Icon for Socrata external plugin

Query the Data Delivery Network

Query the DDN

The 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 procotol. 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 asotin_county_library_district_services table in this repository, by referencing it like:


or in a full query, like:

    ":id", -- Socrata column ID
    "virtvisits", -- Virtual visits. The annual number of users connecting to a networked library resource, such as the online public catalog or library website. Beginning in 2018, this category’s definition was clarified to include only visits to webpages on the library’s domain, not visits to library social media pages. This did not affect ACLD counts, which have never included social media site visits.
    "wifisessions", -- Wireless Sessions, or the annual number of times patrons connect to the library’s wireless internet.  An empty cell means the figure was not reported that year.
    "physmatcirc", -- Physical Materials Circulation, or the annual number of check-outs or renewals of physical items such as books. Includes interlibrary loans checked out directly to a patron, but not those checked out to other libraries. An empty cell means the figure was not reported that year. 
    "year", -- Year represented, from Jan. 1 to Dec. 31.
    "physvisits", -- Physical Visits. The annual number of people visiting library facilities in person, for any purpose. 
    "dbasesearch", -- Database searches, or the annual number of searches on licensed databases provided by the library. Does not include searches of free online resources.
    "servpop", -- Service Population, including those living in areas legally designated to support the library through taxes or contracting fees. 
    "pubcompuses", -- Public Computer Uses, or the annual number of times patrons use the library’s public computers connected to the internet.
    "totalcirc", -- Total Circulation, or the annual number of library items checked out or renewed. Includes interlibrary loans checked out directly to a patron, but not those checked out to other libraries.
    "ematcirc", -- Electronic Materials Circulation, or annual number of check-outs or renewals of digital items (e.g., e-books) distributed online to authenticated library users for limited periods, and which can be accessed by a computer, tablet, mobile phone or e-book reader. Does not include database use. An empty cell means the figure was not reported that year. 
    "virtref24_7" -- Is Virtual Reference Service provided 24 hours a day, 7 days a week? 
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 wa-gov/asotin-county-library-district-services-j8pm-xq6k with SQL in under 60 seconds.

This repository is an "external" repository. That means it's hosted elsewhere, in this case at data.wa.gov. When you querywa-gov/asotin-county-library-district-services-j8pm-xq6k: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

Install Splitgraph Locally
bash -c "$(curl -sL https://github.com/splitgraph/splitgraph/releases/latest/download/install.sh)"

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.wa.gov, 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 \
  "wa-gov/asotin-county-library-district-services-j8pm-xq6k" \
  --handler-options '{
    "domain": "data.wa.gov",
    "tables": {
        "asotin_county_library_district_services": "j8pm-xq6k"

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, wa-gov/asotin-county-library-district-services-j8pm-xq6k is just another Postgres schema.

Related Documentation: