Re: Updates of IoTDB Group By Fill Query

[HW-Chao Wang]

great，this query is important.

---Original---
From: "Xiangwei Wei"<wxw19981...@gmail.com&gt;
Date: Tue, Dec 28, 2021 16:22 PM
To: "dev"<dev@iotdb.apache.org&gt;;
Subject: Re: Updates of IoTDB Group By Fill Query


Hi, Great work!

Eric Pai <ericpa...@hotmail.com&gt; 于2021年12月27日周一 17:00写道：

&gt; Excellent work! Now our query is more completed and can support more real
&gt; world requirements! Besides the feature, the GroupByFillDataSet is almostly
&gt; decoupled from GroupByEngineDataSet. Now I can develop the UDF nesting
&gt; aggregations in GROUP BY FILL query easily __
&gt;
&gt; 在 2021/12/27 下午4:54，“Mr.Crazy”<532741...@qq.com.INVALID&gt; 写入:
&gt;
&gt;&nbsp;&nbsp;&nbsp;&nbsp; Hi!
&gt;&nbsp;&nbsp;&nbsp;&nbsp; &amp;nbsp; I'm working on Group By Fill Query 
these days, to enrich the
&gt; capabilities of group by fill. Formerly, group by fill only support
&gt; last_value aggregation using PreviousFill. But now group by fill supports
&gt; all aggregation functions and fill methods! I modified the fill syntax and
&gt; GroupByFillDataSet to make this feature work, you can get an overview of
&gt; the changes below.
&gt;&nbsp;&nbsp;&nbsp;&nbsp; &amp;nbsp; Firstly, our old fill syntax perform 
Fill by specifying the
&gt; fill method for each type. But specifying multiple fill methods in a single
&gt; SQL can impose a significant logic burden of GroupByFill. So we simplify
&gt; the fill syntax from FILL(<data_type&amp;gt;(fill_method)(,
&gt; <data_type&amp;gt;(fill_method))*) to FILL(fill_method) (on Previous or 
Linear
&gt; fill) and FILL(constant) (on Value Fill). While the old syntax can be
&gt; compatible. You should notice that even the old fill syntax doesn't allow
&gt; for multiple fill methods in a single SQL.
&gt;&nbsp;&nbsp;&nbsp;&nbsp; &amp;nbsp; You can get more information of fill 
syntax updates from our
&gt; UserGuide in master branch. Click&amp;nbsp;here&amp;nbsp;for English 
version.
&gt;&nbsp;&nbsp;&nbsp;&nbsp; &amp;nbsp; The GroupByFillDataSet is also rebuilt 
for supporting new
&gt; feature. You can see&amp;nbsp;this doc for new group by fill examples and 
get
&gt; more rebuilt details.
&gt;&nbsp;&nbsp;&nbsp;&nbsp; &amp;nbsp;&amp;nbsp;
&gt;&nbsp;&nbsp;&nbsp;&nbsp; &amp;nbsp; Rongzhao Chen
&gt;&nbsp;&nbsp;&nbsp;&nbsp; &amp;nbsp; School of Software, Tsinghua university
&gt;
&gt;

-- 
Best,
Xiangwei Wei