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 public_charging_stations_for_electric_vehicles table in this repository, by referencing it like:
"edmonton-ca/public-charging-stations-for-electric-vehicles-xzhy-xe8z:latest"."public_charging_stations_for_electric_vehicles"or in a full query, like:
SELECT
":id", -- Socrata column ID
"open_date", -- Either the date provided by the charging network or the date it appeared in the Station Locator if the charging network does not provide an open date. For planned and temporarily unavailable stations, see expected_date for the date when the station is expected to open or reopen
"street_address", -- The street address of the station's location
"ev_other_evse", -- The number and type of additional EVSE ports, such as SP Inductive (Small paddle inductive), LP Inductive (Large paddle inductive), Avcon Conductive
"access_code", -- A description of who is allowed to access the station
"longitude", -- The longitude of the station's address
"latitude", -- The latitude of the station's address
"station_phone", -- The phone number of the station.
"expected_date", -- For planned stations, the date the station is expected to open or start carrying alternative fuel. For temporarily unavailable stations, the date the station is expected to reopen. This date is estimated.
"ev_network_web", -- The EV charging network Web site, if applicable.
"station_name", -- The name of the station
"access_days_time", -- Hours of operation for the station.
"access_detail_code", -- A description of other station access information
"total_ports", -- Number of charging ports present at location
"ev_pricing", -- Information about whether and how much users must pay to use the EVSE port.
"installer", -- Indicates whether the station is installed by the City of Edmonton, ATCO, Encor by EPCOR, or another agency. This field is maintained by the City of Edmonton.
"status", -- The current status of the station
"id", -- A unique identifier for this specific station
"ev_level1_evse_num", -- Number of Level 1 EVSE charging ports present at location
"ev_network", -- The name of the EV charging network, if applicable
"city", -- The city of the station's location
"ev_level2_evse_num", -- Number of Level 2 EVSE charging ports present at location
"ev_connector_types", -- An array of strings identifying the connector types available at this station
"ev_dc_fast_num" -- Number of DC Fast charging ports present at location
FROM
"edmonton-ca/public-charging-stations-for-electric-vehicles-xzhy-xe8z:latest"."public_charging_stations_for_electric_vehicles"
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 edmonton-ca/public-charging-stations-for-electric-vehicles-xzhy-xe8z 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 edmonton-ca/public-charging-stations-for-electric-vehicles-xzhy-xe8z: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 edmonton-ca/public-charging-stations-for-electric-vehicles-xzhy-xe8zCheckout 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 edmonton-ca/public-charging-stations-for-electric-vehicles-xzhy-xe8z:latestThis will download all the objects for the latest tag of edmonton-ca/public-charging-stations-for-electric-vehicles-xzhy-xe8z 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 edmonton-ca/public-charging-stations-for-electric-vehicles-xzhy-xe8z: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 edmonton-ca/public-charging-stations-for-electric-vehicles-xzhy-xe8z: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, edmonton-ca/public-charging-stations-for-electric-vehicles-xzhy-xe8z is just another Postgres schema.