V Luong created SPARK-23467:
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Summary: Enable way to create DataFrame from pre-partitioned files
(Parquet/ORC/etc.) with each in-memory partition mapped to 1 physical file
partition
Key: SPARK-23467
URL: https://issues.apache.org/jira/browse/SPARK-23467
Project: Spark
Issue Type: Improvement
Components: Spark Core, SQL
Affects Versions: 2.2.1
Reporter: V Luong
I would like to echo the need described here:
[https://forums.databricks.com/questions/12323/how-to-create-a-dataframe-that-has-one-filepartiti.html]
In many of my use cases, data is appended by date (say, date X) into an S3
subdir `s3://bucket/path/to/parquet/date=X`, after which I need to run
analytics by date. The analytics involves sorts and window functions. But I'm
only interested in within-date sorts/windows, and don't care about the
between-dates sorts and windows.
Currently, if I simply load the entire data set from the parent dir
`s3://bucket/path/to/parquet`, and then write Spark SQL statements involving
"SORT" or "WINDOW", then very expensive shuffles will be invoked. Hence I am
exploring ways to write analytics code/function per Spark partition, and send
such code/function to each partition.
The biggest problem now is that Spark's in-memory partitions do not correspond
to the physical files loaded from S3, so there is no way to guarantee that the
analytics by partition is done by date as desired.
Is there a way we can explicitly enable a direct correspondence between file
partitions and in-memory partitions?
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