Fixes DB query that returns large result set when there are thousands of

subscribers

lib/API/Endpoints/SendingQueue.php

@@ -48,7 +48,6 @@ class SendingQueue extends APIEndpoint {
         APIError::NOT_FOUND => __('This newsletter is already being sent.', 'mailpoet')
       ));
     }
-
     $queue = SendingQueueModel::where('newsletter_id', $newsletter->id)
       ->where('status', SendingQueueModel::STATUS_SCHEDULED)
       ->findOne();
@@ -73,9 +72,8 @@ class SendingQueue extends APIEndpoint {
       $segment_ids = array_map(function($segment) {
         return $segment['id'];
       }, $segments);
-      $subscribers = Subscriber::getSubscribedInSegments($segment_ids)
+      $subscribers = Subscriber::getSubscribedInSegments($segment_ids)->findArray();
-        ->findArray();
+      $subscribers = Helpers::arrayColumn($subscribers, 'id');
-      $subscribers = Helpers::arrayColumn($subscribers, 'subscriber_id');
       $subscribers = array_unique($subscribers);
       if(!count($subscribers)) {
         return $this->errorResponse(array(

lib/Cron/Workers/Scheduler.php

@@ -76,9 +76,8 @@ class Scheduler {
     }, $segments);
 
     // ensure that subscribers are in segments
-    $subscribers = Subscriber::getSubscribedInSegments($segment_ids)
+    $subscribers = Subscriber::getSubscribedInSegments($segment_ids)->findArray();
-      ->findArray();
+    $subscribers = Helpers::arrayColumn($subscribers, 'id');
-    $subscribers = Helpers::arrayColumn($subscribers, 'subscriber_id');
     $subscribers = array_unique($subscribers);
 
     if(empty($subscribers)) {
@@ -107,9 +106,8 @@ class Scheduler {
     $segment_ids = array_map(function($segment) {
       return $segment['id'];
     }, $segments);
-    $subscribers = Subscriber::getSubscribedInSegments($segment_ids)
+    $subscribers = Subscriber::getSubscribedInSegments($segment_ids)->findArray();
-      ->findArray();
+    $subscribers = Helpers::arrayColumn($subscribers, 'id');
-    $subscribers = Helpers::arrayColumn($subscribers, 'subscriber_id');
     $subscribers = array_unique($subscribers);
 
     // update current queue

lib/Models/Subscriber.php

@@ -448,6 +448,7 @@ class Subscriber extends Model {
         'subscribers.id = relation.subscriber_id',
         'subscribers'
       )
+      ->select('subscribers.id')
       ->whereNull('subscribers.deleted_at')
       ->where('subscribers.status', 'subscribed');
     return $subscribers;