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https://issues.apache.org/jira/browse/SOLR-236?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=12791986#action_12791986
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Martijn van Groningen commented on SOLR-236:
--------------------------------------------
Shalin.
1. This configuration also looks fine by me. The reason I added
<fieldCollapsing> ... </fieldCollapsing> was to be able support sharing of
collapseCollectorFactory instances between different collapse components in the
near future. You think that is a valid reason for that? Or do you think that
collapseCollectorFactories shouldn't be shared?
2. I forgot to create that, so a good thing you added it.
3. I think leaving out those changes will make the distributed integration
tests fail (Haven't checked it).
Noble.
1. The reason I gave a name to collaspeCollectorFactory was for using an
instance twice for different collapse components.
2. Moving the classname to the class attribute looks better, then in the
function element. So I think we should change that.
Grant.
1. I think you also referring to sharding. Sharding is supported, but not in a
very elegant way. You will need to partition your documents to your shards in
such a way that all documents belonging to a collapse group appear on one
shard. To be honest I have never tested the patch on a corpus of 100M docs.
2. Field collapsing can impact the search time in a very negative way. I wrote
a small paragraph about it on my
[blog|http://blog.jteam.nl/2009/10/20/result-grouping-field-collapsing-with-solr/].
3. The first two response examples are for 'old' patches. The last response
example is for the more recent patches (and current patch).
> Field collapsing
> ----------------
>
> Key: SOLR-236
> URL: https://issues.apache.org/jira/browse/SOLR-236
> Project: Solr
> Issue Type: New Feature
> Components: search
> Affects Versions: 1.3
> Reporter: Emmanuel Keller
> Assignee: Shalin Shekhar Mangar
> Fix For: 1.5
>
> Attachments: collapsing-patch-to-1.3.0-dieter.patch,
> collapsing-patch-to-1.3.0-ivan.patch, collapsing-patch-to-1.3.0-ivan_2.patch,
> collapsing-patch-to-1.3.0-ivan_3.patch, field-collapse-3.patch,
> field-collapse-4-with-solrj.patch, field-collapse-5.patch,
> field-collapse-5.patch, field-collapse-5.patch, field-collapse-5.patch,
> field-collapse-5.patch, field-collapse-5.patch, field-collapse-5.patch,
> field-collapse-5.patch, field-collapse-5.patch, field-collapse-5.patch,
> field-collapse-5.patch, field-collapse-5.patch, field-collapse-5.patch,
> field-collapse-5.patch, field-collapse-5.patch,
> field-collapse-solr-236-2.patch, field-collapse-solr-236.patch,
> field-collapsing-extended-592129.patch, field_collapsing_1.1.0.patch,
> field_collapsing_1.3.patch, field_collapsing_dsteigerwald.diff,
> field_collapsing_dsteigerwald.diff, field_collapsing_dsteigerwald.diff,
> quasidistributed.additional.patch, SOLR-236-FieldCollapsing.patch,
> SOLR-236-FieldCollapsing.patch, SOLR-236-FieldCollapsing.patch,
> SOLR-236.patch, solr-236.patch, SOLR-236_collapsing.patch,
> SOLR-236_collapsing.patch
>
>
> This patch include a new feature called "Field collapsing".
> "Used in order to collapse a group of results with similar value for a given
> field to a single entry in the result set. Site collapsing is a special case
> of this, where all results for a given web site is collapsed into one or two
> entries in the result set, typically with an associated "more documents from
> this site" link. See also Duplicate detection."
> http://www.fastsearch.com/glossary.aspx?m=48&amid=299
> The implementation add 3 new query parameters (SolrParams):
> "collapse.field" to choose the field used to group results
> "collapse.type" normal (default value) or adjacent
> "collapse.max" to select how many continuous results are allowed before
> collapsing
> TODO (in progress):
> - More documentation (on source code)
> - Test cases
> Two patches:
> - "field_collapsing.patch" for current development version
> - "field_collapsing_1.1.0.patch" for Solr-1.1.0
> P.S.: Feedback and misspelling correction are welcome ;-)
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