Mathew created SOLR-18466:
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Summary: Support _route_ in the streaming expression function to
prune shard fan-out
Key: SOLR-18466
URL: https://issues.apache.org/jira/browse/SOLR-18466
Project: Solr
Issue Type: Improvement
Components: SolrJ, streaming expressions
Reporter: Mathew
The {{search()}} function in streaming expressions currently ignores
{{_route_}} for shard selection and queries every active slice of the target
collection. Users with known routing keys therefore incur unnecessary request
and response overhead, which can be significant on large clusters. This change
adds support for {{_route_}} param in the streaming expression search function,
reusing {{docCol.getRouter().getSearchSlices()}} which is used for shard
selection in normal distributed search.
*Changes:*
Two files in {{{}solr/solrj-streaming{}}}:
# *the {{CloudSolrStream}} class:*
the existing method:
{{List<Slice> getSlices(
String collectionName,
CloudSolrClient cloudSolrClient,
boolean checkAlias)}}
is kept for existing calls from {{{}TopicStream{}}}, {{{}TextLogitStream{}}},
{{{}FeaturesSelectionStream{}}}, and {{StatementImpl}} (all out of scope for
this change); these are unaffected and continue to receive all active slices
A new overloaded helper method is added:
{{List<Slice> getSlices(
String collectionName,
CloudSolrClient cloudSolrClient,
boolean checkAlias,
SolrParams solrParams)}}
When {{solrParams}} contains a nonempty {{{}_route_{}}}, each collection's
slices are resolved via {{docCol.getRouter().getSearchSlices(routeKeys, params,
docCol)}} and when {{_route_}} is absent (or empty), all active slices are
returned exactly as before.
# *the {{TupleStream}} class:*
{{CloudSolrStream.getSlices(collection, cloudSolrClient, true, solrParams)}} is
called after the request params are assembled and passed to the route aware
{{{}getSlices{}}}.
*Example usages:*
{{expr=search(collection1,
zkHost="localhost:9983",
qt="/export",
q="*:*",
fl="id,a_s,a_i,a_f",
sort="a_f asc, a_i asc", _route_="routeKeyA")}}
{{expr=search(collection1,
zkHost="localhost:9983",
qt="/export",
q="*:*",
fl="id,a_s,a_i,a_f",
sort="a_f asc, a_i asc", _route_="routeKeyA,routeKeyB,routeKeyC")}}
{{}}
*One note on backward compatibility:*
Previously, {{_route_}} was ignored during shard selection for streaming
expression {{{}search(){}}}. With this change, nonempty route values are passed
to {{{}docCol.getRouter().getSearchSlices(routeKeys, params, docCol){}}}. For
collections using the implicit router, an invalid {{_route_}} value now causes
the request to fail. Previously, the same request searched all active shards
despite the invalid {{{}_route_{}}}. This should be documented in the release/
upgrade notes.
Tests cover single and multiple route keys, composite id routing, missing and
empty route values, and invalid implicit router shard names.
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