[jira] [Commented] (IOTDB-1823) Support group by multi level

["Jun Yuan (Jira)" <ji...@apache.org>]

    [ https://issues.apache.org/jira/browse/IOTDB-1823?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=17429784#comment-17429784 ] 

Jun Yuan commented on IOTDB-1823:
---------------------------------

select count(speed) from root.** group by level = 1

Here, level=1 should be sg1 and sg2 rather than f1?

> Support group by multi level 
> -----------------------------
>
>                 Key: IOTDB-1823
>                 URL: https://issues.apache.org/jira/browse/IOTDB-1823
>             Project: Apache IoTDB
>          Issue Type: Task
>            Reporter: Alima777
>            Assignee: Alima777
>            Priority: Major
>              Labels: pull-request-available
>   Original Estimate: 72h
>  Remaining Estimate: 72h
>
> Group by level is simliar to group by clause in relative database.
>  
> For example, a relative table is like the following:
>  
> |Time|storage_group|factory|device|temperature|speed|
> |1|sg1|f1|d1|V|V|
> |1|sg2|f1|d1|V|V|
> |1|sg2|f1|d2|V|V|
>  
> Then the group by query may be like: 
> 1. select device, count(speed) from table group by device
> the result will be:
> |device|count(speed)|
> |d1|2|
> |d2|1|
>  
> *In IoTDB:*
> select count(speed) from root.** group by level = 3
>  
> |count(root.*..*.d1.speed)|count(root.*.*.d2.speed)|
> |2|1|
> 2. select storage_group, count(speed) from table group by factory
>  
> |storage_group|count(speed)|
> |f1|3|
>  
> *In IoTDB:*
> select count(speed) from root.** group by level = 1
>  
> |count(root.*f1.*.speed)|
> |3|
>  
> 3. *多层 level*
> select count(speed) from table group by factory, device
> |(To help understand)|count(speed)|
> |f1.d1|2|
> |f1.d2|1|
>  
> *In IoTDB:*
> select count(speed) from root.** group by level = 2, 3
> |count(root.*.f1.d1.speed)|count(root.*.f1.d2.speed)|
> |2|1|
>  
> 4. *limit 对应 slimit*
> select count(speed) from table group by factory, device limit 1
>  
> |(To help understand)|count(speed)|
> |f1.d1|2|
>  
> *In IoTDB:*
> select count(speed) from root.** group by level = 1, 2 *slimit 1*
> |count(root.*.f1.d1.speed)|
> |2|
>  



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