Hi The FacetsConfig object is the one that you use to index facets, and at search time it is consulted about the facets attributes (multi-valued, hierarchical etc.). You can make changes to the FacetsConfig, as long as they don't contradict the indexed data in a problematic manner.
Usually the facets configuration does not change, but I believe it will work if you add new dimensions. Current in-flight searches won't query/count those dimensions anyway, and new searches will find those dimensions in recently indexed documents only. It is up to you to decide if the old 1 million documents that don't contain the new Person facet are OK to display together w/ the 10 new documents that do, but as long as you're OK with that, application-wise, adding new dimensions should just work. Contradicting changes are changes to the attributes of one dimension, e.g. from hierarchical to flat. In that case, that that there are 1 million old documents indexed w/ A/B/C hierarchy and 10 new documents w/ only A/B doesn't matter to the FacetsConfig - all documents will be considered flat in that case. Here I'm less sure about the effects of that on search (I don't think we have a test for it), but I hope that you don't do that. It's not advisable, just like any other schema changes to your fields while there are already indexed documents. Shai
