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 roadway_markings_work_orders table in this repository, by referencing it like:

"datahub-austintexas-gov/roadway-markings-work-orders-nyhn-669r:latest"."roadway_markings_work_orders"

or in a full query, like:

SELECT
    ":id", -- Socrata column ID
    "road_class", -- The list of road class codes
    "work_groups_required", -- The list of workgroups who did work at this work order.
    "atd_work_order_id", -- The work order ID
    "id", -- The unique record ID in the source database (Knack).
    "sum_segment_miles", -- The total length in miles of all street segment associated with this work order
    "segment_id", -- The list of street segments associated with this work order
    "sr_number", -- The 311 service request number related to this work order.
    "requester_work_order_id", -- The requesters work order ID.
    "task_order_number", -- The task order number
    "remove_hold_date", -- The datetime the work order had the hold removed.
    "modified_date", -- The datetime the work order record was last modified.
    "created_date", -- The datetime the work order record was created.
    "priority", -- The priority of work order. This is set by requesters.
    "location_name", -- The location of the work order.
    "funding_number", -- The funding number.
    "sbo_completed_date", -- The datetime Street and Bridge (SBO) from Austin Public Works department completed work.
    "completed_date", -- The date the work was completed
    "on_hold_date", -- The datetime the work order was on-hold.
    "work_sub_type", -- Additional detail about the type of work completed.
    "work_order_status", -- The status of the work order.
    "requester", -- The type of requester who submitted the work order.
    "work_type", -- The type of work. Default is Markings.
    "safety_device_maintenance" -- The Y/N indicator of whether the work order involves the Safety Device Maintenance unit
FROM
    "datahub-austintexas-gov/roadway-markings-work-orders-nyhn-669r:latest"."roadway_markings_work_orders"
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 datahub-austintexas-gov/roadway-markings-work-orders-nyhn-669r with SQL in under 60 seconds.

This repository is an "external" repository. That means it's hosted elsewhere, in this case at datahub.austintexas.gov. When you querydatahub-austintexas-gov/roadway-markings-work-orders-nyhn-669r: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 datahub.austintexas.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 \
  "datahub-austintexas-gov/roadway-markings-work-orders-nyhn-669r" \
  --handler-options '{
    "domain": "datahub.austintexas.gov",
    "tables": {
        "roadway_markings_work_orders": "nyhn-669r"
    }
}'

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, datahub-austintexas-gov/roadway-markings-work-orders-nyhn-669r is just another Postgres schema.