Hi, Atomic updates (single field updates) do not depend on DocValues. They were implemented in Solr4.0 and works fine (but all fields have to be retrievable). DocValues are supposed to be more efficient than FieldCache. Why not enabled by default ? Maybe because they are not for all fields and because of their limitations (a field has to be single-valued, required or to have default value). Regards.
On 29 March 2013 17:20, Timothy Potter <thelabd...@gmail.com> wrote: > Hi Jack, > > I've just started to dig into this as well, so sharing what I know but > still some holes in my knowledge too. > > DocValues == Column Stride Fields (best resource I know of so far is > Simon's preso from Lucene Rev 2011 - > > http://www.slideshare.net/LucidImagination/column-stride-fields-aka-docvalues > ). > It's pretty dense but some nuggets I've gleaned from this are: > > 1) DocValues are more efficient in terms of memory usage and I/O > performance for building an alternative to FieldCache (slide 27 is very > impressive) > 2) DocValues has a more efficient way to store primitive types, such as > packed ints > 3) Faster random access to stored values > > In terms of switch-over, you have to re-index to change your fields to use > DocValues on disk, which is why they are not enabled by default. > > Lastly, another goal of DocValues is to allow updates to a single field w/o > re-indexing the entire doc. That's not implemented yet but I think still > planned. > > Cheers, > Tim > > > > On Fri, Mar 29, 2013 at 9:31 AM, Jack Krupansky <j...@basetechnology.com > >wrote: > > > I’m still a little fuzzy on DocValues (maybe because I’m still grappling > > with how it does or doesn’t still relate to “Column Stride Fields”), so > can > > anybody clue me in as to how useful DocValues is/are? > > > > Are DocValues simply an alternative to “stored fields”? > > > > If so, and if DocValues are so great, why aren’t we just switching Solr > > over to DocValues under the hood for all fields? > > > > And if there are “issues” with DocValues that would make such a complete > > switchover less than absolutely desired, what are those issues? > > > > In short, when should a user use DocValues over stored fields, and vice > > versa? > > > > As things stand, all we’ve done is make Solr more confusing than it was > > before, without improving its OOBE. OOBE should be job one in Solr. > > > > Thanks. > > > > P.S., And if I actually want to do Column Stride Fields, is there a way > to > > do that? > > > > -- Jack Krupansky >
