I think you should be able to do this. I don’t know if this is the issue, but it’s worth a try. When you reindex from druid, if you don’t keep a dimension or metric as-is, you might have to include it in the ioConfig. Otherwise, druid might not read it from the input source. (I think this must be a known bug somewhere, but I didn’t find it right away.) Eg, something like this for your ioconfig:
"ioConfig": {
"type": "index_parallel",
"inputSource": {
"type": "druid",
"dataSource": "ingest_no_rollup",
"interval": "2020-11-02T00:00:00.000Z/2020-11-04T00:00:00.000Z",
"filter": null,
"dimensions": ["ts","id","string_field","long_field"],
"metrics": null
},
"inputFormat": null,
"appendToExisting": false
}
},
where the dimensions are the ones you want to have it read from the input - not necessarily the same as the one you want in the new datasource. (Same can apply to metrics, but I grabbed this from something I was doing that only needed the dimensions to be “fixed”.