[
https://issues.apache.org/jira/browse/HIVE-416?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=12699957#action_12699957
]
Raghotham Murthy commented on HIVE-416:
---------------------------------------
How about the following:
Add the production:
{{{
expr -> expr ',' expr
}}}
With this production and expr -> '(' expr ')' we can support arbitrarily nested
parentheses. The issue is that the new production will create a left-deep tree
of comma-expressions. We could implement a method which takes such a tree and
flatten out comma expressions into expression lists.
Also, I remember Venky asking for arbitrarily nested parentheses around queries
for his query authoring tool. We could do something similar and create
comma-query-expressions.
> Get rid of backtrack in Hive.g
> ------------------------------
>
> Key: HIVE-416
> URL: https://issues.apache.org/jira/browse/HIVE-416
> Project: Hadoop Hive
> Issue Type: Improvement
> Components: Query Processor
> Affects Versions: 0.4.0
> Reporter: Zheng Shao
> Assignee: Zheng Shao
> Fix For: 0.4.0
>
> Attachments: HIVE-416.1.1.patch, HIVE-416.1.patch
>
>
> Hive.g now still uses "backtrack=true". "backtrack" not only slows down the
> parsing in case of error, it can also produce wrong syntax error messages
> (usually based on the last try of the backtracking).
> We should follow
> http://www.antlr.org/wiki/display/ANTLR3/How+to+remove+global+backtracking+from+your+grammar
> to remove the need of doing backtrack.
--
This message is automatically generated by JIRA.
-
You can reply to this email to add a comment to the issue online.
