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https://issues.apache.org/jira/browse/SOLR-5244?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel
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Joel Bernstein updated SOLR-5244:
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Attachment: SOLR-5244.patch
New patch with all tests passing. Also added syntax error handling.
It lookes like rows=-1 is not the best way to signal the export because it
seems to already be used to signal other behavior.
So right now the syntax is:
q=hello&rq={!xport}&wt=xsort&fl=...&sort=...
In general the use of the RankQuery (rq param) is more intuitive then when a
PostFilter was being used to collect the BitSet.
Happy to try a different syntax though if there are more ideas.
> Exporting Full Sorted Result Sets
> ---------------------------------
>
> Key: SOLR-5244
> URL: https://issues.apache.org/jira/browse/SOLR-5244
> Project: Solr
> Issue Type: New Feature
> Components: search
> Affects Versions: 5.0
> Reporter: Joel Bernstein
> Assignee: Joel Bernstein
> Priority: Minor
> Fix For: 5.0, 4.10
>
> Attachments: 0001-SOLR_5244.patch, SOLR-5244.patch, SOLR-5244.patch,
> SOLR-5244.patch, SOLR-5244.patch
>
>
> This ticket allows Solr to export full sorted result sets. The proposed
> syntax is:
> {code}
> q=*:*&rows=-1&wt=xsort&fl=a,b,c&sort=a desc,b desc
> {code}
> Under the covers, the rows=-1 parameter will signal Solr to use the
> ExportQParserPlugin as a RankQuery, which will simply collect a BitSet of the
> results. The SortingResponseWriter will sort the results based on the sort
> criteria and stream the results out.
> This capability will open up Solr for a whole range of uses that were
> typically done using aggregation engines like Hadoop. For example:
> *Large Distributed Joins*
> A client outside of Solr calls two different Solr collections and returns the
> results sorted by a join key. The client iterates through both streams and
> performs a merge join.
> *Fully Distributed Field Collapsing/Grouping*
> A client outside of Solr makes individual calls to all the servers in a
> single collection and returns results sorted by the collapse key. The client
> merge joins the sorted lists on the collapse key to perform the field
> collapse.
> *High Cardinality Distributed Aggregation*
> A client outside of Solr makes individual calls to all the servers in a
> single collection and sorts on a high cardinality field. The client then
> merge joins the sorted lists to perform the high cardinality aggregation.
> *Large Scale Time Series Rollups*
> A client outside Solr makes individual calls to all servers in a collection
> and sorts on time dimensions. The client merge joins the sorted result sets
> and rolls up the time dimensions as it iterates through the data.
> In these scenarios Solr is being used as a distributed sorting engine.
> Developers can write clients that take advantage of this sorting capability
> in any way they wish.
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