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 population_estimates_statewide_county_current table in this repository, by referencing it like:
"pa-gov/population-estimates-statewide-county-current-hv5f-e4e3:latest"."population_estimates_statewide_county_current"or in a full query, like:
SELECT
":id", -- Socrata column ID
"state_fips", -- These are the first 2 digits of the 5-digit Federal Information Processing Standard (FIPS) code that designate the State association. Each State has its own 2-digit number and each County within the state has its own 3-digit number which are combined into a 5-digit number to uniquely identify every US county. For more technical details : Federal Information Processing Standards Publications (FIPS PUBS) are issued by the National Institute of Standards and Technology (NIST) after approval by the Secretary of Commerce pursuant to Section 111 (d) of the Federal Property and Administrative Services Act of 1949 as amended by the Computer Security Act of 1987, Public Law 100-235. Federal Information Processing Standard (FIPS) 6-4, Counties and Equivalent Entities of the U.S., Its Possessions, and Associated Areas -- 90 Aug 31 , provides the names and codes that represent the counties and other entities treated as equivalent legal and/or statistical subdivisions of the 50 States, the District of Columbia, and the possessions and freely associated areas of the United States. Counties are considered to be the "first-order subdivisions" of each State and statistically equivalent entity, regardless of their local designations (county, parish, borough, etc.). Information gathered from census data - https://www.census.gov/library/reference/code-lists/ansi.html
"georeferenced_latitude", -- A generic georeferenced Latitude & Longitude point within the county. These points can be used to create visualizations such as maps to show the data by county. A point is also provided for outside of the state (on a map it will sit to the southeast of the state). This number represents the total number for the state and this location provides a spot on a map to display the PA number without having it duplicate within a county when using in a mapping visual.
"population", -- The population estimated by the Census Bureau's Population Estimates Program utilizing current data on births, deaths, and migration.
"as_of_date", -- Provides the "As of" date of the population estimate.
"date_description", -- Provides the as of date and type of population estimate.
"population_description", -- Describes the year, type, as of date, and vintage of the population estimate.
"county_fips", -- The FIPS county code is a five-digit Federal Information Processing Standard (FIPS) code (FIPS 6-4) which uniquely identifies counties and county equivalents in the United States, certain U.S. possessions, and certain freely associated states. This is the 3-digit part of the 5-digit county FIPS code specifically standing for the county.
"county_name", -- This is the name of the Pennsylvania County. Pennsylvania has 67 counties or Pennsylvania for Statewide information.
"geographic_area", -- Designates the population estimate as either statewide (Pennsylvania) or for the county (County Name, Pennsylvania).
"vintage", -- The vintage year (e.g., 2021) refers to the final year of the time series for the reference year (as of date) of the population estimate.
":@computed_region_4fjn_fq7k", -- This column was automatically created in order to record in what polygon from the dataset 'PA County Boundaries Spatial Data Current Transportation' (4fjn-fq7k) the point in column 'georeferenced_latitude' is located. This enables the creation of region maps (choropleths) in the visualization canvas and data lens.
":@computed_region_3x3q_vpda" -- This column was automatically created in order to record in what polygon from the dataset 'US House Districts for PA 2019' (3x3q-vpda) the point in column 'georeferenced_latitude' is located. This enables the creation of region maps (choropleths) in the visualization canvas and data lens.
FROM
"pa-gov/population-estimates-statewide-county-current-hv5f-e4e3:latest"."population_estimates_statewide_county_current"
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/population-estimates-statewide-county-current-hv5f-e4e3 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/population-estimates-statewide-county-current-hv5f-e4e3: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/population-estimates-statewide-county-current-hv5f-e4e3Checkout 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/population-estimates-statewide-county-current-hv5f-e4e3:latestThis will download all the objects for the latest tag of pa-gov/population-estimates-statewide-county-current-hv5f-e4e3 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/population-estimates-statewide-county-current-hv5f-e4e3: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/population-estimates-statewide-county-current-hv5f-e4e3: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/population-estimates-statewide-county-current-hv5f-e4e3 is just another Postgres schema.