The development of the field collapse feature is a long and confusing story. The main point is that SOLR-236 was never going to scale and the performance in general was bad. A new approach was needed. This was implemented in SOLR-1682 and added to the trunk (4.0-dev) around September last year. Later in LUCENE-1421 the code was moved from Solr to Lucene as a module / contrib. After that the grouping module and contrib were wired into Solr 3.3 and 4.0-dev in SOLR-2524 and SOLR-2564.
Field collapsing is not gone, but it is just a form of result grouping. The core SOLR-236 feature is in 3.3 / 4.0-dev. Other features that SOLR-236 offered will eventually get in. Like for example post grouping facets. The http parameters and response have changed without keeping it compatible with the SOLR-236 patches. I think that isn't a problem since SOLR-236 was never a committed feature. But a widely used feature should never be attached as a patch to a Jira issue for 3+ years.... On 3 August 2011 18:33, baronDodd <barond...@googlemail.com> wrote: > I am working on an implementation of search within our application using > solr. > > About 2 months ago we had the need to group results by a certain field. > After some searching I came across the JIRA in progress for this - field > collapsing: https://issues.apache.org/jira/browse/SOLR-236 > > It was scheduled for the next solr release and had a full set of proper > JIRA > subtasks and patch files of almost complete implementations attached. So as > you can imagine I was happy to apply this patch and build it into our > application and await for the next release when it would be part of the > main > trunk. > > Now imagine my surprise when we have come around to upgrade to see that > suddenly field collapsing has been thrown away in favour of a totally > different grouping implementation > https://issues.apache.org/jira/browse/SOLR-2524 > > How was it decided that this would be used instead? It was not made very > clear that LUCENE-1421 was in progress which would effectively make the > field collapsing work irrelevant by fixing the problem in lucene rather > than > primarily in solr. This has cost me days of work to now merge our custom > changes somehow to the new implementation. I guess it is my own fault for > basing our custom changes around an unresolved enhancement but as SOLR-236 > had been 3-4 years in progress and SOLR-2524 did not exist at the time it > seemed pretty safe to assume that the same problem was not being fixed in 2 > totally different ways! > > -- > View this message in context: > http://lucene.472066.n3.nabble.com/A-rant-about-field-collapsing-tp3222798p3222798.html > Sent from the Solr - User mailing list archive at Nabble.com. > -- Met vriendelijke groet, Martijn van Groningen
