Hi Josh, For post grouping the documents don't need to reside in the same segment. Lucene's grouping module has a collector (TermAllGroupHeadsCollector) that can collect the most relevant document for each group (GroupHead). This collector can produce a int[] or a FixedBitSet that can be used during faceting to produce post group facets (patch in SOLR-2665 uses this). During faceting only the the groupheads are known, because of this field values that are different in documents less relevant than the most relevant document of a group aren't taken into account. This is the same as in example described in the description of LUCENE-3097. Hope this helps!
Martijn On 4 August 2011 22:59, Joshua Harness <jkharnes...@gmail.com> wrote: > Hello - > > Please let me know if this question is more appropriate of the user > list. I had assumed the developer list was more appropriate since the ticket > is still open. I was analyzing the comments on > LUCENE-3097<https://issues.apache.org/jira/browse/LUCENE-3097>and had a > couple of questions. > > A > comment<https://issues.apache.org/jira/browse/LUCENE-3097?focusedCommentId=13033953&page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel#comment-13033953>started > a small thread that mentioned that all documents in a given group > would need to be contiguous and in the same segment. Also - a statement was > made that ' The app would have to ensure this'. I was unclear the result of > this conversation. It sounded like maybe this could have turned out to not > be the case. What is the status of this? Does my application have to ensure > all the documents in the group are in the same segment? How would one > accomplish this? > > Another > comment<https://issues.apache.org/jira/browse/LUCENE-3097?focusedCommentId=13038297&page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel#comment-13038297>mentioned > that 'we pick only the head doc...as long as the head doc is > guaranteed to have the same value for field X, it safe to use that doc to > represent the entire group for facet counting'. Does this mean that there > is a restriction placed on me that the head document must have field values > that match the rest of the documents in the same group? Or is this simply an > implementation detail that uses the head document when this condition is the > case or chooses another strategy when this is not the case? > > I am very interested in adopting this patch. However - I am attempting > to understand any limitations/conditions so that I may use it correctly. Any > advice would be greatly appreciated. > > Thanks! > > Josh Harness > -- Met vriendelijke groet, Martijn van Groningen
