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 onstreet_car_park_bay_restrictions table in this repository, by referencing it like:
"melbourne-vic-gov-au/onstreet-car-park-bay-restrictions-ntht-5rk7:latest"."onstreet_car_park_bay_restrictions"or in a full query, like:
SELECT
":id", -- Socrata column ID
"endtime2", -- The time each day when the restriction ends.
"duration2", -- The time (in minutes) that a vehicle can park at this location.
"description6", -- A compact, semi-human-readable description of the overall restrictions.
"starttime3", -- The time each day when the restriction applies.
"description2", -- Description: A compact, semi-human-readable description of the overall restrictions.
"endtime4", -- The time each day when the restriction ends.
"exemption1", -- Which vehicles are exempt.
"disabilityext3", -- For bays that aren't limited to disabled permits, how much time (minutes) a vehicle with disabled permit can spend in the spot. Usually twice the regular amount of time.
"duration1", -- The time (in minutes) that a vehicle can park at this location.
"endtime3", -- The time each day when the restriction ends.
"starttime2", -- The time each day when the restriction applies.
"duration5", -- The time (in minutes) that a vehicle can park at this location.
"fromday4", -- The first day in the range on which this restriction applies (0=Sunday, 6=Saturday)
"typedesc5", -- The type of restriction. Eg: "2P Meter" (two hour parking, paid for using a meter), "Disabled Only" (only vehicles with disabled permits can park).
"starttime5", -- The time each day when the restriction applies.
"starttime1", -- The time each day when the restriction applies.
"description3", -- Description: A compact, semi-human-readable description of the overall restrictions.
"disabilityext1", -- For bays that aren't limited to disabled permits, how much time (minutes) a vehicle with disabled permit can spend in the spot. Usually twice the regular amount of time.
"duration3", -- The time (in minutes) that a vehicle can park at this location.
"typedesc1", -- The type of restriction. Eg: "2P Meter" (two hour parking, paid for using a meter), "Disabled Only" (only vehicles with disabled permits can park).
"endtime1", -- The time each day when the restriction ends.
"effectiveonph3", -- Does this restriction apply on public holidays.
"effectiveonph2", -- Does this restriction apply on public holidays.
"description5", -- Description: A compact, semi-human-readable description of the overall restrictions.
"description4", -- Description: A compact, semi-human-readable description of the overall restrictions.
"description1", -- Description: A compact, semi-human-readable description of the overall restrictions.
"deviceid", -- A system id for uniquely identifying the sensor device.
"bayid", -- A system generated id tag for each bay object.
"typedesc4", -- The type of restriction. Eg: "2P Meter" (two hour parking, paid for using a meter), "Disabled Only" (only vehicles with disabled permits can park).
"typedesc3", -- The type of restriction. Eg: "2P Meter" (two hour parking, paid for using a meter), "Disabled Only" (only vehicles with disabled permits can park).
"today5", -- The final day in the range, inclusive. (1-5=Monday to Friday)
"today2", -- The final day in the range, inclusive. (1-5=Monday to Friday)
"fromday2", -- The first day in the range on which this restriction applies (0=Sunday, 6=Saturday)
"fromday3", -- The first day in the range on which this restriction applies (0=Sunday, 6=Saturday)
"fromday6", -- The first day in the range on which this restriction applies (0=Sunday, 6=Saturday)
"effectiveonph1", -- Does this restriction apply on public holidays.
"effectiveonph4", -- Does this restriction apply on public holidays.
"duration6", -- The time (in minutes) that a vehicle can park at this location.
"disabilityext2", -- For bays that aren't limited to disabled permits, how much time (minutes) a vehicle with disabled permit can spend in the spot. Usually twice the regular amount of time.
"exemption5", -- Which vehicles are exempt.
"effectiveonph6", -- Does this restriction apply on public holidays.
"disabilityext4", -- For bays that aren't limited to disabled permits, how much time a vehicle with disabled permit can spend in the spot. Usually twice the regular amount of time.
"today6", -- The final day in the range, inclusive. (1-5=Monday to Friday)
"exemption3", -- Which vehicles are exempt.
"disabilityext5", -- For bays that aren't limited to disabled permits, how much time a vehicle with disabled permit can spend in the spot. Usually twice the regular amount of time.
"today4", -- The final day in the range, inclusive. (1-5=Monday to Friday)
"typedesc2", -- The type of restriction. Eg: "2P Meter" (two hour parking, paid for using a meter), "Disabled Only" (only vehicles with disabled permits can park).
"disabilityext6", -- For bays that aren't limited to disabled permits, how much time (minutes) a vehicle with disabled permit can spend in the spot. Usually twice the regular amount of time.
"exemption2", -- Which vehicles are exempt.
"endtime6", -- The time each day when the restriction ends.
"starttime4", -- The time each day when the restriction applies.
"exemption6", -- Which vehicles are exempt.
"exemption4", -- Which vehicles are exempt.
"today3", -- The final day in the range, inclusive. (1-5=Monday to Friday)
"effectiveonph5", -- Does this restriction apply on public holidays.
"starttime6", -- The time each day when the restriction applies.
"endtime5", -- The time each day when the restriction ends.
"fromday1", -- The first day in the range on which this restriction applies (0=Sunday, 6=Saturday)
"fromday5", -- The first day in the range on which this restriction applies (0=Sunday, 6=Saturday)
"typedesc6", -- The type of restriction. Eg: "2P Meter" (two hour parking, paid for using a meter), "Disabled Only" (only vehicles with disabled permits can park).
"today1", -- The final day in the range, inclusive. (1-5=Monday to Friday)
"duration4" -- The time (in minutes) that a vehicle can park at this location.
FROM
"melbourne-vic-gov-au/onstreet-car-park-bay-restrictions-ntht-5rk7:latest"."onstreet_car_park_bay_restrictions"
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 melbourne-vic-gov-au/onstreet-car-park-bay-restrictions-ntht-5rk7 with SQL in under 60 seconds.
This repository is an "external" repository. That means it's hosted elsewhere, in this case at data.melbourne.vic.gov.au. When you querymelbourne-vic-gov-au/onstreet-car-park-bay-restrictions-ntht-5rk7: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.melbourne.vic.gov.au, 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 \
"melbourne-vic-gov-au/onstreet-car-park-bay-restrictions-ntht-5rk7" \
--handler-options '{
"domain": "data.melbourne.vic.gov.au",
"tables": {
"onstreet_car_park_bay_restrictions": "ntht-5rk7"
}
}'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, melbourne-vic-gov-au/onstreet-car-park-bay-restrictions-ntht-5rk7 is just another Postgres schema.