Top-Level Document Model

Using a top-level document view of the JSON data provides ready access to top-level elements. The adapter returns nested elements in aggregate, as single columns.

One aspect to consider is performance. You forego the time and resources to process and parse nested elements -- the adapter parses the returned data once, using streaming to read the JSON data. Another consideration is your need to access any data stored in nested parent elements, and the ability of your tool or application to process JSON.

Modeling a Top-Level Document View

With DataModel set to "Document" (the default), the adapter scans only a single object array, the top-level object array by default. The top-level object elements are available as columns due to the default object flattening. Nested object arrays are returned as aggregated JSON.

You can set JSONPath to specify an object array other than the top-level one.

Example

Below is a sample query and the results, based on the sample document in Raw Data. The query results in a single "people" table based on the JSON path "$.people".

Connection String

Set the DataModel connection property to "Document" to perform the following query and see the example result set. The adapter will scan only the JSONPath value below:

URI=C:\people.txt;DataModel=Document;JSONPath='$.people';

Query

The following query pulls the top-level object elements and the vehicles array into the results.

SELECT
  "personal.age" AS age,
  "personal.gender" AS gender,
  "personal.name.first" AS name_first,
  "personal.name.last" AS name_last,
  "source",
  "vehicles"
FROM
  "people"

Results

With a document view of the data, the personal object is flattened into 4 columns and the source and vehicles elements are returned as individual columns, resulting in a table with 6 columns.

age

gender

name_first

name_last

source

vehicles

John

Doe

internet

[{"type":"car","model":"Honda Civic","insurance":{"company":"ABC Insurance","policy_num":"12345"},"maintenance":[{"date":"07-17-2017","desc":"oil change"},{"date":"01-03-2018","desc":"new tires"}]},{"type":"truck","model":"Dodge Ram","insurance":{"company":"ABC Insurance","policy_num":"12345"},"maintenance":[{"date":"08-27-2017","desc":"new tires"},{"date":"01-08-2018","desc":"oil change"}]}]

Jane

Roberts

phone

[{"type":"car","model":"Toyota Camry","insurance":{"company":"Car Insurance","policy_num":"98765"},"maintenance":[{"date":"05-11-2017","desc":"tires rotated"},{"date":"11-03-2017","desc":"oil change"}]},{"type":"car","model":"Honda Accord","insurance":{"company":"Car Insurance","policy_num":"98765"},"maintenance":[{"date":"10-07-2017","desc":"new air filter"},{"date":"01-13-2018","desc":"new brakes"}]}]