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Posted to dev@tajo.apache.org by "Hyunsik Choi (JIRA)" <ji...@apache.org> on 2013/11/30 06:46:35 UTC
[jira] [Commented] (TAJO-341) Implement substr function
[ https://issues.apache.org/jira/browse/TAJO-341?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13835621#comment-13835621 ]
Hyunsik Choi commented on TAJO-341:
-----------------------------------
+1 for this patch
That error is caused by the parser problem. I'll create a separate issue for parse to deal negative integer and real values.
> Implement substr function
> -------------------------
>
> Key: TAJO-341
> URL: https://issues.apache.org/jira/browse/TAJO-341
> Project: Tajo
> Issue Type: New Feature
> Components: operator/function/udf
> Reporter: Hyunsik Choi
> Assignee: hyoungjunkim
> Priority: Minor
> Fix For: 0.8-incubating
>
> Attachments: TAJO-341.patch
>
>
> h3. Function Definition
> {code}
> text substr(string text, from int4 [, count int4])
> {code}
> h3. Description
> * It extracts substring (same as substring(string from from for count)).
> * If string is null, the result also should be null.
> * Note that *from* is one based index.
> * *from* can be negative integer.
> * *count* can be omitted. If then, all string after *from* will be returned.
> * *count* cannot be negative integer.
> * If *count* is 0, the result should be '' instead of null.
> h3. Example and Sementic
> {code}
> hyunsik=> select substr('abcdef', 3, 2);
> substr
> --------
> cd
> (1 row)
> hyunsik=> select substr('abcdef',3) ;
> substr
> --------
> cdef
> (1 row)
> hyunsik=> select substr('abcdef',1,1) ;
> substr
> --------
> a
> (1 row)
> hyunsik=> select substr('abcdef',0,1) ;
> substr
> --------
>
> (1 row)
> hyunsik=> select substr('abcdef',0,2) ;
> substr
> --------
> a
> (1 row)
> {code}
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