[jira] [Commented] (SOLR-5027) Field Collapsing PostFilter

["Simon Endele (JIRA)" <ji...@apache.org>]

    [ https://issues.apache.org/jira/browse/SOLR-5027?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13894749#comment-13894749 ] 

Simon Endele commented on SOLR-5027:
------------------------------------

Hi Joel,

a similar question to Phil John's one: Is it correct that no equivalent for "group.limit" of the old grouping is/will be available?
I.e. only one document is returned for each group and the ExpandComponent can be used to get more, right?

I always thought that the aim of the ExpandComponent is to return _additional_ docs in a sense that these documents were not hit by the query (we wrote a component by ourselves for that based on the old grouping functionality).
Will that be possible with the ExpandComponent, or will it only be possible to fetch n (or all) documents of each group that were hit and collapsed by the CollapsingQParserPlugin (each only for a single page, of course)?

See also my question above concerning a filter query for the ExpandComponent.

Thanks in advance,
Simon

> Field Collapsing PostFilter
> ---------------------------
>
>                 Key: SOLR-5027
>                 URL: https://issues.apache.org/jira/browse/SOLR-5027
>             Project: Solr
>          Issue Type: New Feature
>          Components: search
>    Affects Versions: 5.0
>            Reporter: Joel Bernstein
>            Assignee: Joel Bernstein
>            Priority: Minor
>             Fix For: 4.6, 5.0
>
>         Attachments: SOLR-5027.patch, SOLR-5027.patch, SOLR-5027.patch, SOLR-5027.patch, SOLR-5027.patch, SOLR-5027.patch, SOLR-5027.patch, SOLR-5027.patch, SOLR-5027.patch
>
>
> This ticket introduces the *CollapsingQParserPlugin* 
> The *CollapsingQParserPlugin* is a PostFilter that performs field collapsing. This is a high performance alternative to standard Solr field collapsing (with *ngroups*) when the number of distinct groups in the result set is high.
> For example in one performance test, a search with 10 million full results and 1 million collapsed groups:
> Standard grouping with ngroups : 17 seconds.
> CollapsingQParserPlugin: 300 milli-seconds.
> Sample syntax:
> Collapse based on the highest scoring document:
> {code}
> fq=(!collapse field=<field_name>}
> {code}
> Collapse based on the min value of a numeric field:
> {code}
> fq={!collapse field=<field_name> min=<field_name>}
> {code}
> Collapse based on the max value of a numeric field:
> {code}
> fq={!collapse field=<field_name> max=<field_name>}
> {code}
> Collapse with a null policy:
> {code}
> fq={!collapse field=<field_name> nullPolicy=<null_policy>}
> {code}
> There are three null policies:
> ignore : removes docs with a null value in the collapse field (default).
> expand : treats each doc with a null value in the collapse field as a separate group.
> collapse : collapses all docs with a null value into a single group using either highest score, or min/max.
> The CollapsingQParserPlugin also fully supports the QueryElevationComponent
> *Note:*  The July 16 patch also includes and ExpandComponent that expands the collapsed groups for the current search result page. This functionality will be moved to it's own ticket.



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