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 parks_closure_status_due_to_covid19_playgrounds table in this repository, by referencing it like:

"cityofnewyork-us/parks-closure-status-due-to-covid19-playgrounds-a4qt-mpr5:latest"."parks_closure_status_due_to_covid19_playgrounds"

or in a full query, like:

SELECT
    ":id", -- Socrata column ID
    ":@computed_region_f5dn_yrer",
    ":@computed_region_efsh_h5xi",
    ":@computed_region_sbqj_enih",
    "accessibilitylevel", -- If a Children's Play Area (CPA), level of accessibility, ranging from 1-4. 
    "accessibility", -- If a Children's Play Area (CPA), whether the play units associated with CPA are modified for accessibility to children with special physical needs.
    "location", -- Indicates the cross streets of where the playground is located. 
    "name", -- Indicates Playground Name
    "closuretype", -- Indicates the type of closure
    "system", -- Unique identifier for Childrens Play Areas (CPAs). If a System ID exists here, it can be used to join to the CPA dataset; if the field is NULL that row does not correspond to a CPA. Records with NULL System IDs are most likely coming from Parks Properties and can be joined on GISPropNum.
    "community_board", -- NYC Community Board
    "district", -- Name of the Parks maintenance district that contains the Playground.
    "latitude",
    "longitude",
    "editdate", -- Date last edited
    "gispropnum", -- This is the identification number for the property that contains the playground.
    "omppropid", -- Unique identification number for a property or portion of a property. In some cases – a standalone, smaller park for example – this number will be equivalent to the GIS Property Number. In other cases – a zone, playground or other site within a larger park – an additional designation of letters and/or numbers will be added.
    "borough", -- Borough in which the playground is located.
    "red_sign_installed", -- Indicates whether a red closed sign was installed
    "rules", -- Rules posted on playground sign
    "status", -- Indicates whether the playground is still active and open to the public, has been closed to observe COVID-19 social distancing, has been reopened following COVID-19 closure, or is under construction. 
    "point",
    "approx_date_reopened", -- Date playground reopened from Covid closure
    "approx_date_closed", -- Approximate date playground closed because of Covid
    ":@computed_region_92fq_4b7q",
    ":@computed_region_yeji_bk3q"
FROM
    "cityofnewyork-us/parks-closure-status-due-to-covid19-playgrounds-a4qt-mpr5:latest"."parks_closure_status_due_to_covid19_playgrounds"
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/parks-closure-status-due-to-covid19-playgrounds-a4qt-mpr5 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/parks-closure-status-due-to-covid19-playgrounds-a4qt-mpr5: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/parks-closure-status-due-to-covid19-playgrounds-a4qt-mpr5" \
  --handler-options '{
    "domain": "data.cityofnewyork.us",
    "tables": {
        "parks_closure_status_due_to_covid19_playgrounds": "a4qt-mpr5"
    }
}'

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/parks-closure-status-due-to-covid19-playgrounds-a4qt-mpr5 is just another Postgres schema.