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 city_record_online table in this repository, by referencing it like:
"cityofnewyork-us/city-record-online-dg92-zbpx:latest"."city_record_online"or in a full query, like:
SELECT
":id", -- Socrata column ID
"type_of_notice_description", -- A description of the published notice
"vendor_address", -- For procurement award notices: address of vendor
"due_date", -- For procurement notices: The date when the bid or other response is due
"selection_method_description", -- For procurement notices: the selection method to be used, such as Competitive Sealed Bids or Competitive Sealed Proposals
"other_info_2", -- Further information regarding the notice(2)
"other_info_3", -- Further information regarding the notice(3)
"printout_2", -- Formatted OtherInfo or AdditionalDescription, depending on the notice(2)
"document_links", -- Links to the public facing City Record website to view any documents associated with the notice
"additional_description_3", -- Additional information regarding the notice not included in other fields(3)
"other_info_1", -- Further information regarding the notice
"printout_1", -- Formatted OtherInfo or AdditionalDescription, depending on the notice
"section_name", -- The section of the City Record in which the notice appears
"additional_description_2", -- Additional information regarding the notice not included in other fields(2)
"additional_description_1", -- Additional information regarding the notice not included in other fields
"zip_code", -- For public hearings and meetings notices: Zip Code for the location where the event is being held
"street_address_2", -- For public hearings and meetings notices: Address where the event is being held(2)
"building_name", -- For public hearings and meetings notices: Building name where the event is being held
"vendor_name", -- For procurement award notices: name of vendor
"contract_amount", -- For procurement notices: The amount of the contract for which bids or other responses are being solicited
"email", -- For procurement notices: The email address to which requests for procurement notice information can be sent
"short_title", -- Short Title
"agency_name", -- The agency which has submitted the notice
"end_date", -- The last date on which the notice appears in the paper publication
"request_id", -- Unique identifier for the City Record notice
"contact_fax", -- For procurement notices: The fax number for procurement notice information
"start_date", -- The first date on which the notice appears in the paper publication
"pin", -- For procurement notices: Procurement Identification Number
"category_description", -- The category of the published notice
"special_case_reason_description", -- For procurement notices: the rationale for using the listed selection method, such as "available only from a single source"
"contact_name", -- For procurement notices: The person to contact for procurement notice information
"street_address_1", -- For public hearings and meetings notices: Address where the event is being held
"state", -- For public hearings and meetings notices: State where the event is being held
"printout_3", -- Formatted OtherInfo or AdditionalDescription, depending on the notice(3)
"city", -- For public hearings and meetings notices: City where the event is being held
"contact_phone", -- For procurement notices: The person to contact for procurement notice information
"event_date", -- For public hearings and meetings notices: Date and time of event
"address_to_request" -- For procurement notices: The address to which bids or other responses are to be sent
FROM
"cityofnewyork-us/city-record-online-dg92-zbpx:latest"."city_record_online"
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 cityofnewyork-us/city-record-online-dg92-zbpx with SQL in under 60 seconds.
This repository is an "external" repository. That means it's hosted elsewhere, in this case at data.cityofnewyork.us. When you querycityofnewyork-us/city-record-online-dg92-zbpx: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.cityofnewyork.us, 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 \
"cityofnewyork-us/city-record-online-dg92-zbpx" \
--handler-options '{
"domain": "data.cityofnewyork.us",
"tables": {
"city_record_online": "dg92-zbpx"
}
}'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, cityofnewyork-us/city-record-online-dg92-zbpx is just another Postgres schema.