GitHub user sudheeshkatkam opened a pull request:
https://github.com/apache/drill/pull/193
DRILL-3623: Use shorter query path for LIMIT 0 queries on schema-ed tables
Initial patch.
DrillTable#providesDeferredSchema function is used by the
NonDeferredSchemaTableLimit0Visitor to check if the table can provide schema
directly, and if so the result is directly returned.
It seems the shorter query path for this query needs a hacky "otherPlan" in
the DefaultSqlHandler without major refactoring (Should I go ahead and make
changes?). This also means that "EXPLAIN PLAN ..." returns a plan that is
different the actual query plan (without a check in ExplainHandler, another
hack).
I think the classes need more meaningful names
(NonDeferredSchemaTableLimit0Visitor).
Also, note the type conversion using CALCITE_TO_DRILL_TYPE_MAPPING.
You can merge this pull request into a Git repository by running:
$ git pull https://github.com/sudheeshkatkam/drill DRILL-3623
Alternatively you can review and apply these changes as the patch at:
https://github.com/apache/drill/pull/193.patch
To close this pull request, make a commit to your master/trunk branch
with (at least) the following in the commit message:
This closes #193
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commit a766c54b34697df8b851204705ea1ce16c7114b7
Author: Sudheesh Katkam <[email protected]>
Date: 2015-10-08T22:38:00Z
DRILL-3623: Use shorter query path for LIMIT 0 queries on schema-ed tables
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