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 annual_average_daily_traffic_aadt_beginning_1977 table in this repository, by referencing it like:
"ny-gov/annual-average-daily-traffic-aadt-beginning-1977-6amx-2pbv:latest"."annual_average_daily_traffic_aadt_beginning_1977"or in a full query, like:
SELECT
":id", -- Socrata column ID
"municipality", -- Name of the municipality in which the AADT was calculated
"ending_description", -- The verbal description of the end of the segment of roadway for which the AADT applies
"road_name", -- The name of the road.
"county_road", -- A road designated with a county-level road number.
"state_route", -- A road designated with an Interstate or NY route number.
"signing", -- Designates what kind of a route or roadway the segment of roadway is. • Interstate: Interstate designation commonly known as the Interstate Highway System, a network of controlled-access highways that forms a part of the National Highway System. • US: US designation of a set of roads typically called U.S. Routes or U.S. Highways which forms an integrated network of roads and highways numbered within a nationwide grid in the United States. • NY: New York State Highway designation assigned at the State level. A blank field designates a ‘Local’ town, municipality or city roadway.
"beginning_description", -- The verbal description of the start of the segment of roadway for which the AADT applies
"ramp", -- Signifies by either a “Y” for yes or blank for no if a ramp is included in the roadway segment.
"bridge", -- Signifies by either a “Y” for yes or blank for no if a bridge is included in the roadway segment.
"oneway", -- Signifies by either a “Y” for yes or blank for no if the roadway segment is a one-way direction.
"county", -- The county where the count station exists.
"station_id", -- Unique identifier for each traffic count station concatenated from the region county code and the station number.
"aadt_year", -- Year for which the annual average daily traffic (AADT) volume value is recorded.
"rr_xing", -- Signifies by either a “Y” for yes or blank for no if a railroad crossing is included in the roadway segment.
"fc", -- The functional class of the roadway segment to which the count station applies. For more information on functional class, consult the FHWA link below. https://www.dot.ny.gov/gisapps/functional-class-maps
"count", -- Annual Average Daily Traffic (AADT) volume value: On any given day, the average numbers of vehicles that pass the segment of roadway as described by the Begin/End Descriptions. These figures are based on an actual count taken for that year or statistically validated estimated and forecasted values.
"length" -- The length of the road segment to which the count station applies.
FROM
"ny-gov/annual-average-daily-traffic-aadt-beginning-1977-6amx-2pbv:latest"."annual_average_daily_traffic_aadt_beginning_1977"
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 ny-gov/annual-average-daily-traffic-aadt-beginning-1977-6amx-2pbv with SQL in under 60 seconds.
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, 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 (like this repository), where the author has pushed Splitgraph Images to the repository, you can "clone" and/or "checkout" the data using sgr cloneand sgr checkout.
Cloning Data
Because ny-gov/annual-average-daily-traffic-aadt-beginning-1977-6amx-2pbv:latest is a Splitgraph Image, you can clone the data from Spltgraph Cloud to your local engine, where you can query it like any other Postgres database, using any of your existing tools.
First, install Splitgraph if you haven't already.
Clone the metadata with sgr clone
This will be quick, and does not download the actual data.
sgr clone ny-gov/annual-average-daily-traffic-aadt-beginning-1977-6amx-2pbvCheckout the data
Once you've cloned the data, you need to "checkout" the tag that you want. For example, to checkout the latest tag:
sgr checkout ny-gov/annual-average-daily-traffic-aadt-beginning-1977-6amx-2pbv:latestThis will download all the objects for the latest tag of ny-gov/annual-average-daily-traffic-aadt-beginning-1977-6amx-2pbv and load them into the Splitgraph Engine. Depending on your connection speed and the size of the data, you will need to wait for the checkout to complete. Once it's complete, you will be able to query the data like you would any other Postgres database.
Alternatively, use "layered checkout" to avoid downloading all the data
The data in ny-gov/annual-average-daily-traffic-aadt-beginning-1977-6amx-2pbv:latest is 0 bytes. If this is too big to download all at once, or perhaps you only need to query a subset of it, you can use a layered checkout.:
sgr checkout --layered ny-gov/annual-average-daily-traffic-aadt-beginning-1977-6amx-2pbv:latestThis will not download all the data, but it will create a schema comprised of foreign tables, that you can query as you would any other data. Splitgraph will lazily download the required objects as you query the data. In some cases, this might be faster or more efficient than a regular checkout.
Read the layered querying documentation to learn about when and why you might want to use layered queries.
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, ny-gov/annual-average-daily-traffic-aadt-beginning-1977-6amx-2pbv is just another Postgres schema.