[jira] [Created] (DRILL-6976) SchemaChangeException happens when using split function in subquery if it returns empty result.

["Anton Gozhiy (JIRA)" <ji...@apache.org>]

Anton Gozhiy created DRILL-6976:
-----------------------------------

             Summary: SchemaChangeException happens when using split function in subquery if it returns empty result.
                 Key: DRILL-6976
                 URL: https://issues.apache.org/jira/browse/DRILL-6976
             Project: Apache Drill
          Issue Type: Bug
    Affects Versions: 1.15.0
            Reporter: Anton Gozhiy


*Query:*
{code:sql}
select substr(col, 2, 3) 
from (select split(n_comment, ' ') [3] col 
      from cp.`tpch/nation.parquet` 
      where n_nationkey = -1 
      group by n_comment 
      order by n_comment 
      limit 5);
{code}

*Expected result:*
{noformat}
+---------+
| EXPR$0  |
+---------+
+---------+
{noformat}

*Actual result:*
{noformat}
Error: SYSTEM ERROR: SchemaChangeException: Failure while trying to materialize incoming schema.  Errors:
 
Error in expression at index -1.  Error: Missing function implementation: [castVARCHAR(NULL-OPTIONAL, BIGINT-REQUIRED)].  Full expression: --UNKNOWN EXPRESSION--..

Fragment 0:0

Please, refer to logs for more information.

[Error Id: 86515d74-7b9c-4949-8ece-c9c17e00afc3 on userf87d-pc:31010]

  (org.apache.drill.exec.exception.SchemaChangeException) Failure while trying to materialize incoming schema.  Errors:
 
Error in expression at index -1.  Error: Missing function implementation: [castVARCHAR(NULL-OPTIONAL, BIGINT-REQUIRED)].  Full expression: --UNKNOWN EXPRESSION--..
    org.apache.drill.exec.physical.impl.project.ProjectRecordBatch.setupNewSchemaFromInput():498
    org.apache.drill.exec.physical.impl.project.ProjectRecordBatch.setupNewSchema():583
    org.apache.drill.exec.record.AbstractUnaryRecordBatch.innerNext():101
    org.apache.drill.exec.physical.impl.project.ProjectRecordBatch.innerNext():143
    org.apache.drill.exec.record.AbstractRecordBatch.next():186
    org.apache.drill.exec.physical.impl.BaseRootExec.next():104
    org.apache.drill.exec.physical.impl.ScreenCreator$ScreenRoot.innerNext():83
    org.apache.drill.exec.physical.impl.BaseRootExec.next():94
    org.apache.drill.exec.work.fragment.FragmentExecutor$1.run():297
    org.apache.drill.exec.work.fragment.FragmentExecutor$1.run():284
    java.security.AccessController.doPrivileged():-2
    javax.security.auth.Subject.doAs():422
    org.apache.hadoop.security.UserGroupInformation.doAs():1746
    org.apache.drill.exec.work.fragment.FragmentExecutor.run():284
    org.apache.drill.common.SelfCleaningRunnable.run():38
    java.util.concurrent.ThreadPoolExecutor.runWorker():1149
    java.util.concurrent.ThreadPoolExecutor$Worker.run():624
    java.lang.Thread.run():748 (state=,code=0)
{noformat}

*Note:* Filter "where n_nationkey = -1" doesn't return any rows. In case of " = 1", for example, the query will return result without error.

*Workaround:* Use cast on the split function, like
{code:sql}
cast(split(n_comment, ' ') [3] as varchar)
{code}




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