AshScylla.Migration (AshScylla v0.2.0)

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Helpers for working with ScyllaDB migrations using Exandra.

This module provides utilities to help generate CQL statements for ScyllaDB tables based on Ash resource definitions.

Note: For actual migrations, use Exandra with Ecto.Migration directly. See the Exandra documentation for more details on writing migrations.

Example Migration

defmodule MyApp.Repo.Migrations.CreateUsers do
  use Ecto.Migration

  def change do
    execute "CREATE TABLE users (id UUID PRIMARY KEY, name TEXT, email TEXT)"
  end
end

Important Note on create_table_cql/1

This function reads compile-time module attributes (:table, :attributes) set by the Ash resource DSL. It is intended to be called at compile time within a migration module (e.g., inside a defmacro or at the module top level). It will not work correctly at runtime when called with a resource module that has already been compiled, because Module.get_attribute/2 only works during compilation of that module.

For runtime use, prefer passing explicit parameters or use the AshScylla DSL getter functions (AshScylla.DataLayer.Dsl.table/1) combined with Ash.Resource.Info.attributes/1.

Summary

Functions

create_secondary_indexes_cql(resource)

Generates CQL CREATE INDEX statements for secondary indexes.

create_table_cql(resource)

Generates a CQL CREATE TABLE statement for an Ash resource.

create_type(type_name, list)

Define a User Defined Type (UDT) in ScyllaDB.

drop_secondary_index_cql(resource, index_name)

Generates a CQL DROP INDEX statement for a secondary index.

drop_type(type_name)

Drop a User Defined Type (UDT) in ScyllaDB.

keyspace(resource)

Returns the keyspace for a resource if configured via DSL. Note: This is a placeholder for future DSL implementation.

Functions

create_secondary_indexes_cql(resource)

@spec create_secondary_indexes_cql(module()) :: [String.t()]

Generates CQL CREATE INDEX statements for secondary indexes.

Returns a list of CQL strings that should be executed in migrations.

Example

defmodule MyApp.Repo.Migrations.CreateUserIndexes do
  use Ecto.Migration

  def change do
    AshScylla.Migration.create_secondary_indexes_cql(MyApp.User)
    |> Enum.each(&execute/1)
  end
end

create_table_cql(resource)

@spec create_table_cql(module()) :: String.t()

Generates a CQL CREATE TABLE statement for an Ash resource.

Important: This function reads compile-time module attributes (:table, :attributes) and must be called during the resource module's compilation. For runtime use, build the CQL explicitly or use Ash.Resource.Info.attributes/1 combined with AshScylla.DataLayer.Dsl.table/1.

Note: This is a helper that returns a CQL string. You need to execute this in an Ecto migration using execute/1.

create_type(type_name, list)

@spec create_type(
  String.t(),
  keyword()
) :: String.t()

Define a User Defined Type (UDT) in ScyllaDB.

Example

create_type "full_name" do
  field :first_name, :text
  field :last_name, :text
end

This generates:

CREATE TYPE full_name (first_name TEXT, last_name TEXT)

drop_secondary_index_cql(resource, index_name)

@spec drop_secondary_index_cql(module(), String.t()) :: String.t()

Generates a CQL DROP INDEX statement for a secondary index.

drop_type(type_name)

@spec drop_type(String.t()) :: String.t()

Drop a User Defined Type (UDT) in ScyllaDB.

keyspace(resource)

@spec keyspace(module()) :: String.t() | nil

Returns the keyspace for a resource if configured via DSL. Note: This is a placeholder for future DSL implementation.