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https://issues.apache.org/jira/browse/HIVE-385?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=12695661#action_12695661
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Neil Conway commented on HIVE-385:
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In looking into this, the first problem appears to be that the driver only has
a single Context, but we might have more than one planned query active at the
same time -- since they'd be using the same context, planning one query will
interfere with the state used by another already-planned query (e.g. the
query's scratch dir).
One way to solve this is to give each planned query it's own Context. Does that
sound reasonable?
> Split Driver.run() into compile() + exec()
> ------------------------------------------
>
> Key: HIVE-385
> URL: https://issues.apache.org/jira/browse/HIVE-385
> Project: Hadoop Hive
> Issue Type: Improvement
> Components: Query Processor
> Reporter: Neil Conway
> Assignee: Neil Conway
>
> Currently, Driver.run() parses, analyzes, and then executes a given query
> string. This isn't very flexible: it would be nice to be able to parse and
> analyze a query to get a query plan, and then execute that query plan at a
> later time (zero or more times). This would also be a necessary prerequisite
> for supporting server-side prepared statements.
> I'd like to change Driver as follows:
> * Add a new method Driver.compile(String), which parses and analyzes the
> given query string, and returns an object representing the planned query
> * Add a new method Driver.execute(Plan), which runs the given planned query
> * Reimplement run(String) as { p = compile(String); execute(p); }
> Comments welcome; I should have a candidate patch ready soon.
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