diff --git a/tox.ini b/tox.ini
index a7ac5f52fd2..15dbb9246b5 100644
--- a/tox.ini
+++ b/tox.ini
@@ -63,7 +63,8 @@ deps =
   {[testenv:functional]deps}
 commands =
   {toxinidir}/tools/deploy_rootwrap.sh {toxinidir} {envdir}/etc {envdir}/bin
-  stestr run --group_regex=(.*MySQL\.|.*PostgreSQL\.) {posargs}
+  stestr run --group-regex .*PostgreSQL\. --exclude-regex .*MySQL\. {posargs}
+  stestr run --combine --concurrency 1 .*MySQL\. {posargs}
 
 [testenv:dsvm-fullstack]
 setenv = {[testenv]setenv}