In a word, "yes". DocValues aren't particularly expensive, or expensive at all. The idea is that when you sort by a field or facet, the field has to be "uninverted" which builds the entire structure in Java's JVM (this is when the field is _not_ DocValues).
DocValues essentially serialize this structure to disk. So your on-disk index size is larger, but that size is MMaped rather than stored on Java's heap. Really, the question I'd have to ask though is "why do you care about the expense?". If you have a functional requirement that has to be served by returning the id via the /export handler, you really have no choice. Best, Erick On Sun, Apr 24, 2016 at 9:55 AM, sudsport s <sudssf2...@gmail.com> wrote: > I was trying to use Streaming for reading basic tuple stream. I am using > sort by id asc , > I am getting following exception > > I am using export search handler as per > https://cwiki.apache.org/confluence/display/solr/Exporting+Result+Sets > > null:java.io.IOException: id must have DocValues to use this feature. > at > org.apache.solr.response.SortingResponseWriter.getFieldWriters(SortingResponseWriter.java:241) > at > org.apache.solr.response.SortingResponseWriter.write(SortingResponseWriter.java:120) > at > org.apache.solr.response.QueryResponseWriterUtil.writeQueryResponse(QueryResponseWriterUtil.java:53) > at > org.apache.solr.servlet.HttpSolrCall.writeResponse(HttpSolrCall.java:742) > at org.apache.solr.servlet.HttpSolrCall.call(HttpSolrCall.java:471) > at > org.apache.solr.servlet.SolrDispatchFilter.doFilter(SolrDispatchFilter.java:214) > at > org.apache.solr.servlet.SolrDispatchFilter.doFilter(SolrDispatchFilter.java:179) > at > org.eclipse.jetty.servlet.ServletHandler$CachedChain.doFilter(ServletHandler.java:1652) > at > org.eclipse.jetty.servlet.ServletHandler.doHandle(ServletHandler.java:585) > at > org.eclipse.jetty.server.handler.ScopedHandler.handle(ScopedHandler.java:143) > at > org.eclipse.jetty.security.SecurityHandler.handle(SecurityHandler.java:577) > at > org.eclipse.jetty.server.session.SessionHandler.doHandle(SessionHandler.java:223) > at > org.eclipse.jetty.server.handler.ContextHandler.doHandle(ContextHandler.java:1127) > at > org.eclipse.jetty.servlet.ServletHandler.doScope(ServletHandler.java:515) > at org.eclipse.jetty.server.session.SessionHandler.doScope( > > > does it make sense to enable docValues for unique field? How expensive is it? > > > if I have existing collection can I update schema and optimize > collection to get docvalues enabled for id? > > > -- > > Thanks
