Michael Della Bitta [michael.della.bi...@appinions.com] wrote: > You should of course perform a test first to be sure, but you shouldn't > need to reindex.
One gotcha is that support for DocValuesFormat="Disk" was removed in Solr 4.9, so it simply can't open an index using that format. Fortunately it can be handled by changing format in the schema and performing an optimize using the old Solr version. How the performance/memory-trade-off of the Disk-format falls under "critical bug" and thus is reason enough to break backwards compatibility, I don't know. - Toke Eskildsen
