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 mechanical_permits table in this repository, by referencing it like:
"cambridgema-gov/mechanical-permits-4rb4-q8tj:latest"."mechanical_permits"or in a full query, like:
SELECT
":id", -- Socrata column ID
"weight_of_cooling_tower_in", -- Weight of Cooling Tower (in pounds)
"building_permit_number", -- Building permit number
"_of_radiant_heat_units", -- Number of radiant heat units
"longitude",
"latitude",
"issue_date", -- Date when permit was issued
"_of_air_handling_unit_duct", -- Number of air handling unit duct coils
"_of_range_hoods_residential", -- Number of range hoods (residential)
"geocoded_column_zip",
"applicant_submit_date", -- Date when application was submitted
"_of_pool_heaters", -- Number of pool heaters
"total_tonnage_for_cooling", -- Total Tonnage for Cooling Tower Units over 25 Tons
"_of_fan_coils", -- Number of fan coils
"id", -- ID
"_of_steam_generators", -- Number of steam generators
"_of_ventilation_units", -- Number of ventilation units
"_of_evaporative_coils", -- Number of evaporative coils
"_of_hydro_air_systems", -- Number of hyrdo air systems
"number_of_ac_units_over_25", -- Number of AC Units over 25 Tons
"number_of_cooling_tower_units", -- Number of Cooling Tower Units over 25 Tons
"permit_type", -- Name of worker conducting mechanical work
"_of_process_piping_feet", -- Length of process piping, in feet
"company_name", -- Name of company
"_of_heat_pumps", -- Number of heat pumps
"total_tonnage_for_ac_units", -- Total Tonnage for AC Units over 25 Tons
"_of_direct_vent_fireplaces", -- Number of direct vent fireplaces
"geocoded_column_address",
"_of_ductless_split_systems", -- Number of ductless split systems
"cooling_tower_location",
"number_of_ac_units_up_to", -- Number of AC Units up to 25 Tons
"_of_stove_hoods_commercial", -- Number of stove hoods (commercial)
"does_the_proposed_work_include", -- Does the proposed work include exterior work?
"_of_boilers", -- Number of boilers
"_of_furnaces", -- Number of furnaces
"_of_temporary_heat_and_l", -- Number of Temporary Heat and L.P. Installation Natural Gas
"_of_refrigeration_units", -- Number of refrigeration units
"number_of_cooling_tower_units_1", -- Number of Cooling Tower Units up to 25 Tons
"_of_energy_recovery_systems", -- Number of energy recovery systems
"does_the_proposed_work_include_2", -- Does the proposed work include installation or replacement of a cooling tower?
"_of_condensers", -- Number of condensers
"_of__down_draft_exhaust", -- Number of down draft exhaust
"does_the_proposed_work_include_1", -- Does the proposed work include installation or replacement of a roof top AC unit?
"_of_cogen_generators", -- Number of cogen generators
"geocoded_column", -- Location of the permitted project
"_of_gas_generators", -- Number of gas generators
"_of_draft_inducers", -- Number of draft inducers
"_of_solar_heat_systems", -- Number of solar heat systems
"_of__bathroom_exhaust_fans", -- Number of bathroom exhaust fans (residential)
"_of_high_pressure_unit_psi", -- Number of high pressure units
"geocoded_column_state",
":@computed_region_e4yd_rwk4",
":@computed_region_swkg_bavi",
":@computed_region_rffn_qbt6",
":@computed_region_v7jj_366k",
":@computed_region_guic_hr4a",
"geocoded_column_city"
FROM
"cambridgema-gov/mechanical-permits-4rb4-q8tj:latest"."mechanical_permits"
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/mechanical-permits-4rb4-q8tj 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/mechanical-permits-4rb4-q8tj: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/mechanical-permits-4rb4-q8tj" \
--handler-options '{
"domain": "data.cambridgema.gov",
"tables": {
"mechanical_permits": "4rb4-q8tj"
}
}'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/mechanical-permits-4rb4-q8tj is just another Postgres schema.