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 bovine_manure_tax_credit_program_dept_of table in this repository, by referencing it like:
"oregon-gov/bovine-manure-tax-credit-program-dept-of-cdnv-r4ea:latest"."bovine_manure_tax_credit_program_dept_of"or in a full query, like:
SELECT
":id", -- Socrata column ID
"appl_no", -- Application number.
"tax_credit_certification", -- Amount of tax credit on the approved certificate.
"certified_amount_of_material", -- Amount of material that the applicant/company receiving the tax credit
"date_of_certification", -- Date Oregon Department of Agriculture provided the certificate.
"fiscal_year", -- The year associated with this report, running from July 1, 20xx of one year, to June 30, 20yy of the following year
"appid", -- Applicant identification number.
"biomass_material_type", -- Biomass is renewable organic material that comes from plants and animals. In this case, it is all bovine manure.
"city", -- City of the applicant/company receiving the tax credit.
"tax_credit_rate", -- Credit rate per wet ton of manure.
"applicant_name", -- Name of applicant\company receiving the tax credit.
"zip", -- ZIP code of the applicant/company receiving the tax credit.
"certification_units", -- Weight of the manure.
"certification_decision", -- Was the certification approved or not.
"business_address", -- Address of the applicant/company receiving the tax credit.
"units", -- Tons used as a measurement of the weight of the manure.
"agency_issuing_tax_expenditure" -- Oregon Department of Agriculture issues the tax certification.
FROM
"oregon-gov/bovine-manure-tax-credit-program-dept-of-cdnv-r4ea:latest"."bovine_manure_tax_credit_program_dept_of"
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 oregon-gov/bovine-manure-tax-credit-program-dept-of-cdnv-r4ea 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 oregon-gov/bovine-manure-tax-credit-program-dept-of-cdnv-r4ea: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 oregon-gov/bovine-manure-tax-credit-program-dept-of-cdnv-r4eaCheckout 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 oregon-gov/bovine-manure-tax-credit-program-dept-of-cdnv-r4ea:latestThis will download all the objects for the latest tag of oregon-gov/bovine-manure-tax-credit-program-dept-of-cdnv-r4ea 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 oregon-gov/bovine-manure-tax-credit-program-dept-of-cdnv-r4ea: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 oregon-gov/bovine-manure-tax-credit-program-dept-of-cdnv-r4ea: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, oregon-gov/bovine-manure-tax-credit-program-dept-of-cdnv-r4ea is just another Postgres schema.