DSFB-Database: A Deterministic, Read-Only Structural Observer for Residual Trajectories in SQL Database Telemetry: An Empirical Prior-Art Demonstration on Five Public Workloads

Abstract: We instantiate the Drift–Slew Fusion Bootstrap (DSFB) observer framework as a deter-ministic, read-only structural observer for residual trajectories emitted by production SQLengines (pgₛtatₛtatements, pgₛtatᵢo, SQL Server Query Store and DMVs, MySQL Per-formance Schema, Oracle ASH/AWR). Five operator-legible motif classes — plan-regressiononset, cardinality-mismatch regime, contention ramp, cache/buffer collapse, and workload phasetransition — are emitted as a replayable episode stream with bytewise-deterministic SHA256fingerprints. We evaluate on five public workloads — Snowset, SQLShare, CEB, JOB, and a TPC-DS-shaped controlled-perturbation harness — and report F1 = 1. 0 across all five motifson the controlled tier under a ±20% threshold elasticity sweep. We do not claim to optimisequeries, replace the optimiser, modify execution plans, provide forecasting guarantees, validatedetection on real workloads, or define a universal SQL grammar. The contribution is notimproved detection accuracy, but deterministic reconstruction of structured degrada-tion episodes from multi-signal residual telemetry. The system is a structured, auditable, replayable interpretation layer over residuals SQL engines already emit but discard — positionedas a complement to engine observability surfaces, not a replacement.