Allow inserting modifiers on create table statement

These modifiers are keywords that can be inserted between the tokens "CREATE" and "TABLE".
See https://www.postgresql.org/docs/current/sql-createtable.html.

For example, in postgres we can use :modifiers to create unlogged tables:

    create table(:sessions, modifiers: UNLOGGED)

The statement above now produces the following DDL:

    CREATE UNLOGGED TABLE sessions ...

Author: rwillians

lib/ecto/adapters/postgres/connection.ex

@@ -1269,7 +1269,9 @@ if Code.ensure_loaded?(Postgrex) do
       table_name = quote_name(table.prefix, table.name)
 
       query = [
-        "CREATE TABLE ",
+        "CREATE ",
+        modifiers_expr(table.modifiers),
+        "TABLE ",
         if_do(command == :create_if_not_exists, "IF NOT EXISTS "),
         table_name,
         ?\s,
@@ -1760,6 +1762,10 @@ if Code.ensure_loaded?(Postgrex) do
     defp include_expr(literal),
       do: quote_name(literal)
 
+    defp modifiers_expr(nil), do: []
+    defp modifiers_expr(<<_, _::binary>> = value), do: [String.upcase(String.trim(value)), ?\s]
+    defp modifiers_expr(value), do: error!(nil, "PostgreSQL adapter expects :modifiers to be a non-empty string or nil, got #{inspect(value)}")
+
     defp options_expr(nil),
       do: []
 

lib/ecto/migration.ex

@@ -479,15 +479,16 @@ defmodule Ecto.Migration do
 
     To define a table in a migration, see `Ecto.Migration.table/2`.
     """
-    defstruct name: nil, prefix: nil, comment: nil, primary_key: true, engine: nil, options: nil
+    defstruct name: nil, prefix: nil, comment: nil, primary_key: true, engine: nil, options: nil, modifiers: nil
 
     @type t :: %__MODULE__{
             name: String.t(),
             prefix: String.t() | nil,
             comment: String.t() | nil,
             primary_key: boolean | keyword(),
             engine: atom,
-            options: String.t()
+            options: String.t(),
+            modifiers: String.t() | nil
           }
   end
 
@@ -824,6 +825,10 @@ defmodule Ecto.Migration do
     * `:options` - provide custom options that will be appended after the generated
       statement. For example, "WITH", "INHERITS", or "ON COMMIT" clauses. "PARTITION BY"
       can be provided for databases that support table partitioning.
+    * `:modifiers` - provide custom modifiers that should be inserted to the
+      table creation statement, between the tokens "CREATE" and "TABLE". For
+      example, "UNLOGGED", "GLOBAL", "TEMPORARY", or "GLOBAL TEMPORARY" in
+      PostgreSQL.
 
   """
   def table(name, opts \\ [])

lib/ecto/migration/runner.ex

@@ -434,6 +434,12 @@ defmodule Ecto.Migration.Runner do
   defp command(ddl) when is_binary(ddl) or is_list(ddl),
     do: "execute #{inspect(ddl)}"
 
+  defp command({:create, %Table{modifiers: <<_, _::binary>>} = table, _}),
+    do: "create #{render_modifiers(table.modifiers)} table #{quote_name(table.prefix, table.name)}"
+
+  defp command({:create, %Table{modifiers: value}, _}) when not is_nil(value),
+    do: raise(ArgumentError, "the value of :modifiers must be a non-empty string or nil, got #{inspect(value)}")
+
   defp command({:create, %Table{} = table, _}),
     do: "create table #{quote_name(table.prefix, table.name)}"
 
@@ -502,4 +508,6 @@ defmodule Ecto.Migration.Runner do
   defp quote_name(prefix, name), do: quote_name(prefix) <> "." <> quote_name(name)
   defp quote_name(name) when is_atom(name), do: quote_name(Atom.to_string(name))
   defp quote_name(name), do: name
+
+  defp render_modifiers(value), do: String.downcase(String.trim(value))
 end

test/ecto/adapters/postgres_test.exs

@@ -2285,6 +2285,22 @@ defmodule Ecto.Adapters.PostgresTest do
              ]
   end
 
+  test "create table with modifiers" do
+    create =
+      {:create, table(:posts, modifiers: "UNLOGGED"),
+       [
+         {:add, :id, :serial, [primary_key: true]},
+         {:add, :created_at, :naive_datetime, []}
+       ]}
+
+    assert execute_ddl(create) == [
+             """
+             CREATE UNLOGGED TABLE "posts" ("id" serial, "created_at" timestamp(0), PRIMARY KEY ("id"))
+             """
+             |> remove_newlines
+           ]
+  end
+
   test "create table with composite key" do
     create =
       {:create, table(:posts),

test/ecto/migrator_test.exs

@@ -188,6 +188,16 @@ defmodule Ecto.MigratorTest do
     def change, do: flush()
   end
 
+  defmodule CreateTableWithModifiersMigration do
+    use Ecto.Migration
+
+    def change do
+      create table(:sessions, modifiers: "UNLOGGED") do
+        add :id, :id
+      end
+    end
+  end
+
   @moduletag migrated_versions: [{1, nil}, {2, nil}, {3, nil}]
 
   setup context do
@@ -339,6 +349,15 @@ defmodule Ecto.MigratorTest do
     assert output =~ "== Running 12 Ecto.MigratorTest.UpDownMigration.down/0"
     assert output =~ "execute \"foo\""
     assert output =~ ~r"== Migrated 12 in \d.\ds"
+
+    output =
+      capture_log(fn ->
+        :ok = up(TestRepo, 13, CreateTableWithModifiersMigration)
+      end)
+
+    assert output =~ "== Running 13 Ecto.MigratorTest.CreateTableWithModifiersMigration.change/0"
+    assert output =~ "create unlogged table sessions"
+    assert output =~ ~r"== Migrated 13 in \d.\ds"
   end
 
   test "logs ddl notices" do