The requirement to query the latest data point with other filtering conditions can be implemented through function composition

Author: leto-b

src/UserGuide/Master/Tree/Basic-Concept/Query-Data.md

@@ -427,6 +427,19 @@ Total line number = 2
 It costs 0.002s
 ```
 
+**Note:** The requirement to query the latest data point with other filtering conditions can be implemented through function composition. For example:
+
+```
+IoTDB> select max_time(*), last_value(*) from root.ln.wf01.wt01 where time >= 2017-11-07T23:50:00 and status = false align by device
++-----------------+---------------------+----------------+-----------------------+------------------+
+|           Device|max_time(temperature)|max_time(status)|last_value(temperature)|last_value(status)|
++-----------------+---------------------+----------------+-----------------------+------------------+
+|root.ln.wf01.wt01|        1510077540000|   1510077540000|              21.067368|             false|
++-----------------+---------------------+----------------+-----------------------+------------------+
+Total line number = 1
+It costs 0.021s
+```
+
 ## 3. `WHERE` CLAUSE
 
 In IoTDB query statements, two filter conditions, **time filter** and **value filter**, are supported.

src/UserGuide/V1.3.x/Basic-Concept/Query-Data.md

@@ -427,6 +427,20 @@ Total line number = 2
 It costs 0.002s
 ```
 
+**Note:** The requirement to query the latest data point with other filtering conditions can be implemented through function composition. For example:
+
+```
+IoTDB> select max_time(*), last_value(*) from root.ln.wf01.wt01 where time >= 2017-11-07T23:50:00 and status = false align by device
++-----------------+---------------------+----------------+-----------------------+------------------+
+|           Device|max_time(temperature)|max_time(status)|last_value(temperature)|last_value(status)|
++-----------------+---------------------+----------------+-----------------------+------------------+
+|root.ln.wf01.wt01|        1510077540000|   1510077540000|              21.067368|             false|
++-----------------+---------------------+----------------+-----------------------+------------------+
+Total line number = 1
+It costs 0.021s
+```
+
+
 ## `WHERE` CLAUSE
 
 In IoTDB query statements, two filter conditions, **time filter** and **value filter**, are supported.

src/UserGuide/dev-1.3/Basic-Concept/Query-Data.md

@@ -427,6 +427,20 @@ Total line number = 2
 It costs 0.002s
 ```
 
+**Note:** The requirement to query the latest data point with other filtering conditions can be implemented through function composition. For example:
+
+```
+IoTDB> select max_time(*), last_value(*) from root.ln.wf01.wt01 where time >= 2017-11-07T23:50:00 and status = false align by device
++-----------------+---------------------+----------------+-----------------------+------------------+
+|           Device|max_time(temperature)|max_time(status)|last_value(temperature)|last_value(status)|
++-----------------+---------------------+----------------+-----------------------+------------------+
+|root.ln.wf01.wt01|        1510077540000|   1510077540000|              21.067368|             false|
++-----------------+---------------------+----------------+-----------------------+------------------+
+Total line number = 1
+It costs 0.021s
+```
+
+
 ## `WHERE` CLAUSE
 
 In IoTDB query statements, two filter conditions, **time filter** and **value filter**, are supported.

src/UserGuide/latest/Basic-Concept/Query-Data.md

@@ -427,6 +427,20 @@ Total line number = 2
 It costs 0.002s
 ```
 
+**Note:** The requirement to query the latest data point with other filtering conditions can be implemented through function composition. For example:
+
+```
+IoTDB> select max_time(*), last_value(*) from root.ln.wf01.wt01 where time >= 2017-11-07T23:50:00 and status = false align by device
++-----------------+---------------------+----------------+-----------------------+------------------+
+|           Device|max_time(temperature)|max_time(status)|last_value(temperature)|last_value(status)|
++-----------------+---------------------+----------------+-----------------------+------------------+
+|root.ln.wf01.wt01|        1510077540000|   1510077540000|              21.067368|             false|
++-----------------+---------------------+----------------+-----------------------+------------------+
+Total line number = 1
+It costs 0.021s
+```
+
+
 ## 3. `WHERE` CLAUSE
 
 In IoTDB query statements, two filter conditions, **time filter** and **value filter**, are supported.

src/zh/UserGuide/Master/Tree/Basic-Concept/Query-Data.md

@@ -680,6 +680,20 @@ Total line number = 2
 It costs 0.002s
 ```
 
+**注意：** 可以通过函数组合方式实现其他过滤条件查询最新点的需求，例如
+
+```
+IoTDB> select max_time(*), last_value(*) from root.ln.wf01.wt01 where time >= 2017-11-07T23:50:00 and status = false align by device
++-----------------+---------------------+----------------+-----------------------+------------------+
+|           Device|max_time(temperature)|max_time(status)|last_value(temperature)|last_value(status)|
++-----------------+---------------------+----------------+-----------------------+------------------+
+|root.ln.wf01.wt01|        1510077540000|   1510077540000|              21.067368|             false|
++-----------------+---------------------+----------------+-----------------------+------------------+
+Total line number = 1
+It costs 0.021s
+```
+
+
 ## 3. 查询过滤条件（WHERE 子句）
 
 `WHERE` 子句指定了对数据行的筛选条件，由一个 `whereCondition` 组成。

src/zh/UserGuide/V1.3.x/Basic-Concept/Query-Data.md

@@ -680,6 +680,20 @@ Total line number = 2
 It costs 0.002s
 ```
 
+**注意：** 可以通过函数组合方式实现其他过滤条件查询最新点的需求，例如
+
+```
+IoTDB> select max_time(*), last_value(*) from root.ln.wf01.wt01 where time >= 2017-11-07T23:50:00 and status = false align by device
++-----------------+---------------------+----------------+-----------------------+------------------+
+|           Device|max_time(temperature)|max_time(status)|last_value(temperature)|last_value(status)|
++-----------------+---------------------+----------------+-----------------------+------------------+
+|root.ln.wf01.wt01|        1510077540000|   1510077540000|              21.067368|             false|
++-----------------+---------------------+----------------+-----------------------+------------------+
+Total line number = 1
+It costs 0.021s
+```
+
+
 ## 查询过滤条件（WHERE 子句）
 
 `WHERE` 子句指定了对数据行的筛选条件，由一个 `whereCondition` 组成。

src/zh/UserGuide/dev-1.3/Basic-Concept/Query-Data.md

@@ -613,7 +613,7 @@ select last <Path> [COMMA <Path>]* from < PrefixPath > [COMMA < PrefixPath >]* <
 
 其含义是： 查询时间序列 prefixPath.path 中最近时间戳的数据。
 
-- `whereClause` 中当前只支持时间过滤条件，任何其他过滤条件都将会返回异常。当缓存的最新点不满足过滤条件时，IoTDB 需要从存储中获取结果，此时性能将会有所下降。
+- `whereClause` 中当前**只支持时间过滤条件**，任何其他过滤条件都将会返回异常。当缓存的最新点不满足过滤条件时，IoTDB 需要从存储中获取结果，此时性能将会有所下降。
 
 - 结果集为四列的结构：
 
@@ -680,6 +680,20 @@ Total line number = 2
 It costs 0.002s
 ```
 
+**注意：** 可以通过函数组合方式实现其他过滤条件查询最新点的需求，例如
+
+```
+IoTDB> select max_time(*), last_value(*) from root.ln.wf01.wt01 where time >= 2017-11-07T23:50:00 and status = false align by device
++-----------------+---------------------+----------------+-----------------------+------------------+
+|           Device|max_time(temperature)|max_time(status)|last_value(temperature)|last_value(status)|
++-----------------+---------------------+----------------+-----------------------+------------------+
+|root.ln.wf01.wt01|        1510077540000|   1510077540000|              21.067368|             false|
++-----------------+---------------------+----------------+-----------------------+------------------+
+Total line number = 1
+It costs 0.021s
+```
+
+
 ## 查询过滤条件（WHERE 子句）
 
 `WHERE` 子句指定了对数据行的筛选条件，由一个 `whereCondition` 组成。

src/zh/UserGuide/latest/Basic-Concept/Query-Data.md

@@ -680,6 +680,20 @@ Total line number = 2
 It costs 0.002s
 ```
 
+**注意：** 可以通过函数组合方式实现其他过滤条件查询最新点的需求，例如
+
+```
+IoTDB> select max_time(*), last_value(*) from root.ln.wf01.wt01 where time >= 2017-11-07T23:50:00 and status = false align by device
++-----------------+---------------------+----------------+-----------------------+------------------+
+|           Device|max_time(temperature)|max_time(status)|last_value(temperature)|last_value(status)|
++-----------------+---------------------+----------------+-----------------------+------------------+
+|root.ln.wf01.wt01|        1510077540000|   1510077540000|              21.067368|             false|
++-----------------+---------------------+----------------+-----------------------+------------------+
+Total line number = 1
+It costs 0.021s
+```
+
+
 ## 3. 查询过滤条件（WHERE 子句）
 
 `WHERE` 子句指定了对数据行的筛选条件，由一个 `whereCondition` 组成。