Query the Data Delivery Network
Query the DDNThe 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 housing_stock_and_residential_properties_by table in this repository, by referencing it like:
"cambridgema-gov/housing-stock-and-residential-properties-by-wiba-69ua:latest"."housing_stock_and_residential_properties_by"or in a full query, like:
SELECT
":id", -- Socrata column ID
"bldgs_over_100_units_perc", -- Total number of land parcels with over 100 residential units as a percent of the total number of residential properties
"dwellings_over_100_units_perc", -- Total number of dwelling units in residential properties with over 100 units as a percent of total dwelling units on all residential properties.
"neighborhood_center_point_city",
":@computed_region_e4yd_rwk4",
":@computed_region_guic_hr4a",
":@computed_region_v7jj_366k",
":@computed_region_rffn_qbt6",
":@computed_region_swkg_bavi",
":@computed_region_rcj3_ccgu",
"housing_single_family", -- Total number of dwelling units in single family residential properties
"housing_2_units", -- Total number of dwelling units in residential properties with 2 units
"housing_7_to_12_units", -- Total number of dwelling units in residential properties with 7 to 12 units
"housing_7_to_12_units_perc", -- Total number of dwelling units in residential properties with 7 to 12 units as a percent of total dwelling units on all residential properties.
"dwellings_51_to_100_units_perc", -- Total number of dwelling units in residential properties with 51 to 100 units as a percent of total dwelling units on all residential properties.
"bldgs_single_family", -- Total number of land parcels with single family residential use
"bldgs_2_units", -- Total number of land parcels with 2 residential units
"bldgs_3_units", -- Total number of land parcels with 3 residential units
"bldgs_properties_51_to_100_units", -- Total number of land parcels with 51 to 100 residential units
"bldgs_single_family_perc", -- Total number of land parcels with single family residential use as a percent of the total number of residential properties
"bldgs_4_to_6_units_perc", -- Total number of land parcels with 4 to 6 residential units as a percent of the total number of residential properties
"bldgs_51_to_100_units_perc", -- Total number of land parcels with 51 to 100 residential units as a percent of the total number of residential properties
"centerpoint_y",
"neighborhood_2", -- Concatenation of neighborhood number and name
"neighborhood_center_point_state",
"neighborhood_center_point_zip",
"neighborhood_name", -- Cambridge neighborhood name
"neighborhood_number", -- Cambridge neighborhood number
"total_dwellings", -- Total number of dwelling units in residential properties
"housing_3_units", -- Total number of dwelling units in residential properties with 3 units
"housing_4_to_6_units", -- Total number of dwelling units in residential properties with 4 to 6 units
"dwellings_13_to_25_units", -- Total number of residential units in properties with 13 to 25 units
"dwellings_26_to_50_units", -- Total number of residential units in properties with 26 to 50 units
"dwellings_51_to_100_units", -- Total number of residential units in properties with 51 to 100 units
"dwellings_100_or_more_units", -- Total number of residential units in properties with 100 or more units
"housing_single_family_perc", -- Total number of dwelling units comprising single family residential properties as percent of total dwelling units on all residential properties.
"housing_2_units_perc", -- Total number of dwelling units in residential properties with 2 units as a percent of total dwelling units on all residential properties.
"housing_3_units_perc", -- Total number of dwelling units in residential properties with 3 units as a percent of total dwelling units on all residential properties.
"housing_4_to_6_units_perc", -- Total number of dwelling units in residential properties with 4 to 6 units as a percent of total dwelling units on all residential properties.
"dwellings_13_to_25_units_perc", -- Total number of dwelling units in residential properties with 13 to 25 units as a percent of total dwelling units on all residential properties.
"dwellings_26_to_50_units_perc", -- Total number of dwelling units in residential properties with 26 to 50 units as a percent of total dwelling units on all residential properties.
"total_residential_buildings", -- Total number of land parcels with residential uses
"bldgs_4_to_6_units", -- Total number of land parcels with 4 to 6 residential units
"bldgs_7_to_12_units", -- Total number of land parcels with 7 to 12 residential units
"bldgs_properties_13_to_25_units", -- Total number of land parcels with 13 to 25 residential units
"bldgs_properties_26_to_50_units", -- Total number of land parcels with 26 to 50 residential units
"bldgs_properties_over_100_units", -- Total number of land parcels with over 100 residential units
"bldgs_2_units_perc", -- Total number of land parcels with 2 residential units as a percent of the total number of residential properties
"bldgs_3_units_perc", -- Total number of land parcels with 3 residential units as a percent of the total number of residential properties
"bldgs_7_12_units_perc", -- Total number of land parcels with 7 to 12 residential units as a percent of the total number of residential properties
"bldgs_13_to_25_units_perc", -- Total number of land parcels with 13 to 25 residential units as a percent of the total number of residential properties
"bldgs_26_to_50_units_perc", -- Total number of land parcels with 26 to 50 residential units as a percent of the total number of residential properties
"centerpoint_x",
"neighborhood_center_point",
"neighborhood_center_point_address"
FROM
"cambridgema-gov/housing-stock-and-residential-properties-by-wiba-69ua:latest"."housing_stock_and_residential_properties_by"
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/housing-stock-and-residential-properties-by-wiba-69ua 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/housing-stock-and-residential-properties-by-wiba-69ua: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)"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/housing-stock-and-residential-properties-by-wiba-69ua" \
--handler-options '{
"domain": "data.cambridgema.gov",
"tables": {
"housing_stock_and_residential_properties_by": "wiba-69ua"
}
}'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/housing-stock-and-residential-properties-by-wiba-69ua is just another Postgres schema.