# Hierarchical Document Splitting

Split content at Markdown headings, retaining section structure and source information.

Use it for text with heading levels. To control chunk length in characters, use [Segment](../ai-processing/chunk.md).

## Prepare the input

Bind upstream `documents`. Headings must appear as Markdown heading lines, such as lines starting with `#` or `##`. Visually bold text alone does not create a heading boundary.

Headings determine split positions. There are no chunk-length or overlap settings.

## Splitting behavior

The node recognizes Markdown code fences and does not treat `#` inside them as headings. Code-type records remain intact.

Long sections can therefore produce long chunks. Add length-based chunking afterward if needed, and check that the required structure is preserved.

## Use the output

The main output is `documents`, retaining source metadata and adding position fields such as `parent_index`, `chunk_index`, and `chunk_type`.

These fields relate chunks to parent documents. Continue binding `documents` downstream.

## Example: index manual sections

Flow: General Document Parsing → Hierarchical Document Splitting → Embed and Add to Knowledge Base.

Check that parsed text contains Markdown headings before splitting. For unusually long sections, add length-based chunking and inspect a sample.

## Related pages

- [Variables and data flow](../../variables-and-data.md)
- [Run and debug](../../run-debug.md)