[ispringer]

https://issues.apache.org/jira/browse/SOLR-18625

Description

When pf is set and no phrase qualifies for the boost (single-term queries, q=*:*), eDisMax's pf sub-parser discards every phrase via minClauseSize and returns an empty BooleanQuery rather than null. That passed the phrase != null guard and was added to the main query as an empty SHOULD clause (visible as () in the parsed query, e.g. +(subject:wireless) ()).

It did not affect scoring, but it defeated the single-clause MatchAllDocsQuery unwrapping in ExtendedDismaxQParser.parse(), so q=*:* with pf set scored a BooleanQuery over every doc instead of reaching Solr's MatchAllDocsQuery fast paths.

The same happens with bq: a boost query consisting only of stopwords (e.g. bq=text:a) parses to an empty BooleanQuery and was added unchecked, with the same effect on q=*:*.

Split out from #4652 (closed), where the pf part was agreed to be safe on its own; the bq part is the same fix applied to the other path that can add an empty clause.

Solution

In addShingledPhraseQueries:

• Skip adding the phrase clause when the parsed result is empty, not only when it is null.
• Return early when there are no clauses (e.g. fielded-only queries like q=subject:foo), avoiding creating a sub-parser and analyzing an empty phrase per pf slop group.

In getBoostQueries, skip a boost query that parses to an empty query.

No ranking change.

Co-authored with Claude Code (Opus 5.5).

Tests

TestExtendedDismaxParser.testNoEmptyPhraseBoostClause (new):

• q=wireless → no pf boost and no empty () clause (fails without the fix).
• q=wi-fi (WordDelimiter splits into two tokens) → phrase boost retained.

TestExtendedDismaxParser.testMatchAllDocs (extended): now sets pf, pf2, pf3 and a stopword-only bq, across q=*:*/q=* and both sow values, and still expects MatchAllDocsQuery (fails without the bq fix).

Ran TestExtendedDismaxParser, QueryEqualityTest, DisMaxRequestHandlerTest (all green), plus ./gradlew tidy and ./gradlew check -x test.

Checklist

• I have reviewed the guidelines for How to Contribute and my code conforms to the standards described there to the best of my ability.
• I have created a Jira issue and added the issue ID to my pull request title.
• I have given Solr maintainers access to contribute to my PR branch. (optional but recommended, not available for branches on forks living under an organisation)
• I have developed this patch against the main branch.
• I have run ./gradlew check.
• I have added tests for my changes.
• I have added documentation for the Reference Guide
• I have added a changelog entry for my change

🤖 Generated with Claude Code

[nick-boss-tech]

🤖 AI text below 🤖 (reviewed by Nick Shanin)

@ispringer I prepared an optional test-only follow-up for your current version. It adds plain-token and fielded-only checks in both sow modes, plus independent wi-fi and configured grackle synonym-preservation tests. It retains your expanded pf/pf2/pf3 and stopword-only bq MatchAll coverage. Only TestExtendedDismaxParser.java changes.

Selected suites passed on your head fd106e0 (157 tests) and the follow-up 07328d6 (160 tests), with no failures, errors or skips, seed 5303C0DE, Linux/JDK 21. Root tidy, Error Prone compilation and root check -x test passed at the follow-up head with NODE_ENV unset. Five compiling mutation controls failed at the intended assertions, including false-mode-only regressions. These are selected-suite results, not a full-suite or performance claim. Verification details.

If useful, the test-only diff is one commit directly above your current head and can be taken without rewriting history:

git switch SOLR-18625
git fetch https://github.com/nick-boss-tech/solr.git pr-5303-phrase-coverage-round-2
git merge --ff-only 07328d6973c4bb3385ca6d50bfe871f8808c1550