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From "Lefty Leverenz (JIRA)" <j...@apache.org>
Subject [jira] [Commented] (HIVE-6013) Supporting Quoted Identifiers in Column Names
Date Mon, 27 Jan 2014 04:18:38 GMT

    [ https://issues.apache.org/jira/browse/HIVE-6013?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13882559#comment-13882559
] 

Lefty Leverenz commented on HIVE-6013:
--------------------------------------

I guess I misunderstood.  So with hive.support.quoted.identifiers=column, you can use backticks
to allow Unicode characters in column names but backticks are not required if the names are
restricted to alphanumeric plus underscore.  Is that right, for both DDL and queries?

And if you omit the backticks, you can use * as a wildcard for "all columns" in queries. 
But you can't have regex queries unless hive.support.quoted.identifiers=none, in which case
backticks surround the regular expression.

What happens if hive.support.quoted.identifiers=none (in Hive 0.13) and you use backticks
for a regex, then escape some Unicode characters?  That's probably not a realistic use case,
but I'm wondering if it's a way to select Unicode column names when you've got the wrong configuration
setting.

> Supporting Quoted Identifiers in Column Names
> ---------------------------------------------
>
>                 Key: HIVE-6013
>                 URL: https://issues.apache.org/jira/browse/HIVE-6013
>             Project: Hive
>          Issue Type: Improvement
>          Components: Query Processor
>            Reporter: Harish Butani
>            Assignee: Harish Butani
>             Fix For: 0.13.0
>
>         Attachments: HIVE-6013.1.patch, HIVE-6013.2.patch, HIVE-6013.3.patch, HIVE-6013.4.patch,
HIVE-6013.5.patch, HIVE-6013.6.patch, HIVE-6013.7.patch, QuotedIdentifier.html
>
>
> Hive's current behavior on Quoted Identifiers is different from the normal interpretation.
Quoted Identifier (using backticks) has a special interpretation for Select expressions(as
Regular Expressions). Have documented current behavior and proposed a solution in attached
doc.
> Summary of solution is:
> - Introduce 'standard' quoted identifiers for columns only. 
> - At the langauage level this is turned on by a flag.
> - At the metadata level we relax the constraint on column names.



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