フラット化されたドキュメントモデル
For users who simply need access to the entirety of their Parquet data, flattening the data into a single table is the best option. The 本製品 will use streaming and only parses the data once per query in this mode.
Joining Object Arrays into a Single Table
With DataModel set to "FlattenedDocuments" values will act in the same manner as a SQL JOIN. Any nested sibling 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 データ. 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 データ in this example.
URI=C:\people.parquet;DataModel=FlattenedDocuments;
Query
The following query drills into the nested elements in each people object.
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 |