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Posted to issues@flink.apache.org by "lilizhao (JIRA)" <ji...@apache.org> on 2018/03/12 09:28:00 UTC
[jira] [Commented] (FLINK-8903) Error calculation based on rolling
window in table API and SQL API
[ https://issues.apache.org/jira/browse/FLINK-8903?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=16394986#comment-16394986 ]
lilizhao commented on FLINK-8903:
---------------------------------
[~fhueske] But why the calculated variance is the same as that of the average. I made some examples here. The variance and standard deviation output of processing time and Event Time based on rolling window and sliding window in Table API and SQL API are all the same as average value.
> Error calculation based on rolling window in table API and SQL API
> ------------------------------------------------------------------
>
> Key: FLINK-8903
> URL: https://issues.apache.org/jira/browse/FLINK-8903
> Project: Flink
> Issue Type: Bug
> Components: Table API & SQL
> Affects Versions: 1.4.1
> Reporter: lilizhao
> Priority: Critical
> Fix For: 1.5.0
>
> Attachments: TableAndSQLTest.java
>
>
> Error calculation based on rolling window in table API and SQL API
> The variance of the calculation is equal to the average.
> 1 The test code is detailed in the appendix
> 2 The test data are as follows
> 1 li
> 100 li
> 3 The Table API test result as follows
> (true,50.5,101.0,50.5,li,2018-03-09 09:11:00.0)
> 4 The SQL API test result as follows
> (true,50.5,2,101.0,50.5,li,2018-03-09 09:21:00.0)
>
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