Query the Data Delivery Network

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 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 nyc_city_council_committee_membership table in this repository, by referencing it like:

"cityofnewyork-us/nyc-city-council-committee-membership-aabe-yfm9:latest"."nyc_city_council_committee_membership"

or in a full query, like:

SELECT
    ":id", -- Socrata column ID
    "fullname", -- Name of Council Member
    "committee_active", -- The Committee is currently active; "TRUE" = Committee is currently active "FALSE" = Committee is currently not active; Occasionally, an active Committee will cease to exist. In that scenario, "CommitteeActive" will read as "FALSE". The Committee may have existed at the beginning of the term and then ceased to exist by the end of the term.   
    "enddate", -- Date the Council Member ended or is projected to end membership on Committee; If the end date is in the future, the date is set to the end of the City Council session.
    "committeename", -- Name of City Council Committee
    "id", -- ID for City Council Member Committee Membership for Single Committee 
    "firstname", -- First Name of Council Member
    "lastname", -- Last Name of Council Member
    "startdate", -- Date the Council Member started membership on Committee
    "title", -- Committee Role for Council Member; "Chairperson" or "Committee member"
    "memberactive", -- The Council Member currently has membership on the Committee. "TRUE" = Council Member currently has membership on the Committee "FALSE" = Council Member currently does not have membership on the Committee. Council Members move to different Committees, become Chair of Committees, or Committees cease to exists. In all those scenarios, if a Council Member was on a Committee at the beginning of the term, and their membership changes, then "MemberActive" would be "FALSE"  
    "committeeid", -- ID for Committee
    "lastupdatedutc", -- Date and time record was last updated
    "memberid", -- Unique ID for Council Member
    "membertypeid", -- Committee Role for Council Member; 1= "Chairperson", 3 = "Committee member" or "Council Member" ie, not the Committee Chair; Each Committee has a "Chairperson" who heads the Committee. All other Council Members on the Committee are "Committee Member"s or occasionally, "Council Member". If a Council Person is a "Chairperson" for a Committee, they are not a "Committee Member" or "Council Member".
    "guid", -- Unique ID
    "version" -- Version ID for Record
FROM
    "cityofnewyork-us/nyc-city-council-committee-membership-aabe-yfm9:latest"."nyc_city_council_committee_membership"
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/nyc-city-council-committee-membership-aabe-yfm9 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/nyc-city-council-committee-membership-aabe-yfm9: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)"

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/nyc-city-council-committee-membership-aabe-yfm9" \
  --handler-options '{
    "domain": "data.cityofnewyork.us",
    "tables": {
        "nyc_city_council_committee_membership": "aabe-yfm9"
    }
}'

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/nyc-city-council-committee-membership-aabe-yfm9 is just another Postgres schema.