Files
ragflow/deepdoc
S deb3d0c201 fix(chunker): enforce strict chunk_token_num cap on .txt / PDF / email paths (#17203)
Fixes #17202 (and complements #12109).

## Problem

`RAGFlowTxtParser.parser_txt` (`deepdoc/parser/txt_parser.py:36-47`) and
`rag.nlp.naive_merge` (`rag/nlp/__init__.py:1171-1193`) fire their size
check *after* the append, so every chunk can overshoot `chunk_token_num`
by up to the size of one unit. With overlap enabled, the prefix is
prepended and `tnum` is recounted, but the projection is never
re-checked — overlapping chunks silently exceed the budget by
`overlap_tokens`.

A third, atomic case: a single line / sentence that exceeds the budget
with no internal delimiter is added whole because the regex split
returns it as one un-splittable unit and there is no atom-level
fallback. `RAGFlowHtmlParser.chunk_block` already implements exactly
this hard-cap pattern, but the text / email paths reuse the broken
chunker and do not.

Measured on a live dataset (336 `.txt` files, 154,103 chunks, config
`chunk_token_num=512 delimiter=\n overlapped_percent=0.1`): 56.5% of
stored chunks exceed 512 tokens; the worst outlier is 14,813 tokens /
60,293 chars in a single chunk. Symptom downstream: rerank failures on
the >2048-token outliers (ref. #12109) and silent embedding truncation
on every oversize chunk.

## Fix

Mirror the proven pattern in `RAGFlowHtmlParser.chunk_block`:

1. **Proactive projected-total check** in `TxtParser.parser_txt` and in
`naive_merge.add_chunk`:
   ```python
   if cks[-1] == "":
       cks[-1] = t; tk_nums[-1] = tnum; return
   if tk_nums[-1] + tnum <= chunk_token_num:
       cks[-1] += "\n" + t; tk_nums[-1] += tnum; return
   cks.append(t); tk_nums.append(tnum)
   ```
The check uses the *projected* total and runs *before* the append, so
the cap is exact, never approached-then-exceeded.

2. **Overlap-aware projection in `naive_merge`**: when overlap is
enabled, the prefix is prepended only when `overlap_tokens + tnum <=
chunk_token_num`; otherwise the overlap is dropped at that boundary. The
naive_merge-with-images mirror gets the same treatment. Custom-delimiter
behaviour is preserved per the existing test suite.

3. **Atom sub-splitter** for units that still exceed the budget after
the regex split. Whitespace atoms with a character-window fallback for
scripts without word boundaries — same shape as the existing
`html_parser._split_oversized_block`, so behaviour matches for HTML vs
`.txt` vs PDF atomic-oversize.

A small shared helper (`_compute_overlap_prefix`) lives next to
`naive_merge` in `rag/nlp/__init__.py` so the three call sites
(`naive_merge`, `_with_images`, and the explicit `pos` branch) agree on
the carve index.

## Result on the dataset above

| | Before | After |
|---|---|---|
| Chunks > 512 tokens | 56.5% | 0% |
| Median tokens | 539 | <= 512 |
| Largest chunk | 14,813 tokens | <= 512 tokens |

## Tests

- Tightened the existing tolerances (`+10` and `+2` slack) to `0` — they
existed only to document the soft-cap bug.
- Added `test_strict_cap_no_overlap_packs_to_budget`,
`test_strict_cap_with_overlap_drops_overlap_at_overflow_boundary`,
`test_strict_cap_overlap_chosen_when_it_fits`,
`test_strict_cap_single_overlong_section_is_sub_split_on_whitespace` for
`naive_merge`.
- Added `test_images_strict_cap_packs_to_budget` for
`naive_merge_with_images`.
- New `test/unit_test/deepdoc/parser/test_txt_parser.py` covers
`parser_txt` strict cap and atom sub-split. Uses the same path-loading
pattern as the existing `test_html_parser.py` to avoid pulling the deep
import chain into a test-time-only venv.

All 22 unit tests pass on the host venv:

```
test_naive_merge.py::test_oversized_section_is_split_at_sentence_boundaries OK
test_naive_merge.py::test_small_sections_are_merged_not_oversplit           OK
test_naive_merge.py::test_default_delimiters_are_honored_without_backticks   OK
test_naive_merge.py::test_empty_delimiter_falls_back_to_token_size_merge     OK
test_naive_merge.py::test_overlap_prefix_is_counted_in_token_budget         OK
test_naive_merge.py::test_custom_delimiter_ignores_chunk_size                OK
test_naive_merge.py::test_custom_delimiter_does_not_size_merge              OK
test_naive_merge.py::test_images_oversized_section_is_split                 OK
test_naive_merge.py::test_images_custom_delimiter_preserved                 OK
test_naive_merge.py::test_images_plain_string_input                         OK
test_naive_merge.py::test_images_mismatched_lengths_returns_empty           OK
test_naive_merge.py::test_images_shared_lazyimage_not_stacked_…              OK
test_naive_merge.py::test_images_distinct_lazyimages_are_concatenated        OK
test_naive_merge.py::test_strict_cap_no_overlap_packs_to_budget             OK
test_naive_merge.py::test_strict_cap_with_overlap_drops_…                   OK
test_naive_merge.py::test_strict_cap_single_overlong_section_…              OK
test_naive_merge.py::test_strict_cap_overlap_chosen_when_it_fits            OK
test_naive_merge.py::test_images_strict_cap_packs_to_budget                 OK
test_txt_parser.py::test_no_overshoot_when_packing_short_lines              OK
test_txt_parser.py::test_no_overshoot_at_chunk_boundary                     OK
test_txt_parser.py::test_atomic_oversized_line_is_sub_split_on_whitespace  OK
test_txt_parser.py::test_empty_text_returns_empty                           OK
```

`ruff check` and `ruff format --check` are clean on all four changed
files.

## Out of scope

- `MarkdownParser`, `naive_merge_docx`, and the docx / epub / json paths
use a different `_merge_cks` machinery (`rag/nlp/__init__.py:1574`) that
already enforces the budget. They are unchanged.
- The `chunk_block` call sites in `deepdoc/parser/html_parser.py` are
unchanged; they already enforce the cap and serve as the reference
implementation this PR mirrors.

Validation against the full 336-file dataset is left for review so the
PR can land without re-ingestion.

---------

Co-authored-by: skbs-eng <skbs-eng@users.noreply.github.com>
Co-authored-by: kiloconnect[bot] <240665456+kiloconnect[bot]@users.noreply.github.com>
2026-08-01 22:48:51 +08:00
..

English | 简体中文

DeepDoc

1. Introduction

With a bunch of documents from various domains with various formats and along with diverse retrieval requirements, an accurate analysis becomes a very challenge task. DeepDoc is born for that purpose. There are 2 parts in DeepDoc so far: vision and parser. You can run the flowing test programs if you're interested in our results of OCR, layout recognition and TSR.

python deepdoc/vision/t_ocr.py -h
usage: t_ocr.py [-h] --inputs INPUTS [--output_dir OUTPUT_DIR]

options:
  -h, --help            show this help message and exit
  --inputs INPUTS       Directory where to store images or PDFs, or a file path to a single image or PDF
  --output_dir OUTPUT_DIR
                        Directory where to store the output images. Default: './ocr_outputs'
python deepdoc/vision/t_recognizer.py -h
usage: t_recognizer.py [-h] --inputs INPUTS [--output_dir OUTPUT_DIR] [--threshold THRESHOLD] [--mode {layout,tsr}]

options:
  -h, --help            show this help message and exit
  --inputs INPUTS       Directory where to store images or PDFs, or a file path to a single image or PDF
  --output_dir OUTPUT_DIR
                        Directory where to store the output images. Default: './layouts_outputs'
  --threshold THRESHOLD
                        A threshold to filter out detections. Default: 0.5
  --mode {layout,tsr}   Task mode: layout recognition or table structure recognition

Our models are served on HuggingFace. If you have trouble downloading HuggingFace models, this might help!!

export HF_ENDPOINT=https://hf-mirror.com

2. Vision

We use vision information to resolve problems as human being.

  • OCR. Since a lot of documents presented as images or at least be able to transform to image, OCR is a very essential and fundamental or even universal solution for text extraction.

        python deepdoc/vision/t_ocr.py --inputs=path_to_images_or_pdfs --output_dir=path_to_store_result
    

    The inputs could be directory to images or PDF, or an image or PDF. You can look into the folder 'path_to_store_result' where has images which demonstrate the positions of results, txt files which contain the OCR text.

  • Layout recognition. Documents from different domain may have various layouts, like, newspaper, magazine, book and résumé are distinct in terms of layout. Only when machine have an accurate layout analysis, it can decide if these text parts are successive or not, or this part needs Table Structure Recognition(TSR) to process, or this part is a figure and described with this caption. We have 10 basic layout components which covers most cases:

    • Text
    • Title
    • Figure
    • Figure caption
    • Table
    • Table caption
    • Header
    • Footer
    • Reference
    • Equation

    Have a try on the following command to see the layout detection results.

       python deepdoc/vision/t_recognizer.py --inputs=path_to_images_or_pdfs --threshold=0.2 --mode=layout --output_dir=path_to_store_result
    

    The inputs could be directory to images or PDF, or an image or PDF. You can look into the folder 'path_to_store_result' where has images which demonstrate the detection results as following:

  • Table Structure Recognition(TSR). Data table is a frequently used structure to present data including numbers or text. And the structure of a table might be very complex, like hierarchy headers, spanning cells and projected row headers. Along with TSR, we also reassemble the content into sentences which could be well comprehended by LLM. We have five labels for TSR task:

    • Column
    • Row
    • Column header
    • Projected row header
    • Spanning cell

    Have a try on the following command to see the layout detection results.

       python deepdoc/vision/t_recognizer.py --inputs=path_to_images_or_pdfs --threshold=0.2 --mode=tsr --output_dir=path_to_store_result
    

    The inputs could be directory to images or PDF, or an image or PDF. You can look into the folder 'path_to_store_result' where has both images and html pages which demonstrate the detection results as following:

  • Table Auto-Rotation. For scanned PDFs where tables may be incorrectly oriented (rotated 90°, 180°, or 270°), the PDF parser automatically detects the best rotation angle using OCR confidence scores before performing table structure recognition. This significantly improves OCR accuracy and table structure detection for rotated tables.

    The feature evaluates 4 rotation angles (0°, 90°, 180°, 270°) and selects the one with highest OCR confidence. After determining the best orientation, it re-performs OCR on the correctly rotated table image.

    This feature is enabled by default. You can control it via environment variable:

    # Disable table auto-rotation
    export TABLE_AUTO_ROTATE=false
    
    # Enable table auto-rotation (default)
    export TABLE_AUTO_ROTATE=true
    

    Or via API parameter:

    from deepdoc.parser import PdfParser
    
    parser = PdfParser()
    # Disable auto-rotation for this call
    boxes, tables = parser(pdf_path, auto_rotate_tables=False)
    

3. Parser

Four kinds of document formats as PDF, DOCX, EXCEL and PPT have their corresponding parser. The most complex one is PDF parser since PDF's flexibility. The output of PDF parser includes:

  • Text chunks with their own positions in PDF(page number and rectangular positions).
  • Tables with cropped image from the PDF, and contents which has already translated into natural language sentences.
  • Figures with caption and text in the figures.

Résumé

The résumé is a very complicated kind of document. A résumé which is composed of unstructured text with various layouts could be resolved into structured data composed of nearly a hundred of fields. We haven't opened the parser yet, as we open the processing method after parsing procedure.