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 municipalboundary table in this repository, by referencing it like:
"pa-gov/municipalboundary-23n7-cwjw:latest"."municipalboundary"or in a full query, like:
SELECT
":id", -- Socrata column ID
"the_geom",
"shape_length", -- Shape Length
"shape_area", -- Shape Area
"ansi_code", -- American National Standards Institute, 7 digit code
"county_name", -- PA has 67 counties. This is the name of the county.
"planning_partner", -- Planning partner name. ACTPO - Adams County Transportation Planning Organization; Altoona - Blair County Planning Commission-Altoona MSA; Centre - Centre Region Planning Agency; DVRPC - Delaware Valley Regional Planning Commission; Erie - Erie Area Transportation Study; Franklin - Franklin County Metropolitan Planning Organization; Harrisburg - Harrisburg Area Transportation Study; Johnstown - Johnstown Area Transportation Study; Lancaster - Lancaster County Transportation Coordinating Committee; Lebanon - Lebanon County Planning Department; Lehigh Valley - Lehigh Valley Transportation Study; NEPA - Northwest Pennsylvania Metropolitan Transportation Planning Organization; North Central - North Central PA Planning and Development Commission; Northern Tier - Northern Tier Regional Planning and Development Commission; Northwest - Northwest PA Regional Planning and Development Commission; Reading - Reading Area Transportation Study; Scranton/W-B - Lackawanna/Luzerne Transportation Study; SEDA-COG - SEDA-COG; Southern Alleghenies - Southern Alleghenies Planning and Development Commission; SPC - Southwestern Pennsylvania Commission; SVTS - Shenango Valley Transportation Study; Wayne - Wayne County Planning Commission; Williamsport - Williamsport Area Transportation Study; York - York Area Metropolitan Planning Organization
"class_of_munic", -- Class of municipality; 1st class township - First class townships population density must be greater than 300 people in a square mile; 2nd class township - Second class townships population density cannot be greater than 300 people in a square mile; Borough - Boroughs have no population density requirements; City - Philadelphia - 1st Class City, Pittsburgh - 2nd class City, Scranton - 2nd Class ``A`` City, the remaining cities are 3rd Class; Town - Bloomsburg is the only Town in Pennsylvania
"fed_id_num", -- Federal ID Number
"fips_mun_pop", -- Federal Information Processing Standards Municipal population
"fips_name", -- Federal Information Processing Standards Associated metropolitan area name
"fips_county_code", -- Federal Information Processing Standards, 3 digit code that identifies county
"municipal_name", -- Municipality name
"municipal_code", -- Municipality code number
"county", -- PennDOT County Code
"objectid",
"gnis_ppl",
"dced_id", -- Department of Community and Economic Development identification number
"district_no", -- PennDOT Engineering District number; 01 - District 1-0; 02 - District 2-0; 03 - District 3-0; 04 - District 4-0; 05 - District 5-0; 06 - District 6-0; 08 - District 8-0; 09 - District 9-0; 10 - District 10-0; 11 - District 11-0; 12 - District 12-0
"fips_code", -- Federal Information Processing Standards, 10 digit code that identifies state, county and municipality
"fips_state_code", -- 42 - PENNSYLVANIA - Federal Information Processing Standards, 2 digit code that identifies state
"fips_sq_mi",
"fips_area_code", -- Associated metropolitan area code
"fed_aid_urb_area", -- Federal Aid Urban Area code
"fips_mun_code" -- Federal Information Processing Standards, 5 digit code that identifies municipality
FROM
"pa-gov/municipalboundary-23n7-cwjw:latest"."municipalboundary"
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 pa-gov/municipalboundary-23n7-cwjw 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 pa-gov/municipalboundary-23n7-cwjw: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 pa-gov/municipalboundary-23n7-cwjwCheckout 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 pa-gov/municipalboundary-23n7-cwjw:latestThis will download all the objects for the latest tag of pa-gov/municipalboundary-23n7-cwjw 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 pa-gov/municipalboundary-23n7-cwjw: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 pa-gov/municipalboundary-23n7-cwjw: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, pa-gov/municipalboundary-23n7-cwjw is just another Postgres schema.