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 business_licenses table in this repository, by referencing it like:
"cityofchicago/business-licenses-r5kz-chrr:latest"."business_licenses"or in a full query, like:
SELECT
":id", -- Socrata column ID
":@computed_region_vrxf_vc4k",
"longitude",
"ssa", -- Special Service Areas are local tax districts that fund expanded services and programs, to foster commercial and economic development, through a localized property tax. In other cities these areas are sometimes called Business Improvement Districts (BIDs). This portal contains a map of all Chicago SSAs
"license_status_change_date",
"date_issued",
"license_approved_for_issuance", -- This is the date the license was ready for issuance. Licenses may not be issued if the customer owes debt to the City.
"license_start_date",
"payment_date",
"license_number", -- The license number known to the public and generally used in other data sources that refer to the license. This is the field most users will want for most purposes. Each license has a single license number that stays consistent throughout the lifetime of the license. By contrast, the LICENSE ID field is an internal database ID and not generally useful to external users.
"business_activity_id", -- A code for the business activity. Each ID value corresponds to a specific BUSINESS ACTIVITY value.
"police_district",
"ward_precinct", -- The ward and precinct where the business is located. This column can be used to filter by precinct more easily across multiple wards.
"ward", -- The ward where the business is located.
"address",
"doing_business_as_name",
"legal_name",
"expiration_date",
"zip_code",
"id", -- A calculated ID for each record.
"location",
"application_created_date", -- The date the business license application was created. RENEW type records do not have an application.
"site_number", -- An internal database ID indicating the location of this licensed business to account for business owners with more than one location.
"license_code", -- A code for the type of license. Each code value corresponds to a specific LICENSE DESCRIPTION value.
"precinct", -- The precinct within the ward where the business is located. Note the the same precinct numbers exist in multiple wards.
"license_id", -- An internal database ID for each record. Each license can have multiple records as it goes through renewals and other transactions. See the LICENSE NUMBER field for the number generally known to the public and used in most other data sources that refer to the license.
"license_status",
"business_activity",
"license_description",
"state",
"city",
"account_number", -- The account number of the business owner, which will stay consistent across that owner's licenses and can be used to find the owner in the Business Owners dataset.
"location_state",
"application_requirements_complete", -- For all application types except RENEW, this is the date all required application documents were received. For RENEW type records, this is the date the record was created.
"latitude",
"location_address",
"location_city",
"conditional_approval", -- This pertains to applications that contain liquor licenses. Customers may request a conditional approval prior to building out the space.
"application_type",
"location_zip",
":@computed_region_awaf_s7ux",
":@computed_region_6mkv_f3dw",
":@computed_region_43wa_7qmu",
":@computed_region_bdys_3d7i"
FROM
"cityofchicago/business-licenses-r5kz-chrr:latest"."business_licenses"
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 cityofchicago/business-licenses-r5kz-chrr 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 cityofchicago/business-licenses-r5kz-chrr: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 cityofchicago/business-licenses-r5kz-chrrCheckout 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 cityofchicago/business-licenses-r5kz-chrr:latestThis will download all the objects for the latest tag of cityofchicago/business-licenses-r5kz-chrr 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 cityofchicago/business-licenses-r5kz-chrr: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 cityofchicago/business-licenses-r5kz-chrr: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, cityofchicago/business-licenses-r5kz-chrr is just another Postgres schema.