Apache Druid

```"indexSpec": {
        "bitmap": {
          "type": "concise"
        },
        "dimensionCompression": "lz4",
        "metricCompression": "lz4",
        "longEncoding": "longs",
        "segmentLoader": null
      },```
From the ingestion spec, `longEncoding` is set to `longs` so it’s 8 bytes for each value <https://github.com/apache/druid/blob/master/processing/src/main/java/org/apache/druid/segment/data/CompressionFactory.java#L179-L188>

longEncoding in compaction task payload is also `longs` … I cannot believe lz4 is able to compress so many 8 byte longs with such high compession ratio