diff --git a/src/Symfony/Component/HttpFoundation/Session/Storage/Handler/PdoSessionHandler.php b/src/Symfony/Component/HttpFoundation/Session/Storage/Handler/PdoSessionHandler.php
index daabbc21f0..15945644a4 100644
--- a/src/Symfony/Component/HttpFoundation/Session/Storage/Handler/PdoSessionHandler.php
+++ b/src/Symfony/Component/HttpFoundation/Session/Storage/Handler/PdoSessionHandler.php
@@ -330,13 +330,7 @@ class PdoSessionHandler implements \SessionHandlerInterface
                 return true;
             }
 
-            $updateStmt = $this->pdo->prepare(
-                "UPDATE $this->table SET $this->dataCol = :data, $this->lifetimeCol = :lifetime, $this->timeCol = :time WHERE $this->idCol = :id"
-            );
-            $updateStmt->bindParam(':id', $sessionId, \PDO::PARAM_STR);
-            $updateStmt->bindParam(':data', $data, \PDO::PARAM_LOB);
-            $updateStmt->bindParam(':lifetime', $maxlifetime, \PDO::PARAM_INT);
-            $updateStmt->bindValue(':time', time(), \PDO::PARAM_INT);
+            $updateStmt = $this->getUpdateStatement($sessionId, $data, $maxlifetime);
             $updateStmt->execute();
 
             // When MERGE is not supported, like in Postgres < 9.5, we have to use this approach that can result in
@@ -346,13 +340,7 @@ class PdoSessionHandler implements \SessionHandlerInterface
             // false positives due to longer gap locking.
             if (!$updateStmt->rowCount()) {
                 try {
-                    $insertStmt = $this->pdo->prepare(
-                        "INSERT INTO $this->table ($this->idCol, $this->dataCol, $this->lifetimeCol, $this->timeCol) VALUES (:id, :data, :lifetime, :time)"
-                    );
-                    $insertStmt->bindParam(':id', $sessionId, \PDO::PARAM_STR);
-                    $insertStmt->bindParam(':data', $data, \PDO::PARAM_LOB);
-                    $insertStmt->bindParam(':lifetime', $maxlifetime, \PDO::PARAM_INT);
-                    $insertStmt->bindValue(':time', time(), \PDO::PARAM_INT);
+                    $insertStmt = $this->getInsertStatement($sessionId, $data, $maxlifetime);
                     $insertStmt->execute();
                 } catch (\PDOException $e) {
                     // Handle integrity violation SQLSTATE 23000 (or a subclass like 23505 in Postgres) for duplicate keys
@@ -521,13 +509,7 @@ class PdoSessionHandler implements \SessionHandlerInterface
                 // Exclusive-reading of non-existent rows does not block, so we need to do an insert to block
                 // until other connections to the session are committed.
                 try {
-                    $insertStmt = $this->pdo->prepare(
-                        "INSERT INTO $this->table ($this->idCol, $this->dataCol, $this->lifetimeCol, $this->timeCol) VALUES (:id, :data, :lifetime, :time)"
-                    );
-                    $insertStmt->bindParam(':id', $sessionId, \PDO::PARAM_STR);
-                    $insertStmt->bindValue(':data', '', \PDO::PARAM_LOB);
-                    $insertStmt->bindValue(':lifetime', 0, \PDO::PARAM_INT);
-                    $insertStmt->bindValue(':time', time(), \PDO::PARAM_INT);
+                    $insertStmt = $this->getInsertStatement($sessionId, '', 0);
                     $insertStmt->execute();
                 } catch (\PDOException $e) {
                     // Catch duplicate key error because other connection created the session already.
@@ -662,6 +644,72 @@ class PdoSessionHandler implements \SessionHandlerInterface
         return "SELECT $this->dataCol, $this->lifetimeCol, $this->timeCol FROM $this->table WHERE $this->idCol = :id";
     }
 
+    /**
+     * Returns an insert statement supported by the database for writing session data.
+     *
+     * @param string $sessionId   Session ID
+     * @param string $sessionData Encoded session data
+     * @param int    $maxlifetime session.gc_maxlifetime
+     *
+     * @return \PDOStatement The insert statement
+     */
+    private function getInsertStatement($sessionId, $sessionData, $maxlifetime)
+    {
+        switch ($this->driver) {
+            case 'oci':
+                $data = fopen('php://memory', 'r+');
+                fwrite($data, $sessionData);
+                rewind($data);
+                $sql = "INSERT INTO $this->table ($this->idCol, $this->dataCol, $this->lifetimeCol, $this->timeCol) VALUES (:id, EMPTY_BLOB(), :lifetime, :time) RETURNING $this->dataCol into :data";
+                break;
+            default:
+                $data = $sessionData;
+                $sql = "INSERT INTO $this->table ($this->idCol, $this->dataCol, $this->lifetimeCol, $this->timeCol) VALUES (:id, :data, :lifetime, :time)";
+                break;
+        }
+
+        $stmt = $this->pdo->prepare($sql);
+        $stmt->bindParam(':id', $sessionId, \PDO::PARAM_STR);
+        $stmt->bindParam(':data', $data, \PDO::PARAM_LOB);
+        $stmt->bindParam(':lifetime', $maxlifetime, \PDO::PARAM_INT);
+        $stmt->bindValue(':time', time(), \PDO::PARAM_INT);
+
+        return $stmt;
+    }
+
+    /**
+     * Returns an update statement supported by the database for writing session data.
+     *
+     * @param string $sessionId   Session ID
+     * @param string $sessionData Encoded session data
+     * @param int    $maxlifetime session.gc_maxlifetime
+     *
+     * @return \PDOStatement The update statement
+     */
+    private function getUpdateStatement($sessionId, $sessionData, $maxlifetime)
+    {
+        switch ($this->driver) {
+            case 'oci':
+                $data = fopen('php://memory', 'r+');
+                fwrite($data, $sessionData);
+                rewind($data);
+                $sql = "UPDATE $this->table SET $this->dataCol = EMPTY_BLOB(), $this->lifetimeCol = :lifetime, $this->timeCol = :time WHERE $this->idCol = :id RETURNING $this->dataCol into :data";
+                break;
+            default:
+                $data = $sessionData;
+                $sql = "UPDATE $this->table SET $this->dataCol = :data, $this->lifetimeCol = :lifetime, $this->timeCol = :time WHERE $this->idCol = :id";
+                break;
+        }
+
+        $stmt = $this->pdo->prepare($sql);
+        $stmt->bindParam(':id', $sessionId, \PDO::PARAM_STR);
+        $stmt->bindParam(':data', $data, \PDO::PARAM_LOB);
+        $stmt->bindParam(':lifetime', $maxlifetime, \PDO::PARAM_INT);
+        $stmt->bindValue(':time', time(), \PDO::PARAM_INT);
+
+        return $stmt;
+    }
+
     /**
      * Returns a merge/upsert (i.e. insert or update) statement when supported by the database for writing session data.
      *
@@ -673,18 +721,11 @@ class PdoSessionHandler implements \SessionHandlerInterface
      */
     private function getMergeStatement($sessionId, $data, $maxlifetime)
     {
-        $mergeSql = null;
         switch (true) {
             case 'mysql' === $this->driver:
                 $mergeSql = "INSERT INTO $this->table ($this->idCol, $this->dataCol, $this->lifetimeCol, $this->timeCol) VALUES (:id, :data, :lifetime, :time) ".
                     "ON DUPLICATE KEY UPDATE $this->dataCol = VALUES($this->dataCol), $this->lifetimeCol = VALUES($this->lifetimeCol), $this->timeCol = VALUES($this->timeCol)";
                 break;
-            case 'oci' === $this->driver:
-                // DUAL is Oracle specific dummy table
-                $mergeSql = "MERGE INTO $this->table USING DUAL ON ($this->idCol = ?) ".
-                    "WHEN NOT MATCHED THEN INSERT ($this->idCol, $this->dataCol, $this->lifetimeCol, $this->timeCol) VALUES (?, ?, ?, ?) ".
-                    "WHEN MATCHED THEN UPDATE SET $this->dataCol = ?, $this->lifetimeCol = ?, $this->timeCol = ?";
-                break;
             case 'sqlsrv' === $this->driver && version_compare($this->pdo->getAttribute(\PDO::ATTR_SERVER_VERSION), '10', '>='):
                 // MERGE is only available since SQL Server 2008 and must be terminated by semicolon
                 // It also requires HOLDLOCK according to http://weblogs.sqlteam.com/dang/archive/2009/01/31/UPSERT-Race-Condition-With-MERGE.aspx
@@ -699,29 +740,30 @@ class PdoSessionHandler implements \SessionHandlerInterface
                 $mergeSql = "INSERT INTO $this->table ($this->idCol, $this->dataCol, $this->lifetimeCol, $this->timeCol) VALUES (:id, :data, :lifetime, :time) ".
                     "ON CONFLICT ($this->idCol) DO UPDATE SET ($this->dataCol, $this->lifetimeCol, $this->timeCol) = (EXCLUDED.$this->dataCol, EXCLUDED.$this->lifetimeCol, EXCLUDED.$this->timeCol)";
                 break;
+            default:
+                // MERGE is not supported with LOBs: http://www.oracle.com/technetwork/articles/fuecks-lobs-095315.html
+                return null;
         }
 
-        if (null !== $mergeSql) {
-            $mergeStmt = $this->pdo->prepare($mergeSql);
+        $mergeStmt = $this->pdo->prepare($mergeSql);
 
-            if ('sqlsrv' === $this->driver || 'oci' === $this->driver) {
-                $mergeStmt->bindParam(1, $sessionId, \PDO::PARAM_STR);
-                $mergeStmt->bindParam(2, $sessionId, \PDO::PARAM_STR);
-                $mergeStmt->bindParam(3, $data, \PDO::PARAM_LOB);
-                $mergeStmt->bindParam(4, $maxlifetime, \PDO::PARAM_INT);
-                $mergeStmt->bindValue(5, time(), \PDO::PARAM_INT);
-                $mergeStmt->bindParam(6, $data, \PDO::PARAM_LOB);
-                $mergeStmt->bindParam(7, $maxlifetime, \PDO::PARAM_INT);
-                $mergeStmt->bindValue(8, time(), \PDO::PARAM_INT);
-            } else {
-                $mergeStmt->bindParam(':id', $sessionId, \PDO::PARAM_STR);
-                $mergeStmt->bindParam(':data', $data, \PDO::PARAM_LOB);
-                $mergeStmt->bindParam(':lifetime', $maxlifetime, \PDO::PARAM_INT);
-                $mergeStmt->bindValue(':time', time(), \PDO::PARAM_INT);
-            }
-
-            return $mergeStmt;
+        if ('sqlsrv' === $this->driver) {
+            $mergeStmt->bindParam(1, $sessionId, \PDO::PARAM_STR);
+            $mergeStmt->bindParam(2, $sessionId, \PDO::PARAM_STR);
+            $mergeStmt->bindParam(3, $data, \PDO::PARAM_LOB);
+            $mergeStmt->bindParam(4, $maxlifetime, \PDO::PARAM_INT);
+            $mergeStmt->bindValue(5, time(), \PDO::PARAM_INT);
+            $mergeStmt->bindParam(6, $data, \PDO::PARAM_LOB);
+            $mergeStmt->bindParam(7, $maxlifetime, \PDO::PARAM_INT);
+            $mergeStmt->bindValue(8, time(), \PDO::PARAM_INT);
+        } else {
+            $mergeStmt->bindParam(':id', $sessionId, \PDO::PARAM_STR);
+            $mergeStmt->bindParam(':data', $data, \PDO::PARAM_LOB);
+            $mergeStmt->bindParam(':lifetime', $maxlifetime, \PDO::PARAM_INT);
+            $mergeStmt->bindValue(':time', time(), \PDO::PARAM_INT);
         }
+
+        return $mergeStmt;
     }
 
     /**