Solr/Lucene fieldCache OutOfMemory error sorting on dynamic field

Question

We have a Solr core that has about 250 TrieIntFields (declared as dynamicField). There are about 14M docs in our Solr index and many documents have

Answer 1

We have a way to rework the schema by keeping a single sort field. The dynamic fields we have are like relevance_CLASSID. The current schema has a unique key NODEID and a multi-valued field CLASSID - the relevance scores are for these class Ids. If we instead keep one document per classId per nodeId i.e. the new schema will have NODEID:CLASSID as unique key and store some redundant information across documents with the same NODEID, then we can sort on a single field relevance and do a filter query on CLASSID.

Answer 2

I think you have two options:

1) Add more memory.
2) Force Solr not to use the field cache by specifying facet.method=enum, as per documentation.

There's also a solr-user mailing list thread discussing the same problem.

Unless your index is huge, I'd go with option 1). RAM is cheap these days.