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 electrical_building_permits table in this repository, by referencing it like:

"montgomerycountymd-gov/electrical-building-permits-qxie-8qnp:latest"."electrical_building_permits"

or in a full query, like:

SELECT
    ":id", -- Socrata column ID
    "location_city",
    "finaleddate", -- The final date indicates the date that construction has been completed and approved by DPS.  The final inspection was conducted that date/time by the DPS inspector and was acceptable. 
    "issueddate", -- The date that the permit is issued.  When the permit is issued, construction is allowed to commence.  DPS has reviewed the construction plans according to the applicable building and life safety codes and approved the plans.
    "usecode", -- Type of structure work will be performed on.
    "zip", -- 5 digit Zip Code of work location.
    "city", -- City of work location.
    "stno", -- Street number of work location.
    "location_address",
    "permitno", -- Number assigned to uniquely identify permit.
    "location",
    "postdir", -- Post-direction, if the street name has a direction after the name. For example, University Blvd W.
    "suffix", -- Street suffix, such as ST (Street), PL (Place), RD (Road).
    "stname", -- Street name of work location.
    "location_zip",
    "predir", -- Pre Direction
    "description", -- Description of planned work.
    "addeddate", -- The date that the applicant applied for the permit and the information entered into the database.
    "worktype", -- Type of work to be performed.
    "location_state",
    "state", -- State of work location.
    "status", -- Status of permit.
    "applicationtype", -- Type of permit application.
    ":@computed_region_d7bw_bq6x",
    ":@computed_region_rbt8_3x7n",
    ":@computed_region_kbsp_ykn9",
    ":@computed_region_tx5f_5em3"
FROM
    "montgomerycountymd-gov/electrical-building-permits-qxie-8qnp:latest"."electrical_building_permits"
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 montgomerycountymd-gov/electrical-building-permits-qxie-8qnp with SQL in under 60 seconds.

This repository is an "external" repository. That means it's hosted elsewhere, in this case at data.montgomerycountymd.gov. When you querymontgomerycountymd-gov/electrical-building-permits-qxie-8qnp: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.montgomerycountymd.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 \
  "montgomerycountymd-gov/electrical-building-permits-qxie-8qnp" \
  --handler-options '{
    "domain": "data.montgomerycountymd.gov",
    "tables": {
        "electrical_building_permits": "qxie-8qnp"
    }
}'

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, montgomerycountymd-gov/electrical-building-permits-qxie-8qnp is just another Postgres schema.