cambridgema-gov/city-council-election-2013-wzr3-7kz8
Icon for Socrata external plugin

Query the Data Delivery Network

Query the DDN

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 city_council_election_2013 table in this repository, by referencing it like:

"cambridgema-gov/city-council-election-2013-wzr3-7kz8:latest"."city_council_election_2013"

or in a full query, like:

SELECT
    ":id", -- Socrata column ID
    "round", -- The vote count begins with the sorting of ballots by the first preference shown on each valid ballot. That is the NUMBER 1 vote on each ballot. This is generally known as the "First Count". Any candidates who reach the necessary quota with Number 1 votes are declared elected. Any extra ballots they receive beyond the quota are redistributed to the candidates marked next in preference (the number 2 preference) on those excess ballots. The count continues with the elimination of those candidates receiving fewer than fifty votes in the first count. Their ballots are redistributed to the other candidates according to the next preference marked. After each distribution, the candidate now having the lowest number of votes is eliminated and his/her ballots redistributed to the next indicated preference (number 2,3,4 etc.). Counting continues until nine candidates have been elected. 
    "candidate", -- Candidate for 2013 City Council Election
    "vote_distribution", -- Number of votes each candidate received this counting round. After the first count, votes for elected and eliminated candidates  are redistributed to still-eligible candidates who have not reach the quota of 10 percent of votes plus 1. During the 2013 City Council Election, the quota was 1,775 votes.
    "total_votes", -- Total votes for each candidate at the end of each counting round. 
    "status" -- Status at end of counting round. 
FROM
    "cambridgema-gov/city-council-election-2013-wzr3-7kz8:latest"."city_council_election_2013"
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 cambridgema-gov/city-council-election-2013-wzr3-7kz8 with SQL in under 60 seconds.

This repository is an "external" repository. That means it's hosted elsewhere, in this case at data.cambridgema.gov. When you querycambridgema-gov/city-council-election-2013-wzr3-7kz8: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

Install Splitgraph Locally
bash -c "$(curl -sL https://github.com/splitgraph/splitgraph/releases/latest/download/install.sh)"
 

Read the installation docs.

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.cambridgema.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 \
  "cambridgema-gov/city-council-election-2013-wzr3-7kz8" \
  --handler-options '{
    "domain": "data.cambridgema.gov",
    "tables": {
        "city_council_election_2013": "wzr3-7kz8"
    }
}'

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, cambridgema-gov/city-council-election-2013-wzr3-7kz8 is just another Postgres schema.