[jira] [Commented] (TAJO-378) Implement concat_ws function.

["Jaehwa Jung (JIRA)" <ji...@apache.org>]

    [ https://issues.apache.org/jira/browse/TAJO-378?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13906659#comment-13906659 ] 

Jaehwa Jung commented on TAJO-378:
----------------------------------

I'm sorry about late patch.

First, 'mvn clean install' finished unsuccessfully. I found a error message as follows:
{code:xml}
Tests in error: 
  testConcat_ws(org.apache.tajo.engine.function.TestStringOperatorsAndFunctions): function concat_ws(text,text,text) does not exist
{code}

Second, I recommend to use StringBuilder instead of String at _Concat_ws_ because concat method of _java.lang.String_ always returns new String Object. So, String objects will be targets for GC.

> Implement concat_ws function.
> -----------------------------
>
>                 Key: TAJO-378
>                 URL: https://issues.apache.org/jira/browse/TAJO-378
>             Project: Tajo
>          Issue Type: New Feature
>    Affects Versions: 0.8-incubating
>            Reporter: Seungun Choe
>            Assignee: Seungun Choe
>            Priority: Minor
>             Fix For: 0.8-incubating
>
>         Attachments: TAJO-378.patch
>
>
> This function's definition is, concat_ws(sep text, str "any" [, str "any" [, ...] ]).
> For example, concat_ws(',', 'abcde', 2, NULL, 22)'s result is abcde,2,22.
> Detailed description is "Concatenate all but first arguments with separators. The first parameter is used as a separator. NULL arguments are ignored.".  



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