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 tree_removal_permits table in this repository, by referencing it like:
"cambridgema-gov/tree-removal-permits-vj95-me7d:latest"."tree_removal_permits"or in a full query, like:
SELECT
":id", -- Socrata column ID
"longitude", -- Longitude where tree is located
"mitigation_plan", -- Plan to mitigate losses from tree removal
":@computed_region_guic_hr4a", -- This column was automatically created in order to record in what polygon from the dataset 'Police Neighborhood Regions' (guic-hr4a) the point in column 'points_for_mapping' is located. This enables the creation of region maps (choropleths) in the visualization canvas and data lens.
":@computed_region_v7jj_366k", -- This column was automatically created in order to record in what polygon from the dataset 'Police Response Districts' (v7jj-366k) the point in column 'points_for_mapping' is located. This enables the creation of region maps (choropleths) in the visualization canvas and data lens.
":@computed_region_rffn_qbt6", -- This column was automatically created in order to record in what polygon from the dataset 'cambridge_neighborhoods' (rffn-qbt6) the point in column 'points_for_mapping' is located. This enables the creation of region maps (choropleths) in the visualization canvas and data lens.
":@computed_region_swkg_bavi", -- This column was automatically created in order to record in what polygon from the dataset 'cambridge_cdd_zoning' (swkg-bavi) the point in column 'points_for_mapping' is located. This enables the creation of region maps (choropleths) in the visualization canvas and data lens.
":@computed_region_e4yd_rwk4", -- This column was automatically created in order to record in what polygon from the dataset 'Census Blocks 2010' (e4yd-rwk4) the point in column 'points_for_mapping' is located. This enables the creation of region maps (choropleths) in the visualization canvas and data lens.
"company_name", -- Company responsible for removing tree.
"species", -- Tree species
"mitigation_fee", -- Mitigation fee paid for removal.
"replacements", -- Number of replacements
"exceptional", -- Exceptional Tree. Any Significant Tree thirty (30) inches DBH or larger which is on a Lot.
"number", -- Number of trees removed
"issue_date", -- Issue date for permit application.
"submit_date", -- Submission date for permit application.
"latitude", -- Latitude where tree is located
"fulladdress", -- Address where tree is located
"special_circumstances", -- Special circumstances surrounding the tree removal.
"diameter_six_inch", -- The tree meets or exceeds a diameter of six inches at breast height (DBH)
"status", -- Status of tree removal permit.
"large_project", -- The tree removal constitutes or is part of a large project under relevant ordinances.
"points_for_mapping", -- Coordinates formatted for mapping trees within the Socrata open data portal's built in map generator.
"diameter", -- Diameter at breast height (DBH) of the tree
"reason_description", -- Details of reason
"city_property", -- Tree is located on city property
"location", -- Location of tree on lot
"prior_removal", -- Has tree been removed prior to permit obtainment
"replacement_tree", -- A tree or trees to be planted to replace any Significant Trees to be removed
"id", -- Permit ID
"dead_or_dangerous", -- Tree is dead or dangerous
"reason", -- Reason for removal
"street", -- Street where tree is located.
"planning_board", -- Is this application subject to a special planning board permit?
"height" -- Height of trees
FROM
"cambridgema-gov/tree-removal-permits-vj95-me7d:latest"."tree_removal_permits"
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 cambridgema-gov/tree-removal-permits-vj95-me7d 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 cambridgema-gov/tree-removal-permits-vj95-me7d: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 cambridgema-gov/tree-removal-permits-vj95-me7dCheckout 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 cambridgema-gov/tree-removal-permits-vj95-me7d:latestThis will download all the objects for the latest tag of cambridgema-gov/tree-removal-permits-vj95-me7d 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 cambridgema-gov/tree-removal-permits-vj95-me7d: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 cambridgema-gov/tree-removal-permits-vj95-me7d: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, cambridgema-gov/tree-removal-permits-vj95-me7d is just another Postgres schema.