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Query the Data Delivery Network

Query the DDN

The 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 wdfwcoded_wire_tag_fish_recoveries table in this repository, by referencing it like:


or in a full query, like:

    ":id", -- Socrata column ID
    "tagcode", -- Tag code reading from the wire found in the snout
    "processproject", -- Agency or sub-agency responsible for coring the fish snout and reading the wire extracted.
    "recoverygeartype", -- Method used to harvest or collect the fish.
    "broodyear", -- Calendar year when majority of parents spawned (definition from PSC CWT data specifications)
    "species", -- Species of the fish, as identified by the person collecting the snout.
    "releaseduntagnoadclipcnt", -- Calculated number of untagged fish released without an adipose fin clip mark. Not an imported field from PSC.
    "releaseduntagadclipcnt", -- Calculated number of untagged fish released with an adipose fin clip mark. Not an imported field from PSC.
    "projectfishnumber", -- Unique fish identification number used for study
    "releaserun", -- Run timing of this release group
    "headnumber", -- Sequential number assigned to snout when snouts are bagged during collection under one label
    "firstreleasedate", -- First date of fish release
    "samplecardrecordnumber", -- Card sequential record number with associated sampling information
    "releasedtagnoadclipcnt", -- Calculated number of tagged fish released without an adipose fin clip mark. Not an imported field from PSC.
    "releaseagency", -- Agency responsible for releasing this group into waters of the state
    "releasedtagadclipcnt", -- Calculated number of tagged fish released with an adipose fin clip mark.  Not an imported field from PSC.
    "stockname", -- Geographic location name of the fish stock
    "sex", -- Sex of fish
    "rearinghatchery", -- Geographic location of the site where fish were reared
    "psnet_recoverygeartype", -- Commercial gear used in the Puget Sound Net fishery from which snouts were collected if applicable
    "releasesite", -- Geographic location of the release event
    "verifieddate", -- Description Date and time of record verification
    "locationcode", -- Primary area code as indicated on the snout label.
    "samplecardnumber", -- Card number used in collecting sampling information
    "psc_code", -- PSC code for geographic area where fish was recovered
    "recoverydate", -- Date on which the fish were checked for wire.
    "forklength_cm", -- Measured fork length in centimeters
    "mark", -- Recorded external mark on the fish
    "run", -- Run timing of the fish.
    "fishertype", -- Type of commercial fisher harvesting fish
    "maturity", -- Age class assignment of the fish, based upon length or true saltwater age (the latter used by WDFW Snake River Lab).
    "returnyear", -- Assigned year of fish return, based upon the brood class.  Usually the same as calendar year, except for coho and steelhead escapement.
    "sampletype", -- Describes the sampling method and the sampling group that collected the snouts
    "locationname", -- Short description of the recovery location
    "scalecardnumber", -- Number of the card containing scales from this fish for aging purposes
    "tagresult", -- Results of processing the snout and reading the wire
    "baglabel", -- Identifying number on the label that accompanies one or more snouts from the collection point to the tag recovery lab.
    "lastreleasedate", -- Last date of fish release.
    "scalecardlinenumber", -- Line number from the the card containing scales from this fish for aging purposes
    "otolithnumber" -- Fish identification number used for otolith tissue sample
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 wa-gov/wdfwcoded-wire-tag-fish-recoveries-auvb-4rvk with SQL in under 60 seconds.

This repository is an "external" repository. That means it's hosted elsewhere, in this case at data.wa.gov. When you querywa-gov/wdfwcoded-wire-tag-fish-recoveries-auvb-4rvk: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

Install Splitgraph Locally
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.wa.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 \
  "wa-gov/wdfwcoded-wire-tag-fish-recoveries-auvb-4rvk" \
  --handler-options '{
    "domain": "data.wa.gov",
    "tables": {
        "wdfwcoded_wire_tag_fish_recoveries": "auvb-4rvk"

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, wa-gov/wdfwcoded-wire-tag-fish-recoveries-auvb-4rvk is just another Postgres schema.