Variant B2 of the #78 benchmark: migration FlipAuditLogClusteredKey drops the
twelve non-clustered indexes, re-adds PK_AuditLog as (OccurredAtUtc, EventId)
on ps_AuditLog_Month, adds the aligned unique UX_AuditLog_EventId_Occurred
(EventId, OccurredAtUtc) for the idempotency probe, and rebuilds the twelve
indexes unchanged. Guarded (re-runnable) Up, inverse-rebuild Down; production
scripts docs/plans/sql/FlipAuditLogClusteredKey{,.rollback}.sql.
The partition-switch purge staging table now reads the live clustered key
order from sys.index_columns, so it switches either shape (old binaries
hard-code the old order: ship with the binaries, both centrals stopped).
Evidence: 300k rows, page 1 90,532 -> 34 logical reads (ordered backward
clustered scan under Top), keyset page 90,532 -> 46, probe 14 -> 14;
FlipAuditLogClusteredKeyMigrationTests pins indexes, grants, Down/Up, the
staging key (mutation: hard-coded old key fails SWITCH) and the read ratio.
Claude-Session: https://claude.ai/code/session_01GT67AEHd2Acv1YPwGfXEoV
Audit roadmap T1 (alog.md §11.4): one chain per UTC calendar month of
OccurredAtUtc. Each chained row carries ChainSeq (gap-free within its month)
and RowHash = SHA-256(prev.RowHash || canonical(row)); the v1 canonical form
(AuditChainHasher) is pinned by a known-answer vector computed independently.
- Migration AddAuditLogHashChain: nullable ChainSeq/RowHash on dbo.AuditLog
(metadata-only add), AuditLogChainHead (per-month chain end + partition-purge
checkpoint anchor), AuditLogChainTombstone, two partition-aligned filtered
indexes, scadabridge_audit_chainer role with a column-level UPDATE grant.
Production script docs/plans/sql/AddAuditLogHashChain.sql.
- AuditLogHashChain chains unchained rows oldest month first under an
exclusive sp_getapplock (zero timeout, so a dual-active central pair still
yields one chain), with an optimistic head check and a ChainSeq IS NULL
row-count check that roll a pass back instead of leaving a gap. The ingest
path is untouched.
- Purges keep the chain verifiable: the partition switch records the month's
checkpoint anchor and drops its tombstones; the per-channel DELETE writes a
tombstone per chained row in the same transaction (OUTPUT INTO). Both, and
the SourceNode backfill, hold the chain lock; the backfill skips chained
rows. The switch staging table gains the two new columns.
- AuditChainVerifier reports the first break (partition, ChainSeq, EventId,
kind) for edited, deleted, reordered rows and tail truncation.
- AuditLogHashChainService (central, default OFF via AuditLog:HashChain).
Claude-Session: https://claude.ai/code/session_01GT67AEHd2Acv1YPwGfXEoV
Comment/XML-doc changes only:
- add summaries to ~10k test methods, fixtures, fakes and helpers
(+ <param> on theories, <returns> on async Task methods,
<inheritdoc/> on interface implementations the checker can resolve)
- strip ~2.6k project-tracking references (WP*, P*-*, row-NN, Task N,
#NN, Component-0NN) from comments, keeping the explanatory text;
reword false positives in comments only
- real docs on fakes implementing BCL/library interfaces
(IDisposable, ILogger, IOptionsMonitor, IAsyncLifetime)
- reword the last 5 src/ false positives (CWE-1236, failures-1,
year-0001, M365)
Only non-comment edits: four one-line nested classes split across lines
so members can carry docs. Build 0 errors / 0 warnings.
Joseph Doherty