: <http://e-mats.org/2011/01/solr-memory-usage-and-dynamic-fields/ > : : Just to confirm, the fieldCache doesn't store anything extra when we use : dynamic fields and do sorting query on that...right?
the way the FieldCache works, is that it has to "cache" a value for every document -- even if that document doesn't have a value in the indexed field that FieldCache was built from. so if you have an index of 10K docs, and only 17 of those docs have a value in some field "my_really_sparse_int_field" then if you do a search and sort on "my_really_sparse_int_field" you're going to get a a FieldCache containing an array of 10K ints -- and all but 17 of them will be "0". if you sort on 199 other fields like those, you're going to have 199 other arrays of 10K ints. Instead of relying on the FieldCache, you should consider using DocValues, which -- unless i'm forgetting something -- should give you a lot better memory efficiencies if you have a lot of dynamicFields that are really sparse and you want to sort on them (at the expense of more disk space being used in your index). But i haven't done extensive memory testng of this to prove it to myself. -Hoss http://www.lucidworks.com/
