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From "Edward Capriolo (JIRA)" <j...@apache.org>
Subject [jira] Commented: (HIVE-1096) Hive Variables
Date Tue, 26 Jan 2010 05:26:38 GMT

    [ https://issues.apache.org/jira/browse/HIVE-1096?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=12804895#action_12804895
] 

Edward Capriolo commented on HIVE-1096:
---------------------------------------


@namit, 

>>Static/dynamic binding will also come in when we allow resuming execution of a query-

HIVE-1100 sounds pretty complex. How can you move a query to a new session, when the session
effects how the query is executed? For example, if i start a query in a session with without
strict mode then move it to a session with strict mode is the query even valid anymore? 

This leads me back with my original thinking to do the substitution in  Driver.run. 1) it's
fast 2) it's easy 3)a caveman (like me) can do it. Really, the feature could go all the way
up to the CLI, HiveService/clients really would not have a great use for this.

>>'Hive will be doing string replace on all string literals returned from parser'

sounds good too, but not if it will change the debugging offsets. 

I am sure some crafty sed hacker could cook up out a one-liner for this, which is maybe fine
we punt it and do not support it, might be better then totally obfuscating the code base for
it. 



> Hive Variables
> --------------
>
>                 Key: HIVE-1096
>                 URL: https://issues.apache.org/jira/browse/HIVE-1096
>             Project: Hadoop Hive
>          Issue Type: New Feature
>            Reporter: Edward Capriolo
>            Assignee: Edward Capriolo
>
> From mailing list:
> --Amazon Elastic MapReduce version of Hive seems to have a nice feature called "Variables."
Basically you can define a variable via command-line while invoking hive with -d DT=2009-12-09
and then refer to the variable via ${DT} within the hive queries. This could be extremely
useful. I can't seem to find this feature even on trunk. Is this feature currently anywhere
in the roadmap?--
> This could be implemented in many places.
> A simple place to put this is 
> in Driver.compile or Driver.run we can do string substitutions at that level, and further
downstream need not be effected. 
> There could be some benefits to doing this further downstream, parser,plan. but based
on the simple needs we may not need to overthink this.
> I will get started on implementing in compile unless someone wants to discuss this more.

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