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 mta_debt_outstanding table in this repository, by referencing it like:

"ny-gov/mta-debt-outstanding-sze3-m8qh:latest"."mta_debt_outstanding"

or in a full query, like:

SELECT
    ":id", -- Socrata column ID
    "series_original_final_maturity", -- This is the final maturity date for the bond series (mm/dd/yyyy).   
    "outstanding_variable_rate_par", -- Shows any amount of variable rate bonds for the series that remains outstanding. Variable rate bonds may be in the form of variable rate demand bonds in weekly or daily mode, which are supported by letter of credit from a bank, or floating rate notes. Values are expressed in dollars in millions. 
    "principal_amount_at_issuance", -- This is the amount of principal issued at the time the bonds were first issued in the primary market. Reflects dollars in millions.
    "posted_date", -- Represents the date the data was updated (mm/dd/yyyy).
    "tic", -- This is the All-In True Interest Cost for the bond series. Values are expressed in percentages.
    "total_outstanding_par", -- Reflects total remaining principal outstanding on the bond series as of the posting date. Values are expressed in dollars in millions.
    "outstanding_fixed_rate_par", -- Shows the amount of the series in fixed rate that remains outstanding. Typically, if the bonds are issued in fixed rate, they do not change from that mode. Values are expressed in dollars in millions.
    "outstanding_synthetic_fixed_par", -- Shows any amount of synthetic fixed rate bonds outstanding for the series. The bonds are in a variable rate mode but are synthetically fixed by a swap with a specified counterparty. Values are expressed in dollars in millions. 
    "type_of_credit", -- The dataset is divided into MTA’s active bond credits, which include Transportation Revenue Bonds, Triborough Bridge and Tunnel Authority (TBTA) General Revenue Bonds, TBTA Subordinate Revenue Bonds, TBTA Second Subordinate Revenue Bond Anticipation Notes, Dedicated Tax Fund Bonds, Payroll Mobility Tax Obligations, Sales Tax Revenue Bonds (City Sales Tax – TBTA Capital Lockbox), and MTA Hudson Rail Yard Trust Obligations.
    "ratings", -- Ratings are provided in this order Moody’s, S&P, Fitch, KBRA.  If a rating agency was not used for that credit, the “Not Applied For (NAF)” is shown.
    "bpa_sale_date", -- This is the sale date of the bond series (mm/dd/yyyy).
    "bond_series" -- Specific bond series, generally the series name contains the year the bonds were issued.
FROM
    "ny-gov/mta-debt-outstanding-sze3-m8qh:latest"."mta_debt_outstanding"
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 ny-gov/mta-debt-outstanding-sze3-m8qh with SQL in under 60 seconds.

This repository is an "external" repository. That means it's hosted elsewhere, in this case at data.ny.gov. When you queryny-gov/mta-debt-outstanding-sze3-m8qh: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.ny.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 \
  "ny-gov/mta-debt-outstanding-sze3-m8qh" \
  --handler-options '{
    "domain": "data.ny.gov",
    "tables": {
        "mta_debt_outstanding": "sze3-m8qh"
    }
}'

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, ny-gov/mta-debt-outstanding-sze3-m8qh is just another Postgres schema.