From c34a24b633417084ec0f3ebfc564a55f5dfb960f Mon Sep 17 00:00:00 2001
From: Omar Roth <omarroth@protonmail.com>
Date: Sun, 7 Jul 2019 14:00:42 -0500
Subject: [PATCH] Attempt to optimize query for subscription feed

---
 src/invidious.cr              |  5 +----
 src/invidious/helpers/jobs.cr |  7 ++-----
 src/invidious/users.cr        | 13 +++++--------
 3 files changed, 8 insertions(+), 17 deletions(-)

diff --git a/src/invidious.cr b/src/invidious.cr
index b86d46fa..3fee0a36 100644
--- a/src/invidious.cr
+++ b/src/invidious.cr
@@ -1282,10 +1282,7 @@ post "/login" do |env|
       PG_DB.exec("INSERT INTO session_ids VALUES ($1, $2, $3)", sid, email, Time.utc)
 
       view_name = "subscriptions_#{sha256(user.email)}"
-      PG_DB.exec("CREATE MATERIALIZED VIEW #{view_name} AS \
-        SELECT * FROM channel_videos WHERE
-        ucid IN (SELECT unnest(subscriptions) FROM users WHERE email = E'#{user.email.gsub("'", "\\'")}')
-        ORDER BY published DESC")
+      PG_DB.exec("CREATE MATERIALIZED VIEW #{view_name} AS #{MATERIALIZED_VIEW_SQL.call(user.email)}")
 
       if Kemal.config.ssl || config.https_only
         secure = true
diff --git a/src/invidious/helpers/jobs.cr b/src/invidious/helpers/jobs.cr
index 38494020..b82cb1ac 100644
--- a/src/invidious/helpers/jobs.cr
+++ b/src/invidious/helpers/jobs.cr
@@ -75,7 +75,7 @@ def refresh_feeds(db, logger, config)
                 end
               end
 
-              if db.query_one("SELECT pg_get_viewdef('#{view_name}')", as: String).includes? "ucid = ANY"
+              if !db.query_one("SELECT pg_get_viewdef('#{view_name}')", as: String).includes? "WHERE ((cv.ucid = ANY (u.subscriptions))"
                 logger.puts("Materialized view #{view_name} is out-of-date, recreating...")
                 db.exec("DROP MATERIALIZED VIEW #{view_name}")
               end
@@ -95,10 +95,7 @@ def refresh_feeds(db, logger, config)
                   # While iterating through, we may have an email stored from a deleted account
                   if db.query_one?("SELECT true FROM users WHERE email = $1", email, as: Bool)
                     logger.puts("CREATE #{view_name}")
-                    db.exec("CREATE MATERIALIZED VIEW #{view_name} AS \
-                      SELECT * FROM channel_videos WHERE
-                      ucid IN (SELECT unnest(subscriptions) FROM users WHERE email = E'#{email.gsub("'", "\\'")}')
-                      ORDER BY published DESC")
+                    db.exec("CREATE MATERIALIZED VIEW #{view_name} AS #{MATERIALIZED_VIEW_SQL.call(email)}")
                     db.exec("UPDATE users SET feed_needs_update = false WHERE email = $1", email)
                   end
                 rescue ex
diff --git a/src/invidious/users.cr b/src/invidious/users.cr
index a2143c70..c988c0c4 100644
--- a/src/invidious/users.cr
+++ b/src/invidious/users.cr
@@ -1,5 +1,8 @@
 require "crypto/bcrypt/password"
 
+# Materialized views may not be defined using bound parameters (`$1` as used elsewhere)
+MATERIALIZED_VIEW_SQL = ->(email : String) { "SELECT cv.* FROM channel_videos cv WHERE EXISTS (SELECT subscriptions FROM users u WHERE cv.ucid = ANY (u.subscriptions) AND u.email = E'#{email.gsub("'", "\\'")}') ORDER BY published DESC" }
+
 struct User
   module PreferencesConverter
     def self.from_rs(rs)
@@ -166,10 +169,7 @@ def get_user(sid, headers, db, refresh = true)
 
       begin
         view_name = "subscriptions_#{sha256(user.email)}"
-        db.exec("CREATE MATERIALIZED VIEW #{view_name} AS \
-          SELECT * FROM channel_videos WHERE
-          ucid IN (SELECT unnest(subscriptions) FROM users WHERE email = E'#{user.email.gsub("'", "\\'")}')
-          ORDER BY published DESC")
+        db.exec("CREATE MATERIALIZED VIEW #{view_name} AS #{MATERIALIZED_VIEW_SQL.call(user.email)}")
       rescue ex
       end
     end
@@ -188,10 +188,7 @@ def get_user(sid, headers, db, refresh = true)
 
     begin
       view_name = "subscriptions_#{sha256(user.email)}"
-      db.exec("CREATE MATERIALIZED VIEW #{view_name} AS \
-        SELECT * FROM channel_videos WHERE
-        ucid IN (SELECT unnest(subscriptions) FROM users WHERE email = E'#{user.email.gsub("'", "\\'")}')
-        ORDER BY published DESC")
+      db.exec("CREATE MATERIALIZED VIEW #{view_name} AS #{MATERIALIZED_VIEW_SQL.call(user.email)}")
     rescue ex
     end
   end