docs(15.9): engine-fused hybrid search pages up to pagination_depth (default 1000)

[marevol]

Summary

Document how engine-side rank fusion pages in Fess 15.9 after codelibs/fess#3506 (and #3505).

A search fused in the search engine (rank.fusion.engine.enabled=true, and the request can be fused) used to hand any page past rank.fusion.pagination_depth to Fess-side fusion, which by default meant keyword-only results. With #3506 it pages through at most min(rank.fusion.pagination_depth, indexer.max.result.window.size) results and stops there, the same way any other search stops at index.max_result_window. The default depth goes from 200 to 1000, and the semantic branch's knn k is content_chunker.search.knn.k instead of max(knn.k, pagination_depth).

Changes

All seven languages (ja, en, de, es, fr, ko, zh-cn), development tree (15.9) only.

• config/rank-fusion.rst
  • Example and table: rank.fusion.pagination_depth default 1000; the value sent never exceeds indexer.max.result.window.size.
  • Removed the "page whose start + size exceeds pagination_depth is fused by Fess" case from the list of searches not fused in the engine.
  • New notes for engine-side fusion: paging stops at pagination_depth (page count, next page and page numbers stop there; a page starting beyond it gets the same error as a page beyond index.max_result_window; a page after the last fused hit but within the limit is empty; non-fused searches page as before); the hit count is a lower bound (GREATER_THAN_OR_EQUAL_TO) at or above the depth; a larger depth slows every fused search.
  • knn k of a fused request is content_chunker.search.knn.k.
  • Troubleshooting: the deep-page item no longer tells users to raise pagination_depth; "Slow Search" lists reducing pagination_depth for engine-side fusion.
• config/search-semantic.rst
  • content_chunker.search.knn.k: enlarged for deep paging only when Fess performs the fusion.
  • Deep result pages: with engine-side fusion every page is fused and paging stops at pagination_depth (default 1000).
• config/properties.rst / config/properties.po: regenerated with tools/update_properties_doc.sh against the #3506 branch. Only the rank.fusion.pagination_depth row (default and description) is taken; other differences between the generated pages and the current fess_config.properties are left for a separate update. The catalogues carry no translations yet, so only the msgid changes.

Verification

• python3 tools/gen_properties_doc.py --check: the 7 properties pages agree
• python3 -m unittest discover -s tools -p 'test_*.py': 79 tests OK
• python3 tools/check_headings.py on the 15.8 and 15.9 trees: no mismatches (no headings changed)
• Sphinx build of each language's 15.9 config/ directory before and after the change: no new warnings in the changed files, and no unrendered inline markup in the output

Dependency

This documents codelibs/fess#3506 (milestone 15.9.0), which is still open. Merge it after that PR.