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 index_crimes_by_county_and_agency_beginning_1990 table in this repository, by referencing it like:
"ny-gov/index-crimes-by-county-and-agency-beginning-1990-ca8h-8gjq:latest"."index_crimes_by_county_and_agency_beginning_1990"or in a full query, like:
SELECT
":id", -- Socrata column ID
"motor_vehicle_theft", -- One count per victim. The theft or attempted theft of a motor vehicle, including automobiles, trucks, buses, motorcycles, and snowmobiles.
"region", -- Region where the crime was reported. Regions include New York City (Bronx, Kings, New York, Queens, and Richmond counties) and Non-New York City (all other counties).
"larceny", -- One count per victim. The unlawful taking, carrying, leading, or riding away of property from the possession or constructive possession of another. It includes crimes such as shoplifting, purse snatching, bicycle thefts, etc., in which no use of force, violence, or fraud occurs. This offense category does not include offenses such as embezzlement, forgery, or bad checks.
"burglary", -- One count per victim. The unlawful entry of a structure to commit a felony or theft. The use of force to gain entry is not required to classify an offense as Burglary.
"robbery", -- One count per victim. The taking or attempting to take anything of value from the care, custody, or control of a person or persons by force or threat of force or violence and/or by putting the victim in fear.
"forcible_rape", -- One count per victim. Penetration, no matter how slight, of the vagina or anus with any body part or object, or oral penetration by a sex organ of another person, without the consent of the victim.
"violent", -- Subtotal includes Murder, Rape, Robbery and Aggravated Assault.
"total_index_crimes", -- Includes sum of Murder, Rape, Robbery, Aggravated Assault, Burglary, Larceny and Motor Vehicle Theft.
"months_reported", -- Number of months an individual agency reported for the year.
"county", -- Location where the crime was reported.
"murder", -- One count per victim. The willful killing of one human being by another. Excludes deaths caused by negligence, suicide, or justifiable homicides, and attempts to murder, which are classified as assault.
"agency", -- Police Department that reported the crime.
"year", -- Year the crime incident was reported.
"property", -- Subtotal includes Burglary, Larceny and Motor Vehicle Theft.
"aggravated_assault" -- One count per victim. The unlawful attack by one person upon another for the purpose of inflicting severe or aggravated bodily injury. This type of assault is usually accompanied by the use of a weapon or by means likely to produce death or great bodily harm, and also includes attempts to commit murder.
FROM
"ny-gov/index-crimes-by-county-and-agency-beginning-1990-ca8h-8gjq:latest"."index_crimes_by_county_and_agency_beginning_1990"
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/index-crimes-by-county-and-agency-beginning-1990-ca8h-8gjq with SQL in under 60 seconds.
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, 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 (like this repository), where the author has pushed Splitgraph Images to the repository, you can "clone" and/or "checkout" the data using sgr cloneand sgr checkout.
Cloning Data
Because ny-gov/index-crimes-by-county-and-agency-beginning-1990-ca8h-8gjq:latest is a Splitgraph Image, you can clone the data from Spltgraph Cloud to your local engine, where you can query it like any other Postgres database, using any of your existing tools.
First, install Splitgraph if you haven't already.
Clone the metadata with sgr clone
This will be quick, and does not download the actual data.
sgr clone ny-gov/index-crimes-by-county-and-agency-beginning-1990-ca8h-8gjqCheckout the data
Once you've cloned the data, you need to "checkout" the tag that you want. For example, to checkout the latest tag:
sgr checkout ny-gov/index-crimes-by-county-and-agency-beginning-1990-ca8h-8gjq:latestThis will download all the objects for the latest tag of ny-gov/index-crimes-by-county-and-agency-beginning-1990-ca8h-8gjq and load them into the Splitgraph Engine. Depending on your connection speed and the size of the data, you will need to wait for the checkout to complete. Once it's complete, you will be able to query the data like you would any other Postgres database.
Alternatively, use "layered checkout" to avoid downloading all the data
The data in ny-gov/index-crimes-by-county-and-agency-beginning-1990-ca8h-8gjq:latest is 0 bytes. If this is too big to download all at once, or perhaps you only need to query a subset of it, you can use a layered checkout.:
sgr checkout --layered ny-gov/index-crimes-by-county-and-agency-beginning-1990-ca8h-8gjq:latestThis will not download all the data, but it will create a schema comprised of foreign tables, that you can query as you would any other data. Splitgraph will lazily download the required objects as you query the data. In some cases, this might be faster or more efficient than a regular checkout.
Read the layered querying documentation to learn about when and why you might want to use layered queries.
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/index-crimes-by-county-and-agency-beginning-1990-ca8h-8gjq is just another Postgres schema.