diff --git a/includes/database/pgsql/query.inc b/includes/database/pgsql/query.inc
index f3783a9..31cebbf 100644
--- a/includes/database/pgsql/query.inc
+++ b/includes/database/pgsql/query.inc
@@ -207,3 +207,19 @@ class UpdateQuery_pgsql extends UpdateQuery {
     return $stmt->rowCount();
   }
 }
+
+class TruncateQuery_pgsql extends TruncateQuery {
+  public function __toString() {
+    // TRUNCATE is actually a DDL statement on PostgreSQL, and DDL statements
+    // are not transactional, and result in an implicit COMMIT. When we are in a
+    // transaction, fallback to the slower, but transactional, DELETE.
+    if ($this->connection->inTransaction()) {
+      // Create a comment string to prepend to the query.
+      $comments = $this->connection->makeComment($this->comments);
+      return $comments . 'DELETE FROM {' . $this->connection->escapeTable($this->table) . '}';
+    }
+    else {
+      return parent::__toString();
+    }
+  }
+}