druid/examples/quickstart/tutorial/compaction-day-granularity.json

{
  "type": "compact",
  "dataSource": "compaction-tutorial",
  "interval": "2015-09-12/2015-09-13",
  "segmentGranularity": "DAY",
  "tuningConfig" : {
    "type" : "index",
    "maxRowsPerSegment" : 5000000,
    "maxRowsInMemory" : 25000,
    "forceExtendableShardSpecs" : true
  }
}