M1 IsPoison classified every SQL Server transient as poison:
Microsoft.Data.SqlClient never sets DbException.IsTransient, so a deadlock
(1205), timeout (-2 / Win32 258), dropped connection or AG failover was
counted from memory and the node's row left Applying. Poison is now an
ALLOWLIST: a DbUpdateException (not concurrency) carrying a SqlException
whose number is 8152, 2628, 547, 515, 2627 or 2601. Everything else
retries, bounded by the deadline deferral cap. IsPoison is public for tests.
Acks counted only from memory (poison branch and the deferral cap) are kept
in _memoryOnlyAcks and re-sent by PreRestart alongside _unpersisted, so a
restart before the terminal write does not lose them.
M2 Revisions adopted without an outcome-reporting apply are unconfirmed, so a
same-revision dispatch re-applies instead of short-circuiting a clean
Applied over an empty address space: TryRecoverFromStale (restores only the
revision marker) and RestoreApplied when the artifact read fails (null
blob, LoadArtifactBlob swallows the error) or the restore throws.
L1 The re-drive comment documents the CreatedAtUtc recompute after a second
restart / failover.
L2 _currentRevisionDegraded renamed _currentRevisionUnconfirmed; the stale
TryBootFromCache remark corrected.
L3 docs/Redundancy.md: a Direct node running from cache that still cannot
reach the ConfigDb acks a same-revision re-dispatch Failed
(PartiallyFailed, not Sealed); Stale recovery and failed restores are
unconfirmed too.
Test harness: SqlExceptionFactory builds real SqlExceptions (reflection on
SqlError / SqlErrorCollection / SqlException.CreateException);
ConstraintEnforcingDbFactory now throws DbUpdateException over SQL 2628
(over-length), 547 (poison) and 1205 (transient), plus FailNextContexts.
Tests (all fail on the previous code): poison allowlist theory (1205, 40613,
10054, 4060 not poison) + timeout/concurrency/providerless not poison; a
deadlocked ack write is retried and recorded; a memory-counted ack survives a
coordinator restart; Stale-recovered and failed-restore revisions re-apply on
re-dispatch.
Claude-Session: https://claude.ai/code/session_01GT67AD99zQQqpLCVm3p7xk
1 PersistNodeAck wrote a Failed ack's FailureReason unbounded; the column is
nvarchar(2048), so on SQL Server the write failed forever, the ack retried
forever, the deadline deferred forever and every later deploy was refused.
- One shared bound, Configuration.FailureReasons.Truncate (MaxLength 2048),
used by the coordinator and DriverHostActor.UpsertNodeDeploymentState
(exception messages and degraded reasons).
- A non-transient DbUpdateException (not concurrency, no transient
DbException / timeout / socket / IO underneath) is POISON: the ack is
counted from memory with an Error, never retried.
- Deadline deferral on unpersisted acks is capped at 10 x the retry ceiling;
past it the outcome is decided from the acks held in memory.
2 A node restarting in the outcome window boots the cached revision (cache is
written before the outcome) and never acks. Cache-booted revisions
(BootstrapFromCache / TryBootFromCache) are now marked unconfirmed, so a
re-dispatch re-applies and acks the real outcome instead of a clean
short-circuit. docs/Redundancy.md corrected (replay only on the ConfigDb boot
path).
3 A lost dispatch re-driven near its deadline now gets a FULL deadline (a node
needs its whole outcome timeout + margin = ApplyDeadline, so any shorter
remainder timed out nodes that applied). No dispatched-at column: a second
restart recomputes from CreatedAtUtc and closes it instead (documented).
4 docs/Redundancy.md upgrade note: do not deploy while the central pair is mid
rolling-upgrade across this change.
Tests (all fail on the previous code): oversized Failed reason truncated (on a
SaveChanges interceptor that enforces the column like SQL Server); rejected ack
write counted from memory; bounded deadline deferral; full deadline on a
near-deadline re-drive; cache-booted revision re-applies on re-dispatch;
oversized degraded reason truncated on the node's own row.
Claude-Session: https://claude.ai/code/session_01GT67AD99zQQqpLCVm3p7xk
Joseph Doherty