Teddy Choi created HIVE-20552:
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Summary: Get Schema from LogicalPlan faster
Key: HIVE-20552
URL: https://issues.apache.org/jira/browse/HIVE-20552
Project: Hive
Issue Type: Test
Reporter: Teddy Choi
Assignee: Teddy Choi
To get the schema of a query faster, it currently needs to compile, optimize,
and generate a TezPlan, which creates extra overhead when only the LogicalPlan
is needed.
1. Copy the method \{{HiveMaterializedViewsRegistry.parseQuery}}, making it
\{{public static}} and putting it in a utility class.
2. Change the return statement of the method to \{{return
analyzer.getResultSchema();}}
3. Change the return type of the method to \{{List<FieldSchema>}}
4. Call the new method from \{{GenericUDTFGetSplits.createPlanFragment}}
replacing the current code which does this:
{code}
if(num == 0) {
//Schema only
return new PlanFragment(null, schema, null);
}
{code}
moving the call earlier in \{{getPlanFragment}} ... right after the HiveConf is
created ... bypassing the code that uses \{{HiveTxnManager}} and \{{Driver}}.
5. Convert the \{{List<FieldSchema>}} to
\{{org.apache.hadoop.hive.llap.Schema}}.
6. return from \{{getPlanFragment}} by returning \{{new PlanFragment(null,
schema, null)}}
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