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 nyc_zoning_tax_lot_database
table in this repository, by referencing it like:
"cityofnewyork-us/nyc-zoning-tax-lot-database-fdkv-4t4z:latest"."nyc_zoning_tax_lot_database"
or in a full query, like:
SELECT
":id", -- Socrata column ID
"zoning_district_1", -- The zoning district classification of the tax lot or in a limited number of cases the Zoning Resolution section number that pertains to special requirements for selected properties in Queens.
"commercial_overlay_1", -- The commercial overlay assigned to the tax lot.
"commercial_overlay_2", -- A commercial overlay associated with the tax lot.
"special_district_1", -- The special purpose district assigned to the tax lot.
"zoning_map_number", -- The Department of City Planning Zoning Map Number associated with the tax lot's X and Y Coordinates.
"zoning_district_2", -- If the tax lot is divided by zoning boundary lines, ZONING DISTRICT 2 represents the zoning classification occupying the second greatest percentage of the tax lot's area.
"special_district_2", -- The special purpose district assigned to the tax lot.
"tax_block", -- The tax block that the tax lot is located in. This field contains a one to five digit tax block number which is preceded with leading blanks when the tax block is less than five digits. Each tax block is unique within a borough (see BOROUGH).
"limited_height_district", -- The limited height district assigned to the tax lot.
"zoning_map_code", -- A code (Y) identifies a border Tax Lot, i.e., a Tax Lot on that might be on the border of two or more Zoning Maps.
"tax_lot", -- The number of the tax lot. This field contains a one to four digit tax lot number which is preceded with leading blanks when the tax lot is less than four digits. Each tax lot is unique within a tax block (see TAX BLOCK).
"zoning_district_4", -- If the tax lot is divided by zoning boundary lines, ZONING DISTRICT 4 represents the zoning classification occupying the fourth greatest percentage of the tax lot's area.
"bbl", -- A concatenation of the borough code, tax block and tax lot. This field consists of the borough code followed by the tax block followed by the tax lot. The borough code is one numeric digit. The tax block is one to five numeric digits, preceded with leading zeros when the block is less than five digits. The tax lot is one to four digits and is preceded with leading zeros when the lot is less than four digits. For condominiums, the BBL is for the billing lot. See TAX LOT for more information on how condominiums are handled. Examples: Manhattan Borough Code 1, Tax Block 16, Tax Lot 100 would be stored as 1000160100. Brooklyn Borough Code 3, Tax Block 15828, Tax Lot 7501 would be stored as 3158287501.
"zoning_district_3", -- If the tax lot is divided by zoning boundary lines, ZONING DISTRICT 3 represents the zoning classification occupying the third greatest percentage of the tax lot's area.
"borough_code", -- The borough that the tax lot is located in. (1=Manhattan, 2=Bronx, 3=Brooklyn, 4=Queens, 5=Staten Island)
"special_district_3" -- The special purpose district assigned to the tax lot.
FROM
"cityofnewyork-us/nyc-zoning-tax-lot-database-fdkv-4t4z:latest"."nyc_zoning_tax_lot_database"
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 cityofnewyork-us/nyc-zoning-tax-lot-database-fdkv-4t4z
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; sgr
can 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 clone
and sgr checkout
.
Cloning Data
Because cityofnewyork-us/nyc-zoning-tax-lot-database-fdkv-4t4z: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 cityofnewyork-us/nyc-zoning-tax-lot-database-fdkv-4t4z
Checkout 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 cityofnewyork-us/nyc-zoning-tax-lot-database-fdkv-4t4z:latest
This will download all the objects for the latest
tag of cityofnewyork-us/nyc-zoning-tax-lot-database-fdkv-4t4z
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 cityofnewyork-us/nyc-zoning-tax-lot-database-fdkv-4t4z: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 cityofnewyork-us/nyc-zoning-tax-lot-database-fdkv-4t4z:latest
This 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, cityofnewyork-us/nyc-zoning-tax-lot-database-fdkv-4t4z
is just another Postgres schema.