Issue #2443651 by alexpott, mradcliffe, bzrudi71: PostgreSQL: Fix system\Tests\Cache\DatabaseBackendUnitTest

core/lib/Drupal/Core/Cache/DatabaseBackend.php

@@ -202,18 +202,7 @@ class DatabaseBackend implements CacheBackendInterface {
    * {@inheritdoc}
    */
   public function setMultiple(array $items) {
-    // Use a transaction so that the database can write the changes in a single
+    $values = array();
-    // commit.
-    $transaction = $this->connection->startTransaction();
-
-    try {
-      // Delete all items first so we can do one insert. Rather than multiple
-      // merge queries.
-      $this->deleteMultiple(array_keys($items));
-
-      $query = $this->connection
-        ->insert($this->bin)
-        ->fields(array('cid', 'data', 'expire', 'created', 'serialized', 'tags', 'checksum'));
 
     foreach ($items as $cid => $item) {
       $item += array(
@@ -242,8 +231,28 @@ class DatabaseBackend implements CacheBackendInterface {
         $fields['data'] = $item['data'];
         $fields['serialized'] = 0;
       }
+      $values[] = $fields;
+    }
 
-        $query->values($fields);
+    // Use a transaction so that the database can write the changes in a single
+    // commit. The transaction is started after calculating the tag checksums
+    // since that can create a table and this causes an exception when using
+    // PostgreSQL.
+    $transaction = $this->connection->startTransaction();
+
+    try {
+      // Delete all items first so we can do one insert. Rather than multiple
+      // merge queries.
+      $this->deleteMultiple(array_keys($items));
+
+      $query = $this->connection
+        ->insert($this->bin)
+        ->fields(array('cid', 'expire', 'created', 'tags', 'checksum', 'data', 'serialized'));
+      foreach ($values as $fields) {
+        // Only pass the values since the order of $fields matches the order of
+        // the insert fields. This is a performance optimization to avoid
+        // unnecessary loops within the method.
+        $query->values(array_values($fields));
       }
 
       $query->execute();