Apache Solr Reference Guide Covering Apache Solr 6.0

Some streaming functions act as stream sources to originate the stream flow. Other streaming functions act as
stream decorators to wrap other stream functions and perform operations on the stream of tuples. Many streams
functions can be parallelized across a worker collection. This can be particularly powerful for relational algebra
functions.
Streaming Requests and Responses
Solr has a /stream request handler that takes streaming expression requests and returns the tuples as a JSON
stream. This request handler is implicitly defined, meaning there is nothing that has to be defined in solrconfi
g.xml.
The /stream request handler takes one parameter, expr, which is used to specify the streaming
expression. For example, this curl command encodes and POSTs a simple search() expression to the /strea
m handler:
curl --data-urlencode 'expr=search(enron_emails,
q="from:1800flowers*",
fl="from, to",
sort="from asc",
qt="/export")'
http://localhost:8983/solr/enron_emails/stream
Details of the parameters for each function are included below.
For the above example the /stream handler responded with the following JSON response:
{"result-set":{"docs":[
{"from":"1800flowers.133139412@s2u2.com","to":"lcampbel@enron.com"},
{"from":"1800flowers.93690065@s2u2.com","to":"jtholt@ect.enron.com"},
{"from":"1800flowers.96749439@s2u2.com","to":"alewis@enron.com"},
{"from":"1800flowers@1800flowers.flonetwork.com","to":"lcampbel@enron.com"},
{"from":"1800flowers@1800flowers.flonetwork.com","to":"lcampbel@enron.com"},
{"from":"1800flowers@1800flowers.flonetwork.com","to":"lcampbel@enron.com"},
{"from":"1800flowers@1800flowers.flonetwork.com","to":"lcampbel@enron.com"},
{"from":"1800flowers@1800flowers.flonetwork.com","to":"lcampbel@enron.com"},
{"from":"1800flowers@shop2u.com","to":"ebass@enron.com"},
{"from":"1800flowers@shop2u.com","to":"lcampbel@enron.com"},
{"from":"1800flowers@shop2u.com","to":"lcampbel@enron.com"},
{"from":"1800flowers@shop2u.com","to":"lcampbel@enron.com"},
{"from":"1800flowers@shop2u.com","to":"ebass@enron.com"},
{"from":"1800flowers@shop2u.com","to":"ebass@enron.com"},
{"EOF":true,"RESPONSE_TIME":33}]}
}
Note the last tuple in the above example stream is {"EOF":true,"RESPONSE_TIME":33}. The EOF indicates
the end of the stream. To process the JSON response, you'll need to use a streaming JSON implementation
becausestreaming expressions are designed to return the entire result set which may have millions of records. In
your JSON client you'll need to iterate each doc (tuple) and check for the EOF tuple to determine the end of
stream.
The org.apache.solr.client.solrj.io package provides Java classes that compile streaming
expressions into streaming API objects. These classes can be used to execute streaming expressions from
inside a Java application. For example:
Apache Solr Reference Guide 6.0
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