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 water_valve_maintenance table in this repository, by referencing it like:
"citydata-mesaaz-gov/water-valve-maintenance-9rhp-xjhb:latest"."water_valve_maintenance"or in a full query, like:
SELECT
":id", -- Socrata column ID
"turns", -- Number of turns to open/close System Valve
"normpos", -- Normal position; indicates if water flows or is stopped at the location
"revuser", -- UserID of editor who last updated feature
"valve_location", -- Street name the feature is situated in from WSYSVALVE table
"citysection", -- City Section; Pulled from WQSRevis feature class
"rehabyear", -- Year lining work was done
"warrantydate", -- Should be warranty date, but field not populated
"sysintertie", -- System Valve Intertie, yes or no
"enclosure", -- Type of enclosure a feature is located inside of
"subtype", -- Feature type
"conditiondate", -- Date of condition assessment
"servicezone", -- Service zone
"symscale", -- Symbol scale
"rehabref", -- Plan reference for lining project
"revdate", -- Date feature was last updated in GIS
"make_1", -- System Valve Make
"valve_tag", -- Concatenated values from VALVESEC and VALVENUM from WSYSVALVE table
"valvestatus", -- System Valve is normally open or closed
"maintenance_month", -- Month maintenance was performed
"depth", -- Depth to nut on Fire Hydrant Valve
"model", -- Model number
"valve_objectid", -- Unique SDE ID from WSYSVALVE table
"valvenum", -- System Valve Number from from WSYSVALVE table
"mfg", -- Manufacturer
"legacyid", -- Historic ID of the feature
"adduser", -- UserID of editor who added feature
"flagcd", -- Extra field used for setting scale in detail boxes
"ownerid", -- Who owns the feature
"permalog", -- System Valve Permalog, yes or no
"comments", -- General information about a feature not captured elsewhere
"opendir", -- System Valve open direction
"valveno", -- System valve number
"installdate", -- Date of installation
"planref", -- Source reference number
"cityquarter", -- City Section; Pulled from WQSRevis feature class
"condition", -- Numeric value assigned to some features reflecting the condition of the asset
"rehabtype", -- Lining material type (i.e. copper, metal, etc…)
"assetid", -- City Quarter; pulled from WQSRevis feature class
"valvesec", -- System valve section
"planstatus", -- Status of the source (Permitted, AsBuilt)
"enabled", -- Identifies features that are included in the network
"facilityid", -- Unique object ID
"wvalveid", -- Foreign Key for joining to FacilityID in WSysValve table
"doclink", -- Document link, currently not used
"symname", -- Symbol name, Once was a required field for EMS Viewer; not sure we still need this field
"maint_date", -- System Valve Maintenance Date
"remarks", -- General information about a equipment not captured elsewhere
"serial", -- Serial number
"symrot", -- Symbol rotation
"adddate", -- Date feature was added to GIS
"valveproperty_objectid", -- Unique SDE ID from WTValveProp table
"valveproperty_tag", -- Concatenated values from VALVESEC and VALVENUM from WTValveProp table
"asbyear", -- Year feature record drawing was completed
"maintenance_year", -- Year maintenance was performed
"maintenance_month_date", -- Date maintenance was performed
"opstatus", -- Operation status; InActive is the default value; after the Letter of Acceptance or Record Drawing is received, this is changed to Active
"valveproperty_location", -- System Valve location ties from WTValveProp table
"valvesize" -- Size of the valve
FROM
"citydata-mesaaz-gov/water-valve-maintenance-9rhp-xjhb:latest"."water_valve_maintenance"
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 citydata-mesaaz-gov/water-valve-maintenance-9rhp-xjhb 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 citydata-mesaaz-gov/water-valve-maintenance-9rhp-xjhb: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 citydata-mesaaz-gov/water-valve-maintenance-9rhp-xjhbCheckout 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 citydata-mesaaz-gov/water-valve-maintenance-9rhp-xjhb:latestThis will download all the objects for the latest tag of citydata-mesaaz-gov/water-valve-maintenance-9rhp-xjhb 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 citydata-mesaaz-gov/water-valve-maintenance-9rhp-xjhb: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 citydata-mesaaz-gov/water-valve-maintenance-9rhp-xjhb: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, citydata-mesaaz-gov/water-valve-maintenance-9rhp-xjhb is just another Postgres schema.