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From "Ian (JIRA)" <j...@apache.org>
Subject [jira] [Commented] (SPARK-11153) Turns off Parquet filter push-down for string and binary columns
Date Wed, 01 Jun 2016 21:02:59 GMT

    [ https://issues.apache.org/jira/browse/SPARK-11153?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=15311110#comment-15311110
] 

Ian commented on SPARK-11153:
-----------------------------

Cheng, 
  Can we revisit SPARK-11784? 
CC [~markhamstra]


> Turns off Parquet filter push-down for string and binary columns
> ----------------------------------------------------------------
>
>                 Key: SPARK-11153
>                 URL: https://issues.apache.org/jira/browse/SPARK-11153
>             Project: Spark
>          Issue Type: Bug
>          Components: SQL
>    Affects Versions: 1.5.0, 1.5.1
>            Reporter: Cheng Lian
>            Assignee: Cheng Lian
>            Priority: Blocker
>             Fix For: 1.5.2, 1.6.0
>
>
> Due to PARQUET-251, {{BINARY}} columns in existing Parquet files may be written with
corrupted statistics information. This information is used by filter push-down optimization.
Since Spark 1.5 turns on Parquet filter push-down by default, we may end up with wrong query
results. PARQUET-251 has been fixed in parquet-mr 1.8.1, but Spark 1.5 is still using 1.7.0.
> Note that this kind of corrupted Parquet files could be produced by any Parquet data
models.
> This affects all Spark SQL data types that can be mapped to Parquet {{BINARY}}, namely:
> - {{StringType}}
> - {{BinaryType}}
> - {{DecimalType}} (but Spark SQL doesn't support pushing down {{DecimalType}} columns
for now.)
> To avoid wrong query results, we should disable filter push-down for columns of {{StringType}}
and {{BinaryType}} until we upgrade to parquet-mr 1.8.



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