[jira] [Updated] (DRILL-3921) Hive LIMIT 1 queries take too long

["Sudheesh Katkam (JIRA)" <ji...@apache.org>]

     [ https://issues.apache.org/jira/browse/DRILL-3921?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel ]

Sudheesh Katkam updated DRILL-3921:
-----------------------------------
    Summary: Hive LIMIT 1 queries take too long  (was: Hive LIMIT 1 queries takes too long)

> Hive LIMIT 1 queries take too long
> ----------------------------------
>
>                 Key: DRILL-3921
>                 URL: https://issues.apache.org/jira/browse/DRILL-3921
>             Project: Apache Drill
>          Issue Type: Bug
>          Components: Execution - Flow
>            Reporter: Sudheesh Katkam
>            Assignee: Sudheesh Katkam
>
> Fragment initialization on a Hive table (that is backed by a directory of many files) can take really long. This is evident through LIMIT 1 queries. The root cause is that the underlying reader in the HiveRecordReader is initialized when the ctor is called, rather than when setup is called.
> Two changes need to be made:
> 1) lazily initialize the underlying record reader in HiveRecordReader
> 2) allow for running a callable as a proxy user within an operator (through OperatorContext). This is required as initialization of the underlying record reader needs to be done as a proxy user (proxy for owner of the file). Previously, this was handled while creating the record batch tree.



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