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 road_attributes_in_colorado_2021 table in this repository, by referencing it like:
"colorado-gov/road-attributes-in-colorado-2021-ccz9-ggrb:latest"."road_attributes_in_colorado_2021"or in a full query, like:
SELECT
":id", -- Socrata column ID
"objectid", -- Esri auto generated unique identifier
"guid", -- globally unique ID
"tofeature", -- to feature description
"fromfeature", -- from feature description
"forestroute", -- forest service route
"yrrehab", -- year rehab
"iridate", -- International Roughness Index collection date
"iri", -- International Roughness Index
"aadtcomb", -- AADT for combination axle trucks
"aadt", -- The annual average daily traffic count for the segment. (Total of all vehicles counted in a year divided by 365 days)
"surfwd", -- Roadway surface width in feet
"uabname", -- urban area name
"urban", -- The appropriate urbanized area code, depending on which urbanized area the section mileage falls within. City FIPS code is used for small urban cities (5,000-50,000 population).
"gisid", -- GIS ID
"routename", -- name of route
"length_", -- segment length in miles
"runlength_to", -- end measure
"segmid", -- segment ID
"countyear", -- traffic count year
"aadtsingle", -- AADT for single axle trucks
"adminclass", -- administrative class
"govlevel", -- A designation of the level of government responsible for the naming of the segment of the road and establish traffic countrols on the segment as defined by FHWA.
"todesc", -- description to
"runlength_from", -- begin measure
"lrsroute", -- CDOT local route identifier
"segprefix", -- segment prefix
"fips", -- FIPS code for city or county
"terrain", -- terrain type
"treatmentdepth", -- treatment depth
"builtyr", -- year built
"hutf_projyr", -- Highway Users Tax Fund project year
"hutf_inspyr", -- Highway Users Tax Fund inspection year
"psr", -- n/a
"dvmt", -- Daily Vehicle Miles Traveled
"countstationid", -- Traffic count station identifier
"thrulnwd", -- Through lane width in feet
"operation", -- One-way or two-way operation
"tprid", -- Transportation Planning Region number
"region", -- CDOT region number
"specialsys", -- A code that indicates whether the roadway segment is on the STRAHNET or is a STRAHNET connector. STRAHNET is used by the Department of Defense (DOD) to identify strategic deployment routes.
"fipscounty", -- County FIPS code
"segmdir", -- segment direction
"route", -- route ID
"rrxid", -- railroad crossing
"surf", -- Roadway surface type
"access_", -- Access Control code
"trkrestrict", -- truck restrictions
"fundid", -- federal funding class
"fromdesc", -- description from
"aadtyr", -- AADT calculation year
"thrulnqty", -- Through Lane Quantity
"population", -- A numeric code, established by the U.S. Bureau of census, which categorizes a geographic area by the population count.
"funcclassid", -- functional class code
"nhsdesig", -- The road segment has been designated as being part of the National Highway System
"updateyr", -- year of publication (one year newer than data year)
"jursplit", -- n/a
"aadtderiv" -- Code Associated with the Factoring Method used in calculating the AADT determination Value.
FROM
"colorado-gov/road-attributes-in-colorado-2021-ccz9-ggrb:latest"."road_attributes_in_colorado_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 colorado-gov/road-attributes-in-colorado-2021-ccz9-ggrb with SQL in under 60 seconds.
This repository is an "external" repository. That means it's hosted elsewhere, in this case at data.colorado.gov. When you querycolorado-gov/road-attributes-in-colorado-2021-ccz9-ggrb: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.colorado.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 \
"colorado-gov/road-attributes-in-colorado-2021-ccz9-ggrb" \
--handler-options '{
"domain": "data.colorado.gov",
"tables": {
"road_attributes_in_colorado_2021": "ccz9-ggrb"
}
}'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, colorado-gov/road-attributes-in-colorado-2021-ccz9-ggrb is just another Postgres schema.