diff --git a/src/Drivers/ZB.MOM.WW.OtOpcUa.Driver.Historian.SqlServer/SqlServerAlarmHistorianWriter.cs b/src/Drivers/ZB.MOM.WW.OtOpcUa.Driver.Historian.SqlServer/SqlServerAlarmHistorianWriter.cs
new file mode 100644
index 00000000..4d7bdb1f
--- /dev/null
+++ b/src/Drivers/ZB.MOM.WW.OtOpcUa.Driver.Historian.SqlServer/SqlServerAlarmHistorianWriter.cs
@@ -0,0 +1,168 @@
+using System.Data;
+using System.Security.Cryptography;
+using System.Text;
+using Microsoft.Data.SqlClient;
+using Microsoft.Extensions.Logging;
+using Microsoft.Extensions.Logging.Abstractions;
+using ZB.MOM.WW.OtOpcUa.Core.AlarmHistorian;
+using ZB.MOM.WW.OtOpcUa.Core.Abstractions;
+
+namespace ZB.MOM.WW.OtOpcUa.Driver.Historian.SqlServer;
+
+///
+/// over the SQL Event table. Per event: insert-if-absent keyed by a
+/// deterministic , so the store-and-forward drain's at-least-once redelivery (and both
+/// pair nodes writing the same event) converge on one row. Outcomes: Ack on insert or already-present;
+/// RetryPlease on transient SQL / schema-bootstrap / unclassified SQL errors and on cancellation; PermanentFail only
+/// for data errors (truncation, conversion, null, range) and non-SQL exceptions. Never throws.
+///
+internal sealed class SqlServerAlarmHistorianWriter : IAlarmHistorianWriter
+{
+ // 2628/8152 string truncation, 515 null into NOT NULL, 245/8114 conversion, 220/8115 overflow, 242/241 datetime range.
+ private static readonly int[] DataErrorNumbers = [2628, 8152, 515, 245, 8114, 220, 8115, 242, 241];
+
+ private readonly SqlHistorianConnection _conn;
+ private readonly SqlServerSchemaBootstrapper _bootstrap;
+ private readonly ILogger _log;
+
+ /// Creates the writer.
+ /// Connection helper.
+ /// Schema bootstrapper.
+ /// Optional logger.
+ public SqlServerAlarmHistorianWriter(SqlHistorianConnection conn, SqlServerSchemaBootstrapper bootstrap, ILogger? log = null)
+ {
+ _conn = conn;
+ _bootstrap = bootstrap;
+ _log = log ?? NullLogger.Instance;
+ }
+
+ ///
+ public async Task> WriteBatchAsync(IReadOnlyList batch, CancellationToken cancellationToken)
+ {
+ ArgumentNullException.ThrowIfNull(batch);
+ if (batch.Count == 0) return [];
+ var outcomes = new HistorianWriteOutcome[batch.Count];
+ try
+ {
+ await _bootstrap.EnsureAsync(cancellationToken).ConfigureAwait(false);
+ }
+ catch (Exception ex)
+ {
+ _log.LogWarning("SQL alarm historian bootstrap failed ({Exception}); will retry.", ex.GetType().Name);
+ Array.Fill(outcomes, HistorianWriteOutcome.RetryPlease);
+ return outcomes;
+ }
+
+ for (var i = 0; i < batch.Count; i++)
+ {
+ if (cancellationToken.IsCancellationRequested) { outcomes[i] = HistorianWriteOutcome.RetryPlease; continue; }
+ outcomes[i] = await WriteOneAsync(batch[i], cancellationToken).ConfigureAwait(false);
+ }
+
+ return outcomes;
+ }
+
+ private async Task WriteOneAsync(AlarmHistorianEvent e, CancellationToken ct)
+ {
+ try
+ {
+ // String parameters are NVARCHAR(MAX) on purpose: a sized parameter silently truncates client-side, which would
+ // hide an over-long value; the server-side 8152 is what classifies it PermanentFail.
+ var sql =
+ $"INSERT INTO {_conn.Q("Event")} (EventId, SourceName, AlarmId, AlarmName, AlarmTypeName, Severity, EventKind, Message, UserName, Comment, EventTimeUtc, ReceivedTimeUtc) " +
+ "SELECT @id, @src, @aid, @an, @at, @sev, @ek, @msg, @usr, @cmt, @t, SYSUTCDATETIME() " +
+ $"WHERE NOT EXISTS (SELECT 1 FROM {_conn.Q("Event")} x WITH (UPDLOCK, HOLDLOCK) WHERE x.EventId = @id)";
+ {
+ try
+ {
+ await using var conn = await _conn.OpenAsync(ct).ConfigureAwait(false);
+ await using var cmd = _conn.CreateCommand(conn, sql);
+ cmd.Parameters.Add(new SqlParameter("@id", SqlDbType.NVarChar, 64) { Value = ComputeEventId(e) });
+ cmd.Parameters.Add(new SqlParameter("@src", SqlDbType.NVarChar, -1) { Value = e.EquipmentPath ?? "" });
+ cmd.Parameters.Add(new SqlParameter("@aid", SqlDbType.NVarChar, -1) { Value = e.AlarmId ?? "" });
+ cmd.Parameters.Add(new SqlParameter("@an", SqlDbType.NVarChar, -1) { Value = e.AlarmName ?? "" });
+ cmd.Parameters.Add(new SqlParameter("@at", SqlDbType.NVarChar, -1) { Value = e.AlarmTypeName ?? "" });
+ cmd.Parameters.Add(new SqlParameter("@sev", SqlDbType.Int) { Value = ToNumericSeverity(e.Severity) });
+ cmd.Parameters.Add(new SqlParameter("@ek", SqlDbType.NVarChar, -1) { Value = e.EventKind ?? "" });
+ cmd.Parameters.Add(new SqlParameter("@msg", SqlDbType.NVarChar, -1) { Value = (object?)e.Message ?? DBNull.Value });
+ cmd.Parameters.Add(new SqlParameter("@usr", SqlDbType.NVarChar, -1) { Value = (object?)e.User ?? DBNull.Value });
+ cmd.Parameters.Add(new SqlParameter("@cmt", SqlDbType.NVarChar, -1) { Value = (object?)e.Comment ?? DBNull.Value });
+ SqlHistorianConnection.AddDateTime2(cmd, "@t", e.TimestampUtc);
+ await cmd.ExecuteNonQueryAsync(ct).ConfigureAwait(false);
+ return HistorianWriteOutcome.Ack;
+ }
+ // Single-row statement: a duplicate-key error means the row IS there (a concurrent writer won).
+ catch (SqlException ex) when (SqlHistorianConnection.IsDuplicateKey(ex))
+ {
+ return HistorianWriteOutcome.Ack;
+ }
+ }
+ }
+ catch (OperationCanceledException) when (ct.IsCancellationRequested)
+ {
+ return HistorianWriteOutcome.RetryPlease;
+ }
+ catch (Exception ex)
+ {
+ var outcome = Classify(ex);
+ _log.LogWarning("SQL alarm event write failed ({Exception}); outcome {Outcome}.", ex.GetType().Name, outcome);
+ return outcome;
+ }
+ }
+
+ private static HistorianWriteOutcome Classify(Exception ex)
+ {
+ if (SqlHistorianConnection.IsTransient(ex)) return HistorianWriteOutcome.RetryPlease;
+ if (ex is SqlException sql)
+ return sql.Errors.Cast().Any(x => Array.IndexOf(DataErrorNumbers, x.Number) >= 0)
+ ? HistorianWriteOutcome.PermanentFail
+ : HistorianWriteOutcome.RetryPlease; // config/auth/availability problems must not dead-letter data
+ return HistorianWriteOutcome.PermanentFail;
+ }
+
+ // Same numeric Part 9 priorities the gateway path sends (AlarmEventMapper.ToNumericSeverity).
+ private static int ToNumericSeverity(AlarmSeverity s) => s switch
+ {
+ AlarmSeverity.Low => 200,
+ AlarmSeverity.Medium => 500,
+ AlarmSeverity.High => 700,
+ AlarmSeverity.Critical => 900,
+ _ => 500,
+ };
+
+ ///
+ /// Lowercase-hex SHA-256 over length-prefixed UTF-8 fields (little-endian int32 byte length, -1 for null):
+ /// EquipmentPath, AlarmId, EventKind, TimestampUtc.Ticks (decimal), User, Comment, Message. Length-prefixing keeps
+ /// field boundaries unambiguous ("a|b"+"c" ≠ "a"+"b|c").
+ ///
+ /// The event.
+ /// 64 hex characters.
+ internal static string ComputeEventId(AlarmHistorianEvent e)
+ {
+ using var ms = new MemoryStream();
+ Field(ms, e.EquipmentPath);
+ Field(ms, e.AlarmId);
+ Field(ms, e.EventKind);
+ Field(ms, e.TimestampUtc.Ticks.ToString(System.Globalization.CultureInfo.InvariantCulture));
+ Field(ms, e.User);
+ Field(ms, e.Comment);
+ Field(ms, e.Message);
+ return Convert.ToHexStringLower(SHA256.HashData(ms.ToArray()));
+ }
+
+ private static void Field(MemoryStream ms, string? value)
+ {
+ Span len = stackalloc byte[4];
+ if (value is null)
+ {
+ System.Buffers.Binary.BinaryPrimitives.WriteInt32LittleEndian(len, -1);
+ ms.Write(len);
+ return;
+ }
+
+ var bytes = Encoding.UTF8.GetBytes(value);
+ System.Buffers.Binary.BinaryPrimitives.WriteInt32LittleEndian(len, bytes.Length);
+ ms.Write(len);
+ ms.Write(bytes);
+ }
+}
diff --git a/src/Drivers/ZB.MOM.WW.OtOpcUa.Driver.Historian.SqlServer/SqlServerHistorianValueWriter.cs b/src/Drivers/ZB.MOM.WW.OtOpcUa.Driver.Historian.SqlServer/SqlServerHistorianValueWriter.cs
new file mode 100644
index 00000000..c1e9582c
--- /dev/null
+++ b/src/Drivers/ZB.MOM.WW.OtOpcUa.Driver.Historian.SqlServer/SqlServerHistorianValueWriter.cs
@@ -0,0 +1,134 @@
+using Microsoft.Data.SqlClient;
+using Microsoft.Extensions.Logging;
+using Microsoft.Extensions.Logging.Abstractions;
+using ZB.MOM.WW.OtOpcUa.Core.Abstractions;
+
+namespace ZB.MOM.WW.OtOpcUa.Driver.Historian.SqlServer;
+
+///
+/// The one place that maps value kinds to Tag.DataType (the schema stores a byte).
+/// Used only when the writer has to create a tag row on a miss; provisioning later corrects it.
+///
+internal static class SqlHistorianDataTypes
+{
+ /// Data type used when a tag is created from a batch that holds no typed value.
+ public const DriverDataType DefaultForEmpty = DriverDataType.Float64;
+
+ /// Maps a value kind to the stored Tag.DataType byte (Empty ⇒ ).
+ /// Value kind.
+ /// The as a byte.
+ public static byte FromKind(HistorianValueKind kind) => (byte)(kind switch
+ {
+ HistorianValueKind.Double => DriverDataType.Float64,
+ HistorianValueKind.Int64 => DriverDataType.Int64,
+ HistorianValueKind.Boolean => DriverDataType.Boolean,
+ HistorianValueKind.String => DriverDataType.String,
+ HistorianValueKind.DateTime => DriverDataType.DateTime,
+ _ => DefaultForEmpty,
+ });
+}
+
+///
+/// over the SQL Sample table. Redelivery-idempotent: rows are
+/// inserted only where (TagId, SourceTimeUtc) is absent, so the recorder's at-least-once redelivery
+/// leaves the first-stored sample untouched. Never throws; returns false on any failure so the recorder keeps
+/// the entries and its #538 per-tag quarantine keeps working.
+///
+///
+/// Non-finite doubles. NaN / ±Infinity cannot live in a SQL float (the TVP throws). They are stored
+/// as keeping the original status code, so the sample's presence and
+/// status survive and the tag is not quarantined for one bad reading.
+/// Duplicate timestamps within a batch collapse to the first (matching insert-if-absent across batches).
+///
+internal sealed class SqlServerHistorianValueWriter : IHistorianValueWriter
+{
+ private readonly SqlHistorianConnection _conn;
+ private readonly SqlServerSchemaBootstrapper _bootstrap;
+ private readonly SqlServerTagCatalog _catalog;
+ private readonly ILogger _log;
+ private readonly Func _utcNow;
+
+ /// Creates the writer.
+ /// Connection helper.
+ /// Schema bootstrapper.
+ /// Tag catalog.
+ /// Optional logger.
+ /// Clock for null timestamps (tests).
+ public SqlServerHistorianValueWriter(SqlHistorianConnection conn, SqlServerSchemaBootstrapper bootstrap,
+ SqlServerTagCatalog catalog, ILogger? log = null, Func? utcNow = null)
+ {
+ _conn = conn;
+ _bootstrap = bootstrap;
+ _catalog = catalog;
+ _log = log ?? NullLogger.Instance;
+ _utcNow = utcNow ?? (() => DateTime.UtcNow);
+ }
+
+ ///
+ public async Task WriteLiveValuesAsync(string tag, IReadOnlyList values, CancellationToken ct)
+ {
+ try
+ {
+ await _bootstrap.EnsureAsync(ct).ConfigureAwait(false);
+ if (values is null || values.Count == 0) return true;
+
+ var rows = Prepare(values, _utcNow);
+ var dataType = SqlHistorianDataTypes.FromKind(rows.Select(r => r.Value.Kind).FirstOrDefault(k => k != HistorianValueKind.Empty));
+ var tagId = await _catalog.GetOrCreateTagIdAsync(tag, dataType, ct).ConfigureAwait(false);
+
+ var sql =
+ $"INSERT INTO {_conn.Q("Sample")} (TagId, SourceTimeUtc, ValueKind, NumValue, IntValue, StrValue, StatusCode, ServerTimeUtc) " +
+ "SELECT @tagId, r.SourceTimeUtc, r.ValueKind, r.NumValue, r.IntValue, r.StrValue, r.StatusCode, SYSUTCDATETIME() " +
+ "FROM @rows r WHERE NOT EXISTS (SELECT 1 FROM " + _conn.Q("Sample") +
+ " s WITH (UPDLOCK, HOLDLOCK) WHERE s.TagId = @tagId AND s.SourceTimeUtc = r.SourceTimeUtc)";
+
+ // A duplicate-key error rolls the WHOLE statement back, so "someone else wrote a row" is NOT proof our rows are
+ // present. The retry re-evaluates NOT EXISTS against what is now there; only its success counts.
+ for (var attempt = 0; ; attempt++)
+ {
+ try
+ {
+ await using var conn = await _conn.OpenAsync(ct).ConfigureAwait(false);
+ await using var cmd = _conn.CreateCommand(conn, sql);
+ cmd.Parameters.Add(new SqlParameter("@tagId", System.Data.SqlDbType.Int) { Value = tagId });
+ _conn.AddStructured(cmd, "@rows", "SampleRow", SampleRowMapper.ToSampleRecords(rows));
+ await cmd.ExecuteNonQueryAsync(ct).ConfigureAwait(false);
+ return true;
+ }
+ catch (SqlException ex) when (attempt < 2 && SqlHistorianConnection.IsDuplicateKey(ex))
+ {
+ }
+ }
+ }
+ catch (Exception ex)
+ {
+ _log.LogWarning("SQL historian live-value write failed ({Exception}); will retry.", ex.GetType().Name);
+ return false;
+ }
+ }
+
+ ///
+ /// Normalises a batch for the TVP: null timestamp ⇒ now, non-finite doubles ⇒ Empty (status kept), and
+ /// duplicate timestamps collapsed to the first.
+ ///
+ /// Input samples, in append order.
+ /// Clock for null timestamps.
+ /// Time-unique rows.
+ internal static List Prepare(IReadOnlyList values, Func utcNow)
+ {
+ var seen = new HashSet();
+ var rows = new List(values.Count);
+ foreach (var v in values)
+ {
+ var t = v.TimestampUtc ?? utcNow();
+ t = t.Kind == DateTimeKind.Local ? t.ToUniversalTime() : DateTime.SpecifyKind(t, DateTimeKind.Utc);
+ if (!seen.Add(t.Ticks)) continue;
+ var value = v.Value;
+ if (value.Kind == HistorianValueKind.Double && !double.IsFinite(value.Number))
+ value = HistorianValue.Empty;
+ rows.Add(new SqlSampleRow(t, value, v.StatusCode));
+ }
+
+ return rows;
+ }
+}
diff --git a/src/Drivers/ZB.MOM.WW.OtOpcUa.Driver.Historian.SqlServer/SqlServerTagProvisioner.cs b/src/Drivers/ZB.MOM.WW.OtOpcUa.Driver.Historian.SqlServer/SqlServerTagProvisioner.cs
new file mode 100644
index 00000000..c0582b88
--- /dev/null
+++ b/src/Drivers/ZB.MOM.WW.OtOpcUa.Driver.Historian.SqlServer/SqlServerTagProvisioner.cs
@@ -0,0 +1,120 @@
+using System.Data;
+using System.Text;
+using Microsoft.Data.SqlClient;
+using Microsoft.Extensions.Logging;
+using Microsoft.Extensions.Logging.Abstractions;
+using ZB.MOM.WW.OtOpcUa.Core.Abstractions;
+
+namespace ZB.MOM.WW.OtOpcUa.Driver.Historian.SqlServer;
+
+///
+/// for the SQL backend: one MERGE … WITH (HOLDLOCK) upsert per chunk of
+/// tags (chunked only to stay under SQL's 2100-parameter limit). Every data type is provisionable (Skipped is
+/// always 0). A null engineering unit / description in a request keeps the stored value rather than wiping it.
+/// Never throws.
+///
+internal sealed class SqlServerTagProvisioner : IHistorianProvisioning
+{
+ private const int ChunkSize = 400; // 4 parameters per tag
+ private const int MaxNameLength = 400;
+ private const int MaxUnitLength = 64;
+ private const int MaxDescriptionLength = 400;
+ private const int MaxAttempts = 4;
+
+ private readonly SqlHistorianConnection _conn;
+ private readonly SqlServerSchemaBootstrapper _bootstrap;
+ private readonly ILogger _log;
+
+ /// Creates the provisioner.
+ /// Connection helper.
+ /// Schema bootstrapper.
+ /// Optional logger.
+ public SqlServerTagProvisioner(SqlHistorianConnection conn, SqlServerSchemaBootstrapper bootstrap, ILogger? log = null)
+ {
+ _conn = conn;
+ _bootstrap = bootstrap;
+ _log = log ?? NullLogger.Instance;
+ }
+
+ ///
+ public async Task EnsureTagsAsync(IReadOnlyList requests, CancellationToken ct)
+ {
+ var requested = requests?.Count ?? 0;
+ if (requested == 0) return new HistorianProvisionResult(0, 0, 0, 0);
+ var failed = 0;
+ var ensured = 0;
+ try
+ {
+ await _bootstrap.EnsureAsync(ct).ConfigureAwait(false);
+
+ // Distinct names (a MERGE source must not repeat a key); last request wins. Over-long/empty names fail alone.
+ var byName = new Dictionary(StringComparer.Ordinal);
+ foreach (var r in requests!)
+ {
+ if (r is null || string.IsNullOrWhiteSpace(r.TagName) || r.TagName.Length > MaxNameLength) { failed++; continue; }
+ byName[r.TagName] = (r, byName.TryGetValue(r.TagName, out var e) ? e.Count + 1 : 1);
+ }
+
+ var ordered = byName.OrderBy(kv => kv.Key, StringComparer.Ordinal).Select(kv => kv.Value).ToList();
+ for (var i = 0; i < ordered.Count; i += ChunkSize)
+ {
+ var chunk = ordered.Skip(i).Take(ChunkSize).ToList();
+ var weight = chunk.Sum(c => c.Count);
+ if (await TryMergeAsync(chunk.Select(c => c.Req).ToList(), ct).ConfigureAwait(false)) ensured += weight;
+ else failed += weight;
+ }
+ }
+ catch (Exception ex)
+ {
+ _log.LogWarning("SQL historian provisioning failed ({Exception}).", ex.GetType().Name);
+ failed = requested - ensured;
+ }
+
+ return new HistorianProvisionResult(requested, ensured, 0, failed);
+ }
+
+ private async Task TryMergeAsync(List chunk, CancellationToken ct)
+ {
+ var sql = new StringBuilder();
+ sql.Append($"MERGE {_conn.Q("Tag")} WITH (HOLDLOCK) AS t USING (VALUES ");
+ for (var i = 0; i < chunk.Count; i++)
+ sql.Append(i == 0 ? "" : ",").Append($"(@n{i},@d{i},@e{i},@c{i})");
+ sql.Append(") AS s (Name, DataType, EngineeringUnit, Description) ON t.Name = s.Name " +
+ "WHEN MATCHED THEN UPDATE SET DataType = s.DataType, EngineeringUnit = COALESCE(s.EngineeringUnit, t.EngineeringUnit), " +
+ "Description = COALESCE(s.Description, t.Description), UpdatedUtc = SYSUTCDATETIME() " +
+ "WHEN NOT MATCHED THEN INSERT (Name, DataType, EngineeringUnit, Description, CreatedUtc, UpdatedUtc) " +
+ "VALUES (s.Name, s.DataType, s.EngineeringUnit, s.Description, SYSUTCDATETIME(), SYSUTCDATETIME());");
+
+ for (var attempt = 1; ; attempt++)
+ {
+ try
+ {
+ await using var conn = await _conn.OpenAsync(ct).ConfigureAwait(false);
+ await using var cmd = _conn.CreateCommand(conn, sql.ToString());
+ for (var i = 0; i < chunk.Count; i++)
+ {
+ var r = chunk[i];
+ cmd.Parameters.Add(new SqlParameter($"@n{i}", SqlDbType.NVarChar, MaxNameLength) { Value = r.TagName });
+ cmd.Parameters.Add(new SqlParameter($"@d{i}", SqlDbType.TinyInt) { Value = (byte)r.DataType });
+ cmd.Parameters.Add(new SqlParameter($"@e{i}", SqlDbType.NVarChar, MaxUnitLength) { Value = Clip(r.EngineeringUnit, MaxUnitLength) });
+ cmd.Parameters.Add(new SqlParameter($"@c{i}", SqlDbType.NVarChar, MaxDescriptionLength) { Value = Clip(r.Description, MaxDescriptionLength) });
+ }
+
+ await cmd.ExecuteNonQueryAsync(ct).ConfigureAwait(false);
+ return true;
+ }
+ catch (SqlException ex) when (attempt < MaxAttempts &&
+ (SqlHistorianConnection.IsDuplicateKey(ex) || SqlHistorianConnection.IsTransient(ex)))
+ {
+ await Task.Delay(20 * attempt, ct).ConfigureAwait(false);
+ }
+ catch (Exception ex)
+ {
+ _log.LogWarning("SQL historian tag MERGE failed ({Exception}).", ex.GetType().Name);
+ return false;
+ }
+ }
+ }
+
+ private static object Clip(string? s, int max) => s is null ? DBNull.Value : s.Length <= max ? s : s[..max];
+}
diff --git a/tests/Drivers/ZB.MOM.WW.OtOpcUa.Driver.Historian.SqlServer.IntegrationTests/AlarmWriterTests.cs b/tests/Drivers/ZB.MOM.WW.OtOpcUa.Driver.Historian.SqlServer.IntegrationTests/AlarmWriterTests.cs
new file mode 100644
index 00000000..36faa9fc
--- /dev/null
+++ b/tests/Drivers/ZB.MOM.WW.OtOpcUa.Driver.Historian.SqlServer.IntegrationTests/AlarmWriterTests.cs
@@ -0,0 +1,89 @@
+using Microsoft.Data.SqlClient;
+using Shouldly;
+using Xunit;
+using ZB.MOM.WW.OtOpcUa.Core.Abstractions;
+using ZB.MOM.WW.OtOpcUa.Core.AlarmHistorian;
+
+namespace ZB.MOM.WW.OtOpcUa.Driver.Historian.SqlServer.IntegrationTests;
+
+[Collection(SqlHistorianCollection.Name)]
+public sealed class AlarmWriterTests(SqlHistorianFixture fx)
+{
+ private static readonly DateTime T = new DateTime(2026, 10, 9, 1, 2, 3, DateTimeKind.Utc).AddTicks(1234567);
+
+ private (SqlServerAlarmHistorianWriter W, string S) Make(string? connection = null, bool auto = true)
+ {
+ var s = SqlHistorianFixture.UniqueSchema();
+ var o = new SqlServerHistorianOptions { ConnectionString = connection ?? fx.ConnectionString, Schema = s, AutoCreateSchema = auto };
+ var c = new SqlHistorianConnection(o);
+ return (new SqlServerAlarmHistorianWriter(c, new SqlServerSchemaBootstrapper(c, o)), s);
+ }
+
+ private static AlarmHistorianEvent Ev(string kind = "Activated", string type = "LimitAlarm", string? comment = "c") =>
+ new("alarm-1", "Plant/Line/Eq", "HiTemp", type, AlarmSeverity.High, kind, "msg", "user", comment, T);
+
+ [Fact]
+ public async Task Event_round_trips_and_a_repeat_is_one_row_with_both_Ack()
+ {
+ fx.SkipIfUnavailable();
+ var (w, s) = Make();
+ var first = await w.WriteBatchAsync([Ev(), Ev()], CancellationToken.None);
+ first.ShouldBe([HistorianWriteOutcome.Ack, HistorianWriteOutcome.Ack]);
+ (await w.WriteBatchAsync([Ev()], CancellationToken.None)).ShouldBe([HistorianWriteOutcome.Ack]);
+ (await w.WriteBatchAsync([Ev(kind: "Cleared")], CancellationToken.None)).ShouldBe([HistorianWriteOutcome.Ack]);
+
+ await using var c = new SqlConnection(fx.ConnectionString);
+ await c.OpenAsync();
+ await using var cmd = c.CreateCommand();
+ cmd.CommandText = $"SELECT SourceName, AlarmId, AlarmName, AlarmTypeName, Severity, EventKind, Message, UserName, Comment, EventTimeUtc, ReceivedTimeUtc FROM [{s}].Event WHERE EventKind='Activated'";
+ await using var r = await cmd.ExecuteReaderAsync();
+ (await r.ReadAsync()).ShouldBeTrue();
+ r.GetString(0).ShouldBe("Plant/Line/Eq");
+ r.GetString(1).ShouldBe("alarm-1");
+ r.GetString(2).ShouldBe("HiTemp");
+ r.GetString(3).ShouldBe("LimitAlarm");
+ r.GetInt32(4).ShouldBe(700);
+ r.GetString(6).ShouldBe("msg");
+ r.GetString(7).ShouldBe("user");
+ r.GetString(8).ShouldBe("c");
+ SqlHistorianConnection.GetUtc(r, 9).Ticks.ShouldBe(T.Ticks);
+ (DateTime.UtcNow - SqlHistorianConnection.GetUtc(r, 10)).ShouldBeLessThan(TimeSpan.FromMinutes(1));
+ (await r.ReadAsync()).ShouldBeFalse();
+ await r.CloseAsync();
+ cmd.CommandText = $"SELECT COUNT(*) FROM [{s}].Event";
+ Convert.ToInt32(await cmd.ExecuteScalarAsync()).ShouldBe(2);
+ }
+
+ [Fact]
+ public async Task Over_long_AlarmTypeName_is_PermanentFail_and_siblings_still_Ack()
+ {
+ fx.SkipIfUnavailable();
+ var (w, s) = Make();
+ var r = await w.WriteBatchAsync([Ev(kind: "A"), Ev(kind: "B", type: new string('t', 101)), Ev(kind: "C", comment: null)], CancellationToken.None);
+ r.ShouldBe([HistorianWriteOutcome.Ack, HistorianWriteOutcome.PermanentFail, HistorianWriteOutcome.Ack]);
+ }
+
+ [Fact]
+ public async Task Concurrent_writers_of_the_same_event_all_Ack_with_one_row()
+ {
+ fx.SkipIfUnavailable();
+ var (w, s) = Make();
+ await w.WriteBatchAsync([Ev(kind: "warm")], CancellationToken.None);
+ var rs = await Task.WhenAll(Enumerable.Range(0, 12).Select(_ => Task.Run(() => w.WriteBatchAsync([Ev()], CancellationToken.None))));
+ rs.ShouldAllBe(x => x[0] == HistorianWriteOutcome.Ack);
+ await using var c = new SqlConnection(fx.ConnectionString);
+ await c.OpenAsync();
+ await using var cmd = c.CreateCommand();
+ cmd.CommandText = $"SELECT COUNT(*) FROM [{s}].Event WHERE EventKind='Activated'";
+ Convert.ToInt32(await cmd.ExecuteScalarAsync()).ShouldBe(1);
+ }
+
+ [Fact]
+ public async Task Unreachable_database_is_RetryPlease_not_an_exception_and_empty_batch_is_empty()
+ {
+ fx.SkipIfUnavailable();
+ var (w, _) = Make(fx.ConnectionString + ";Connect Timeout=1", auto: false); // schema missing
+ (await w.WriteBatchAsync([Ev()], CancellationToken.None)).ShouldBe([HistorianWriteOutcome.RetryPlease]);
+ (await w.WriteBatchAsync([], CancellationToken.None)).ShouldBeEmpty();
+ }
+}
diff --git a/tests/Drivers/ZB.MOM.WW.OtOpcUa.Driver.Historian.SqlServer.IntegrationTests/ProvisioningTests.cs b/tests/Drivers/ZB.MOM.WW.OtOpcUa.Driver.Historian.SqlServer.IntegrationTests/ProvisioningTests.cs
new file mode 100644
index 00000000..5ddff410
--- /dev/null
+++ b/tests/Drivers/ZB.MOM.WW.OtOpcUa.Driver.Historian.SqlServer.IntegrationTests/ProvisioningTests.cs
@@ -0,0 +1,94 @@
+using Microsoft.Data.SqlClient;
+using Shouldly;
+using Xunit;
+using ZB.MOM.WW.OtOpcUa.Core.Abstractions;
+
+namespace ZB.MOM.WW.OtOpcUa.Driver.Historian.SqlServer.IntegrationTests;
+
+[Collection(SqlHistorianCollection.Name)]
+public sealed class ProvisioningTests(SqlHistorianFixture fx)
+{
+ private (SqlServerTagProvisioner P, string S) Make(string? schema = null)
+ {
+ var s = schema ?? SqlHistorianFixture.UniqueSchema();
+ var o = new SqlServerHistorianOptions { ConnectionString = fx.ConnectionString, Schema = s };
+ var c = new SqlHistorianConnection(o);
+ return (new SqlServerTagProvisioner(c, new SqlServerSchemaBootstrapper(c, o)), s);
+ }
+
+ private async Task<(byte Type, string? Eu, string? Desc)> TagAsync(string s, string name)
+ {
+ await using var c = new SqlConnection(fx.ConnectionString);
+ await c.OpenAsync();
+ await using var cmd = c.CreateCommand();
+ cmd.CommandText = $"SELECT DataType, EngineeringUnit, Description FROM [{s}].Tag WHERE Name=@n";
+ cmd.Parameters.AddWithValue("@n", name);
+ await using var r = await cmd.ExecuteReaderAsync();
+ (await r.ReadAsync()).ShouldBeTrue();
+ return (r.GetByte(0), r.IsDBNull(1) ? null : r.GetString(1), r.IsDBNull(2) ? null : r.GetString(2));
+ }
+
+ [Fact]
+ public async Task Upsert_creates_then_changes_DataType_on_rerun_and_every_type_is_accepted()
+ {
+ fx.SkipIfUnavailable();
+ var (p, s) = Make();
+ var r1 = await p.EnsureTagsAsync([new("a", DriverDataType.Boolean, "degC", "desc"), new("s", DriverDataType.String, null, null)], CancellationToken.None);
+ r1.ShouldBe(new HistorianProvisionResult(2, 2, 0, 0));
+ (await TagAsync(s, "a")).ShouldBe(((byte)DriverDataType.Boolean, "degC", "desc"));
+ var r2 = await p.EnsureTagsAsync([new("a", DriverDataType.Float64, null, null)], CancellationToken.None);
+ r2.ShouldBe(new HistorianProvisionResult(1, 1, 0, 0));
+ (await TagAsync(s, "a")).ShouldBe(((byte)DriverDataType.Float64, "degC", "desc")); // null keeps stored metadata
+ }
+
+ [Fact]
+ public async Task Duplicate_names_and_bad_names_are_tallied_not_thrown()
+ {
+ fx.SkipIfUnavailable();
+ var (p, _) = Make();
+ var r = await p.EnsureTagsAsync([
+ new("d", DriverDataType.Int32, null, null), new("d", DriverDataType.Int64, null, null),
+ new("", DriverDataType.Int32, null, null), new(new string('x', 401), DriverDataType.Int32, null, null)], CancellationToken.None);
+ r.ShouldBe(new HistorianProvisionResult(4, 2, 0, 2));
+ }
+
+ [Fact]
+ public async Task More_tags_than_one_chunk_all_land()
+ {
+ fx.SkipIfUnavailable();
+ var (p, s) = Make();
+ var reqs = Enumerable.Range(0, 1000).Select(i => new HistorianTagProvisionRequest($"bulk{i}", DriverDataType.Float32, null, null)).ToList();
+ (await p.EnsureTagsAsync(reqs, CancellationToken.None)).ShouldBe(new HistorianProvisionResult(1000, 1000, 0, 0));
+ }
+
+ [Fact]
+ public async Task Two_concurrent_provisioners_of_the_same_new_tags_both_report_Ensured_with_no_Failed()
+ {
+ fx.SkipIfUnavailable();
+ var s = SqlHistorianFixture.UniqueSchema();
+ var (p0, _) = Make(s);
+ await p0.EnsureTagsAsync([new("warm", DriverDataType.Int32, null, null)], CancellationToken.None); // bootstrap once
+ for (var round = 0; round < 10; round++)
+ {
+ var reqs = Enumerable.Range(0, 60).Select(i => new HistorianTagProvisionRequest($"r{round}.t{i}", DriverDataType.Float64, "u", null)).ToList();
+ var rs = await Task.WhenAll(Enumerable.Range(0, 4).Select(_ => Task.Run(() => Make(s).P.EnsureTagsAsync(reqs, CancellationToken.None))));
+ foreach (var r in rs) r.ShouldBe(new HistorianProvisionResult(60, 60, 0, 0));
+ }
+
+ await using var c = new SqlConnection(fx.ConnectionString);
+ await c.OpenAsync();
+ await using var cmd = c.CreateCommand();
+ cmd.CommandText = $"SELECT COUNT(*) FROM [{s}].Tag";
+ Convert.ToInt32(await cmd.ExecuteScalarAsync()).ShouldBe(601);
+ }
+
+ [Fact]
+ public async Task A_connection_failure_is_a_Failed_tally_not_an_exception()
+ {
+ fx.SkipIfUnavailable();
+ var o = new SqlServerHistorianOptions { ConnectionString = fx.ConnectionString + ";Connect Timeout=1", Schema = SqlHistorianFixture.UniqueSchema(), AutoCreateSchema = false };
+ var c = new SqlHistorianConnection(o);
+ var p = new SqlServerTagProvisioner(c, new SqlServerSchemaBootstrapper(c, o));
+ (await p.EnsureTagsAsync([new("x", DriverDataType.Int32, null, null)], CancellationToken.None)).ShouldBe(new HistorianProvisionResult(1, 0, 0, 1));
+ }
+}
diff --git a/tests/Drivers/ZB.MOM.WW.OtOpcUa.Driver.Historian.SqlServer.IntegrationTests/WriteTests.cs b/tests/Drivers/ZB.MOM.WW.OtOpcUa.Driver.Historian.SqlServer.IntegrationTests/WriteTests.cs
new file mode 100644
index 00000000..946ac321
--- /dev/null
+++ b/tests/Drivers/ZB.MOM.WW.OtOpcUa.Driver.Historian.SqlServer.IntegrationTests/WriteTests.cs
@@ -0,0 +1,166 @@
+using System.Diagnostics;
+using Microsoft.Data.SqlClient;
+using Shouldly;
+using Xunit;
+using ZB.MOM.WW.OtOpcUa.Core.Abstractions;
+
+namespace ZB.MOM.WW.OtOpcUa.Driver.Historian.SqlServer.IntegrationTests;
+
+[Collection(SqlHistorianCollection.Name)]
+public sealed class WriteTests(SqlHistorianFixture fx)
+{
+ // Non-ms-aligned: sub-millisecond ticks must round-trip exactly.
+ private static readonly DateTime T0 = new DateTime(2026, 10, 9, 1, 2, 3, DateTimeKind.Utc).AddTicks(1234567);
+
+ private (SqlServerHistorianValueWriter W, string S) Make()
+ {
+ var s = SqlHistorianFixture.UniqueSchema();
+ var o = new SqlServerHistorianOptions { ConnectionString = fx.ConnectionString, Schema = s };
+ var c = new SqlHistorianConnection(o);
+ var b = new SqlServerSchemaBootstrapper(c, o);
+ return (new SqlServerHistorianValueWriter(c, b, new SqlServerTagCatalog(c, b)), s);
+ }
+
+ private async Task> RowsAsync(string schema, string tag)
+ {
+ await using var c = new SqlConnection(fx.ConnectionString);
+ await c.OpenAsync();
+ await using var cmd = c.CreateCommand();
+ cmd.CommandText = $"SELECT s.SourceTimeUtc, s.ValueKind, s.NumValue, s.IntValue, s.StrValue, s.StatusCode, t.Name FROM [{schema}].Sample s JOIN [{schema}].Tag t ON t.TagId=s.TagId WHERE t.Name=@n ORDER BY s.SourceTimeUtc";
+ cmd.Parameters.AddWithValue("@n", tag);
+ var l = new List<(DateTime, byte, double?, long?, string?, int, string)>();
+ await using var r = await cmd.ExecuteReaderAsync();
+ while (await r.ReadAsync())
+ l.Add((SqlHistorianConnection.GetUtc(r, 0), r.GetByte(1), r.IsDBNull(2) ? null : r.GetDouble(2), r.IsDBNull(3) ? null : r.GetInt64(3),
+ r.IsDBNull(4) ? null : r.GetString(4), r.GetInt32(5), r.GetString(6)));
+ return l;
+ }
+
+ [Fact]
+ public async Task Every_kind_round_trips_with_exact_ticks_and_status()
+ {
+ fx.SkipIfUnavailable();
+ var (w, s) = Make();
+ var dt = new DateTime(2026, 1, 2, 3, 4, 5, DateTimeKind.Utc).AddTicks(77);
+ HistorizationValue[] vals =
+ [
+ new(T0, HistorianValue.FromDouble(1.25), 0),
+ new(T0.AddTicks(1), HistorianValue.FromInt64(long.MaxValue), 0x40000000u),
+ new(T0.AddTicks(2), HistorianValue.FromBoolean(true), 0),
+ new(T0.AddTicks(3), HistorianValue.FromString("héllo"), 0),
+ new(T0.AddTicks(4), HistorianValue.FromDateTime(dt), 0),
+ new(T0.AddTicks(5), HistorianValue.Empty, 0x80310000u),
+ ];
+ (await w.WriteLiveValuesAsync("tag.a", vals, CancellationToken.None)).ShouldBeTrue();
+ var rows = await RowsAsync(s, "tag.a");
+ rows.Count.ShouldBe(6);
+ for (var i = 0; i < 6; i++) rows[i].T.Ticks.ShouldBe(vals[i].TimestampUtc!.Value.Ticks);
+ var back = rows.Select(r => SampleRowMapper.FromColumns(r.Kind, r.N, r.I, r.S)).ToList();
+ back.ShouldBe(vals.Select(v => v.Value).ToList());
+ rows[1].Status.ShouldBe(unchecked((int)0x40000000u));
+ SampleRowMapper.FromDbStatus(rows[5].Status).ShouldBe(0x80310000u);
+ }
+
+ [Fact]
+ public async Task Writing_the_same_batch_twice_is_idempotent()
+ {
+ fx.SkipIfUnavailable();
+ var (w, s) = Make();
+ HistorizationValue[] vals = [new(T0, HistorianValue.FromDouble(1), 0), new(T0.AddSeconds(1), HistorianValue.FromDouble(2), 0)];
+ (await w.WriteLiveValuesAsync("tag.b", vals, CancellationToken.None)).ShouldBeTrue();
+ (await w.WriteLiveValuesAsync("tag.b", vals, CancellationToken.None)).ShouldBeTrue();
+ // Overlapping batch: only the new row lands, the stored first value is untouched.
+ (await w.WriteLiveValuesAsync("tag.b", [new(T0, HistorianValue.FromDouble(99), 0), new(T0.AddSeconds(2), HistorianValue.FromDouble(3), 0)], CancellationToken.None)).ShouldBeTrue();
+ var rows = await RowsAsync(s, "tag.b");
+ rows.Count.ShouldBe(3);
+ rows[0].N.ShouldBe(1);
+ }
+
+ [Fact]
+ public async Task Within_batch_duplicate_timestamps_do_not_fail_and_first_wins()
+ {
+ fx.SkipIfUnavailable();
+ var (w, s) = Make();
+ (await w.WriteLiveValuesAsync("tag.c", [new(T0, HistorianValue.FromDouble(1), 0), new(T0, HistorianValue.FromDouble(2), 0)], CancellationToken.None)).ShouldBeTrue();
+ var rows = await RowsAsync(s, "tag.c");
+ rows.Count.ShouldBe(1);
+ rows[0].N.ShouldBe(1);
+ }
+
+ [Fact]
+ public async Task Non_finite_doubles_store_as_Empty_with_their_status_and_do_not_fail_the_write()
+ {
+ fx.SkipIfUnavailable();
+ var (w, s) = Make();
+ (await w.WriteLiveValuesAsync("tag.d", [
+ new(T0, HistorianValue.FromDouble(double.NaN), 0x40000000u),
+ new(T0.AddTicks(1), HistorianValue.FromDouble(double.PositiveInfinity), 0),
+ new(T0.AddTicks(2), HistorianValue.FromDouble(7), 0)], CancellationToken.None)).ShouldBeTrue();
+ var rows = await RowsAsync(s, "tag.d");
+ rows.Count.ShouldBe(3);
+ rows[0].Kind.ShouldBe((byte)HistorianValueKind.Empty);
+ rows[0].N.ShouldBeNull();
+ rows[0].Status.ShouldBe(unchecked((int)0x40000000u));
+ rows[2].N.ShouldBe(7);
+ }
+
+ [Fact]
+ public async Task Empty_batch_succeeds_without_a_call_and_null_timestamp_is_stamped()
+ {
+ fx.SkipIfUnavailable();
+ var (w, s) = Make();
+ (await w.WriteLiveValuesAsync("tag.e", [], CancellationToken.None)).ShouldBeTrue();
+ (await w.WriteLiveValuesAsync("tag.e", [new(null, HistorianValue.FromInt64(5), 0)], CancellationToken.None)).ShouldBeTrue();
+ var rows = await RowsAsync(s, "tag.e");
+ rows.Count.ShouldBe(1);
+ (DateTime.UtcNow - rows[0].T).ShouldBeLessThan(TimeSpan.FromMinutes(1));
+ }
+
+ [Fact]
+ public async Task Tag_is_created_with_the_first_typed_values_data_type()
+ {
+ fx.SkipIfUnavailable();
+ var (w, s) = Make();
+ await w.WriteLiveValuesAsync("tag.f", [new(T0, HistorianValue.Empty, 0x80310000u), new(T0.AddTicks(1), HistorianValue.FromString("x"), 0)], CancellationToken.None);
+ await using var c = new SqlConnection(fx.ConnectionString);
+ await c.OpenAsync();
+ await using var cmd = c.CreateCommand();
+ cmd.CommandText = $"SELECT DataType FROM [{s}].Tag WHERE Name='tag.f'";
+ Convert.ToByte(await cmd.ExecuteScalarAsync()).ShouldBe((byte)DriverDataType.String);
+ }
+
+ [Fact]
+ public async Task Ten_thousand_values_write_in_under_five_seconds()
+ {
+ fx.SkipIfUnavailable();
+ var (w, s) = Make();
+ await w.WriteLiveValuesAsync("tag.warm", [new(T0, HistorianValue.FromDouble(0), 0)], CancellationToken.None); // bootstrap
+ var vals = Enumerable.Range(0, 10_000).Select(i => new HistorizationValue(T0.AddMilliseconds(i), HistorianValue.FromDouble(i), 0)).ToArray();
+ var sw = Stopwatch.StartNew();
+ (await w.WriteLiveValuesAsync("tag.big", vals, CancellationToken.None)).ShouldBeTrue();
+ sw.Elapsed.ShouldBeLessThan(TimeSpan.FromSeconds(5));
+ (await RowsAsync(s, "tag.big")).Count.ShouldBe(10_000);
+ }
+
+ [Fact]
+ public async Task Concurrent_overlapping_writers_all_succeed_and_leave_one_row_per_timestamp()
+ {
+ fx.SkipIfUnavailable();
+ var (w, s) = Make();
+ var vals = Enumerable.Range(0, 200).Select(i => new HistorizationValue(T0.AddMilliseconds(i), HistorianValue.FromDouble(i), 0)).ToArray();
+ var results = await Task.WhenAll(Enumerable.Range(0, 8).Select(_ => Task.Run(() => w.WriteLiveValuesAsync("tag.race", vals, CancellationToken.None))));
+ results.ShouldAllBe(r => r);
+ (await RowsAsync(s, "tag.race")).Count.ShouldBe(200);
+ }
+
+ [Fact]
+ public async Task A_SQL_failure_returns_false_instead_of_throwing()
+ {
+ fx.SkipIfUnavailable();
+ var o = new SqlServerHistorianOptions { ConnectionString = fx.ConnectionString + ";Connect Timeout=1", Schema = SqlHistorianFixture.UniqueSchema(), AutoCreateSchema = false };
+ var c = new SqlHistorianConnection(o);
+ var b = new SqlServerSchemaBootstrapper(c, o);
+ var w = new SqlServerHistorianValueWriter(c, b, new SqlServerTagCatalog(c, b));
+ (await w.WriteLiveValuesAsync("x", [new(T0, HistorianValue.FromDouble(1), 0)], CancellationToken.None)).ShouldBeFalse();
+ }
+}
diff --git a/tests/Drivers/ZB.MOM.WW.OtOpcUa.Driver.Historian.SqlServer.Tests/AlarmEventIdTests.cs b/tests/Drivers/ZB.MOM.WW.OtOpcUa.Driver.Historian.SqlServer.Tests/AlarmEventIdTests.cs
new file mode 100644
index 00000000..69d67dc0
--- /dev/null
+++ b/tests/Drivers/ZB.MOM.WW.OtOpcUa.Driver.Historian.SqlServer.Tests/AlarmEventIdTests.cs
@@ -0,0 +1,47 @@
+using Shouldly;
+using Xunit;
+using ZB.MOM.WW.OtOpcUa.Core.Abstractions;
+using ZB.MOM.WW.OtOpcUa.Core.AlarmHistorian;
+
+namespace ZB.MOM.WW.OtOpcUa.Driver.Historian.SqlServer.Tests;
+
+public sealed class AlarmEventIdTests
+{
+ private static readonly DateTime T = new(2026, 10, 9, 1, 2, 3, DateTimeKind.Utc);
+
+ private static AlarmHistorianEvent Ev(string path = "P", string id = "A", string kind = "Activated", string user = "u",
+ string? comment = "c", string msg = "m", DateTime? t = null) =>
+ new(id, path, "n", "LimitAlarm", AlarmSeverity.High, kind, msg, user, comment, t ?? T);
+
+ [Fact]
+ public void Id_is_stable_lowercase_hex_sha256()
+ {
+ var a = SqlServerAlarmHistorianWriter.ComputeEventId(Ev());
+ a.ShouldBe(SqlServerAlarmHistorianWriter.ComputeEventId(Ev()));
+ a.Length.ShouldBe(64);
+ a.ShouldBe(a.ToLowerInvariant());
+ }
+
+ [Fact]
+ public void Field_boundaries_are_unambiguous()
+ {
+ // The delimiter-based scheme collided on these; length prefixes must not.
+ SqlServerAlarmHistorianWriter.ComputeEventId(Ev(path: "a|b", id: "c"))
+ .ShouldNotBe(SqlServerAlarmHistorianWriter.ComputeEventId(Ev(path: "a", id: "b|c")));
+ SqlServerAlarmHistorianWriter.ComputeEventId(Ev(path: "ab", id: "c"))
+ .ShouldNotBe(SqlServerAlarmHistorianWriter.ComputeEventId(Ev(path: "a", id: "bc")));
+ }
+
+ [Fact]
+ public void Null_and_empty_differ_and_every_field_participates()
+ {
+ var basis = SqlServerAlarmHistorianWriter.ComputeEventId(Ev());
+ SqlServerAlarmHistorianWriter.ComputeEventId(Ev(comment: null)).ShouldNotBe(SqlServerAlarmHistorianWriter.ComputeEventId(Ev(comment: "")));
+ foreach (var other in new[]
+ {
+ Ev(path: "Q"), Ev(id: "B"), Ev(kind: "Cleared"), Ev(user: "v"), Ev(comment: "d"), Ev(msg: "x"),
+ Ev(t: T.AddTicks(1)),
+ })
+ SqlServerAlarmHistorianWriter.ComputeEventId(other).ShouldNotBe(basis);
+ }
+}
diff --git a/tests/Drivers/ZB.MOM.WW.OtOpcUa.Driver.Historian.SqlServer.Tests/ValueWriterPrepareTests.cs b/tests/Drivers/ZB.MOM.WW.OtOpcUa.Driver.Historian.SqlServer.Tests/ValueWriterPrepareTests.cs
new file mode 100644
index 00000000..02b86fde
--- /dev/null
+++ b/tests/Drivers/ZB.MOM.WW.OtOpcUa.Driver.Historian.SqlServer.Tests/ValueWriterPrepareTests.cs
@@ -0,0 +1,46 @@
+using Shouldly;
+using Xunit;
+using ZB.MOM.WW.OtOpcUa.Core.Abstractions;
+
+namespace ZB.MOM.WW.OtOpcUa.Driver.Historian.SqlServer.Tests;
+
+public sealed class ValueWriterPrepareTests
+{
+ private static readonly DateTime T = new(2026, 10, 9, 1, 2, 3, DateTimeKind.Utc);
+
+ [Fact]
+ public void Non_finite_doubles_become_Empty_keeping_status()
+ {
+ const uint status = 0x40000000u;
+ var rows = SqlServerHistorianValueWriter.Prepare(
+ [
+ new(T, HistorianValue.FromDouble(double.NaN), status),
+ new(T.AddTicks(1), HistorianValue.FromDouble(double.PositiveInfinity), 0),
+ new(T.AddTicks(2), HistorianValue.FromDouble(double.NegativeInfinity), 0),
+ new(T.AddTicks(3), HistorianValue.FromDouble(1.5), 0),
+ ], () => T);
+ rows.Select(r => r.Value.Kind).ShouldBe([HistorianValueKind.Empty, HistorianValueKind.Empty, HistorianValueKind.Empty, HistorianValueKind.Double]);
+ rows[0].StatusCode.ShouldBe(status);
+ }
+
+ [Fact]
+ public void Duplicate_timestamps_keep_the_first_and_null_timestamp_uses_the_clock()
+ {
+ var rows = SqlServerHistorianValueWriter.Prepare(
+ [
+ new(T, HistorianValue.FromInt64(1), 0), new(T, HistorianValue.FromInt64(2), 0),
+ new(null, HistorianValue.FromInt64(3), 0),
+ ], () => T.AddDays(1));
+ rows.Count.ShouldBe(2);
+ rows[0].Value.Integer.ShouldBe(1);
+ rows[1].TimeUtc.ShouldBe(T.AddDays(1));
+ }
+
+ [Fact]
+ public void Data_type_mapping_is_one_table()
+ {
+ SqlHistorianDataTypes.FromKind(HistorianValueKind.Double).ShouldBe((byte)DriverDataType.Float64);
+ SqlHistorianDataTypes.FromKind(HistorianValueKind.Boolean).ShouldBe((byte)DriverDataType.Boolean);
+ SqlHistorianDataTypes.FromKind(HistorianValueKind.Empty).ShouldBe((byte)DriverDataType.Float64);
+ }
+}