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Posted to reviews@iotdb.apache.org by GitBox <gi...@apache.org> on 2022/10/18 08:44:53 UTC
[GitHub] [iotdb] CritasWang opened a new issue, #7644: 能否支持对不固定子节点的函数运算
CritasWang opened a new issue, #7644:
URL: https://github.com/apache/iotdb/issues/7644
**Is your feature request related to a problem? Please describe.**
当我查询一些最新数据时，比如查询最新的10条，可以通过order by time desc limit 10。
但是有时候需要对查询回来的每一行的数据做运算，比如求和、取平均值等等。
当子节点明确时 可以通过 select s1+s2+s3 from root.data.g_0.d_0 order by time desc limit 10;
但现实的场景中子节点是不固定的，名称也是未知的。
可以通过目前的group by对子节点进行聚合后进行函数运算，但是无法支持取最近10个时间序列每一个时间点的单独计算。
**Describe the solution you'd like**
是否可以增加一些函数用来对子节点的值进行计算。比如 增加 node_sum 函数
比如 select node_sum(*) from root.data.g_0.d_0.* order by time desc limit 10;
+-----------------------------+-------------------------------------------------------------------+
| Time| node_sum(root.data.g_0.d_0.*)|
+-----------------------------+-------------------------------------------------------------------+
|2022-10-18T16:41:24.195+08:00| 0.0|
|2022-10-18T16:41:09.195+08:00| 0.0|
|2022-10-18T16:40:54.195+08:00| 0.0|
|2022-10-18T16:40:39.195+08:00| 0.0|
|2022-10-18T16:40:24.195+08:00| 0.0|
|2022-10-18T16:40:09.195+08:00| 0.0|
|2022-10-18T16:39:54.195+08:00| 5.36E8|
|2022-10-18T16:39:39.822+08:00| 5.82E8|
|2022-10-18T16:39:24.195+08:00| 0.0|
|2022-10-18T16:39:09.195+08:00| 0.0|
+--------------------------------+----------------------------------------------------------------+
**Describe alternatives you've considered**
现有的方案只能查询出来后通过遍历每一行、每一个子节点来进行计算。
**Additional context**
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[GitHub] [iotdb] CritasWang closed issue #7644: 能否支持对不固定子节点的函数运算
Posted by GitBox <gi...@apache.org>.
CritasWang closed issue #7644: 能否支持对不固定子节点的函数运算
URL: https://github.com/apache/iotdb/issues/7644
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[GitHub] [iotdb] zhangyf001 commented on issue #7644: 能否支持对不固定子节点的函数运算
Posted by GitBox <gi...@apache.org>.
zhangyf001 commented on issue #7644:
URL: https://github.com/apache/iotdb/issues/7644#issuecomment-1362363032
花里胡哨
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