GitHub user junegunn opened a pull request:
https://github.com/apache/spark/pull/16347
[SPARK-18934][SQL] Writing to dynamic partitions does not preserve sort
order if spills occur
## What changes were proposed in this pull request?
Make dynamic partition writer perform stable sort by the partition key, so
that the sort order within the partition specified via `sortWithinPartitions`
or `SORT BY` is preserved even when spill occurs.
## How was this patch tested?
Manually tested with the following code snippet and orcdump.
```scala
// FileFormatWriter
sc.parallelize(1 to 10000000).toDS.withColumn("part", 'value.mod(2))
.repartition(1, 'part).sortWithinPartitions("value")
.write.mode("overwrite").format("orc").partitionBy("part")
.saveAsTable("test_sort_within")
spark.read.table("test_sort_within").filter('part === 0).show
spark.read.table("test_sort_within").filter('part === 1).show
// SparkHiveDynamicPartitionWriterContainer
// Insert into an existing Hive table with dynamic partitions
// CREATE TABLE TEST_SORT_WITHIN (VALUE INT) PARTITIONED BY (PART INT)
STORED AS ORC
spark.conf.set("hive.exec.dynamic.partition.mode", "nonstrict")
sc.parallelize(1 to 10000000).toDS.withColumn("part", 'value.mod(2))
.repartition(1, 'part).sortWithinPartitions("value")
.write.mode("overwrite").insertInto("test_sort_within_hive")
spark.read.table("test_sort_within_hive").filter('part === 0).show
spark.read.table("test_sort_within_hive").filter('part === 1).show
```
It was not straightforward to come up with a unit test as the problem is
only reproducible if spill occurs due to memory constraint. I'd appreciate any
suggestions or pointers.
You can merge this pull request into a Git repository by running:
$ git pull https://github.com/junegunn/spark
dynamic-partition-writer-stable-sort
Alternatively you can review and apply these changes as the patch at:
https://github.com/apache/spark/pull/16347.patch
To close this pull request, make a commit to your master/trunk branch
with (at least) the following in the commit message:
This closes #16347
----
commit bfeccd80ef032cab3525037be3d3e42519619493
Author: Junegunn Choi <junegun...@gmail.com>
Date: 2016-12-19T05:54:42Z
[SPARK-18934][SQL] Writing to dynamic partitions does not preserve sort
order if spills occur
----
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