINDOW 是计数窗口，按固定的数据行数来划分窗口。 count_val 是常量，是正整数，必须大于等于 2，小于 2147483648。 count_val 表示每个 COUNT_WINDOW 包含的最大数据行数，总数据行数不能整除 count_val 时，最后一个窗口的行数会小于 count_val 。 sliding_val 是常量，表示窗口滑动的数量，类似于 INTERVAL 的 SLIDING 。
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窗口的定义与时序数据窗口查询中的定义完全相同，具体可参考 TDengine 窗口函数部分。
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@ -10,7 +10,7 @@ description: 流式计算的相关 SQL 的详细语法
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```sql
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CREATE STREAM [IF NOT EXISTS] stream_name [stream_options] INTO stb_name[(field1_name, field2_name [PRIMARY KEY], ...)] [TAGS (create_definition [, create_definition] ...)] SUBTABLE(expression) AS subquery
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stream_options: {
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TRIGGER [AT_ONCE | WINDOW_CLOSE | MAX_DELAY time]
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TRIGGER [AT_ONCE | WINDOW_CLOSE | MAX_DELAY time | FORCE_WINDOW_CLOSE]
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WATERMARK time
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IGNORE EXPIRED [0|1]
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DELETE_MARK time
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@ -56,6 +56,10 @@ window_clause: {
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其中，SESSION 是会话窗口，tol_val 是时间间隔的最大范围。在 tol_val 时间间隔范围内的数据都属于同一个窗口，如果连续的两条数据的时间超过 tol_val，则自动开启下一个窗口。该窗口的 _wend 等于最后一条数据的时间加上 tol_val。
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STATE_WINDOW 是状态窗口，col 用来标识状态量，相同的状态量数值则归属于同一个状态窗口，col 数值改变后则当前窗口结束，自动开启下一个窗口。
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INTERVAL 是时间窗口，又可分为滑动时间窗口和翻转时间窗口。INTERVAL 子句用于指定窗口相等时间周期，SLIDING 字句用于指定窗口向前滑动的时间。当 interval_val 与 sliding_val 相等的时候，时间窗口即为翻转时间窗口，否则为滑动时间窗口，注意：sliding_val 必须小于等于 interval_val。
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EVENT_WINDOW 是事件窗口，根据开始条件和结束条件来划定窗口。当 start_trigger_condition 满足时则窗口开始，直到 end_trigger_condition 满足时窗口关闭。 start_trigger_condition 和 end_trigger_condition 可以是任意 TDengine 支持的条件表达式，且可以包含不同的列。
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COUNT_WINDOW 是计数窗口,按固定的数据行数来划分窗口。 count_val 是常量，是正整数，必须大于等于2，小于2147483648。 count_val 表示每个 COUNT_WINDOW 包含的最大数据行数，总数据行数不能整除 count_val 时，最后一个窗口的行数会小于 count_val 。 sliding_val 是常量，表示窗口滑动的数量，类似于 INTERVAL 的 SLIDING 。
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