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 2020_ncfo_operators_file table in this repository, by referencing it like:
"bts-gov/2020-ncfo-operators-file-wgzf-9czk:latest"."2020_ncfo_operators_file"or in a full query, like:
SELECT
":id", -- Socrata column ID
"trip_purpose_pleasure", -- Indicates whether the operator services pleasure transit trips
"pub_fund_prog_1", -- Name of public funding program 1
"other_funding_revenue", -- Percentage of annual revenue from all other revenue sources
"local_funding_revenue", -- Percentage of annual revenue from direct public funding (local)
"pub_fund_prog_7", -- Name of public funding program 7
"pub_fund_source_1", -- Name of public funding agency 1
"pub_fund_source_3", -- Name of public funding agency 3
"pub_fund_source_4", -- Name of public funding agency 4
"pub_fund_source_5", -- Name of public funding agency 5
"pub_fund_source_6", -- Name of public funding agency 6
"pub_fund_source_7", -- Name of public funding agency 7
"pub_fund_source_8", -- Name of public funding agency 8
"pub_fund_type_1", -- Public funding type 1
"pub_fund_type_2", -- Public funding type 2
"pub_fund_type_3", -- Public funding type 3
"pub_fund_type_4", -- Public funding type 4
"pub_fund_type_6", -- Public funding type 6
"pub_fund_type_7", -- Public funding type 7
"pub_fund_type_8", -- Public funding type 8
"state_funding_revenue", -- Percentage of annual revenue from direct public funding (state)
"trip_purpose_lifeline", -- Indicates whether the operator services lifeline trips to mainland
"trip_purpose_nps", -- Indicates whether the operator services trips to National Park Service locations
"trip_purpose_other_desc", -- Indicates the other purposes
"pub_fund_source_2", -- Name of public funding agency 2
"trip_purpose_roadway_conn", -- Indicates whether the operator services roadway connector trips
"url", -- Company Web Site
"op_strzip", -- Zip code of the ferry operator mailing address
"op_country", -- Country of the ferry operator street address
"census_year", -- Year of the census
"private_contract_revenue", -- Percentage of annual revenues from private contract payments
"trip_purpose_other", -- Indicates whether the operator services trips for other purposes
"pub_fund_prog_3", -- Name of public funding program 3
"pub_fund_prog_8", -- Name of public funding program 8
"operator_id", -- A unique numeric identifier assigned to each ferry operator
"op_strcity", -- City of the ferry operator mailing address
"ticket_revenue", -- Percentage of annual revenue from individual purchased tickets or fares (including fare cards)
"public_contract_revenue", -- Percentage of annual revenue from contracts with public agencies
"data_year", -- Year of the collected data
"pub_fund_prog_5", -- Name of public funding program 5
"trip_purpose_commuter_transit", -- Indicates whether the operator services commuter transit trips
"trip_purpose_emergency", -- Indicates whether the operator services emergency transit trips
"pub_fund_type_5", -- Public funding type 5
"accepts_public_funding", -- Indicates whether the operator accepts public funding
"advertising_revenue", -- Percentage of annual revenue from advertising contract payments
"federal_funding_revenue", -- Percentage of annual revenue from direct public funding (federal)
"federal_state_local", -- Completing the census on behalf of a federal, state or local government agency
"op_state", -- State of the ferry operator mailing address
"operator_name", -- The complete company name of the ferry operator
"pub_fund_prog_4", -- Name of public funding program 4
"pub_fund_prog_2", -- Name of public funding program 2
"pub_fund_prog_6" -- Name of public funding program 6
FROM
"bts-gov/2020-ncfo-operators-file-wgzf-9czk:latest"."2020_ncfo_operators_file"
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 bts-gov/2020-ncfo-operators-file-wgzf-9czk with SQL in under 60 seconds.
This repository is an "external" repository. That means it's hosted elsewhere, in this case at data.bts.gov. When you querybts-gov/2020-ncfo-operators-file-wgzf-9czk: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.bts.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 \
"bts-gov/2020-ncfo-operators-file-wgzf-9czk" \
--handler-options '{
"domain": "data.bts.gov",
"tables": {
"2020_ncfo_operators_file": "wgzf-9czk"
}
}'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, bts-gov/2020-ncfo-operators-file-wgzf-9czk is just another Postgres schema.