[zantvoort]

Fixes #741

suggest ignores a word shorter than the database's substring index serves, and matches no rows when no word is left. A word the index does serve can be as useless when it occurs in a large share of the rows: the is three characters, so the trigram index on PostgreSQL serves it, but it matches a third of the titles in a movie catalog. Typed alone it returns a page of noise, and next to another word it narrows nothing.

Which words those are depends on the column's content, so the search box names them, as it names the columns. suggest takes the words to ignore right after the input, in both languages:

val titleNoise = setOf("the", "a", "of")

.where(suggest(input, titleNoise, Movie_.title, Movie_.director.name))

private static final Set<String> TITLE_NOISE = Set.of("the", "a", "of");

.where(it -> it.suggest(input, TITLE_NOISE, Movie_.title, Movie_.director.name))

An ignored word is treated as a short word is: it takes no part in the predicate, compared ignoring case as the words themselves match, and an input without a remaining word matches no rows. A quoted phrase is one word, ignored when it equals an ignored word. the god matches on god alone; the alone matches no rows.

search takes no set: on a results page a frequent word next to a longer one costs nothing and still narrows correctly.

Changes

• PredicateBuilderFactory.suggest(input, ignore, paths): ignored words are filtered before the Search node is built, so the node and its dialect-dependent resolve step are unchanged.
• WhereBuilder.suggest(input, ignore, path, more...) in Java; the abstract suggestImpl takes the set. The Kotlin top-level suggest gains the same overload.
• Tests in storm-core, storm-java21 and storm-kotlin: case-insensitive ignoring, ignored words alone, a quoted phrase equal to an ignored word, and the dialect that treats every word alike.
• Docs: "Ignoring Words" under the suggest section of the Search page; the Java and Kotlin query skills; the CHANGELOG line for suggest.

[codecov]

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