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_services_purchases table in this repository, by referencing it like:
"citydata-mesaaz-gov/business-services-purchases-u5x3-dvhs:latest"."business_services_purchases"or in a full query, like:
SELECT
":id", -- Socrata column ID
"dept_ytd_purchase_az", -- Field used for PM calculation that shows the department's monthly purchase in Arizona total for the fiscal year to date
"dept_ytd_small_purchase_az", -- Field used for PM calculation that shows the department's monthly small purchase in Arizona total for the fiscal year to date
"award_header_actual_amount", -- Amount of the award as shown on the header of the purchasing award document
"award_header_citied_authority", -- Code indicating how the award was authorized (Council, administratively, etc.)
"accounting_period_date_format", -- Date format of the Award Header Fiscal Year and Accounting Period
"award_header_accounting_12", -- Accounting period on the header of the purchasing award document, with Period 13 listed as Period 12
"award_header_accounting_period", -- Accounting period on the header of the purchasing award document
"award_header_reporting_code_1", -- Field on the header of the purchasing award document that indicates the name of the type of purchase
"award_department_name", -- Code that identifies the department name of the purchasing award document
"award_department_code", -- Code that identifies the department code of the purchasing award document
"concatenated_award_document", -- Concatenated field that includes the Document Code, Department Code and Document ID number of the Purchasing award document from the document header
"dept_ytd_purchase_mesa", -- Field used for PM calculation that shows the department's monthly purchase in Mesa total for the fiscal year to date
"dept_ytd_small_purchase_mesa", -- Field used for PM calculation that shows the department's monthly small purchase in Mesa total for the fiscal year to date
"award_header_reporting_code", -- Field on the header of the purchasing award document that indicates type of purchase (we exclude code 800 and 810 as those are Warehouse inventory adjustments)
"vendor_state", -- Field from the vendor address record that indicates the state the vendor is in (for the vendor of record on the Purchasing document)
"vendor_city", -- Field from vendor address record that indicated the city the vendor is in (for the vendor of record on the purchasing document)
"award_document_name", -- Name of the purchasing award document as shown on the header
"row_number", -- Field used for PM calculation to indicate the row number of the purchase over department and accounting period
"award_document_procurement_1", -- Name for the procurement type used on the award document
"dept_ytd_purchase_total", -- Field used for PM calculation that shows the department's monthly purchase total for the fiscal year to date
"purchase_under_25000_flag", -- Field which indicates if the header of the purchasing award document was greater than or equal to $25,000
"award_document_version_number", -- Version number of the purchasing award document from the document header (we only look at version 1 so the document isn’t included multiple times)
"award_document_code", -- Code that identifies the type of purchasing award document (i.e. PO, DO, CT)
"award_document_procurement", -- Code for the procurement type used on the award document (we only look at Purchasing Procurement Types 1, 2, 3, 4, 5, 6, and 7)
"award_header_fiscal_year", -- Fiscal year on the header of the purchasing award document
"award_document_id", -- Document ID number of the Purchasing award document from the document header
"dept_ytd_small_purchase_total" -- Field used for PM calculation that shows the department's monthly small purchase total for the fiscal year to date
FROM
"citydata-mesaaz-gov/business-services-purchases-u5x3-dvhs:latest"."business_services_purchases"
LIMIT 100;Connecting to the DDN is easy. All you need is an existing SQL client that can connect to Postgres. As long as you have a SQL client ready, you'll be able to query citydata-mesaaz-gov/business-services-purchases-u5x3-dvhs with SQL in under 60 seconds.
This repository is an "external" repository. That means it's hosted elsewhere, in this case at citydata.mesaaz.gov. When you querycitydata-mesaaz-gov/business-services-purchases-u5x3-dvhs:latest on the DDN, we "mount" the repository using the socrata mount handler. The mount handler proxies your SQL query to the upstream data source, translating it from SQL to the relevant language (in this case SoQL).
We also cache query responses on the DDN, but we run the DDN on multiple nodes so a CACHE_HIT is only guaranteed for subsequent queries that land on the same node.
Query Your Local Engine
bash -c "$(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 citydata.mesaaz.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 \
"citydata-mesaaz-gov/business-services-purchases-u5x3-dvhs" \
--handler-options '{
"domain": "citydata.mesaaz.gov",
"tables": {
"business_services_purchases": "u5x3-dvhs"
}
}'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, citydata-mesaaz-gov/business-services-purchases-u5x3-dvhs is just another Postgres schema.