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Posted to issues@spark.apache.org by "Xiao Li (JIRA)" <ji...@apache.org> on 2016/10/07 07:18:20 UTC
[jira] [Commented] (SPARK-5511) [SQL] Possible optimisations for
predicate pushdowns from Spark SQL to Parquet
[ https://issues.apache.org/jira/browse/SPARK-5511?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=15554357#comment-15554357 ]
Xiao Li commented on SPARK-5511:
--------------------------------
This requires the changes on Parquet.
> [SQL] Possible optimisations for predicate pushdowns from Spark SQL to Parquet
> ------------------------------------------------------------------------------
>
> Key: SPARK-5511
> URL: https://issues.apache.org/jira/browse/SPARK-5511
> Project: Spark
> Issue Type: Improvement
> Components: SQL
> Affects Versions: 1.2.0
> Reporter: Mick Davies
> Priority: Minor
>
> The following changes could make predicate pushdown more effective under certain conditions, which are not uncommon.
> 1. Parquet predicate evaluation does not use dictionary compression information, furthermore it circumvents dictionary decoding optimisations (https://issues.apache.org/jira/browse/PARQUET-36). This means predicates are re-evaluated repeatedly for the same Strings, and also Binary->String conversions are repeated. This is a change purely on the Parquet side.
> 2. Support IN clauses in predicate pushdown. This requires changes to Parquet and then subsequently in Spark SQL.
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