Post-convergence engine studies against the ADR-003 kv pin, using
POC #3's harness unchanged (sqlite/fs arms byte-identical) plus the
concurrency axis POC #3 never measured:
- #5 postgres (B1-B6): solo pg floor ~1 ms (fsync-dominated, strace-
decomposed), ~40x storage overhead; decisive scale-out — pg PUTs ~12x
at 12 conns / ~37k ops/s while sqlite flatlines at its ~1.2k WAL
single-writer ceiling. Viable future ADR for the multi-client
replicator shape; durability/ops posture change, not a drop-in.
- #6 redb (C1-C6): the "2-7x over sqlite" folklore inverted — sqlite
~430x over redb at crash-consistent puts (redb Immediate = 1
fdatasync/commit, 8-30 ms on this disk; its None tier is not
crash-consistent). Reads ~530k/s but irrelevant. Ruled out at a
durability-tier mismatch: WAL-NORMAL's shipped tier is not
expressible in redb 4.x's two-level API.
- Net: sqlite's pin now has four-way triangulated evidence (fs vs
sqlite #3, pg #5, redb #6, lineage citation); batched commits proven
as the universal lever across all three engines.
Code: /workspace/alkblobs-postgres-poc, /workspace/alkblobs-redb-poc
(standalone crates per the POC placement convention; 14 inherited
tests passing in each, clippy -D warnings + fmt clean).
Verification: no src/ changes — docs only; both POC crates verified
(test/clippy/fmt) with findings recorded above.
glm-5.3-flash
5eea656295