Add FROM hints (#88)

Author: pavancse17

.gitignore

@@ -29,3 +29,6 @@ exqlite-*.tar
 /tmp
 
 *.db
+
+# ADR files
+.tool-versions

integration_test/hints_test.exs

@@ -20,4 +20,17 @@ defmodule Ecto.Integration.HintsTest do
 
     assert [%Post{id: 1}] = results
   end
+
+  test "from hints" do
+    {:ok, _} = TestRepo.query("CREATE INDEX post_id_idx ON posts (id)")
+    TestRepo.insert!(%Post{id: 1})
+
+    results =
+      from(Post,
+        hints: ["INDEXED BY post_id_idx"]
+      )
+      |> TestRepo.all()
+
+    assert [%Post{id: 1}] = results
+  end
 end

lib/ecto/adapters/sqlite3/connection.ex

@@ -857,14 +857,15 @@ defmodule Ecto.Adapters.SQLite3.Connection do
     end)
   end
 
-  def from(%{from: %{source: source}} = query, sources) do
+  def from(%{from: %{source: source, hints: hints}} = query, sources) do
     {from, name} = get_source(query, sources, 0, source)
 
     [
       " FROM ",
       from,
       " AS ",
       name
+      | Enum.map(hints, &[?\s | &1])
     ]
   end
 

test/ecto/adapters/sqlite3/connection_test.exs

@@ -115,14 +115,15 @@ defmodule Ecto.Adapters.SQLite3.ConnectionTest do
     assert all(query) == ~s{SELECT s0."x" FROM "schema" AS s0}
   end
 
-  test "ignores from with hints" do
+  test "from with hints" do
     query =
       Schema
-      |> from(hints: ["USE INDEX FOO", "USE INDEX BAR"])
+      |> from(hints: ["INDEXED BY FOO", "INDEXED BY BAR"])
       |> select([r], r.x)
       |> plan()
 
-    assert all(query) == ~s{SELECT s0."x" FROM "schema" AS s0}
+    assert all(query) ==
+             ~s{SELECT s0."x" FROM "schema" AS s0 INDEXED BY FOO INDEXED BY BAR}
   end
 
   test "from without schema" do