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From "Arina Ielchiieva (JIRA)" <j...@apache.org>
Subject [jira] [Created] (DRILL-6204) Pass tables columns without partition columns to empty Hive reader
Date Fri, 02 Mar 2018 13:31:00 GMT
Arina Ielchiieva created DRILL-6204:
---------------------------------------

             Summary: Pass tables columns without partition columns to empty Hive reader
                 Key: DRILL-6204
                 URL: https://issues.apache.org/jira/browse/DRILL-6204
             Project: Apache Drill
          Issue Type: Bug
          Components: Storage - Hive
    Affects Versions: 1.12.0
            Reporter: Arina Ielchiieva
            Assignee: Arina Ielchiieva
             Fix For: 1.13.0


When {{store.hive.optimize_scan_with_native_readers}} is enabled, {{HiveDrillNativeScanBatchCreator}}
is used to read data from Hive tables directly from file system. In case when table is empty
or no row group are matched, empty {{HiveDefaultReader}} is called to output the schema.

If such situation happens, currently Drill fails with the following error:
{noformat}
org.apache.drill.common.exceptions.UserRemoteException: SYSTEM ERROR: NullPointerException
Setup failed for null 
{noformat}
This happens because instead of passing only table columns to the empty reader (as we do when
creating non-empty reader), we passed all columns which may contain partition columns as well.
As mentioned in on lines 81 - 82 in {{HiveDrillNativeScanBatchCreator}} , we deliberately
separate out partition columns and table columns to pass partition columns separately:
{noformat}
      // Separate out the partition and non-partition columns. Non-partition columns are passed
directly to the
      // ParquetRecordReader. Partition columns are passed to ScanBatch.
{noformat}
To fix the problem we need to pass table columns instead of all columns.
{code:java}
    if (readers.size() == 0) {
      readers.add(new HiveDefaultReader(table, null, null, newColumns, context, conf,
        ImpersonationUtil.createProxyUgi(config.getUserName(), context.getQueryUserName())));
    }
{code}



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