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 library_circulation_statistics table in this repository, by referencing it like:
"norfolk-gov/library-circulation-statistics-e68x-a47n:latest"."library_circulation_statistics"or in a full query, like:
SELECT
":id", -- Socrata column ID
"young_adult_cd_books", -- Young Adult Books on CD.
"vhs_tapes", -- VHS tapes.
"music_cds", -- Music CDs.
"music_scores", -- Music Scores.
"interlibrary_loans", -- Interlibrary Loans.
"hoopla_ebooks", -- Total number of digital checkouts from Hoopla.
"reference_federal_depository_government_documents", -- Available government documents from the federal depository that are only available for reference.
"rated_r_dvds", -- DVDs that are rated R.
"digital_magazines", -- Digital Magazines available online for downloading.
"juvenile_music_cds", -- Juvenile Music CDs.
"digital_movies", -- Digital Movies available online for downloading.
"adult_magazines", -- Adult Mass Market Magazines.
"e_devices", -- Video Game Controllers, Meeting Room Borrowed, Laptops only available for in house use at Jordan-Newby and Van Wyck branch locations.
"adult_reference_books", -- Reference Books.
"adult_nonfiction_digital_books", -- Digital Books Adult Non-Fiction available online only for downloading.
"juvenile_trade_paperback_books", -- Juvenile Trade Paperback Books.
"digital_audiobooks", -- Audiobooks available online only for downloading.
"digital_music", -- Digital Music available online for downloading.
"dvds", -- DVDs.
"equipment", -- Realia items available for checkout including Puzzles, Board Games, Electricity Usage Monitors, Etc.
"mobile_hotspot_devices", -- Wi-Fi devices.
"location", -- The library branch location.
"express_books", -- Popular titles that have a limited checkout period.
"high_demand_adult_fiction_books", -- High Demand Adult Fiction Titles that have checkout and extension restrictions.
"young_adult_trade_paperback_books", -- Young Adult Trade Paperback Books.
"young_adult_mass_market_paperback_books", -- Young Adult Mass Market Books.
"juvenile_cd_books", -- Juvenile Books on CD.
"other_reference_government_documents", -- Available government documents not in the federal depository that are only available for reference.
"month", -- The month the items were circulated.
"total", -- Total items that were circulated.
"adult_hardcover_books", -- Adult Hardcover Books.
"adult_mass_market_paperback_books", -- Adult Mass Market Paperback Books.
"adult_trade_paperback_books", -- Adult Trade Paperback Books.
"mp3_cd_books", -- Digital (MP3) Books on CD available for downloads.
"cd_books", -- Books on CD.
"cassette_books", -- Books on Cassette.
"juvenile_fiction_digital_books", -- Digital Books Juvenile Fiction available online only for downloading.
"juvenile_book_kits", -- Juvenile Books with Additional Materials.
"juvenile_mass_market_paperback_books", -- Juvenile Mass Market Paperback Books.
"adult_fiction_digital_books", -- Digital Books Adult Fiction available online only for downloading.
"young_adult_hardcover_books", -- Young Adult Hardcover Books.
"juvenile_hardcover_books", -- Juvenile Hardcover Books.
"juvenile_cassette_books", -- Juvenile Books on Cassette.
"juvenile_board_books", -- Juvenile Board Books.
"young_adult_dvds", -- Young Adult DVD.
"young_adult_nonfiction_digital_books", -- Digital Books Young Adult Non-Fiction available online only for downloading.
"young_adult_fiction_digital_books", -- Digital Books Young Adult Fiction available online only for downloading.
"other_circulating_government_documents", -- Available government documents not in the federal depository that are available via circulation.
"book_club_kits", -- Multiple Copies of a Single Title Available for Book Clubs to Borrow.
"young_adult_cassette_books", -- Young Adult Books on Cassette.
"rated_r_vhs_tapes", -- VHS tapes that are rated R.
"young_adult_high_demand_books", -- Young Adult High Demand Books.
"juvenile_high_demand_books", -- Juvenile High Demand Titles.
"stem_equipment", -- Realia items defined as science, technology, engineering, and mathematic (STEM) items available for checkout, including Telescopes, Microscopes, Gopro Cameras, Ukuleles, Etc.
"used_marked_item", -- Library items used inhouse for reference only.
"playaway_audio_books", -- Playaway Audio Books
"juvenile_reference_books", -- Juvenile Reference Books.
"circulating_federal_depository_government_documents", -- Available government documents from the federal depository that are available via circulation.
"juvenile_nonfiction_digital_books", -- Digital Books Juvenile Non-Fiction available online only for downloading.
"young_adult_vhs_tapes", -- Young Adult VHS Tapes.
"juvenile_vhs_tapes", -- Juvenile VHS Tapes.
"year", -- The year the items were circulated.
"juvenile_dvds" -- Juvenile DVDs.
FROM
"norfolk-gov/library-circulation-statistics-e68x-a47n:latest"."library_circulation_statistics"
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 norfolk-gov/library-circulation-statistics-e68x-a47n with SQL in under 60 seconds.
This repository is an "external" repository. That means it's hosted elsewhere, in this case at data.norfolk.gov. When you querynorfolk-gov/library-circulation-statistics-e68x-a47n: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.norfolk.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 \
"norfolk-gov/library-circulation-statistics-e68x-a47n" \
--handler-options '{
"domain": "data.norfolk.gov",
"tables": {
"library_circulation_statistics": "e68x-a47n"
}
}'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, norfolk-gov/library-circulation-statistics-e68x-a47n is just another Postgres schema.