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 real_property_transactions_of_local_development table in this repository, by referencing it like:
"ny-gov/real-property-transactions-of-local-development-ajgp-mddq:latest"."real_property_transactions_of_local_development"or in a full query, like:
SELECT
":id", -- Socrata column ID
"property_description", -- Description of the real property transacted. Can be either commercial building, industrial facility/plant, mixed use, office building, residential building, or vacant lot/Undeveloped land.
"relation_with_authority", -- Yes/No field to indicate whether the Seller/Purchaser/Tenant has, or had within the last two years, a personal or professional relationship with a Board member or senior management of the authority.
"estimated_fair_market_value", -- Estimated fair market value of the transacted property.
"property_postal_code", -- Zip code of the real property transacted
"seller_purchaser_tenant", -- Lease rate ($ per square foot) of the transacted property. This field is blank if it doesn't apply or if the authority didn’t enter any information.
"seller_purchaser_tenant_state", -- State of the Seller's/Purchaser's/Tenant's address
"lease_period", -- Duration (months) of the lease of the transacted property. This field is blank if it doesn't apply or if the authority didn’t enter any information.
"market_rate", -- Market rate ($ per square foot) of the transacted property. This field is blank if it doesn't apply or if the authority didn’t enter any information.
"property_address1", -- Address of the real property transacted
"purchase_sale_price", -- Price for which the property was transacted (purchased or sold). This field is blank if it doesn't apply or if the authority didn't enter any information.
"seller_purchaser_tenant_city", -- City of the Seller's/Purchaser's/Tenant's address
"authority_name", -- Name of the Public Authority
"property_transactions", -- No indicates that the authority reported having no real property transactions during the fiscal year. No other information is provided for the reporting period. A blank indicates that property transactions are reported, and data is reported in the remaining fields.
"property_state", -- State of the real property transacted
"fiscal_year_end_date", -- Date of Fiscal Year end for the Authority
"property_address2", -- Additional address detail of the real property transacted
"seller_purchaser_tenant_postal_code", -- Zip code of the Seller's/Purchaser's/Tenant's address
"transaction_type", -- Indicates whether the property transaction was an acquisition, disposition (lease), disposition (lease purchase), disposition (sale), or disposition (other).
"property_city", -- City of the real property transacted
"fair_market_description", -- Indicates how the estimated fair market value of the transacted property was determined. Can be either appraisal, competitive bid, or other.
"transaction_type_other", -- Provides additional information about the transaction type. This field is blank if the authority didn’t enter any information.
"transaction_date", -- Date when the property transaction took place.
"lease_rate" -- Lease rate ($ per square foot) of the transacted property. This field is blank if it doesn't apply or if the authority didn’t enter any information.
FROM
"ny-gov/real-property-transactions-of-local-development-ajgp-mddq:latest"."real_property_transactions_of_local_development"
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/real-property-transactions-of-local-development-ajgp-mddq with SQL in under 60 seconds.
This repository is an "external" repository. That means it's hosted elsewhere, in this case at data.ny.gov. When you queryny-gov/real-property-transactions-of-local-development-ajgp-mddq:latest on the DDN, we "mount" the repository using the socrata mount handler. The mount handler proxies your SQL query to the upstream data source, translating it from SQL to the relevant language (in this case SoQL).
We also cache query responses on the DDN, but we run the DDN on multiple nodes so a CACHE_HIT is only guaranteed for subsequent queries that land on the same node.
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 (like this repository), 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, where the author has pushed Splitgraph Images to the repository, you can "clone" and/or "checkout" the data using sgr cloneand sgr checkout.
Mounting Data
This repository is an external repository. It's not hosted by Splitgraph. It is hosted by data.ny.gov, and Splitgraph indexes it. This means it is not an actual Splitgraph image, so you cannot use sgr clone to get the data. Instead, you can use the socrata adapter with the sgr mount command. Then, if you want, you can import the data and turn it into a Splitgraph image that others can clone.
First, install Splitgraph if you haven't already.
Mount the table with sgr mount
sgr mount socrata \
"ny-gov/real-property-transactions-of-local-development-ajgp-mddq" \
--handler-options '{
"domain": "data.ny.gov",
"tables": {
"real_property_transactions_of_local_development": "ajgp-mddq"
}
}'That's it! Now you can query the data in the mounted table like any other Postgres table.
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/real-property-transactions-of-local-development-ajgp-mddq is just another Postgres schema.