Allow hints on joins (#83)

Co-authored-by: Greg Rychlewski <[email protected]>

Author: greg-rychlewski

integration_test/hints_test.exs

@@ -0,0 +1,23 @@
+defmodule Ecto.Integration.HintsTest do
+  use Ecto.Integration.Case, async: true
+
+  import Ecto.Query, only: [from: 2]
+
+  alias Ecto.Integration.Post
+  alias Ecto.Integration.TestRepo
+
+  test "join hints" do
+    {:ok, _} = TestRepo.query("CREATE INDEX post_id_idx ON posts (id)")
+    TestRepo.insert!(%Post{id: 1})
+
+    results =
+      from(p in Post,
+        join: p2 in Post,
+        on: p.id == p2.id,
+        hints: ["INDEXED BY post_id_idx"]
+      )
+      |> TestRepo.all()
+
+    assert [%Post{id: 1}] = results
+  end
+end

lib/ecto/adapters/sqlite3/connection.ex

@@ -976,7 +976,8 @@ defmodule Ecto.Adapters.SQLite3.Connection do
         on: %QueryExpr{expr: expression},
         qual: qual,
         ix: ix,
-        source: source
+        source: source,
+        hints: hints
       } ->
         {join, name} = get_source(query, sources, ix, source)
 
@@ -985,6 +986,7 @@ defmodule Ecto.Adapters.SQLite3.Connection do
           join,
           " AS ",
           name,
+          Enum.map(hints, &[?\s | &1]),
           join_on(qual, expression, sources, query)
         ]
     end)

test/ecto/adapters/sqlite3/connection_test.exs

@@ -1620,18 +1620,18 @@ defmodule Ecto.Adapters.SQLite3.ConnectionTest do
              """
   end
 
-  test "join ignores hints" do
+  test "join hints" do
     query =
       Schema
-      |> join(:inner, [p], q in Schema2, hints: ["USE INDEX FOO", "USE INDEX BAR"])
+      |> join(:inner, [p], q in Schema2, hints: ["INDEXED BY FOO", "INDEXED BY BAR"])
       |> select([], true)
       |> plan()
 
     assert all(query) ==
              """
              SELECT 1 \
              FROM "schema" AS s0 \
-             INNER JOIN "schema2" AS s1 ON 1\
+             INNER JOIN "schema2" AS s1 INDEXED BY FOO INDEXED BY BAR ON 1\
              """
   end