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From "yucai (JIRA)" <j...@apache.org>
Subject [jira] [Created] (SPARK-25206) Wrong data may be returned when enable pushdown
Date Thu, 23 Aug 2018 07:41:00 GMT
yucai created SPARK-25206:
-----------------------------

             Summary: Wrong data may be returned when enable pushdown
                 Key: SPARK-25206
                 URL: https://issues.apache.org/jira/browse/SPARK-25206
             Project: Spark
          Issue Type: Bug
          Components: SQL
    Affects Versions: 2.3.1
            Reporter: yucai


In current Spark 2.3.1, below query returns wrong data silently.
{code:java}
spark.range(10).write.parquet("/tmp/data")
sql("DROP TABLE t")
sql("CREATE TABLE t (ID LONG) USING parquet LOCATION '/tmp/data'")
scala> sql("select * from t where id > 0").show
+---+
| ID|
+---+
+---+{code}
 

*Root Cause*
Spark pushdowns FilterApi.gt(intColumn("{color:#ff0000}ID{color}"), 0: Integer) into parquet,
but {color:#ff0000}ID{color} does not exist in /tmp/data (parquet is case sensitive, it has
{color:#ff0000}id{color} actually).
So no records are returned.

In Spark 2.1, the user will get Exception:
{code:java}
Caused by: java.lang.IllegalArgumentException: Column [ID] was not found in schema!{code}
But in Spark 2.3, they will get the wrong results sliently.

 

Since SPARK-24716, Spark uses Parquet schema instead of Hive metastore schema to do the pushdown,
perfect for this issue.

[~yuming] , [~cloud_fan], [~smilegator], any thoughts? Should we backport it?



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