[jira] [Resolved] (IMPALA-11127) Document the UTF8_MODE query option and relavent string functions

["Quanlong Huang (Jira)" <ji...@apache.org>]

     [ https://issues.apache.org/jira/browse/IMPALA-11127?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel ]

Quanlong Huang resolved IMPALA-11127.
-------------------------------------
    Fix Version/s: Impala 4.1.0
       Resolution: Fixed

> Document the UTF8_MODE query option and relavent string functions
> -----------------------------------------------------------------
>
>                 Key: IMPALA-11127
>                 URL: https://issues.apache.org/jira/browse/IMPALA-11127
>             Project: IMPALA
>          Issue Type: Documentation
>    Affects Versions: Impala 4.1.0
>            Reporter: Quanlong Huang
>            Assignee: shajini thayasingh
>            Priority: Major
>             Fix For: Impala 4.1.0
>
>
> Since IMPALA-2019 is resolved, we can document the UTF8_MODE query option added in it now. The query option will turn on the UTF-8 aware behavior of string functions. The relevant string functions and their UTF-8 aware behaviors are:
>  * LENGTH(STRING a)
>  ** returns the number of UTF-8 characters instead of bytes
>  * SUBSTR(STRING a, INT start [, INT len])
> SUBSTRING(STRING a, INT start [, INT len])()
>  ** the substring start position and length is counted by UTF-8 characters instead of bytes
>  * REVERSE(STRING a)
>  ** the unit of the operation is a UTF-8 character, ie. it won't reverse bytes inside a UTF-8 character.
>  * INSTR(STRING str, STRING substr[, BIGINT position[, BIGINT occurrence]])
> LOCATE(STRING substr, STRING str[, INT pos])
>  ** These functions have an optional position argument. The return values are also positions in the string. In UTF-8 mode, these positions are counted by UTF-8 characters instead of bytes.
>  * mask functions
>  ** The unit of the operation is a UTF-8 character, ie. they won't mask the string byte-to-byte.
>  * upper/lower/initcap
>  ** These functions will recognize non-ascii characters and transform them based on the current locale used by the Impala process.



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