Just to be clear, I was suggesting that the filter query (fq) was slow, not the MatchAllDocsQuery, which should be just as speedy as before. You can test for yourself whether the MADQ by itself is any slower.
You could also test using the fq as the main query (q) - with no fq parameter, and see if that is a lot faster, both with old and new Solr. -- Jack Krupansky On Fri, Nov 6, 2015 at 3:01 PM, wei <sw90...@gmail.com> wrote: > Thanks Jack and Shawn. I checked these Jira tickets, but I am not sure if > the slowness of MatchAllDocsQuery is also caused by the removal of > fieldcache. Can someone please explain a little bit? > > Thanks, > Wei > > On Fri, Nov 6, 2015 at 7:15 AM, Shawn Heisey <apa...@elyograg.org> wrote: > > > On 11/5/2015 10:25 PM, Jack Krupansky wrote: > > > I vaguely recall some discussion concerning removal of the field cache > in > > > Lucene. > > > > The FieldCache wasn't exactly *removed* ... it's more like it was > > renamed, improved, and sort of hidden in a miscellaneous package. Some > > things still require this functionality, so they use the hidden class > > instead, which was changed to use the DocValues API. > > > > https://issues.apache.org/jira/browse/LUCENE-5666 > > > > I am not qualified to discuss LUCENE-5666 beyond what I wrote in the > > paragraph above, and it's possible that some of what I said is wrong > > because I do not really understand the APIs involved. > > > > The change has caused problems for Solr. End result from Solr's > > perspective: Certain things which used to work perfectly fine (mostly > > facets and grouping) in Solr 4.x have one of two problems in 5.x: > > Either they don't work at all, or performance has gone way down. Some > > of these problems are documented in Jira. These are the issues I know > > about: > > > > https://issues.apache.org/jira/browse/SOLR-8088 > > https://issues.apache.org/jira/browse/SOLR-7495 > > https://issues.apache.org/jira/browse/SOLR-8096 > > > > For fields where adding docValues is a viable option (most field types > > other than solr.TextField), adding docValues and reindexing is very > > likely to solve those problems. > > > > Sometimes adding docValues won't work, either because the field type > > doesn't allow it, or because it's the indexed terms that are needed, not > > the original field value. For those situations, there is currently no > > solution. > > > > Thanks, > > Shawn > > > > >
