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 baseline_study_of_food_for_peace_title_ii table in this repository, by referencing it like:

"usaid-gov/baseline-study-of-food-for-peace-title-ii-2b2q-4uba:latest"."baseline_study_of_food_for_peace_title_ii"

or in a full query, like:

SELECT
    ":id", -- Socrata column ID
    "a05", -- DEPARTMENT
    "b18", -- B18 Has ever attended school
    "b03", -- B03 Relationship to head of household
    "member_id", -- Household member ID for merging with other modules
    "b21b", -- B21B Course he attended during 2012 2013
    "b19a", -- B19A What is the highest educational level you have completed
    "b10", -- B10 Adults available to answer questions about the services and household expenses
    "education_level", -- Education level
    "b06", -- B06 Responsible for preparing the household food yesterday
    "b01", -- B01 Order Number
    "female_adult", -- Household has at least one female 18 or older
    "b20", -- B20 During the 2012 2013 school attended a
    "id",
    "b12", -- B12 Mother of a child under 5 years
    "b17", -- B17 Do you live the natural father in the home
    "b15", -- B15 natural mother lives in the home or was asleep here last night
    "b14", -- B14 is alive natural mother
    "b08", -- B08 Main responsible for child care
    "b05", -- B05 Age of household member
    "b21a", -- B21A Level you attended during 2012 2013
    "a02", -- LISTING NUMBER
    "strata", -- Strata
    "cluster", -- Cluster
    "male_adult", -- Household has at least one male 18 or older
    "b19b", -- B19B What is the course B19B higher than obtained at this level
    "b16", -- B16 is alive the natural father of
    "hhwt", -- Sampling weight for households and household members
    "b05_bin", -- Age Binned
    "b09", -- B08 Women aged 15 49 B09
    "child", -- Household has at least one child under 18
    "b13", -- B13 Marital status
    "hog", -- NUMBER OF HOUSEHOLD
    "b07", -- B07 Low 6 years
    "pvo", -- PVO
    "b11", -- B11 Farmer
    "b04" -- B04 Sex of household member
FROM
    "usaid-gov/baseline-study-of-food-for-peace-title-ii-2b2q-4uba:latest"."baseline_study_of_food_for_peace_title_ii"
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 usaid-gov/baseline-study-of-food-for-peace-title-ii-2b2q-4uba with SQL in under 60 seconds.

This repository is an "external" repository. That means it's hosted elsewhere, in this case at data.usaid.gov. When you queryusaid-gov/baseline-study-of-food-for-peace-title-ii-2b2q-4uba: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.usaid.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 \
  "usaid-gov/baseline-study-of-food-for-peace-title-ii-2b2q-4uba" \
  --handler-options '{
    "domain": "data.usaid.gov",
    "tables": {
        "baseline_study_of_food_for_peace_title_ii": "2b2q-4uba"
    }
}'

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, usaid-gov/baseline-study-of-food-for-peace-title-ii-2b2q-4uba is just another Postgres schema.