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 siding_building_permit table in this repository, by referencing it like:
"cambridgema-gov/siding-building-permit-ddej-349p:latest"."siding_building_permit"or in a full query, like:
SELECT
":id", -- Socrata column ID
"debris_removal_date", -- Construction debris removal will be completed by
"debris_removal_location", -- Construction debris will be disposed at/by
":@computed_region_e4yd_rwk4", -- This column was automatically created in order to record in what polygon from the dataset 'Census Blocks 2010' (e4yd-rwk4) the point in column 'geocoded_column' is located. This enables the creation of region maps (choropleths) in the visualization canvas and data lens.
":@computed_region_swkg_bavi", -- This column was automatically created in order to record in what polygon from the dataset 'cambridge_cdd_zoning' (swkg-bavi) the point in column 'geocoded_column' is located. This enables the creation of region maps (choropleths) in the visualization canvas and data lens.
":@computed_region_v7jj_366k", -- This column was automatically created in order to record in what polygon from the dataset 'Police Response Districts' (v7jj-366k) the point in column 'geocoded_column' is located. This enables the creation of region maps (choropleths) in the visualization canvas and data lens.
"status", -- Status of application
"condo_association", -- Is the property part of a condo association?
"mcm", -- Will metal composite materials (MCM) be used for any part of the new exterior wall covering?
"geocoded_column_address",
"hpl", -- Will high-pressure decorative exterior-grade compact laminates (HPL) be used for any part of the new exterior wall covering?
"geocoded_column_state",
"owner_occupied", -- Is the property owner-occuped?
":@computed_region_rffn_qbt6", -- This column was automatically created in order to record in what polygon from the dataset 'cambridge_neighborhoods' (rffn-qbt6) the point in column 'geocoded_column' is located. This enables the creation of region maps (choropleths) in the visualization canvas and data lens.
":@computed_region_guic_hr4a", -- This column was automatically created in order to record in what polygon from the dataset 'Police Neighborhood Regions' (guic-hr4a) the point in column 'geocoded_column' is located. This enables the creation of region maps (choropleths) in the visualization canvas and data lens.
"geocoded_column_zip",
"construction_type",
"eifs", -- Will exterior insulation and finish systems (EIFS) be used for any part of the new exterior wall covering?
"temporary_dumpsters", -- How many temporary dumpsters would you like to apply for?
"license_number", -- License Number
"id", -- Permit ID
"dwelling_units", -- Number of Dwelling Units in the building
"hpl_description", -- Provide a description of the product below, including any minimum fire separation required, height of installation above grade, percent of exterior wall surface that is covered with such product, surface-burning characteristics, thermal barriers required. Also attach product specifications to this permit application.
"combustible_water_resistive", -- Will any part of the new exterior wall covering contain a combustible water-resistive barrier?
"building_cost", -- Building Cost of Construction
"method_of_removal", -- Method of Removal (Demolition)
"exterior_insulation", -- Will new continuous exterior insulation be installed as part of this permit?
"latitude",
"longitude",
"register_class", -- Register: Class
"license_expiration_date", -- License Expiration Date
"eifs_description", -- Provide a description of the drainage, water-resistive barrier, and the structural characteristics of the underlying framing and substrate.
"demolition_type", -- Type of Demolition
"flashing_installation", -- Will new flashing or fascia be required and installed?
"building_use", -- Type of building (home, commercial, etc.)
"submit_date", -- Applicant Submit Date
"licensed_class", -- Licensed: Class
"insulation_installation", -- Describe the type of insulation and thickness to be installed
"temporary_dumpster_permit", -- Would you like to apply for a temporary dumpster permit as part of this building permit application?
"geocoded_column", -- Use this column to create maps using the open data portal's mapping tools.
"geocoded_column_city",
"siding_work_description", -- Detailed Description of Work, including siding materials to be installed and fasteners to be used
"mcm_description", -- Provide a description of the new MCM covering below – include descriptions of required thermal barriers, required fire-resistance rating of the exterior walls, surface-burning characteristics, height of MCM installation above grade and occupancy classification(s) of the building, and area/size limitations required. Also attach product specifications to this permit application.
"total_construction_cost", -- Total Cost of Construction
"barrier_description", -- Provide a description of the product below, including any minimum fire separation required and percent of exterior wall
"electrical_cost", -- Electrical cost of construction
"demolition_description",
"address", -- Address where siding work is being done
"issue_date", -- Date when permit was issued
"dumpster_license_number" -- Cambridge Dumpster License Number
FROM
"cambridgema-gov/siding-building-permit-ddej-349p:latest"."siding_building_permit"
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/siding-building-permit-ddej-349p 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/siding-building-permit-ddej-349p: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/siding-building-permit-ddej-349p" \
--handler-options '{
"domain": "data.cambridgema.gov",
"tables": {
"siding_building_permit": "ddej-349p"
}
}'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/siding-building-permit-ddej-349p is just another Postgres schema.