Details
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Bug
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Status: Closed
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Major
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Resolution: Fixed
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4.1, 5.0, 6.0
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None
Description
The DefaultSolrParams class, which is used as the basis for the implementation of defaults, appends and invariants params had a bug in it's implementation of getParameterNamesIterator() that could result in the same param key being returned multiple times.
In many code paths of Solr, this bug had no effects – but in other cases, it resulted in code which iterated over the list of all parameters to take action multiple times for the (valid) key=value pairs.
There were 4 main areas where this bug had unexpected & problematic behavior for end users:
- ExtractingRequestHandler
- "literal.*" params will be duplicated if overridden by defaults/invariants/appends - this will result in redundent literal field=value params being added to the document.
- impact: multiple values in literal fields when not expected/desired
- FacetComponent
- "facet.*" params will be duplicated if overridden by defaults/invariants/appends - this can result in redundent computation and identical facet.field, facet.query, or facet.range blocks in the response
- impact: wasted computation & increased response size
- SpellCheckComponent
- when "custom params" (ie: "spellcheck.[dictionary name].XXXX=YYYY" are used in used in defaults, appends, or invariants, it can cause redudent XXXXX=YYYY params to be used.
- when "spellcheck.collateParam.XXXX=YYYY" type params are used defaults, appends, or invariants, it can cause redundent XXXX=YYYY params to exist in the collation verification queries.
- impact: unclear to me at first glance, probably just wasted computation & increased response size
- AnalyticsComponent
- "olap.*" params will be duplicated if overridden by defaults/invariants/appends - this can result in redundent computation
- impact: unclear to me at first glance, probably just wasted computation & increased response size
Other less serious impacts were redundent values in "echoParams" as well as some small amounts of wasted computation in other code paths that iterated over the set of params (due to a slightly larger set of param values)
When a parameter (e.g. echoParams) is specified and overrides the default on the handler, it actually generates two entries for that key with the same value.
Most of the time it is just a confusion and not an issue, however, some components will do the work twice. For example faceting component as described in http://search-lucene.com/m/QTPaSlFUQ1/duplicate
It may also be connected to SOLR-6369
The cause seems to be the interplay between DefaultSolrParams#getParameterNamesIterator() which just returns param names in sequence and SolrParams#toNamedList() which uses the first (override then default) value for each key, without deduplication.
It's easily reproducible in trunk against schemaless example with
curl "http://localhost:8983/solr/schemaless/select?indent=true&echoParams=all"
I've also spot checked it and it seems to be reproducible back to Solr 4.1.
