RAG Deserves an Index: Why Ingest-Time Compilation Beats Query-Time Interpretation

AuthorsKyle Wild, Yusuke Takahashi, Asako Uraki

arXiv 20262026

TL;DR

Ingest-Time Semantic Compilation (ISC) compiles a validated semantic substrate at ingest, yielding 85.2% accuracy from ~2.2k tokens vs 72.5% from ~16.3k for the best chunk baseline.

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THE PROBLEM

RAG Systems Keep Re-Interpreting the Same Corpus (33.7× Cost Gap and 21× Token Overhead)

Query-time semantic reconstruction forces language models to re-derive corpus meaning on every query, inflating inference spend as context volume grows faster than token prices fall.

Ingest-Time Semantic Compilation shows that incremental updates can be 33.7× cheaper than full reconstruction, while compiled claims answer 85.2% of questions using ~2.2k tokens versus 72.5% using ~16.3k, exposing wasted compute, degraded accuracy, and fragile provenance in current RAG systems.

HOW IT WORKS

Ingest-Time Semantic Compilation: A Compiled Semantic Substrate

Ingest-Time Semantic Compilation builds a geometric layer, symbolic layer, validation gate, and index_outbox inside PostgreSQL, treating the semantic substrate as a first-class database object with its own contracts.

ISC is like adding indexes and materialized views to a database: expensive semantic work moves from read time to write time, so queries hit a compiled structure instead of scanning raw text.

This lets ISC deliver atomic, provenance-validated claims as the retrieval payload, enabling cheaper, more accurate reads than a plain context window that repeatedly re-interprets unstructured transcripts.

DIAGRAM

Query-Time vs Ingest-Time Flow in ISC

This diagram contrasts query-time semantic reconstruction with ingest-time semantic compilation, showing how ISC shifts work to ingest and serves compiled claims.

DIAGRAM

ISC Evaluation Pipeline on Broadcast-Interview Transcripts

This diagram shows how ISC compiles transcripts, runs question answering, and compares compiled claims against chunk-based baselines and a contextualized stack.

PROCESS

How Ingest-Time Semantic Compilation Handles a Broadcast QA Session

  1. 01

    Compilation Contract

    ISC applies the compilation contract to each transcript, deciding which facts and embeddings to generate under a defined semantic DDL.

  2. 02

    Validation Gate

    ISC runs the validation gate, requiring exact-quote matches and correct speaker attribution before inserting rows into facts and fact_evidence.

  3. 03

    Maintenance Contract

    ISC uses index_outbox and incremental low-rank updates to maintain the geometric layer and vector index proportional to corpus change, not size.

  4. 04

    Migration Contract

    ISC applies orthogonal Procrustes alignment during embedding model upgrades, migrating the geometric layer without full re-embedding the entire corpus.

KEY CONTRIBUTIONS

Key Contributions

  • 01

    Ingest-Time Semantic Compilation

    ISC defines a compiled semantic substrate with a geometric layer and symbolic layer, showing incremental updates are 33.7× cheaper than full reconstruction while matching floating-point precision.

  • 02

    Provenance-Validated Claims

    ISC’s validation gate enforces exact-quote provenance, admitting 69,746 claims and rejecting 1.1% of candidates whose quotes cannot be located in source transcripts.

  • 03

    Cost Model with Break-Even Reads

    ISC introduces a cost model with break-even read count R*, estimating that compiling 500 documents amortizes within about 580 queries against a contextualized chunk stack.

RESULTS

By the Numbers

QA accuracy

85.2%

+12.7 points over best chunk configuration at 72.5%

Reader tokens

2.2k tokens

vs best chunk configuration using roughly 16.3k tokens

Incremental update cost

8.4 ms per update

33.7× cheaper than 283 ms full re-decomposition

Break-even reads

≈580 queries

compilation cost equals extra query-path tokens of contextualized stack

On a held-out sample of 500 broadcast-interview transcripts and 499 questions, ISC’s compiled claims are compared against fixed-width, turn-aware, semantic chunking and a contextualized chunk stack. The 85.2% accuracy from ~2.2k tokens shows that ISC’s compiled substrate can beat chunk baselines and match a heavy contextualized stack while using about 21× fewer query-path tokens.

BENCHMARK

By the Numbers

On a held-out sample of 500 broadcast-interview transcripts and 499 questions, ISC’s compiled claims are compared against fixed-width, turn-aware, semantic chunking and a contextualized chunk stack. The 85.2% accuracy from ~2.2k tokens shows that ISC’s compiled substrate can beat chunk baselines and match a heavy contextualized stack while using about 21× fewer query-path tokens.

BENCHMARK

Read-Time Frontier on Broadcast-Interview QA

Accuracy versus reader tokens per query for compiled claims, best chunk configuration, and contextualized stack.

KEY INSIGHT

The Counterintuitive Finding

ISC shows that reading more raw context can reduce accuracy: chunk reading accuracy drops from 81% to 73% as more text is supplied.

This breaks the common assumption that more retrieved tokens always help; ISC’s compiled claims maintain 98–99% evidence coverage while avoiding the degradation seen in long-context reading.

WHY IT MATTERS

What this unlocks for the field

ISC makes meaning a compiled, queryable substrate with integrity constraints, enabling RAG systems to treat semantics like indexed database structures instead of ephemeral context.

Builders can now design planners, maintenance pipelines, and shared semantic substrates that price compilation explicitly, validate provenance mechanically, and deliver high-accuracy answers with far fewer tokens.

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