Show HN: RAG chunk size "best practices" failed on legal text – I benchmarked it

[metawake]

Author here. Built RagTune to stop guessing at RAG configs.

Surprising findings:

1. On legal text (CaseHOLD), 1024 chunks scored WORST (0.618). The "small" 256 chunks won (0.664). 7% swing.

2. On Wikipedia text? All chunk sizes hit ~99%. No difference.

3. Plot twist: At 5K docs, optimal chunk size FLIPPED from 256→1024. Scale changes everything.

Code is MIT: github.com/metawake/ragtune

Happy to discuss methodology.

[patrakov]

Now that you have 5K docs, can you try estimating the statistical uncertainty of the Recall@5 and MRR metrics measured via smaller datasets? Just make some different 400-document subsets of the whole 5K HotpotQA dataset and recalculate the metrics.