[jasperblues]

Closes #422. Port of liberation-data/drivine4j#607 (drivine4j PR #619), with the statements of liberation-data/drivine#637 byte for byte. Not to merge until train 2026.11.1 is cut, and not before drivine#637. Once #637 merges, re-record tests/golden/VERSION with scripts/sync_golden.py. The statements already match its branch byte for byte.

On Postgres, SQLite and Oracle without Oracle Text, a full-text term written again at once was counted every other time: "kiwi kiwi kiwi" counted 2. Since BM25 (#423), that undercount reaches the ranking.

How each store counts now

This follows drivine4j#619 and drivine#637 (drivine/backend/sql/text_query.py: looking_ahead, counted, SEPARATOR).

• Postgres and SQLite: the term's trailing boundary is a lookahead, (?=$|[^[:alnum:]_]).

• Oracle, in oracle_search._oracle_count, by one of three ways:

  • Most terms: two counts, the term ending where its last word does minus the same followed by [[:alnum:]_].
  • A phrase that repeats a word or whose last word starts its first: its own expression over the text with every separator doubled.
  • Prefix terms, and terms holding a number that isn't a digit: the one expression, as before.

  A word is letters (isalpha), decimal digits (isdecimal) and _, which is \p{L}, \p{Nd} and _, as in Java and TypeScript.

Tests

• tests/integration/test_bm25.py, and its sync copy, on Neo4j, Postgres, Postgres indexed, SQLite and Oracle:
  • "okapi okapi okapi" outranks "okapi lemur okapi";
  • +"la la" finds "la la land";
  • +"tapirs tapir" finds "tapirs tapirs tapir";
  • many's pinned score is now 0.1359.
• tests/unit/test_text_query_counting.py: each of drivine4j's cases counted both ways through Patterns, with exact counts.
• tests/unit/test_bm25.py: the SQL and bindings for each of Oracle's three ways.
• Goldens: the Oracle *.matching statements, copied from drivine#637. Byte-identical.

Verification

• Three fresh-reviewer passes. Pass 1 added the exact-count and Oracle SQL tests and the docs notes, pass 2 a docstring, and pass 3 came back clean.
• Unit tests: 2,480 passed. ruff and pyright are clean, and the sync code is current.
• Integration, on the test box with Oracle: the BM25 tests and their sync copy, the search tests, and the Postgres, SQLite and Oracle store and schema tests. 239 passed, and agreement with Neo4j is 17/21 on every SQL store.