From 8f39981fab10bc796a5b53d9d6dca3a1fafcf1a9 Mon Sep 17 00:00:00 2001
From: Yuval Oren <yuval@n3twork.com>
Date: Fri, 24 Jan 2014 16:12:10 -0800
Subject: [PATCH] Documentation for query data sources

---
 docs/content/DataSource.md   | 25 +++++++++++++++++++++++++
 docs/content/GroupByQuery.md |  2 +-
 2 files changed, 26 insertions(+), 1 deletion(-)
 create mode 100644 docs/content/DataSource.md

diff --git a/docs/content/DataSource.md b/docs/content/DataSource.md
new file mode 100644
index 00000000000..49c583561ba
--- /dev/null
+++ b/docs/content/DataSource.md
@@ -0,0 +1,25 @@
+---
+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](GroupByQuery.html) queries.
+
+### Table Data Source
+The table data source the most common type. It's represented by a string, or by the full structure:
+
+```json
+{
+	"type": "table",
+	"name": <string_value>
+}
+```
+
+### Query Data Source
+```json
+{
+	"type": "query",
+	"query": {
+		"type": "groupBy",
+		...
+	}
+}
+```
diff --git a/docs/content/GroupByQuery.md b/docs/content/GroupByQuery.md
index dd7f49f7179..34a10c28d64 100644
--- a/docs/content/GroupByQuery.md
+++ b/docs/content/GroupByQuery.md
@@ -47,7 +47,7 @@ There are 9 main parts to a groupBy query:
 |property|description|required?|
 |--------|-----------|---------|
 |queryType|This String should always be "groupBy"; this is the first thing Druid looks at to figure out how to interpret the query|yes|
-|dataSource|A String defining the data source to query, very similar to a table in a relational database|yes|
+|dataSource|A String defining the data source to query, very similar to a table in a relational database, or a [DataSource](DataSource.html) structure.|yes|
 |dimensions|A JSON list of dimensions to do the groupBy over|yes|
 |orderBy|See [OrderBy](OrderBy.html).|no|
 |having|See [Having](Having.html).|no|