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https://issues.apache.org/jira/browse/HIVE-887?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=12767442#action_12767442
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Ning Zhang commented on HIVE-887:
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After looking more carefully at the code, the fetch task spawn a fetch operator
at its initialization, and the fetch operator is not subclass of Operator. So
we probably need to extend it to Operator class and make the select Operator as
a child of fetch, or push select operator's logic to fetch operator's
implementation. Will have a discussion first and put it as a lower priority in
my task list for now.
> Allow SELECT <col> without a mapreduce job
> ------------------------------------------
>
> Key: HIVE-887
> URL: https://issues.apache.org/jira/browse/HIVE-887
> Project: Hadoop Hive
> Issue Type: New Feature
> Environment: All
> Reporter: Eric Sun
> Assignee: Ning Zhang
>
> I often find myself needing to take a quick look at a particular column of a
> Hive table.
> I usually do this by doing a
> SELECT * from <table> LIMIT 20;
> from the CLI. Doing this is pretty fast since it doesn't require a mapreduce
> job. However, it's tough to examine just 1 or 2 columns when the table is
> very wide.
> So, I might do
> SELECT <col> from <table> LIMIT 20;
> but it's much slower since it requires a map-reduce. It'd be really
> convenient if a map-reduce wasn't necessary.
> Currently a good work around is to do
> hive -e "select * from table" | cut --key=n
> but it'd be more convenient if it were built in since it alleviates the need
> for column counting.
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