6 files changed, 45 insertions, 7 deletions
diff --git a/migrations/2018-04-14-145711_create_index_view/down.sql b/migrations/2018-04-14-145711_create_index_view/down.sql
new file mode 100644
index 000000000000..87d26820f7e2
--- /dev/null
+++ b/migrations/2018-04-14-145711_create_index_view/down.sql
@@ -0,0 +1 @@
+DROP VIEW thread_index;
diff --git a/migrations/2018-04-14-145711_create_index_view/up.sql b/migrations/2018-04-14-145711_create_index_view/up.sql
new file mode 100644
index 000000000000..3b7ddc1d647a
--- /dev/null
+++ b/migrations/2018-04-14-145711_create_index_view/up.sql
@@ -0,0 +1,15 @@
+-- Create a simple view that returns the list of threads ordered by
+-- the last post that occured in the thread.
+
+CREATE VIEW thread_index AS
+  SELECT t.id AS thread_id,
+         t.title AS title,
+         t.author_name AS author_name,
+         t.posted AS posted,
+         p.id AS post_id
+    FROM threads t
+    JOIN (SELECT DISTINCT ON (thread_id) id, thread_id
+          FROM posts
+          ORDER BY thread_id, id DESC) AS p
+    ON t.id = p.thread_id
+    ORDER BY p.id DESC;
diff --git a/src/db.rs b/src/db.rs
index c26597293706..5a66fbb0fc74 100644
--- a/src/db.rs
+++ b/src/db.rs
@@ -36,19 +36,18 @@ impl Actor for DbExecutor {
 pub struct ListThreads;
 
 impl Message for ListThreads {
-    type Result = Result<Vec<Thread>>;
+    type Result = Result<Vec<ThreadIndex>>;
 }
 
 impl Handler<ListThreads> for DbExecutor {
     type Result = <ListThreads as Message>::Result;
 
     fn handle(&mut self, _: ListThreads, _: &mut Self::Context) -> Self::Result {
-        use schema::threads::dsl::*;
+        use schema::thread_index::dsl::*;
 
         let conn = self.0.get()?;
-        let results = threads
-            .order(posted.desc())
-            .load::<Thread>(&conn)?;
+        let results = thread_index
+            .load::<ThreadIndex>(&conn)?;
         Ok(results)
     }
 }
diff --git a/src/models.rs b/src/models.rs
index 29d196b9a998..159a85469aeb 100644
--- a/src/models.rs
+++ b/src/models.rs
@@ -26,6 +26,18 @@ pub struct Thread {
     pub author_email: String,
 }
 
+/// This struct is used as the query type for the thread index view,
+/// which lists the index of threads ordered by the last post in each
+/// thread.
+#[derive(Queryable, Serialize)]
+pub struct ThreadIndex {
+    pub thread_id: i32,
+    pub title: String,
+    pub author_name: String,
+    pub posted: DateTime<Utc>,
+    pub post_id: i32,
+}
+
 #[derive(Identifiable, Queryable, Serialize, Associations)]
 #[belongs_to(Thread)]
 pub struct Post {
diff --git a/src/render.rs b/src/render.rs
index ca1fd8ac3bc9..66b3fe19c867 100644
--- a/src/render.rs
+++ b/src/render.rs
@@ -47,7 +47,7 @@ impl From<DateTime<Utc>> for FormattedDate {
 
 /// Message used to render the index page.
 pub struct IndexPage {
-    pub threads: Vec<Thread>,
+    pub threads: Vec<ThreadIndex>,
 }
 
 impl Message for IndexPage {
@@ -69,7 +69,7 @@ impl Handler<IndexPage> for Renderer {
         let threads: Vec<IndexThread> = msg.threads
             .into_iter()
             .map(|thread| IndexThread {
-                id: thread.id,
+                id: thread.thread_id,
                 title: escape_html(&thread.title),
                 posted: thread.posted.into(),
                 author_name: thread.author_name,
diff --git a/src/schema.rs b/src/schema.rs
index d14c89c4c7f8..02392c8fc60c 100644
--- a/src/schema.rs
+++ b/src/schema.rs
@@ -19,6 +19,17 @@ table! {
     }
 }
 
+// Note: Manually inserted as print-schema does not add views.
+table! {
+    thread_index (thread_id){
+        thread_id -> Integer,
+        title -> Text,
+        author_name -> Text,
+        posted -> Timestamptz,
+        post_id -> Integer,
+    }
+}
+
 joinable!(posts -> threads (thread_id));
 
 allow_tables_to_appear_in_same_query!(