The Archive task will submit a metadata update task https://github.com/druid-io/druid/blob/druid-0.9.1/indexing-service/src/main/java/io/druid/indexing/common/task/ArchiveTask.java#L99 regardless of if a segment is moved or not in the S3 mover at https://github.com/druid-io/druid/blob/druid-0.9.1/extensions-core/s3-extensions/src/main/java/io/druid/storage/s3/S3DataSegmentMover.java#L123 This causes a large quantity of writes to the database compared to what needs to occur.
The Archive task will submit a metadata update task https://github.com/druid-io/druid/blob/druid-0.9.1/indexing-service/src/main/java/io/druid/indexing/common/task/ArchiveTask.java#L99 regardless of if a segment is moved or not in the S3 mover at https://github.com/druid-io/druid/blob/druid-0.9.1/extensions-core/s3-extensions/src/main/java/io/druid/storage/s3/S3DataSegmentMover.java#L123
This causes a large quantity of writes to the database compared to what needs to occur.