druid/docs/content/DataSource.md

layout
doc_page

A data source is the Druid equivalent of a database table. However, a query can also masquerade as a data source, providing subquery-like functionality. Query data sources are currently only supported by GroupBy queries.

Table Data Source

The table data source the most common type. It's represented by a string, or by the full structure:

{
	"type": "table",
	"name": <string_value>
}

Query Data Source

{
	"type": "query",
	"query": {
		"type": "groupBy",
		...
	}
}