Fixed query result caching when FetchMode::COLUMN is used

Internally, ArrayStatement expects every row to be represented as an array regardless of the fetch mode, however FetchMode::COLUMN produces one value per row.

lib/Doctrine/DBAL/Cache/ResultCacheStatement.php

@@ -167,7 +167,15 @@ class ResultCacheStatement implements IteratorAggregate, ResultStatement
      */
     public function fetchAll($fetchMode = null, $fetchArgument = null, $ctorArgs = null)
     {
-        $this->data    = $this->statement->fetchAll($fetchMode, $fetchArgument, $ctorArgs);
+        $data = $this->statement->fetchAll($fetchMode, $fetchArgument, $ctorArgs);
+
+        if ($fetchMode === FetchMode::COLUMN) {
+            foreach ($data as $key => $value) {
+                $data[$key] = [$value];
+            }
+        }
+
+        $this->data    = $data;
         $this->emptied = true;
 
         return $this->data;

tests/Doctrine/Tests/DBAL/Functional/ResultCacheTest.php

@@ -177,6 +177,22 @@ class ResultCacheTest extends DbalFunctionalTestCase
         self::assertCount(1, $layerCache->fetch('testcachekey'));
     }
 
+    public function testFetchAllColumn() : void
+    {
+        $query = $this->connection->getDatabasePlatform()
+            ->getDummySelectSQL('1');
+
+        $qcp = new QueryCacheProfile(0, 0, new ArrayCache());
+
+        $stmt = $this->connection->executeCacheQuery($query, [], [], $qcp);
+        $stmt->fetchAll(FetchMode::COLUMN);
+        $stmt->closeCursor();
+
+        $stmt = $this->connection->executeCacheQuery($query, [], [], $qcp);
+
+        self::assertEquals([1], $stmt->fetchAll(FetchMode::COLUMN));
+    }
+
     /**
      * @param array<int, array<int, int|string>> $expectedResult
      */