[jira] [Updated] (DRILL-7001) Documentation - renaming columns name in csv header

["Bridget Bevens (JIRA)" <ji...@apache.org>]

     [ https://issues.apache.org/jira/browse/DRILL-7001?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel ]

Bridget Bevens updated DRILL-7001:
----------------------------------
    Labels: doc-impacting  (was: )

> Documentation - renaming columns name in csv header
> ---------------------------------------------------
>
>                 Key: DRILL-7001
>                 URL: https://issues.apache.org/jira/browse/DRILL-7001
>             Project: Apache Drill
>          Issue Type: Wish
>    Affects Versions: 1.15.0
>            Reporter: benj
>            Priority: Minor
>              Labels: doc-impacting
>
> Don't know how if this is the best place for this request but,
> Some operation are realized that eventually change the name of the column when requesting a csvh file (with header),
>  These operations are not documented.
>  Although it's possible to read [HeaderBuilder.java|https://github.com/apache/drill/blob/master/exec/java-exec/src/main/java/org/apache/drill/exec/store/easy/text/compliant/HeaderBuilder.java], It will be interesting to create a section in documentation to explain at least the principle of these different cases to avoid stupid problems/difficulties
> List of operations (maybe not exhaustive) :
>  * Trim() on CSV column name
> {noformat}
>  Name , Age,PoB  , Info
> =>
> `Name`, `Age`, `PoB` and `Info`{noformat}
>  * Others characters than [a-zA-Z0-9_] are replace by '_' (underscore)
> {noformat}
> Name,Sum$,em@il
> =>
> `Name`,'`Sum_`,`em_il`{noformat}
>  * Fieldname starting with '_' (underscore) are prefixed by 'col'
> {noformat}
> _name,_age_,pob_,_col_
> =>
> `col_name`, `col_age_`, `pob_`, `col_col_`{noformat}
>  * Fieldname starting with [^a-zA-Z] are prefixed 'col_'
> {noformat}
> 0_name, 1_age,@pob,#other1,'other2'
> =>
> `col_0_name`, `col_1_age`, `col_pob`, `col_other1`, `col_other2_`{noformat}
>  *  Quotation marks are removed
>  * If char is unique
>  ** if [a-zA-Z] do nothing
>  ** elif [0-9] prefix with col_
>  ** else reanme in column_[0-9]+ where [0-9]+ designs the position of the column
>  * Duplicate columns names (case insensitive) are suffixed with _[0-9]+ (starting from "_2")
> {noformat}
> 0_name,col_0_name,colx,COLX,colx,colx_2
> =>
> `col_0_name`, `col_0_name_2`, `colx`, `COLX_2`, `colx_3`, `colx_2_2`{noformat}
>  



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