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
"population_description", -- Describes the year, type, as of date, and vintage of the population estimate.
"population", -- The population estimated by the Census Bureau's Population Estimates Program utilizing current data on births, deaths, and migration.
":@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.
":@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.
"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.
"geographic_area", -- Designates the population estimate as either statewide (Pennsylvania) or for the county (County Name, Pennsylvania).
"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.
"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
"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.
"date_description", -- Provides the as of date and type of population estimate.
"as_of_date" -- Provides the "As of" date of the population estimate.
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.
This repository is an "external" repository. That means it's hosted elsewhere, in this case at data.pa.gov. When you querypa-gov/population-estimates-statewide-county-current-hv5f-e4e3:latest on the DDN, we "mount" the repository using the socrata mount handler. The mount handler proxies your SQL query to the upstream data source, translating it from SQL to the relevant language (in this case SoQL).
We also cache query responses on the DDN, but we run the DDN on multiple nodes so a CACHE_HIT is only guaranteed for subsequent queries that land on the same node.
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 (like this repository), 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, where the author has pushed Splitgraph Images to the repository, you can "clone" and/or "checkout" the data using sgr cloneand sgr checkout.
Mounting Data
This repository is an external repository. It's not hosted by Splitgraph. It is hosted by data.pa.gov, and Splitgraph indexes it. This means it is not an actual Splitgraph image, so you cannot use sgr clone to get the data. Instead, you can use the socrata adapter with the sgr mount command. Then, if you want, you can import the data and turn it into a Splitgraph image that others can clone.
First, install Splitgraph if you haven't already.
Mount the table with sgr mount
sgr mount socrata \
"pa-gov/population-estimates-statewide-county-current-hv5f-e4e3" \
--handler-options '{
"domain": "data.pa.gov",
"tables": {
"population_estimates_statewide_county_current": "hv5f-e4e3"
}
}'That's it! Now you can query the data in the mounted table like any other Postgres table.
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.