Amperity Delta Sharing Library

A native clojure implementation of a delta sharing client. More details about the delta sharing protocol can be found at the official docs page.

Client construction

The following is an example of how to construct an instance of the client against Databricks' open delta sharing server.

The client is constructed an endpoint URL, a bearer token & share credentials version. More details about these profile credentials can be found under the "Profile File Format" section of the official docs page.

;; Pull in namespace
user=> (require '[delta-sharing.client :as dsc])
nil

;; Create an instance of the client using the endpoint, token and version
user=> (def client (dsc/new-client "https://sharing.delta.io/delta-sharing/" "my auth token" 1 {}))
#'user/client

;; Invoke the method(s) you want using the client
user=> (dsc/list-shares client {:max-results 50})
=> {:data [{:name "delta_sharing"}]}

user=> (dsc/list-share-tables client "delta_sharing" {:max-results 2})
=> {:next-page-token "CgE1Eg1kZWx0YV9zaGFyaW5n",
    :data [{:name "COVID_19_NYT"
            :schema "default",
            :share "delta_sharing"}
           {:name "boston-housing",
            :schema "default",
            :share "delta_sharing"}]]}

user=> (dsc/read-table-data client "delta_sharing" "default" "COVID_19_NYT" {:min-reader-version 1})
{:delta-table-version "1710371505697",
 :files [{:expiration-timestamp 1713812921776,
          :id "5ds7z3rjK3qFxy54zRre1GSXiy9fap",
          :partition-values {},
          :size 550,
          :url "https://open-delta-sharing.s3.us-west-2.amazonaws.com/samples/COVID-19_NYT/some-signature"}],
 :metadata {:format {:provider "parquet"},
            :id "7245fd1d-8a6d-4988-af72-92a95b646511",
            :schema {
                :fields [{:metadata {}, :name "date", :nullable true, :type "string"}
                         {:metadata {}, :name "county", :nullable true, :type "string"}
                         {:metadata {}, :name "state", :nullable true, :type "string"}
                         {:metadata {}, :name "fips", :nullable true, :type "integer"}
                         {:metadata {}, :name "cases", :nullable true, :type "integer"}
                         {:metadata {}, :name "deaths", :nullable true, :type "integer"}],
                     :type "struct"}},
 :protocol {:min-reader-version 1}}

Reader version options

Delta tables support these features.

Supported reader versions include:

Reader Version	Feature map
1 (default)	{:response-format 'parquet'}
2	{:response-format 'delta' :reader-features 'columnMapping'}
3	{:response-format 'delta' :reader-features 'columnMapping, deletionVectors, timestampNtz, v2Checkpoint, vacuumProtocolCheck'}

The default min-reader-version is 1, but you can pass a :response-format and/or :reader-features to override the default or selected reader version as well.

Using a custom flow handler

You may want to Implement your own custom flow handler for (a)sync calls, retries, observability etc. For these cases, you can pass a handler that implements the protocol here as an optional argument during client construction.

Here's an example of how to construct a client using the provided CompletableFuture flow handler included with this library.

;; Pull in relevant namespaces
user=> (require '[delta-sharing.client :as dsc])
nil

user=> (require '[delta-sharing.client.flow :as f])
nil

;; Construct the client leveraging the optional parameters to inject a custom flow handler
user=> (def client (dsc/new-client "https://sharing.delta.io/delta-sharing/" "my auth token" 1 {:flow (f/completable-future-handler)}))
#'user/client

user=> (dsc/list-shares client {:max-results 50})
=> #object[java.util.concurrent.CompletableFuture 0x27210a69 "java.util.concurrent.CompletableFuture@27210a69[Not completed]"]

Local Development

The client code can all be exercised in a REPL this is as simple as running lein repl .