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zeekayandHanzo Dev 03c6289dfc A skeleton for sparse-basis indexes and part-level routing in a column store
Design, prior art and a measurement protocol for a weighted inverted index
over a mixed sparse basis and part-level routing before per-part HNSW in a
ClickHouse-derived store. Each component is marked prior art or proposed.
The protocol fits C(N) = aN^alpha to parts, granules and bytes touched per
correct answer at a held recall. No numbers: every results cell is a
placeholder read from results-data.tex until the baseline lane writes it.

Co-authored-by: Hanzo Dev <[email protected]>
2026-09-23 00:00:11 -07:00

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\section{Limitations}
\label{sec:limits}
\textbf{Nothing here is measured.} The design has not been built at the scale
it is argued for, and the protocol in \S\ref{sec:method} has produced no
numbers. Every statement about cost in this paper is a statement about what a
bound permits, not about what a machine did.
\textbf{The per-type calibration is unsolved.} A single score over a mixed
basis needs weights $w_t$ that put an entity linker's confidence and a lexical
impact on one scale. Learning them requires relevance judgements over the
mixture, which the lane does not yet have; until it does, any reported
effectiveness is the effectiveness of a hand-set combination, and should be
read as such.
\textbf{Bounds loosen with dimension, and that is not fixable by tuning.}
Covering radii stop separating regions in high intrinsic dimension, so the
exact routing rule can degenerate to a full visit; the approximate rule then
carries the load and converts a cost problem into a recall problem. The
protocol measures where that transition happens for a given corpus, but no
choice of region size avoids it.
\textbf{The routing metadata is itself a cost that grows.} The number of region
summaries is proportional to the number of regions, so a design that scanned
them all would be linear in the corpus with a small constant. The tree over
part summaries is what keeps that term sublinear, and its depth, fan-out and
maintenance cost during merges are unmeasured.
\textbf{Merge-time maintenance is a write-side cost we do not price.} Carrying
posting lists, block maxima and region summaries through a merge is work that
competes with ingestion. A design that makes reads cheap and merges expensive
can be a net loss for a table that is written more often than it is queried.
\textbf{The claim is about a query distribution.} An exponent fitted under one
distribution says nothing about another. The strata in \S\ref{sec:method} are
there so a reader can see which queries the average is made of, but the
protocol cannot certify that a deployment's queries resemble the set measured.
\textbf{Exactness is relative to the per-part search.} The routing rule is
exact given the region bounds, but the dense leg inside a part is an
approximate graph search, so the system's answer is exact only with respect to
what that search returns. Conflating the two would make a recall failure look
like a routing success.
\textbf{The largest sizes are not yet reachable.} A corpus of $10^9$ rows with
dense vectors and a mixed sparse basis needs hardware the lane has not yet been
given, the first pass stops two decades below it, and the collection it samples
holds $3.5 \times 10^7$ rows. A fit over the sizes actually run is a fit over
those sizes.