Yes have a look at the PageIndexer, http://find.episerver.com/Documentation/episerver-cms-integration-indexing.
PageIndexer.Instance.Conventions.ForInstancesOf<PageData>().ShouldIndex(page => !page.PageTypeName.StartsWith("[ExtensionSys]"));
Thanks for that. But will it also change the behaviour of "EPiServer Find CMS Indexing Job"?
Yes it will.
Put the code in global.asax in application start or in an IInitializableModule
I am testing EPiServer Find and are executing "EPiServer Find CMS Indexing Job" on a composer based EPiServer CMS R2 website. While browsing using the "Find" module I can see that It is indexing "[ExtensionSys] Extension Container" page types. Is there any way of exculding composer page types from indexing using "EPiServer Find CMS Indexing Job"