very large collection

We use Omeka for smaller digital collections no problem, I am wondering if anyone out there has any huge collections? I'm thinking of 250,000 items or more. Does Omeka run into any indexing difficulties at this level? Omeka seems to just use MySQL and no specialist indexing engine like Lucene or Solr. But maybe someone could let me know their experiences.



There is a SolrSearch plugin, though I can't say I have direct experience with using it.

I know that there are Omeka sites that go over a million records , but again don't know the details of how they've set up their servers. Florida Memory is an example of a big site, but it looks like they're on an older version of Omeka.