[jira] [Updated] (ARROW-17301) implement compute function "utf8_slice_charunits"

["Antoine Pitrou (Jira)" <ji...@apache.org>]

     [ https://issues.apache.org/jira/browse/ARROW-17301?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel ]

Antoine Pitrou updated ARROW-17301:
-----------------------------------
    Priority: Major  (was: Critical)

> implement compute function "utf8_slice_charunits"
> -------------------------------------------------
>
>                 Key: ARROW-17301
>                 URL: https://issues.apache.org/jira/browse/ARROW-17301
>             Project: Apache Arrow
>          Issue Type: Improvement
>          Components: C++
>    Affects Versions: 8.0.1
>            Reporter: ChenTsing
>            Priority: Major
>             Fix For: 10.0.0
>
>
> In some situations, may  request an access method to get binary or sting likes array one or some continuous bytes , for example start 1 end 3 step 1,  the two bytes, it seems like "{{{}binary_replace_slice{}}} " function, provide byte and code two measurement unit
>  
>  
> h1. *application case:*
>  
> here, I can give one example to descirbe why need a function to extract binary in byte unit:
>  
>           In distribute database, data has distribute policy and relatived hash algorithm for different data type, here we just discuss string-like and binary type, the hash algorithm need detach string-like or binary in bytes to calculating, for example , take 1-4 byte cast to integer and shift-left 16 bits, then take 5-6byte cast to integer and the result from last step, and so on, the  'utf8_slice_codeunits' function can partly meet the require if all are ascii,  but if the string-like contain chinese, one chinese may occupied three bytes,  start 1 to end 3, three utf8 character
>   may take nine bytes, but it not meet the hash algorithm, it only need 3 bytes, so if provide a function but not cast, the same function arguments like 'utf8_slice_codeunits', it may called 'binary_slice_byteunit'



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