fix item purger for PostgreSQL

Signed-off-by: anoy <anoymouserver+github@mailbox.org>

3 files changed, 23 insertions, 5 deletions

diff --git a/CHANGELOG.md b/CHANGELOG.md
index 31bb4e35a..9f3b7a83b 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -7,6 +7,7 @@ The format is almost based on [Keep a Changelog](https://keepachangelog.com/en/1
 ### Changed
 
 ### Fixed
+- Item purger does not work with PostgreSQL (#1094)
 
 ## [15.2.0-rc1] - 2021-01-31
 
diff --git a/lib/Db/ItemMapperV2.php b/lib/Db/ItemMapperV2.php
index 256621815..9b69cc9f2 100644
--- a/lib/Db/ItemMapperV2.php
+++ b/lib/Db/ItemMapperV2.php
@@ -149,7 +149,8 @@ class ItemMapperV2 extends NewsMapperV2
     public function deleteOverThreshold(int $threshold, bool $removeUnread = false): ?int
     {
         $feedQb = $this->db->getQueryBuilder();
-        $feedQb->addSelect('feed_id', $feedQb->func()->count('*', 'itemCount'), 'feeds.articles_per_update')
+        $feedQb->select('feed_id', $feedQb->func()->count('*', 'itemCount'))
+               ->addSelect($feedQb->func()->max('feeds.articles_per_update', 'articlesPerUpdate'))
                ->from($this->tableName, 'items')
                ->innerJoin('items', FeedMapperV2::TABLE_NAME, 'feeds', 'items.feed_id = feeds.id')
                ->groupBy('feed_id');
@@ -165,11 +166,11 @@ class ItemMapperV2 extends NewsMapperV2
         $rangeQuery->select('id')
             ->from($this->tableName)
             ->where('feed_id = :feedId')
-            ->andWhere('starred = 0')
+            ->andWhere('starred = false')
             ->orderBy('updated_date', 'DESC');
 
         if ($removeUnread === false) {
-            $rangeQuery->andWhere('unread = 0');
+            $rangeQuery->andWhere('unread = false');
         }
 
         $total_items = [];
@@ -178,7 +179,7 @@ class ItemMapperV2 extends NewsMapperV2
                 continue;
             }
 
-            $rangeQuery->setFirstResult(max($threshold, $feed['articles_per_update']));
+            $rangeQuery->setFirstResult(max($threshold, $feed['articlesPerUpdate']));
 
             $items = $this->db->executeQuery($rangeQuery->getSQL(), ['feedId' => $feed['feed_id']])
                               ->fetchAll(FetchMode::COLUMN);
@@ -190,7 +191,16 @@ class ItemMapperV2 extends NewsMapperV2
         $deleteQb->delete($this->tableName)
                  ->where('id IN (?)');
 
-        return $this->db->executeUpdate($deleteQb->getSQL(), [$total_items], [IQueryBuilder::PARAM_INT_ARRAY]);
+        $affected_rows = 0;
+        // split $total_items into multiple chunks because of the parameter limit
+        foreach (array_chunk($total_items, NewsMapperV2::PDO_PARAMS_LIMIT) as $items_chunk) {
+            $affected_rows += $this->db->executeUpdate(
+                $deleteQb->getSQL(),
+                [$items_chunk],
+                [IQueryBuilder::PARAM_INT_ARRAY]
+            );
+        }
+        return $affected_rows;
     }
 
     /**
diff --git a/lib/Db/NewsMapperV2.php b/lib/Db/NewsMapperV2.php
index f7179574c..b33266f8b 100644
--- a/lib/Db/NewsMapperV2.php
+++ b/lib/Db/NewsMapperV2.php
@@ -35,6 +35,13 @@ abstract class NewsMapperV2 extends QBMapper
     const TABLE_NAME = null;
 
     /**
+     * Maximum number of prepared parameters that PDO can handle
+     *
+     * @var int
+     */
+    const PDO_PARAMS_LIMIT = 65535;
+
+    /**
      * @var Time
      */
     private $time;