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 annual_town_gown_report_higher_education table in this repository, by referencing it like:
"cambridgema-gov/annual-town-gown-report-higher-education-46sm-9zs4:latest"."annual_town_gown_report_higher_education"or in a full query, like:
SELECT
":id", -- Socrata column ID
"total_payments", -- Total payments from the institutions to the City of Cambridge from property taxes, PILOT payments, water and sewer fees, and all other sources
"land_taxable", -- Total area of taxable land owned by the institutions
"land_non_taxable", -- Total area of non-taxable land owned by the institutions
"gfa_lesley", -- Gross floor area of all taxable and non-taxable Lesley University facilities
"gfa_hult", -- Gross floor area of all taxable and non-taxable Hult International School of Business facilities
"gfa_harvard", -- Gross floor area of all taxable and non-taxable Harvard University facilities
"student_residents_off_campus", -- Students who reside off campus in Cambridge
"student_residents_affiliate", -- Students who reside in institution-owned affiliate housing
"post_doctoral_fellows", -- Total number of post-doctoral fellow employed by the institutions
"graduate_students", -- Total number of students enrolled in any graduate degree program
"undergraduate_students", -- Total number of students enrolled in an undergraduate program
"non_degree_students", -- Total number of students not enrolled in a degree granting program.
"students_mit", -- Total enrollment at Massachusetts Institute of Technology
"students_lesley", -- Total enrollment at Lesley University
"students_hult", -- Total enrollment at Hult International School of Business
"students_cambridge_college", -- Total enrollment at Cambridge College
"all_employees", -- Total persons employed by institutions in FTEs
"year", -- Year Town Gown Report received
"payments_fiscal_year", -- Fiscal year covered by total payments data. May not align with reporting period for institution.
"gfa_mit", -- Gross floor area of all taxable and non-taxable Massachusetts Institute of Technology facilities
"student_residents_dormitory", -- Students who reside in institution-owned dormitory style housing
"degree_students", -- Total enrollment in degree granting programs
"students_harvard", -- Total enrollment at Harvard University
"reside_in_cambridge", -- Number of employed persons who reside in Cambridge
"faculty", -- Academic employees of institutions in FTEs
"staff", -- Non-academic employees of institutions in FTEs
"gfa_cambridge_college" -- Gross floor area of all taxable and non-taxable Cambridge College facilities
FROM
"cambridgema-gov/annual-town-gown-report-higher-education-46sm-9zs4:latest"."annual_town_gown_report_higher_education"
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 cambridgema-gov/annual-town-gown-report-higher-education-46sm-9zs4 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 cambridgema-gov/annual-town-gown-report-higher-education-46sm-9zs4: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 cambridgema-gov/annual-town-gown-report-higher-education-46sm-9zs4Checkout 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 cambridgema-gov/annual-town-gown-report-higher-education-46sm-9zs4:latestThis will download all the objects for the latest tag of cambridgema-gov/annual-town-gown-report-higher-education-46sm-9zs4 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 cambridgema-gov/annual-town-gown-report-higher-education-46sm-9zs4: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 cambridgema-gov/annual-town-gown-report-higher-education-46sm-9zs4: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, cambridgema-gov/annual-town-gown-report-higher-education-46sm-9zs4 is just another Postgres schema.