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 calls_for_service_2017 table in this repository, by referencing it like:
"nola-gov/calls-for-service-2017-bqmt-f3jk:latest"."calls_for_service_2017"or in a full query, like:
SELECT
":id", -- Socrata column ID
"block_address", -- The BLOCK unique address number for the incident. The block address has been obscured to protect the sensitivity of the data.
":@computed_region_spev_d8jm",
"type_", -- The NOPD Type associated with the call for service.
"mapx", -- The NOPD MapX associated with the call for service. This is provided in state plane and obscured to protect the sensitivity of the data.
"timearrive", -- The NOPD TimeArrive associated with the call for service. This is the entered time by OPCD or NOPD when an officer arrived.
"disposition", -- The NOPD Disposition associated with the call for service.
"mapy", -- The NOPD MapY associated with the call for service. This is provided in state plane and obscured to protect the sensitivity of the data.
"dispositiontext", -- The NOPD DispositionText associated with the call for service.
"nopd_item", -- The NOPD unique item number for the incident.
"typetext", -- The NOPD TypeText associated with the call for service.
"priority", -- The NOPD Priority associated with the call for service. Code 3 is considered the highest priority and is reserved for officer needs assistance. Code 2 are considered "emergency" calls for service. Code 1 are considered "non-emergency" calls for service. Code 0 calls do not require a police presence. Priorities are differentiated further using the letter designation with "A" being the highest priority within that level.
"initialtypetext", -- The NOPD InitialTypeText associated with the call for service.
"timecreate", -- The NOPD TimeCreate associated with the call for service. This is the time stamp of the create time of the incident in the CAD system.
"timedispatch", -- The NOPD TimeDispatch associated with the call for service. This is the entered time by OPCD or NOPD when an officer was dispatched.
"timeclosed", -- The NOPD TimeClosed associated with the call for service. This is the time stamp of the time the call was closed in the CAD system.
"beat", -- The NOPD Beat associated with the call for service. This is the area within Orleans Parish that the call for service occurred. The first number is the NOPD District, the letter is the zone, and the numbers are the subzone.
"zip", -- The NOPD Zip associated with the call for service.
"location", -- The NOPD Location associated with the call for service. The X,Y coordinates for the call for service obscured to protect the sensitivity of the data.
"initialpriority", -- The NOPD InitialPriority associated with the call for service. See Priority description for more information.
"selfinitiated", -- The NOPD SelfInitiated associated with the call for service. A call is considered self-initiated if the Officer generates the item in the field as opposed to responding to a 911 call.
"policedistrict", -- The NOPD PoliceDistrict associated with the call for service.
"location_zip",
"location_state",
"location_address",
"location_city",
":@computed_region_sikx_bdeb",
":@computed_region_k37d_then",
":@computed_region_u4yh_3wk9",
"initialtype", -- The NOPD InitialType associated with the call for service.
":@computed_region_7fw3_kdpf",
":@computed_region_evki_aju8",
":@computed_region_m56f_hbma",
":@computed_region_ewbu_t8bu"
FROM
"nola-gov/calls-for-service-2017-bqmt-f3jk:latest"."calls_for_service_2017"
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 nola-gov/calls-for-service-2017-bqmt-f3jk with SQL in under 60 seconds.
This repository is an "external" repository. That means it's hosted elsewhere, in this case at data.nola.gov. When you querynola-gov/calls-for-service-2017-bqmt-f3jk: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.nola.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 \
"nola-gov/calls-for-service-2017-bqmt-f3jk" \
--handler-options '{
"domain": "data.nola.gov",
"tables": {
"calls_for_service_2017": "bqmt-f3jk"
}
}'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, nola-gov/calls-for-service-2017-bqmt-f3jk is just another Postgres schema.