Currently I have a system, which is based solely on Solr. Which means, that I store all data in Solr (using SolrJ) with no other datastore involved. The problem is now, that I experience some performance issues. I thought, that it maybe could make sense to store in MySQL and then synchronize the data with Solr with e.g. the DataImportHandler. So that I have the reading operations on the Solr index and the main writing operations in MySQL and then sometimes only Solr-Writing operations when synchronizing with Solr.
The thing is that I expect hundreds of millions documents which should be stored and I don't really now if that the MySQL/Solr makes sense.
Is there another better solution? Maybe Master-Solr for writing and Solr-slaves for reading?
Update: What I forgot to say is, that also in case of a schema.xml change, the "storing data in MySQL" solution could be useful in my opinion, because then I can re-commit all the data without caring about Solr's self-stored data.