View Source Vtc.Ecto.Postgres.PgRational.Migrations (vtc v0.10.5)
Migrations for adding rational types, functions and constraints to a Postgres database.
Link to this section Summary
Full
Adds raw SQL queries to a migration for creating the database types, associated functions, casts, operators, and operator families.
PgConstraints
Creates basic constraints for a PgRational
database field.
PgFunctions
Adds rational_private.greatest_common_denominator(a, b)
function that finds the
greatest common denominator between two bigint values.
Adds rational_private.simplify(rat)
function that simplifies a rational. Used at
the end of every rational operation to avoid overflows.
Link to this section Full
@spec create_all() :: :ok
Adds raw SQL queries to a migration for creating the database types, associated functions, casts, operators, and operator families.
This migration included all migraitons under the PgTypes and PgFunctions headings.
Safe to run multiple times when new functionality is added in updates to this library. Existing values will be skipped.
types-created
Types Created
Calling this macro creates the following type definitions:
CREATE TYPE public.rational AS (
numerator bigint,
denominator bigint
);
schemas-created
Schemas Created
Up to two schemas are created as detailed by the Configuring Database Objects section below.
configuring-database-objects
Configuring Database Objects
To change where supporting functions are created, add the following to your Repo confiugration:
config :vtc, Vtc.Test.Support.Repo,
adapter: Ecto.Adapters.Postgres,
...
vtc: [
pg_rational: [
functions_schema: :rational,
functions_private_schema: :rational_private,
functions_prefix: "rational"
]
]
Option definitions are as follows:
functions_schema
: The schema for "public" functions that will have backwards compatibility guarantees and application code support. Default::public
.functions_private_schema:
The schema for for developer-only "private" functions that support the functions in the "rational" schema. Will NOT havr backwards compatibility guarantees NOR application code support. Default::public
.functions_prefix
: A prefix to add before all functions. Defaults to "rational" for any function created in the "public" schema, and "" otherwise.
functions-created
Functions Created
See PgFunctions section of these docs for details on native database functions created.
examples
Examples
defmodule MyMigration do
use Ecto.Migration
alias Vtc.Ecto.Postgres.PgRational
require PgRational.Migrations
def change do
PgRational.Migrations.create_all()
end
end
Link to this section PgConstraints
Creates basic constraints for a PgRational
database field.
constraints-created
Constraints created:
{field_name}_denominator_positive
: Checks that the denominator of the field is positive.
examples
Examples
create table("rationals", primary_key: false) do
add(:id, :uuid, primary_key: true, null: false)
add(:a, PgRational.type())
add(:b, PgRational.type())
end
PgRational.migration_add_field_constraints(:rationals, :a)
PgRational.migration_add_field_constraints(:rationals, :b)
Link to this section PgTypes
@spec create_function_schemas() :: :ok
Creates schemas to act as namespaces for rational functions:
rational
: for user-facing "public" functions that will have backwards compatibility guarantees and application code support.rational_private
: for developer-only "private" functions that support the functions in the "rational" schema. Will NOT havr backwards compatibility guarantees NOR application code support.
@spec create_type() :: :ok
Adds:
rational
composite typerationals
schemarationals_helpers
schema
Link to this section PgFunctions
@spec create_greatest_common_denominator() :: :ok
Adds rational_private.greatest_common_denominator(a, b)
function that finds the
greatest common denominator between two bigint values.
@spec create_simplify() :: :ok
Adds rational_private.simplify(rat)
function that simplifies a rational. Used at
the end of every rational operation to avoid overflows.