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 2022_ntd_annual_data_funding_sources_federal table in this repository, by referencing it like:
"datahub-transportation-gov/2022-ntd-annual-data-funding-sources-federal-qpjk-b3zw:latest"."2022_ntd_annual_data_funding_sources_federal"or in a full query, like:
SELECT
":id", -- Socrata column ID
"total_federal_funds", -- Total of federal funding sources in previous columns.
"other_dot_funds", -- Funding from grants provided by divisions of the federal Department of Transportation other than FTA.
"other_federal_funds", -- Funding from departments of the federal government other than Transportation.
"reporter_type", -- The type of NTD report that the agency completed this year.
"report_year", -- The year for which the data was reported
"uace_code", -- UACE Code remains consistent across census years.
"organization_type", -- Description of the agency's legal entity.
"ntd_id", -- A five-digit identifying number for each agency used in the current NTD system.
"state", -- The state in which the agency is headquartered.
"agency", -- The transit agency's name.
"agency_voms", -- The number of revenue vehicles operated across the whole agency to meet the annual maximum service requirement. This is the revenue vehicle count during the peak season of the year; on the week and day that maximum service is provided. Vehicles operated in maximum service (VOMS) exclude atypical days and one-time special events.
"city", -- The city in which the agency is headquartered.
"uza_name", -- The name of the agency's Urbanized Area.
"primary_uza_population", -- The population of the urbanized area primarily served by the agency.
"fta_urbanized_area_formula", -- The Urbanized Area Formula Funding program (49 U.S.C. 5307) provides Federal resources to urbanized areas for transit capital and operating assistance and for transit related planning. The Bus and Bus Facilities program is a formula program that finances capital projects to replace, rehabilitate, and purchase buses and related equipment and to construct bus-related facilities.
"fta_capital_program_5309", -- The Capital Program provided capital assistance for three primary activities: • New and replacement buses and facilities • Modernization of existing fixed guideway (FG) systems • New fixed FG systems In MAP-21, the Capital Program was split into three separate programs. The State of Good Repair program is one of these successor programs. The other two are the Bus and Bus Facilities (5339) program and the Fixed Guideway Capital Investment (5309) program.
"fta_rural_progam_5311", -- This program provides formula funding to States and Indian Tribes for supporting public transportation in areas with a population of less than 50,000. Funding may be used for capital, operating, State administration, and project administration expenses.
"other_fta_funds" -- Funding from FTA grants other than the ones already listed (5307, 5339, 5309, 5337, 5311). May include: -5303 Metropolitan Planning -5308 Clean Fuels -5310 Special Needs/ADA -5316 Job Access and Reverse Commute -5317 New Freedom -5320 Transit in the Park
FROM
"datahub-transportation-gov/2022-ntd-annual-data-funding-sources-federal-qpjk-b3zw:latest"."2022_ntd_annual_data_funding_sources_federal"
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 datahub-transportation-gov/2022-ntd-annual-data-funding-sources-federal-qpjk-b3zw 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 datahub-transportation-gov/2022-ntd-annual-data-funding-sources-federal-qpjk-b3zw: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 datahub-transportation-gov/2022-ntd-annual-data-funding-sources-federal-qpjk-b3zwCheckout 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 datahub-transportation-gov/2022-ntd-annual-data-funding-sources-federal-qpjk-b3zw:latestThis will download all the objects for the latest tag of datahub-transportation-gov/2022-ntd-annual-data-funding-sources-federal-qpjk-b3zw 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 datahub-transportation-gov/2022-ntd-annual-data-funding-sources-federal-qpjk-b3zw: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 datahub-transportation-gov/2022-ntd-annual-data-funding-sources-federal-qpjk-b3zw: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, datahub-transportation-gov/2022-ntd-annual-data-funding-sources-federal-qpjk-b3zw is just another Postgres schema.