Yes, the IDFs will be different. You could probably implement a custom component that would take term statistics from the previous collections to pre-populate the stats of the current collection, but this is an uncharted area, there’s a lot that could go wrong. Eg. if there’s a genuine shift in the term distribution in more recent documents then you probably would not want the old statistics to skew the more recent results, at least you would want to use some weighting factor - and at this point predicting the final term IDFs (and consequently document rankings) becomes quite complicated.
> On 18 May 2019, at 08:14, SOLR4189 <klin892...@yandex.ru> wrote: > > I ask my question due to I want to use TRA (Time Routed Aliases). Let's say > SOLR will open new collection every month. In the beginning of month a new > collection will be empty almost. > So IDF will be different between new collection and collection of previous > month? > > > > -- > Sent from: http://lucene.472066.n3.nabble.com/Solr-User-f472068.html >
