lucene-solr-user mailing list archives

Site index · List index
Message view « Date » · « Thread »
Top « Date » · « Thread »
From Morten Bøgeskov ...@dbc.dk>
Subject Re: SolrCloud different score for same document on different replicas.
Date Mon, 09 Jan 2017 08:44:28 GMT
On Fri, 6 Jan 2017 10:45:02 -0600
Webster Homer <webster.homer@sial.com> wrote:

> I was seeing something like this, and it turned out to be a problem with
> our autoCommit and autoSoftCommit settings. We had overly aggressive
> settings that eventually started failing with errors around too many
> warming searchers etc...
> 
> You can test this by doing a commit and seeing if the replicas start
> returning consistent results
> 

Commit changes nothing, since number og deleted documents doesn't
change much.
Optimize makes ranking consistent over replicas for the time being,
until too many updates has hit the shard, and the number of deleted
documents (in the largest, it takes some time to prune due to a merge)
segment. Optimizing hourly is not really an option.


> On Thu, Jan 5, 2017 at 10:31 AM, Charlie Hull <charlie@flax.co.uk> wrote:
> 
> > On 05/01/2017 13:30, Morten Bøgeskov wrote:
> >
> >>
> >>
> >> Hi.
> >>
> >> We've got a SolrCloud which is sharded and has a replication factor of
> >> 2.
> >>
> >> The 2 replicas of a shard may look like this:
> >>
> >> Num Docs:    5401023
> >> Max Doc:    6388614
> >> Deleted Docs:    987591
> >>
> >>
> >> Num Docs:    5401023
> >> Max Doc:    5948122
> >> Deleted Docs:    547099
> >>
> >> We've seen >10% difference in Max Doc at times with same Num Docs.
> >> Our use case is few documents that are search and many small that
> >> are filtered against (often updated multiple times a day), so the
> >> difference in deleted docs aren't surprising.
> >>
> >> This results in a different score for a document depending on which
> >> replica it comes from. As I see it: it has to do with the different
> >> maxDoc value when calculating idf.
> >>
> >> This in turn alters a specific document's position in the search
> >> result over reloads. This is quite confusing (duplicates in pagination).
> >>
> >> What is the trick to get homogeneous score from different replicas.
> >> We've tried using ExactStatsCache & ExactSharedStatsCache, but that
> >> didn't seem to make any difference.
> >>
> >> Any hints to this will be greatly appreciated.
> >>
> >>
> > This was one of things we looked at during our recent Lucene London
> > Hackday (see item 3) https://github.com/flaxsearch/london-hackday-2016
> >
> > I'm not sure there is a way to get a homogenous score - this patch tries
> > to keep you connected to the same replica during a session so you don't see
> > results jumping over pagination.
> >
> > Cheers
> >
> > Charlie
> >
> >
> > --
> > Charlie Hull
> > Flax - Open Source Enterprise Search
> >
> > tel/fax: +44 (0)8700 118334
> > mobile:  +44 (0)7767 825828
> > web: www.flax.co.uk
> >
> 



-- 
 Morten Bøgeskov <mb@dbc.dk>


Mime
View raw message