Relational Model

The Elasticsearch Adapter can be configured to create a relational model of the data, treating nested documents as individual tables containing a primary key and a foreign key that links to the parent document. This is particularly useful if you need to work with your Elasticsearch data in existing BI, reporting, and ETL tools that expect a relational data model.

Joining Nested Arrays as Tables

With DataModel set to "Relational", any JOINs are controlled by the query. Any time you perform a JOIN query, the Elasticsearch index will be queried once for each table (nested document) included in the query.

Example

Below is a sample query against the sample document in Raw Data, using a relational model.

Query

The following query explicitly JOINs the insured and vehiclestables. 

SELECT 
  "insured"."_id", 
  "insured"."name", 
  "insured"."address.street" AS address_street, 
  "insured"."address.city.first" AS address_city, 
  "insured"."address.state.last" AS address_state, 
  "insured"."insured_ages", 
  "vehicles"."year", 
  "vehicles"."make", 
  "vehicles"."model", 
  "vehicles"."body_style",
  "vehicles"."_insured_id",
  "vehicles"."_c_id"
FROM 
  "insured"
JOIN 
  "vehicles" 
ON 
  "insured"."_id" = "vehicles"."_insured_id"

Results

In the example query, each vehicle document is JOINed to its parent insured object to produce a table with 5 rows.

_id name address_street address_city address_state insured_ages year make model body_style _insured_id _vehicles_c_id
1 John Smith Main Street Chapel Hill NC [ 17, 43, 45 ] 2015 Dodge RAM 1500 TK 1 1
1 John Smith Main Street Chapel Hill NC [ 17, 43, 45 ] 2015 Suzuki V-Strom 650 XT MC 1 2
1 John Smith Main Street Chapel Hill NC [ 17, 43, 45 ] 1992 Harley Davidson FXR MC 1 3
2 Joseph Newman Oak Street Raleigh NC [ 23, 25 ] 2010 Honda Accord SD 2 4
2 Joseph Newman Oak Street Raleigh NC [ 23, 25 ] 2008 Honda Civic CP 2 5

See Also

  • Automatic Schema Discovery: Configure the columns reported in the table schemas.
  • FreeForm;: Use dot notation to select nested data.
  • VerticalFlattening;: Access nested object arrays as separate tables.
  • JSON Functions: Manipulate the data returned to perform client-side aggregation and transformations.