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 state_of_iowa_expenditures table in this repository, by referencing it like:
"mydata-iowa-gov/state-of-iowa-expenditures-mn9y-cwp6:latest"."state_of_iowa_expenditures"or in a full query, like:
SELECT
":id", -- Socrata column ID
"amount", -- The total of all expenditures for the specified combination of Budget FY, Fund, Department, etc
"object_class_name", -- A description of the type of expenditure such as travel, supplies, utilities, equipment, etc
"object_class", -- The code used to designate the type of expenditure
"appropriation_name", -- The name of the appropriation to which the expenditures were charged
"fund_name", -- The name of the fund to which the expenditures were charged
"unit_name", -- The name of the organizational unit within the department that made the expenditure
"unit", -- The code used to designate the organizational unit within the department the expenditure was associated with
"spec_dept", -- Name of the state agency
"function", -- Functions are groups of agencies which make expenditures for similar programs and purposes
"fiscal_period_name", -- Name of fiscal period the expenditure occurred
"fund", -- The code used to designate the source of funds for the expenditure
"dept_1", -- The code used to designate the department the expenditure was associated to
"budget_fy", -- Budget Fiscal Year (July 1 - June 30 + 60 days) expenditure was made
"appropriation", -- The code used to designate the legislative authorization for the expenditures
"fiscal_period", -- Fiscal Period (1-15) the expenditure was made
"dept_2" -- The name of the department that made the expenditure
FROM
"mydata-iowa-gov/state-of-iowa-expenditures-mn9y-cwp6:latest"."state_of_iowa_expenditures"
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 mydata-iowa-gov/state-of-iowa-expenditures-mn9y-cwp6 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 mydata-iowa-gov/state-of-iowa-expenditures-mn9y-cwp6: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 mydata-iowa-gov/state-of-iowa-expenditures-mn9y-cwp6Checkout 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 mydata-iowa-gov/state-of-iowa-expenditures-mn9y-cwp6:latestThis will download all the objects for the latest tag of mydata-iowa-gov/state-of-iowa-expenditures-mn9y-cwp6 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 mydata-iowa-gov/state-of-iowa-expenditures-mn9y-cwp6: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 mydata-iowa-gov/state-of-iowa-expenditures-mn9y-cwp6: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, mydata-iowa-gov/state-of-iowa-expenditures-mn9y-cwp6 is just another Postgres schema.