aokolnychyi commented on a change in pull request #2452:
URL: https://github.com/apache/iceberg/pull/2452#discussion_r614599746
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File path:
spark/src/main/java/org/apache/iceberg/spark/actions/BaseSparkAction.java
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@@ -159,7 +159,7 @@ protected Table newStaticTable(TableMetadata metadata,
FileIO io) {
.repartition(spark.sessionState().conf().numShufflePartitions()) //
avoid adaptive execution combining tasks
.as(Encoders.bean(ManifestFileBean.class));
- return allManifests.flatMap(new ReadManifest(ioBroadcast),
Encoders.STRING()).toDF("file_path");
+ return allManifests.flatMap(new ReadManifest(ioBroadcast),
Encoders.STRING()).toDF("file_path").distinct();
Review comment:
This place makes sense to me. We can consider exposing an argument to
make the dedup step optional (I am not sure it is a good idea but I want to
think this through together). The dedup step is going to trigger a shuffle.
Technically, we are fine in the existing expire snapshots action as it does the
dedup in `except`.
The question is what kind of performance impact deduplicating here will
have. We only have duplicates if multiple manifests reference the same files.
In `rewrite_manifests` procedure, we rewrite all manifests, meaning we produce
a new snapshot with new manifests where entries are old data files. Also, there
are updates and deletes that may rewrite manifests.
I think deduplicating here makes sense to me in all cases.
Thoughts, @rdblue @flyrain @RussellSpitzer @karuppayya?
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