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 summary_of_real_property_tax_exemptions_by_code_by table in this repository, by referencing it like:
"ny-gov/summary-of-real-property-tax-exemptions-by-code-by-ykg4-r7ad:latest"."summary_of_real_property_tax_exemptions_by_code_by"or in a full query, like:
SELECT
":id", -- Socrata column ID
"exemption_description", -- A brief description of the application/purpose of the exemption. Detailed descriptions are available through the on-line Assessor’s Manual, Volume 4 (Exemption Administration), at: http://www.tax.ny.gov/research/property/assess/manuals/vol4/pt1/section2/sec2_02.htm
"county_name", -- Name of County of Municipality
"exempt_parcels", -- The number of parcels containing the exemption
"exemption_code_number", -- The first four digits of the exemption code number used to identify and record the exemption on the assessment roll
"exemption_group_type", -- Group classification of exemption according to property type and/or owner; the types are defined as: A – Residential, other than multiple dwellings; B – New York State government; C – Municipal governments; D – U.S., foreign governments, interstate agencies; E – Private community service and social organizations; F – Industrial, commercial and public service; G – Multiple dwellings and urban renewal; H – Agricultural and forest.
"swis_code", -- Tax and Finance Code for Municipality
"law_type_section", -- The law reference (law type and section) to the exemption. The types are abbreviated and are identified more completely at: http://www.tax.ny.gov/research/property/assess/manuals/vol4/pt1/section1.htm
"estimated_total_full_value_of_exempt_amount", -- The estimated full value of the exemption amounts for parcels containing the exemption
"total_exempt_amount", -- The assessed value of the exemption amounts for parcels containing the exemption
"estimated_total_full_value_of_exempt_parcels", -- The estimated full value of the parcels containing the exemption
"total_assessed_value_of_exempt_parcels", -- The assessed value of the parcels containing the exemption
"municipality_name", -- Name of Municipality
"roll_year" -- Assessment Roll Year
FROM
"ny-gov/summary-of-real-property-tax-exemptions-by-code-by-ykg4-r7ad:latest"."summary_of_real_property_tax_exemptions_by_code_by"
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 ny-gov/summary-of-real-property-tax-exemptions-by-code-by-ykg4-r7ad 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 ny-gov/summary-of-real-property-tax-exemptions-by-code-by-ykg4-r7ad: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 ny-gov/summary-of-real-property-tax-exemptions-by-code-by-ykg4-r7adCheckout 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 ny-gov/summary-of-real-property-tax-exemptions-by-code-by-ykg4-r7ad:latestThis will download all the objects for the latest tag of ny-gov/summary-of-real-property-tax-exemptions-by-code-by-ykg4-r7ad 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 ny-gov/summary-of-real-property-tax-exemptions-by-code-by-ykg4-r7ad: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 ny-gov/summary-of-real-property-tax-exemptions-by-code-by-ykg4-r7ad: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, ny-gov/summary-of-real-property-tax-exemptions-by-code-by-ykg4-r7ad is just another Postgres schema.