[
https://issues.apache.org/jira/browse/LUCENE-1421?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13032145#comment-13032145
]
Michael McCandless commented on LUCENE-1421:
--------------------------------------------
{quote}
I think we also need a strategy mechanism (or at least an GroupCollector class
hierarchy) inside this module. The mechanism should select the right group
collector(s) for a certain request. Some users maybe only care about the top
group document, so I second pass won't be necessary. Another example with
faceting in mind. When group based faceting is necessary. The top N groups
don't suffice. You'll need all group docs (I currently don't see a other way).
These groups docs are then used to create a grouped Solr DocSet. But this
should be a completely different implementation.
{quote}
I agree, there's much more we could do here! Specialized collection for the
maxDocsPerGroup=1 case, and for the "I want all groups" case, would be nice.
For the "not many unique values in the group field" case we could do a
single-pass collector, I think.
Grouping by a multi-valued field should be possible (we now have DocTermOrds in
Lucene, but it doesn't load the term byte[] data), as well as support for
sharding, ie, by merging top groups and docs w/in each group (but I think we
need an addition to FieldComparator API for this).
I think we should commit this starting point, today, and then iterate from
there...
Martijn, thank you for persisting for so long on SOLR-236! We are
finally getting grouping functionality accessible from Lucene and
Solr...
> Ability to group search results by field
> ----------------------------------------
>
> Key: LUCENE-1421
> URL: https://issues.apache.org/jira/browse/LUCENE-1421
> Project: Lucene - Java
> Issue Type: New Feature
> Components: Search
> Reporter: Artyom Sokolov
> Assignee: Michael McCandless
> Priority: Minor
> Fix For: 3.2, 4.0
>
> Attachments: LUCENE-1421.patch, LUCENE-1421.patch,
> lucene-grouping.patch
>
>
> It would be awesome to group search results by specified field. Some
> functionality was provided for Apache Solr but I think it should be done in
> Core Lucene. There could be some useful information like total hits about
> collapsed data like total count and so on.
> Thanks,
> Artyom
--
This message is automatically generated by JIRA.
For more information on JIRA, see: http://www.atlassian.com/software/jira
---------------------------------------------------------------------
To unsubscribe, e-mail: [email protected]
For additional commands, e-mail: [email protected]
