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 inmate_vocational_training_status_cy_2018_current table in this repository, by referencing it like:
"pa-gov/inmate-vocational-training-status-cy-2018-current-xpkf-94wz:latest"."inmate_vocational_training_status_cy_2018_current"or in a full query, like:
SELECT
":id", -- Socrata column ID
":@computed_region_amqz_jbr4",
":@computed_region_d3gw_znnf",
"month", -- Month the inmate is receiving the training or certification
":@computed_region_nmsq_hqvv",
"mn_yr", -- Month and Year combined date field signifying what month and year the inmate is receiving the training or certification
"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
"year", -- Year the inmate is receiving the training or certification
"num_of_inmates", -- Total number of inmates enrolled in vocational programs with a minimum sentence of 2 years or less
":@computed_region_r6rf_p9et",
"county_name", -- County from which the inmate was sentenced to the Pennsylvania Department of Corrections
"num_of_inmates_with", -- Total number of inmates with vocation program certifications with a minimum sentence of 2 years or less
":@computed_region_rayf_jjgk",
"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_code_number", -- Two-digit State Number for County from which the inmate was sentenced to the Pennsylvania Department of Corrections
"geocoded_column", -- Georeferenced column for use in creating mapping visualizations with both latitude and longitude of the inmate's county
"avg_hrs", -- Average number of hours of vocational training taken for inmates in vocational programs with a minimum sentence of 2 years or less
"county_code", -- Two-digit State code for County from which the inmate was sentenced to the Pennsylvania Department of Corrections
"longitude", -- If the Longitude point is null, then the county is outside of Pennsylvania or unknown. This is a generic point for longitude in each county to give the ability to create visualizations such as map layers. The longitude for the state of Pennsylvanian will fall to the south east of Pennsylvania actually in Maryland so that the information for a statewide total can also be displayed on a map layer without affecting information in another county.
"latitude" -- If the Latitude point is null, then the county is outside of Pennsylvania or unknown. This is a generic point for latitude in each county to give the ability to create visualizations such as map layers. The latitude for the state of Pennsylvanian will fall to the south east of Pennsylvania actually in Maryland so that the information for a statewide total can also be displayed on a map layer without affecting information in another county.
FROM
"pa-gov/inmate-vocational-training-status-cy-2018-current-xpkf-94wz:latest"."inmate_vocational_training_status_cy_2018_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/inmate-vocational-training-status-cy-2018-current-xpkf-94wz 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/inmate-vocational-training-status-cy-2018-current-xpkf-94wz: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/inmate-vocational-training-status-cy-2018-current-xpkf-94wzCheckout 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/inmate-vocational-training-status-cy-2018-current-xpkf-94wz:latestThis will download all the objects for the latest tag of pa-gov/inmate-vocational-training-status-cy-2018-current-xpkf-94wz 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/inmate-vocational-training-status-cy-2018-current-xpkf-94wz: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/inmate-vocational-training-status-cy-2018-current-xpkf-94wz: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/inmate-vocational-training-status-cy-2018-current-xpkf-94wz is just another Postgres schema.