Query the Data Delivery Network
Query the DDNThe easiest way to query any data on Splitgraph is via the "Data Delivery Network" (DDN). The DDN is a single endpoint that speaks the PostgreSQL wire protocol. Any Splitgraph user can connect to it at data.splitgraph.com:5432 and query any version of over 40,000 datasets that are hosted or proxied by Splitgraph.
For example, you can query the ct_high_value_data_inventory table in this repository, by referencing it like:
"ct-gov/ct-high-value-data-inventory-rym6-myq3:latest"."ct_high_value_data_inventory"or in a full query, like:
SELECT
":id", -- Socrata column ID
"data_steward_name", -- The person responsible for the governance of the data (including: support data request processes, assessing data requests, transfer, alteration, storage, retention, disposition, classification, etc.).
"data_owner_name", -- The person who is accountable for the quality and security of the data. Generally the data owner has signatory authority for access and use of the data for permissible purposes and is responsible for data sharing agreements.
"policy_requirements", -- Policy requirements that govern the collection, use, and management of the data asset (HIPAA, FERPA, FOIA, etc).
"demographic_data", -- Types of demographic data contained in the data asset
"location_data", -- Types of location contained in the data asset
"dataset_native_data_structure", -- Structure of the data asset: Non-GIS Structured, Non-GIS Unstructure, Non-GIS Mixed GIS Cloud/Online Database, GIS Enterprise Database , GIS:Shapefile, GIS:Raster Image, GIS:Other Native File Format
"application_dataset_data", -- The name of the item in the inventory. The National Institute for Standards and Technology defines a data asset as “any entity that is comprised of data. For example, a database is a data asset that is comprised of data records. A data asset may be a system or application output file, database, document, or web page. A data asset also includes a service that may be provided to access data from an application".
"business_function_area", -- Part of the agency which is the business owner of the data asset
"agency", -- Agency that owns the asset
"inventory_id", -- Asset inventory ID
"data_classification_impact_level", -- The level of impact that a breach of the data asset would have in accordance with the CT Office of Policy and Management Data Classification Policy.
"gis_or_non_gis", -- Indicates whether the data is GIS or non-GIS data
"application_dataset" -- Description of the data asset
FROM
"ct-gov/ct-high-value-data-inventory-rym6-myq3:latest"."ct_high_value_data_inventory"
LIMIT 100;Connecting to the DDN is easy. All you need is an existing SQL client that can connect to Postgres. As long as you have a SQL client ready, you'll be able to query ct-gov/ct-high-value-data-inventory-rym6-myq3 with SQL in under 60 seconds.
Query Your Local Engine
bash -c "$(curl -sL https://github.com/splitgraph/splitgraph/releases/latest/download/install.sh)"Read the installation docs.
Splitgraph Cloud is built around Splitgraph Core (GitHub), which includes a local Splitgraph Engine packaged as a Docker image. Splitgraph Cloud is basically a scaled-up version of that local Engine. When you query the Data Delivery Network or the REST API, we mount the relevant datasets in an Engine on our servers and execute your query on it.
It's possible to run this engine locally. You'll need a Mac, Windows or Linux system to install sgr, and a Docker installation to run the engine. You don't need to know how to actually use Docker; sgrcan manage the image, container and volume for you.
There are a few ways to ingest data into the local engine.
For external repositories, the Splitgraph Engine can "mount" upstream data sources by using sgr mount. This feature is built around Postgres Foreign Data Wrappers (FDW). You can write custom "mount handlers" for any upstream data source. For an example, we blogged about making a custom mount handler for HackerNews stories.
For hosted datasets (like this repository), where the author has pushed Splitgraph Images to the repository, you can "clone" and/or "checkout" the data using sgr cloneand sgr checkout.
Cloning Data
Because ct-gov/ct-high-value-data-inventory-rym6-myq3:latest is a Splitgraph Image, you can clone the data from Spltgraph Cloud to your local engine, where you can query it like any other Postgres database, using any of your existing tools.
First, install Splitgraph if you haven't already.
Clone the metadata with sgr clone
This will be quick, and does not download the actual data.
sgr clone ct-gov/ct-high-value-data-inventory-rym6-myq3Checkout the data
Once you've cloned the data, you need to "checkout" the tag that you want. For example, to checkout the latest tag:
sgr checkout ct-gov/ct-high-value-data-inventory-rym6-myq3:latestThis will download all the objects for the latest tag of ct-gov/ct-high-value-data-inventory-rym6-myq3 and load them into the Splitgraph Engine. Depending on your connection speed and the size of the data, you will need to wait for the checkout to complete. Once it's complete, you will be able to query the data like you would any other Postgres database.
Alternatively, use "layered checkout" to avoid downloading all the data
The data in ct-gov/ct-high-value-data-inventory-rym6-myq3:latest is 0 bytes. If this is too big to download all at once, or perhaps you only need to query a subset of it, you can use a layered checkout.:
sgr checkout --layered ct-gov/ct-high-value-data-inventory-rym6-myq3:latestThis will not download all the data, but it will create a schema comprised of foreign tables, that you can query as you would any other data. Splitgraph will lazily download the required objects as you query the data. In some cases, this might be faster or more efficient than a regular checkout.
Read the layered querying documentation to learn about when and why you might want to use layered queries.
Query the data with your existing tools
Once you've loaded the data into your local Splitgraph Engine, you can query it with any of your existing tools. As far as they're concerned, ct-gov/ct-high-value-data-inventory-rym6-myq3 is just another Postgres schema.