Add index and improve pubsub db query.

src/main/java/me/kavin/piped/Main.java

@@ -34,12 +34,9 @@ public class Main {
                     Session s = DatabaseSessionFactory.createSession();
 
                     List<PubSub> pubSubList = s.createNativeQuery(
-                            "select distinct pubsub.* from pubsub inner join users_subscribed on pubsub.id = users_subscribed.channel",
-                            PubSub.class).getResultList();
-
-                    pubSubList.removeIf(pubsub -> {
-                        return System.currentTimeMillis() - pubsub.getSubbedAt() < TimeUnit.DAYS.toMillis(4);
-                    });
+                            "select distinct pubsub.* from pubsub inner join users_subscribed on pubsub.id = users_subscribed.channel where pubsub.subbed_at < :time",
+                            PubSub.class).setParameter("time", System.currentTimeMillis() - TimeUnit.DAYS.toMillis(4))
+                            .getResultList();
 
                     Collections.shuffle(pubSubList);
 

src/main/java/me/kavin/piped/utils/obj/db/PubSub.java

@@ -7,7 +7,8 @@ import javax.persistence.Index;
 import javax.persistence.Table;
 
 @Entity
-@Table(name = "pubsub", indexes = { @Index(columnList = "id", name = "pubsub_id_idx") })
+@Table(name = "pubsub", indexes = { @Index(columnList = "id", name = "pubsub_id_idx"),
+        @Index(columnList = "subbed_at", name = "pubsub_subbed_at_idx") })
 public class PubSub {
 
     @Id