cambridgema-gov/envision-cambridge-mobile-engagement-feedback-sx7w-cut7
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 envision_cambridge_mobile_engagement_feedback table in this repository, by referencing it like:

"cambridgema-gov/envision-cambridge-mobile-engagement-feedback-sx7w-cut7:latest"."envision_cambridge_mobile_engagement_feedback"

or in a full query, like:

SELECT
    ":id", -- Socrata column ID
    "phase", -- Engagement phase, either “Listening” or “Visioning.” All data collected during the visioning phase are of the “Future” point type
    "location_of_topic_city",
    "location_of_topic_state",
    "location_of_topic_zip",
    ":@computed_region_rffn_qbt6",
    ":@computed_region_guic_hr4a",
    ":@computed_region_swkg_bavi",
    ":@computed_region_rcj3_ccgu",
    ":@computed_region_v7jj_366k",
    "location_of_topic", -- Location of the topic being discussed. Note that this differs from the location of the mobile engagement station. For example, a mobile engagement station at Fresh Pond might collect feedback about a location in Central Square.
    "latitude", -- Latitude of the topic being discussed. Note that this is not the latitude of the mobile engagement station at which feedback was collected. A station located at Fresh Pond might have collected feedback about Central Square; this column would list the latitude of Central Square.
    "longitude", -- Longitude of the topic being discussed. Note that this is not the latitude of the mobile engagement station at which feedback was collected. A station located at Fresh Pond might have collected feedback about Central Square; this column would list the longitude of Central Square.
    "tag", -- Qualitative coding of the comments by Envision Cambridge staff
    "location_of_topic_address",
    "date", -- Data when this point was recorded
    "type", -- Whether the participant marked this feature as their current favorite or least favorite place in Cambridge, or if they marked it as a site for future change
    "location_of_engagement", -- Location of the Mobile Engagement Station where this point was recorded. Note that the location of engagement tends to differ from the location of the topic discussed during the engagement. For example, a mobile engagement station at Fresh Pond in North Cambridge may have captured feedback about a location in Central Square. All coordinates listed in this dataset pertain to the topic of discussion rather than the location of mobile engagement stations.
    "comment" -- Participant comments accompanying their marked feature on the map
FROM
    "cambridgema-gov/envision-cambridge-mobile-engagement-feedback-sx7w-cut7:latest"."envision_cambridge_mobile_engagement_feedback"
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/envision-cambridge-mobile-engagement-feedback-sx7w-cut7 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/envision-cambridge-mobile-engagement-feedback-sx7w-cut7: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/envision-cambridge-mobile-engagement-feedback-sx7w-cut7" \
  --handler-options '{
    "domain": "data.cambridgema.gov",
    "tables": {
        "envision_cambridge_mobile_engagement_feedback": "sx7w-cut7"
    }
}'

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/envision-cambridge-mobile-engagement-feedback-sx7w-cut7 is just another Postgres schema.