Flattened Documents Model
For users who simply need access to the entirety of their JSON data, flattening the data into a single table is the best option. The driver will use streaming and only parses the JSON data once per query in this mode.
Joining Object Arrays into a Single Table
With DataModel set to "FlattenedDocuments", nested JSONPath values will act in the same manner as a SQL JOIN. Any nested sibling JSONPath values (child paths at the same height) will be treated as a SQL CROSS JOIN.
Example
Below is a sample query and the results, based on the sample document in Raw Data and parsing based on the JSON paths $.people, $.people.vehicles, and $.people.vehicles.maintenance. This implicitly JOINs the people collection with the vehicles collection and implicitly JOINs the vehicles collection with the maintenance collection.
Connection String
Use the following connection string to query the Raw Data in this example.
URI=C:\people.txt;DataModel=FlattenedDocuments;JSONPath='$.people;$.people.vehicles;$.people.vehicles.maintenance;'
Query
The following query drills into the nested elements in each people object. Since the JSONPath property included the vehicles collection as a JSON path, you can query an element of a vehicle explicitly.
SELECT
[personal.age] AS age,
[personal.gender] AS gender,
[personal.name.first] AS name_first,
[personal.name.last] AS name_last,
[source],
[type],
[model],
[insurance.company] AS ins_company,
[insurance.policy_num] AS ins_policy_num,
[date] AS maint_date,
[desc] AS maint_desc
FROM
[people]
Results
With horizontal and vertical flattening based on the described paths, each vehicle object is implicitly JOINed to its parent people object and each maintenance object is implicitly JOINed to its parent vehicle object.
age | gender | first_name | last_name | source | type | model | ins_company | ins_policy_num | maint_date | maint_desc | |
20 | M | John | Doe | internet | car | Honda Civic | ABC Insurance | 12345 | 2017-07-17 | oil change | |
20 | M | John | Doe | internet | car | Honda Civic | ABC Insurance | 12345 | 2018-01-03 | new tires | |
20 | M | John | Doe | internet | truck | Dodge Ram | ABC Insurance | 12345 | 2017-08-27 | new tires | |
20 | M | John | Doe | internet | truck | Dodge Ram | ABC Insurance | 12345 | 2018-01-08 | oil change | |
24 | F | Jane | Roberts | phone | car | Toyota Camry | Car Insurance | 98765 | 2017-05-11 | tires rotated | |
24 | F | Jane | Roberts | phone | car | Toyota Camry | Car Insurance | 98765 | 2017-11-03 | oil change | |
24 | F | Jane | Roberts | phone | car | Honda Accord | Car Insurance | 98765 | 2017-10-07 | new air filter | |
24 | F | Jane | Roberts | phone | car | Honda Accord | Car Insurance | 98765 | 2018-01-13 | new brakes |
See Also
- Automatic Schema Discovery: Configure the columns reported in the table schemas.
- Free-Form Queries: Use dot notation to select nested data.
- Vertical Flattening: Access nested object arrays as separate tables.
- JSON Functions: Manipulate the data returned to perform client-side aggregation and transformations.