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 buildings_selected_for_the_alternative_enforcement table in this repository, by referencing it like:

"cityofnewyork-us/buildings-selected-for-the-alternative-enforcement-hcir-3275:latest"."buildings_selected_for_the_alternative_enforcement"

or in a full query, like:

SELECT
    ":id", -- Socrata column ID
    "census_tract",
    "nta",
    "aep_start_date", -- The date the building was selected for participation in the AEP. All buildings in a particular round will have the same start date.
    "aep_round", -- The round identifies a group of buildings selected for the AEP annually. 
    "postcode",
    "longitude",
    "building_id", -- The Building ID is a unique numeric identifier assigned to each building by HPD.
    "street_address", -- The Street Name is the name of the street in the building's address. E.g, the street name is 'Gold Street' in '100 Gold Street.' 
    "total_units", -- Total Units reflects the number of units in the building as of the report run date and may vary from the unit count reported when the building was selected for the AEP program. HPD records indicated that all the buildings had at least three dwelling units at the time of selection. 
    "bin",
    "phn", -- The House Number is the street number in the building's address. E.g, the house number is '100' in '100 Gold Street.' 
    "current_status", -- "Active" buildings are currenty participating in program. "Discharged" buildings have met a statutory requirement for removal from the program. 
    "boro", -- The Borough is the borough where the building is located.
    "of_b_c_violations_at_start", -- The count of hazardous and immediately hazardous violations open on the date the building was selected for participation in the AEP. 
    "discharge_date", -- The date the building was removed from the program. 
    "latitude",
    "community_board",
    "council_district",
    "bbl"
FROM
    "cityofnewyork-us/buildings-selected-for-the-alternative-enforcement-hcir-3275:latest"."buildings_selected_for_the_alternative_enforcement"
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/buildings-selected-for-the-alternative-enforcement-hcir-3275 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/buildings-selected-for-the-alternative-enforcement-hcir-3275: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/buildings-selected-for-the-alternative-enforcement-hcir-3275" \
  --handler-options '{
    "domain": "data.cityofnewyork.us",
    "tables": {
        "buildings_selected_for_the_alternative_enforcement": "hcir-3275"
    }
}'

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/buildings-selected-for-the-alternative-enforcement-hcir-3275 is just another Postgres schema.