HyukjinKwon commented on a change in pull request #23622: [SPARK-26677][SQL]
Disable dictionary filtering by default at Parquet
URL: https://github.com/apache/spark/pull/23622#discussion_r251221877
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File path:
sql/core/src/main/scala/org/apache/spark/sql/execution/datasources/parquet/ParquetFileFormat.scala
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@@ -314,6 +314,17 @@ class ParquetFileFormat
SQLConf.CASE_SENSITIVE.key,
sparkSession.sessionState.conf.caseSensitiveAnalysis)
+ // There are two things to note here.
+ //
+ // 1. Dictionary filtering has an issue about the predication on null. For
this reason,
+ // This filtering is disabled. See SPARK-26677.
+ //
+ // 2. We should disable 'parquet.filter.dictionary.enabled' but
+ // the 'parquet.filter.stats.enabled' and
'parquet.filter.dictionary.enabled' were
+ // swapped mistakenly in Parquet side. It should use
'parquet.filter.dictionary.enabled'
+ // when Spark upgrades Parquet. See PARQUET-1309.
+ hadoopConf.setIfUnset(ParquetInputFormat.STATS_FILTERING_ENABLED, "false")
Review comment:
Ah, so we're targeting the upgrade to Parquet 1.10.1? yea, sounds okay to
me. Also, in that way users can also disable
`parquet.filter.dictionary.enabled` explicitly I guess.
BTW, is it something we should enable by default at Parquet side, @rdblue? I
see there can be the performance improvement but was wondering how much stable
dictionary filtering it is.
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