[jira] [Commented] (SPARK-11153) Turns off Parquet filter push-down for string and binary columns

["Michael Armbrust (JIRA)" <ji...@apache.org>]

    [ https://issues.apache.org/jira/browse/SPARK-11153?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=14961147#comment-14961147 ] 

Michael Armbrust commented on SPARK-11153:
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Its actually corrupted statistics in data that is written?  Does parquet write the version in the metadata?  Should we actually be turning this off based on writer version?

> 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
>
> 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.
> 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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