Rajesh Balamohan created SPARK-32225:
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Summary: Parquet footer information is read twice
Key: SPARK-32225
URL: https://issues.apache.org/jira/browse/SPARK-32225
Project: Spark
Issue Type: Improvement
Components: SQL
Affects Versions: 3.0.0
Reporter: Rajesh Balamohan
Attachments: spark_parquet_footer_reads.png
When running queries, spark reads parquet footer information twice. In cloud
env, this would turn out to be expensive (depending on the jobs, # of splits).
It would be nice to reuse the footer information already read via
"ParquetInputFormat::buildReaderWithPartitionValues"
!image-2020-07-08-14-24-23-470.png|width=726,height=730!
Lines of interest:
[https://github.com/apache/spark/blob/master/sql/core/src/main/scala/org/apache/spark/sql/execution/datasources/parquet/ParquetFileFormat.scala#L271]
[https://github.com/apache/spark/blob/master/sql/core/src/main/scala/org/apache/spark/sql/execution/datasources/parquet/ParquetFileFormat.scala#L326]
[https://github.com/apache/spark/blob/master/sql/core/src/main/java/org/apache/spark/sql/execution/datasources/parquet/SpecificParquetRecordReaderBase.java#L105]
[https://github.com/apache/spark/blob/master/sql/core/src/main/java/org/apache/spark/sql/execution/datasources/parquet/SpecificParquetRecordReaderBase.java#L111]
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