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 building_permits_new_construction table in this repository, by referencing it like:
"cambridgema-gov/building-permits-new-construction-9qm7-wbdc:latest"."building_permits_new_construction"or in a full query, like:
SELECT
":id", -- Socrata column ID
"building_height", -- Proposed: Building Height (feet)
"debris_removal_location", -- Construction debris will be disposed at/by
"property_use_other", -- Zoning I: Describe current property use (other)
"architect_firm",
"long_term_bike_parking", -- Number of Proposed Off-Street Bicycle Parking Spaces (Long Term)
"short_term_bike_parking", -- Number of Proposed Off-Street Bicycle Parking Spaces (Short Term)
"building_cost", -- Building Cost of Construction
"impervious_cover", -- Will the proposed work result in an increase to the property’s impervious cover?
"dumpster_no", -- Construction: Cambridge Dumpster Licence #
"employment_arrangement", -- Select the option that best describes you or your company's employment arrangement.
"current_property_use", -- Zoning I: Current Property Use
"proposed_loading_bays", -- Number of Proposed Loading Bays
":@computed_region_swkg_bavi",
":@computed_region_rffn_qbt6",
":@computed_region_v7jj_366k",
":@computed_region_guic_hr4a",
":@computed_region_e4yd_rwk4",
"special_permit_number", -- Special: Planning Board Special Permit Number
"proposed_property_use", -- Zoning I: Proposed Property Use
"cooking_type", -- Cooking Equipment Type
"storm_sewer_connections", -- Will the proposed work result in new, abandoned, or replaced sanitary storm sewer connections?
"geocoded_column_state",
"status", -- Status of application
"geocoded_column_city",
"board_special_permit", -- Special: Is this application subject to a Planning Board Special Permit?
"total_cost_of_construction",
"plumbing_cost", -- Plumbing Cost of Construction
"basement_plumbing_fixture", -- Will the proposed work result in the addition or replacement of a basement plumbing fixture?
"certificate", -- Certificate of Occupancy Required
"geocoded_column_zip",
"latitude",
"temporary_dumpster_permit", -- Would you like to apply for a temporary dumpster permit as part of this building permit application?
"construction_type", -- Proposed: Building Construction Type
"proposed_loading_facilities", -- Number of Proposed Loading Facilities
"description_of_work", -- Detailed Description of Work
"geocoded_column", -- Address geocoded so that it can be used to create a map on the open data portal
"submit_date", -- Date application for permit was submitted
"issue_date", -- Date permit was issued
"electrical_cost", -- Electrical Cost of Construction
"vehicle_parking_spaces", -- Number of Proposed Off-Street Vehicle Parking Spaces
"proposed_count_of_dwelling", -- Zoning I: Proposed number of dwelling units
"longitude",
"other_cooking_equipment", -- Food Est: Other Cooking Equipment
"gas_cost", -- Gas Cost of Construction
"hvac_cost", -- HVAC Cost of Construction
"gross_square_footage", -- Proposed: Gross Square Footage
"geocoded_column_address",
"final_cost", -- Final Cost of Construction
"construction_dewatering", -- Will the proposed work require construction dewatering during any phase of the project?
"right_of_way", -- Will the proposed work result in a new, abandoned or modified curb cut into the public right-of-way?
"new_food_establishment", -- Will the proposed work result in a new food establishment?
"address",
"finish_materials", -- Food Est: Describe the finish materials for the floor, walls, ceiling and cove
"bza_number", -- Special: Board of Zoning Appeal (BZA) Case Number
"proposed_building_use",
"stories_above_grade", -- Proposed: Number of Stories (Above Grade)
"debris_removal_date", -- Construction Debris Removal Completion Date
"air_cafe_windows", -- Will the food establishment include open air cafe windows?
"roof_foundation_drain", -- Will the proposed work result in the addition or alteration of a roof or foundation drain that discharges to the City?
"method_of_removal", -- Construction: Method of Removal
"appeal_bza_case", -- Special: Is this application subject to a Board of Zoning Appeal (BZA) Case?
"building_removal", -- Will removal of buildings be required for this construction?
"id" -- Permit ID
FROM
"cambridgema-gov/building-permits-new-construction-9qm7-wbdc:latest"."building_permits_new_construction"
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/building-permits-new-construction-9qm7-wbdc 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/building-permits-new-construction-9qm7-wbdc: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/building-permits-new-construction-9qm7-wbdc" \
--handler-options '{
"domain": "data.cambridgema.gov",
"tables": {
"building_permits_new_construction": "9qm7-wbdc"
}
}'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/building-permits-new-construction-9qm7-wbdc is just another Postgres schema.