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Merge pull request #814 from metamx/fix-datasource-doc 

Added section on union data sources
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Fangjin Yang 2014-11-11 13:03:41 -07:00
parent e4649a24a1 de7fb5a690
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docs/content/DataSource.md
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---
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.
## Datasources
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 supported only 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:
The table data source is the most common type. It's represented by a string, or by the full structure:
```json
{
"type": "table",
"name": <string_value>
"name": "<string_value>"
}
```
### Union Data Source
This data source unions two or more table data sources.
```json
{
"type": "union",
"dataSources": ["<string_value1>", "<string_value2>", "<string_value3>", ... ]
}
```
Note that the data sources being unioned should have the same schema.
### Query Data Source
```json
{