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 ccgisdata_parcel_2021 table in this repository, by referencing it like:
"datacatalog-cookcountyil-gov/ccgisdata-parcel-2021-77tz-riq7:latest"."ccgisdata_parcel_2021"or in a full query, like:
SELECT
":id", -- Socrata column ID
"the_geom",
"assessornbhd", -- Neighborhoods are based on similar characteristics such as sales and housing type.
"assessorbldgclass", -- Codes for classification of REAL property assigned by the Assessor.
"censustract_geoid", -- Full Census FIPS code of the tract containing the parcel
"chicagoward", -- City of Chicago ward number, if parcel is within the City of Chicago
"unitschltaxdist", -- Name of the Unit School district the parcel falls within
"highschltaxdist", -- Name of the High School district the parcel falls within
"elemschltaxdist", -- Name of the elementary/middle school district the parcel falls within
"tifdistrict", -- TIF District name, if parcel is within a TIF District
"statesenatedistrict", -- Illinois State Senate district
"staterepresentativedistrict", -- Illinois State Representative district
"congressionaldistrict", -- Congressional district
"commissionerdistrict", -- Cook County Commissioner district
"politicaltownship", -- Political Township name
"municipality", -- Municipality name
"latitude", -- Latitude of the parcel centroid (within the polygon)
"longitude", -- Longitude of the parcel centroid (within the polygon)
"parceltype", -- 1-Baseparcel, 2-Elevated, 3-Condominium, 4-NoPIN, 5-ElevatedCondo, 6-Leasehold, 7-ElevatedLeasehold, 8-ROWOverlap, 9-CondominiumLeasehold
"taxcode", -- Tax code data will be added in Spring 2022. A tax code is a code which identifies the combination of taxing districts which provide services and levy property taxes to each tax parcel in Cook County.
"pinu", -- the last 4 digits of the 14 digit number. This is usually 0000, except in cases such as individual Condo units and Leasholds. Individual units are not represented by a polygon.
"pinp", -- The 8th, 9th & 10th digits, that represent a Clerk assigned Parcel number.
"pinb", -- The 5th, 6th & 7th digits, represents the Block area of the Parcel as assigned by the Clerks Office.
"pinsa", -- The 3rd & 4th digits of the parcel number, represents the subarea number (section of an Area)
"pina", -- First 2 digits of the parcel number, represents the Area number, (Township and Range)
"pin10" -- 10 digit parcel number, the first 10 digits of the parcel , often called the base parcel
FROM
"datacatalog-cookcountyil-gov/ccgisdata-parcel-2021-77tz-riq7:latest"."ccgisdata_parcel_2021"
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 datacatalog-cookcountyil-gov/ccgisdata-parcel-2021-77tz-riq7 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 datacatalog-cookcountyil-gov/ccgisdata-parcel-2021-77tz-riq7: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 datacatalog-cookcountyil-gov/ccgisdata-parcel-2021-77tz-riq7Checkout 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 datacatalog-cookcountyil-gov/ccgisdata-parcel-2021-77tz-riq7:latestThis will download all the objects for the latest tag of datacatalog-cookcountyil-gov/ccgisdata-parcel-2021-77tz-riq7 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 datacatalog-cookcountyil-gov/ccgisdata-parcel-2021-77tz-riq7: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 datacatalog-cookcountyil-gov/ccgisdata-parcel-2021-77tz-riq7: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, datacatalog-cookcountyil-gov/ccgisdata-parcel-2021-77tz-riq7 is just another Postgres schema.