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Apache Solr Reference Guide Covering Apache Solr 6.0

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Streaming Expressions<br />

Streaming Expressions provide a simple yet powerful stream processing language for <strong>Solr</strong>Cloud. They are a<br />

suite of functions that can be combined to perform many different parallel computing tasks. These functions are<br />

the basis for the Parallel SQL Interface.<br />

There are several available functions, including those that implement:<br />

continuous push streaming<br />

continuous pull streaming<br />

request/response streaming<br />

MapReduce shuffling aggregation<br />

pushdown faceted aggregation<br />

parallel relational algebra (distributed joins, intersections, unions, complements)<br />

publish/subscribe messaging<br />

Streams from outside systems can be joined with streams originating from <strong>Solr</strong> and users can add their own<br />

stream functions by following <strong>Solr</strong>'s Java streaming API.<br />

Both streaming expressions and the streaming API are considered experimental, and the APIs are<br />

subject to change.<br />

Stream Language Basics<br />

Streaming Requests and Responses<br />

Data Requirements<br />

Stream Sources<br />

search<br />

jdbc<br />

facet<br />

stats<br />

topic<br />

Stream Decorators<br />

complement<br />

daemon<br />

leftOuterJoin<br />

hashJoin<br />

innerJoin<br />

intersect<br />

merge<br />

outerHashJoin<br />

parallel<br />

reduce<br />

rollup<br />

select<br />

top<br />

unique<br />

update<br />

Stream Language Basics<br />

Streaming Expressions are comprised of streaming functions which work with a <strong>Solr</strong> collection. They emit a<br />

stream of tuples (key/value Maps).<br />

Many of the provided streaming functions are designed to work with entire result sets rather then the top N<br />

results like normal search. This is supported by the /export handler.<br />

<strong>Apache</strong> <strong>Solr</strong> <strong>Reference</strong> <strong>Guide</strong> <strong>6.0</strong><br />

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