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 2022_general_election_mail_ballot_requests table in this repository, by referencing it like:
"pa-gov/2022-general-election-mail-ballot-requests-uhfm-zhus:latest"."2022_general_election_mail_ballot_requests"or in a full query, like:
SELECT
":id", -- Socrata column ID
"latitude", -- Generic Latitude for the County(centroid)
"appissuedate", -- his is the date the application was submitted by the voter.
":@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 'georeference' 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 'georeference' is located. This enables the creation of region maps (choropleths) in the visualization canvas and data lens.
"mailapplicationtype", -- This identifies the type of mail ballot requested by the voter. Alt - This is an alternative ballot application where voters who are 65 years of age and the polling place may not be fully accessible. BV - Bedridden Veteran. BVRI - Bedridden Veteran - Remote/Isolated C- This is an absentee ballot application issued during the emergency absentee period. CIV- This is a civilian absentee ballot application that was submitted via paper. CRI- This is an absentee ballot application for an overseas civilian voter in a remote/isolated location. CVO- This is an absentee ballot application for an overseas civilian voter. F- This is an absentee application for an individual who qualifies to vote for federal offices in federal election years. OLMAILV-This is a mail ballot application that was submitted online. M-This is an absentee ballot application for a military voter. MAILIN-This is a mail-in ballot application. MRI-This is an absentee ballot application for a military voter in a remote/isolated location. OLREGV-This is a civilian absentee ballot application that was submitted online. PER-This is an absentee ballot application where a voter has requested permanent status. PMI- This is a mail ballot application where the voter has requested permanent status. REG-This is an absentee ballot application that was submitted via paper. OLMAILNV: Online Mail-In Ballot Application. Not Verified OLREGNV: Online Regular Absentee Ballot Application. V - Veteran. Not Verified BV: Bedridden Veteran (which is a form of Absentee Ballot Application)
"georeference", -- Georeferenced Latitude & Longitude to be used for creating visualizations such as maps.
"senate", -- This is the voter's state senate district.
"dateofbirth", -- This is the voter's date of birth. The reason some birth dates will display as 1/1/1800 is due to confidentiality reasons of the registered votes. Usually this is for victims of domestic violence.
"countyname", -- This identifies the county of the voter when submitting an application to vote by mail ballot in the upcoming election.
"congressional", -- This is the voter's congressional district.
"party", -- This identifies the voter's party when submitting their application. Applicant party code definitions are listed in a text file on the primer or metadata page under attachments.
"longitude", -- Generic Longitude for the County(centroid)
"legislative", -- This is the voter's state house district.
"ballotsentdate", -- This is the date the county confirmed the application to queue a ballot label to mail the ballot materials to the voter.
"ballotreturneddate", -- This is the date the county marked the ballot as received after the voter mailed the voted ballot back to the county.
"appreturndate" -- This is the date the application was processed by the county election office.
FROM
"pa-gov/2022-general-election-mail-ballot-requests-uhfm-zhus:latest"."2022_general_election_mail_ballot_requests"
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/2022-general-election-mail-ballot-requests-uhfm-zhus 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/2022-general-election-mail-ballot-requests-uhfm-zhus: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/2022-general-election-mail-ballot-requests-uhfm-zhusCheckout 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/2022-general-election-mail-ballot-requests-uhfm-zhus:latestThis will download all the objects for the latest tag of pa-gov/2022-general-election-mail-ballot-requests-uhfm-zhus 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/2022-general-election-mail-ballot-requests-uhfm-zhus: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/2022-general-election-mail-ballot-requests-uhfm-zhus: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/2022-general-election-mail-ballot-requests-uhfm-zhus is just another Postgres schema.