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From "Jinfeng Ni (JIRA)" <j...@apache.org>
Subject [jira] [Assigned] (DRILL-5480) Empty batch returning from HBase may cause SchemChangeException or incorrect query result
Date Mon, 15 May 2017 20:15:04 GMT

     [ https://issues.apache.org/jira/browse/DRILL-5480?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel
]

Jinfeng Ni reassigned DRILL-5480:
---------------------------------

    Assignee: Jinfeng Ni

> Empty batch returning from HBase may cause SchemChangeException or incorrect query result
> -----------------------------------------------------------------------------------------
>
>                 Key: DRILL-5480
>                 URL: https://issues.apache.org/jira/browse/DRILL-5480
>             Project: Apache Drill
>          Issue Type: Bug
>            Reporter: Jinfeng Ni
>            Assignee: Jinfeng Ni
>
> The following repo was provided by [~haozhu].
> 1. Create a Hbase table with 4 regions
> {code}
> create 'myhbase', 'cf1','cf2', {SPLITS => ['a', 'b', 'c']}
> put 'myhbase','a','cf1:col1','somedata'
> put 'myhbase','b','cf1:col2','somedata'
> put 'myhbase','c','cf2:col1','somedata'
> {code}
> One region has cf1.col1.  One region has column family 'cf1', but does not have 'col1'
under 'cf1'. One region has only column family 'cf2'. And last region is complete empty.
> 2. Prepare a csv file.
> {code}
> select * from dfs.tmp.`joinhbase.csv`;
> +-------------------+
> |      columns      |
> +-------------------+
> | ["1","somedata"]  |
> | ["2","somedata"]  |
> | ["3","somedata"]  |
> {code}
> Now run the following query on drill 1.11.0-SNAPSHOT:
> {code}
> select cast(H.row_key as varchar(10)) as keyCol, CONVERT_FROM(H.cf1.col1, 'UTF8') as
col1
> from 
> hbase.myhbase H JOIN dfs.tmp.`joinhbase.csv` C
> ON CONVERT_FROM(H.cf1.col1, 'UTF8')= C.columns[1]
> ;
> {code}
> The correct query result show be:
> {code}
> +---------+-----------+
> | keyCol  |   col1    |
> +---------+-----------+
> | a       | somedata  |
> | a       | somedata  |
> | a       | somedata  |
> +---------+-----------+
> {code}
> Turn off broadcast join, then we will see SchemaChangeException, or incorrect result
randomly. By 'randomly', it means in the same session, the same query would hit SchemaChangeException
in one run, while gets incorrect result in a second run. 
> {code}
> alter session set `planner.enable_broadcast_join`=false;
> {code}
> {code}
> select cast(H.row_key as varchar(10)) as keyCol, CONVERT_FROM(H.cf1.col1, 'UTF8') as
col1
> . . . . . . . . . . . . . . . . . .> from
> . . . . . . . . . . . . . . . . . .> hbase.myhbase H JOIN dfs.tmp.`joinhbase.csv`
C
> . . . . . . . . . . . . . . . . . .> ON CONVERT_FROM(H.cf1.col1, 'UTF8')= C.columns[1]
> . . . . . . . . . . . . . . . . . .> ;
> Error: SYSTEM ERROR: SchemaChangeException: Hash join does not support schema changes
> {code}
> {code}
> +---------+-------+
> | keyCol  | col1  |
> +---------+-------+
> +---------+-------+
> No rows selected (0.302 seconds)
> {code}



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