DeltaQuery

Note: This library is in early development (pre-1.0). The API may change between minor versions.

Elixir client for querying Delta Sharing tables.

Delta Sharing is an open protocol for secure data sharing across organizations. This library provides a high-level client for querying shared Delta tables. Results are returned as Elixir data structures, with optional access to the underlying Explorer DataFrames.

Installation

Add delta_query to your list of dependencies in mix.exs:

def deps do
  [
    {:delta_query, "~> 0.2.2"}
  ]
end

Setup

Configure credentials in config/config.exs or config/runtime.exs:

config :delta_query, :config,
  endpoint: System.get_env("DELTA_SHARING_ENDPOINT"),
  bearer_token: System.get_env("DELTA_SHARING_BEARER_TOKEN"),
  share: "my_share",
  schema: "public"

Usage

Discovery

List available schemas, tables, and columns before querying:

# List schemas in the configured share
{:ok, schemas} = DeltaQuery.list_schemas()
# => {:ok, ["public", "analytics"]}

# List tables in the configured schema
{:ok, tables} = DeltaQuery.list_tables()
# => {:ok, ["books", "loans", "members"]}

# List tables in a specific schema
{:ok, tables} = DeltaQuery.list_tables(schema: "analytics")

# Get column names and types for a table
{:ok, columns} = DeltaQuery.get_table_schema(table: "books")
# => {:ok, [
#   %{name: "book_id", type: "long"},
#   %{name: "title", type: "string"},
#   %{name: "author", type: "string"}
# ]}

Basic Query

"books"
|> DeltaQuery.query()
|> DeltaQuery.where("library_id = 100")
|> DeltaQuery.select(["book_id", "title", "author"])
|> DeltaQuery.limit(100)
|> DeltaQuery.execute!()
|> DeltaQuery.to_rows()

Per-Query Configuration

config = DeltaQuery.configure!(
  endpoint: "https://sharing.example.com",
  bearer_token: "your-token",
  share: "my_share"
)

"books"
|> DeltaQuery.query()
|> DeltaQuery.execute!(config: config)

Joining Results

books = DeltaQuery.query("books") |> DeltaQuery.execute!()
publishers = DeltaQuery.query("publishers") |> DeltaQuery.execute!()

joined = DeltaQuery.join(books, publishers, on: "book_id", how: :inner)
DeltaQuery.to_rows(joined)

Post-Query Filtering

results = DeltaQuery.query("books") |> DeltaQuery.execute!()

# Additional filters on fetched data
{:ok, filtered} = DeltaQuery.filter(results, ["page_count > 300"])

# Text search
{:ok, searched} = DeltaQuery.text_search(results, "fiction", ["genre", "title"])

Aggregations

results = DeltaQuery.query("reservations") |> DeltaQuery.execute!()

DeltaQuery.aggregate_by_column(results, :status)
# => [%{status: "Approved", count: 42}, %{status: "Pending", count: 18}]

Configuration Options

Option	Required	Default	Description
:endpoint	Yes	-	Delta Sharing server URL
:bearer_token	Yes	-	Authentication token
:share	Yes	-	Share name to query
:schema	No	"public"	Schema name
:req_options	No	[]	Options passed to Req requests

Predicates

Predicates use SQL-like syntax for filtering:

• Equality: column = value
• Inequality: column != value
• Comparisons: column > value, column >= value, column < value, column <= value

Values can be:

• Integers: 123, -10
• Floats: 99.99, -0.5
• Strings: 'single quoted' or "double quoted"
• Booleans: true, false, TRUE, FALSE
• Null: null, NULL

License

MIT