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https://issues.apache.org/jira/browse/HIVE-1096?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=12893022#action_12893022
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Carl Steinbach commented on HIVE-1096:
--------------------------------------
The reviewboard jiraposter is temporarily down so I'm posting this by hand. The
original comments and context are here: https://review.cloudera.org/r/229/
* trunk/conf/hive-default.xml:
Spelling: substituation
* trunk/ql/src/java/org/apache/hadoop/hive/ql/parse/VariableSubstitution.java:
Make these variables private?
* trunk/ql/src/java/org/apache/hadoop/hive/ql/parse/VariableSubstitution.java:
This should be static. No need to instantiate a VariableSubstitution object.
*
trunk/ql/src/java/org/apache/hadoop/hive/ql/processors/AddResourceProcessor.java:
Since we want to do substitution for all commands it would probably make sense
to do the substitution in CommandProcessorFactory.get() and make
CommandProcessor an abstract class with the following implementation:
{code}
public abstract class {
protected String command;
CommandProcessor(String command) {
this.command = command;
}
public abstract CommandProcessorResponse run();
public String getCommand() {
return command;
}
}
{code}
In other words, CommandProcessorFactory would return a CommandProcessor object
that has been initialized with a substituted copy of the command.
* trunk/ql/src/java/org/apache/hadoop/hive/ql/processors/SetProcessor.java:
Replace these string literals with constants, e.g:
{code}
public static final String ENV_PREFIX = "env:";
public static final String SYSTEM_PREFIX = "system:"
public static final String HIVECONF_PREFIX = "hiveconf:"
{code}
* trunk/ql/src/java/org/apache/hadoop/hive/ql/processors/SetProcessor.java:
String propName = varname.substring(SYSTEM_PREFIX.length());
* trunk/ql/src/java/org/apache/hadoop/hive/ql/processors/SetProcessor.java:
Can we remove this special case for "silent"? In SessionState this actually
maps to "hive.session.silent" and I don't see any test cases that cover this
case, i.e. that call "set silent" or "set silent=x". It also seems that this
introduces in inconsistency since "set silent" will show the value of
"hive.session.silent", but the output of "set" will not list a value for the
property "silent".
Anyone know if there is any older code that depends on this behavior?
> Hive Variables
> --------------
>
> Key: HIVE-1096
> URL: https://issues.apache.org/jira/browse/HIVE-1096
> Project: Hadoop Hive
> Issue Type: New Feature
> Components: Query Processor
> Reporter: Edward Capriolo
> Assignee: Edward Capriolo
> Fix For: 0.6.0, 0.7.0
>
> Attachments: 1096-9.diff, hive-1096-10-patch.txt,
> hive-1096-11-patch.txt, hive-1096-12.patch.txt, hive-1096-2.diff,
> hive-1096-7.diff, hive-1096-8.diff, hive-1096.diff
>
>
> 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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