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 benefits_and_programs_api_historical table in this repository, by referencing it like:
"cityofnewyork-us/benefits-and-programs-api-historical-2j8u-wtju:latest"."benefits_and_programs_api_historical"or in a full query, like:
SELECT
":id", -- Socrata column ID
"population_served", -- Target population for program.
"age_group", -- Target age group for program.
"brief_excerpt", -- One sentence description of program.
"program_acronym", -- Acronym for program (e.g. SNAP).
"apply_online_call_to_action", -- Call to action phrase for applying online (e.g. "Apply online," "File online").
"get_help_online", -- How to get help online, with link(s) to the administering agency's website.
"get_help_by_email", -- How to get help/questions answered by email from the administering agency.
"date",
"plain_language_program_name", -- A plain language name for the program that describes what it is or does (e.g. SNAP = Money to buy food).
"program_description", -- Plain language description of what the program is and how it works.
"get_help_by_calling_311", -- How to get help by calling 311 and what to ask for, or 911 for emergencies.
"apply_in_person_call_to_action", -- Call to action phrase for applying in person (e.g. "Find a location").
"get_help_summary", -- A summary of the different ways you can get help with this program.
"heads_up", -- List of key program attributes/common questions (e.g. facts, application formats, citizenship status, deadlines).
"how_to_apply_or_enroll_in_person", -- Instructions for how to apply to the program in person.
"how_to_apply_or_enroll_by_mail", -- Instructions for how to apply to the program by mail.
"url_of_pdf_application_forms", -- Link to download the PDF application form.
"how_to_apply_or_enroll_online", -- Instructions for how to apply to the program online.
"get_help_in_person", -- How to get help in person, with a link to the administering agency's in-person centers (ACCESS NYC locations page), or the address for the center.
"plain_language_eligibility", -- Plain language overview of the eligibility requirements for the program.
"url_of_online_application", -- Link to the online application for the program.
"government_agency", -- Name of administering government agency(ies).
"office_locations_url", -- Link to location finder on ACCESS NYC - where map of in-person application centers is available.
"how_to_apply_summary", -- Summary of the different ways to apply for the program.
"apply_by_mail_call_to_action", -- Call to action phrase for applying by mail (usually "Download the form").
"page_type", -- Type of information.
"language", -- Language of program information.
"program_code", -- Code used for screening in ACCESS NYC ONLY.
"unique_id_number", -- Unique identifier.
"how_to_apply_or_enroll_by_phone", -- Instructions for how to apply to the program by phone.
"get_help_by_calling_other_than_311", -- How to get help by calling the administering agency, and the phone number.
"required_documents_summary", -- A summary of the documents required to apply for this program.
"program_category", -- Type of program.
"program_name" -- Official name of program (e.g. Supplemental Nutrition Assistance Program).
FROM
"cityofnewyork-us/benefits-and-programs-api-historical-2j8u-wtju:latest"."benefits_and_programs_api_historical"
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 cityofnewyork-us/benefits-and-programs-api-historical-2j8u-wtju with SQL in under 60 seconds.
This repository is an "external" repository. That means it's hosted elsewhere, in this case at data.cityofnewyork.us. When you querycityofnewyork-us/benefits-and-programs-api-historical-2j8u-wtju:latest on the DDN, we "mount" the repository using the socrata mount handler. The mount handler proxies your SQL query to the upstream data source, translating it from SQL to the relevant language (in this case SoQL).
We also cache query responses on the DDN, but we run the DDN on multiple nodes so a CACHE_HIT is only guaranteed for subsequent queries that land on the same node.
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 (like this repository), 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, where the author has pushed Splitgraph Images to the repository, you can "clone" and/or "checkout" the data using sgr cloneand sgr checkout.
Mounting Data
This repository is an external repository. It's not hosted by Splitgraph. It is hosted by data.cityofnewyork.us, and Splitgraph indexes it. This means it is not an actual Splitgraph image, so you cannot use sgr clone to get the data. Instead, you can use the socrata adapter with the sgr mount command. Then, if you want, you can import the data and turn it into a Splitgraph image that others can clone.
First, install Splitgraph if you haven't already.
Mount the table with sgr mount
sgr mount socrata \
"cityofnewyork-us/benefits-and-programs-api-historical-2j8u-wtju" \
--handler-options '{
"domain": "data.cityofnewyork.us",
"tables": {
"benefits_and_programs_api_historical": "2j8u-wtju"
}
}'That's it! Now you can query the data in the mounted table like any other Postgres table.
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, cityofnewyork-us/benefits-and-programs-api-historical-2j8u-wtju is just another Postgres schema.