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 iowa_fire_department_census table in this repository, by referencing it like:
"mydata-iowa-gov/iowa-fire-department-census-hv43-6ksq:latest"."iowa_fire_department_census"or in a full query, like:
SELECT
":id", -- Socrata column ID
"active_firefighters_paid_per_call", -- The total number of firefighters in the department who are not full-time paid firefighters but receive compensation for their participation. A value of 0 is listed if there are no firefighters of this type in the department.
"active_firefighters_volunteer", -- The total number of firefighters who receive no compensation for their services. A value of 0 is listed if there are no firefighters of this type in the department.
"active_firefighters_career", -- The total number of full-time paid fire officers and firefighters. A value of 0 is listed if there are no firefighters of this type in the department.
"county",
"hq_phone",
"mail_city",
"mail_addr2",
"mail_addr1",
"fire_dept_name",
"hq_fax",
"website",
"organization_type",
"mail_zip",
"mail_po_box",
"hq_zip",
"hq_city",
"hq_addr2",
"hq_addr1",
"fdid", -- A unique identifier assigned by the state for fire incident reporting purposes.
"primary_agency_for_em", -- "Yes" indicates the fire department is the primary agency responsible for emergency management in your community. Emergency Management is the integration and coordination of all-hazards mitigation, prevention, preparedness, response and recovery activities within a community for all (or most) agencies such as fire, Emergency Medical Services, public works, public information, volunteer service, etc. If null, answer was not provided in registration.
"dept_type", -- Broad classification for the fire department.
"hq_state",
"non_firefighting_civilian", -- Full time and part-time non-firefighting employees with the department. A value of 0 indicates their are no employees of this type with the department.
"non_firefighting_volunteer", -- Volunteers who receive no compensation. A value of 0 is listed if there are no volunteers of this type in the department.
"number_stations", -- Total number of stations within the department including headquarters.
"mail_state",
"hq_location", -- Geocoded location based on the headquarter address provided for the fire department. Accuracy will largely depend on how well addresses were formatted, and how complete they are. This data field was not included in the federal dataset.
":@computed_region_e7ym_nrbf",
":@computed_region_uhgg_e8y2",
":@computed_region_i9mz_6gmt",
":@computed_region_wnea_7qqw",
":@computed_region_3r5t_5243"
FROM
"mydata-iowa-gov/iowa-fire-department-census-hv43-6ksq:latest"."iowa_fire_department_census"
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 mydata-iowa-gov/iowa-fire-department-census-hv43-6ksq 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 mydata-iowa-gov/iowa-fire-department-census-hv43-6ksq: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 mydata-iowa-gov/iowa-fire-department-census-hv43-6ksqCheckout 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 mydata-iowa-gov/iowa-fire-department-census-hv43-6ksq:latestThis will download all the objects for the latest tag of mydata-iowa-gov/iowa-fire-department-census-hv43-6ksq 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 mydata-iowa-gov/iowa-fire-department-census-hv43-6ksq: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 mydata-iowa-gov/iowa-fire-department-census-hv43-6ksq: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, mydata-iowa-gov/iowa-fire-department-census-hv43-6ksq is just another Postgres schema.