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 beach_water_testing_beginning_2015 table in this repository, by referencing it like:
"ny-gov/beach-water-testing-beginning-2015-wwwd-za77:latest"."beach_water_testing_beginning_2015"or in a full query, like:
SELECT
":id", -- Socrata column ID
"status_reason", -- Please see this link for a description of some of the common Status Reasons that are used while the beach is operating: https://parks.ny.gov/recreation/swimming/beach-results/documents/results/BeachResults.pdf Note: For entries without a sample result, "Beach Status" and "Status Reason" applies to the sample date listed. When a sample result is included in an entry, the "Beach Status" and "Status Reason" applies to the day following the sample date.
"region", -- Name of State Park Region
"indicator_bacteria", -- This field indicates the bacteria that was tested for. Values will be either Escherichia coli, represented in the field as E.coli, or enterococcus. A blank field indicates that the change in beach status reflected a non-bacteria situation as indicated in the “Status Reason” column.
"results_modifier", -- =, <, or >; results are equal to, less than or greater than number listed in Results column
"date_sample_taken", -- Date Sample was Taken or Date of notification of beach status change. Results are typically available the day after the samples are taken because it takes time to culture the bacteria in order to obtain an accurate estimate of their abundance. Beach results are posted and the public is notified 18-24 hours after an elevated concentration of bacteria occurs.
"state_park_beach", -- Name of State Park Beach Station (some parks have multiple beach stations)
"category", -- •Category 1: Beaches with low rates of exceedance, satisfactory resample results within 24 hours, and/or wet sampling results. If these beaches are subject to an exceedance, they are immediately resampled. If other water quality factors are satisfactory at the time of resampling, the beach will remain open and the closure decision will be deferred until the resample results are obtained. The beaches are closed following an exceedance if other water quality factors (such as current weather or beach water conditions) are not satisfactory. •Category 2: Beaches without sufficient resampling data or with unsatisfactory resampling data. At these beaches, an exceedance leads to resampling and an automatic and immediate closure, along with posting a notification of exceedance and alerting appropriate media outlets. Please see this link for additional information: https://parks.ny.gov/recreation/swimming/beach-results/documents/results/BeachResults.pdf
"results", -- Results Numeric • Freshwater samples are analyzed for Escherichia coli (E.coli). A result equal to or above 235 E.coli colonies/100 ml represents an exceedance of the state standard. (All regions except Long Island.) • Ocean (saltwater) samples are analyzed for enterococcus. A result equal to or above 104 enterococci colonies/100 ml represents an exceedance of the state standard. (Applies to Long Island region only.)
"waterbody", -- Name of Waterbody the State Park Beach is located
"beach_status" -- This field indicates the status of the beach as it relates to water quality data, options are “Open”, “Closed”, “Reopened”, “Open with Advisory”, “Off - Season”. “Open with Advisory” is used for the first exceedance at Category 1 beaches. Based on data from previous seasons and the conditions that day, the likelihood that it was safe to swim at the time was high. Varying operating schedules are not taken into account.
FROM
"ny-gov/beach-water-testing-beginning-2015-wwwd-za77:latest"."beach_water_testing_beginning_2015"
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/beach-water-testing-beginning-2015-wwwd-za77 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/beach-water-testing-beginning-2015-wwwd-za77: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/beach-water-testing-beginning-2015-wwwd-za77Checkout 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/beach-water-testing-beginning-2015-wwwd-za77:latestThis will download all the objects for the latest tag of ny-gov/beach-water-testing-beginning-2015-wwwd-za77 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/beach-water-testing-beginning-2015-wwwd-za77: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/beach-water-testing-beginning-2015-wwwd-za77: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/beach-water-testing-beginning-2015-wwwd-za77 is just another Postgres schema.