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https://issues.apache.org/jira/browse/HIVE-1096?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=12804688#action_12804688
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Prasad Chakka commented on HIVE-1096:
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I think most useful global variables are in-built variables that do not really
need metastore (eg. date based stuff, TODAY, THIS_WEEK, THIS_MONTH or user name
or host name etc). Also session variables and user specific variables that can
be loaded with a .hiverc. So it may be possible to implement most of the
requirements without true global variables (and metastore).
String substitution will create problems with comments and also with error
reporting.
> 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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