#1910 Double-buffer SOLR updates for performance
For better search performance, we should have two solr cores we use, a 'hot' core and a 'cold' core. The hot core will be the one all online updates go to, and it should be committed frequently. Periodically (maybe once a day), all the indexing operations on the hot core will be replayed to the cold core and the hot core will be cleared out, keeping its index small. Queries will need to query both cores, and will need to verify each document ID is not in a 'deleted' list if the document comes from the cold core.
dupe of [#1472]
Related
Tickets: #1472