[ https://issues.apache.org/jira/browse/SPARK-23852?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel ]
Henry Robinson updated SPARK-23852: ----------------------------------- Description: Parquet MR 1.9.0 and 1.8.2 both have a bug, PARQUET-1217, that means that pushing certain predicates to Parquet scanners can return fewer results than they should. The bug triggers in Spark when: * The Parquet file being scanner has stats for the null count, but not the max or min on the column with the predicate (Apache Impala writes files like this). * The vectorized Parquet reader path is not taken, and the parquet-mr reader is used. * A suitable <, <=, > or >= predicate is pushed down to Parquet. The bug is that the parquet-mr interprets the max and min of a row-group's column as 0 in the absence of stats. So {{col > 0}} will filter all results, even if some are > 0. There is no upstream release of Parquet that contains the fix for PARQUET-1217, although a 1.10 release is planned. The least impactful workaround is to set the Parquet configuration {{parquet.filter.stats.enabled}} to {{false}}. was: Parquet 1.9.0 and 1.8.2 both have a bug, PARQUET-1217, that means that pushing certain predicates to Parquet scanners can return fewer results than they should. The bug triggers in Spark when: * The Parquet file being scanner has stats for the null count, but not the max or min on the column with the predicate (Apache Impala writes files like this). * The vectorized Parquet reader path is not taken, and the parquet-mr reader is used. * A suitable <, <=, > or >= predicate is pushed down to Parquet. The bug is that the parquet-mr interprets the max and min of a row-group's column as 0 in the absence of stats. So {{col > 0}} will filter all results, even if some are > 0. There is no upstream release of Parquet that contains the fix for PARQUET-1217, although a 1.10 release is planned. The least impactful workaround is to set the Parquet configuration {{parquet.filter.stats.enabled}} to {{false}}. > Parquet MR bug can lead to incorrect SQL results > ------------------------------------------------ > > Key: SPARK-23852 > URL: https://issues.apache.org/jira/browse/SPARK-23852 > Project: Spark > Issue Type: Bug > Components: SQL > Affects Versions: 2.3.0 > Reporter: Henry Robinson > Priority: Critical > > Parquet MR 1.9.0 and 1.8.2 both have a bug, PARQUET-1217, that means that > pushing certain predicates to Parquet scanners can return fewer results than > they should. > The bug triggers in Spark when: > * The Parquet file being scanner has stats for the null count, but not the > max or min on the column with the predicate (Apache Impala writes files like > this). > * The vectorized Parquet reader path is not taken, and the parquet-mr reader > is used. > * A suitable <, <=, > or >= predicate is pushed down to Parquet. > The bug is that the parquet-mr interprets the max and min of a row-group's > column as 0 in the absence of stats. So {{col > 0}} will filter all results, > even if some are > 0. > There is no upstream release of Parquet that contains the fix for > PARQUET-1217, although a 1.10 release is planned. > The least impactful workaround is to set the Parquet configuration > {{parquet.filter.stats.enabled}} to {{false}}. -- This message was sent by Atlassian JIRA (v7.6.3#76005) --------------------------------------------------------------------- To unsubscribe, e-mail: issues-unsubscr...@spark.apache.org For additional commands, e-mail: issues-h...@spark.apache.org