feat(historian): SQL Server retention purge (RetentionDays, Primary-gated, applock) (#667)

src/Drivers/ZB.MOM.WW.OtOpcUa.Driver.Historian.SqlServer/SqlServerHistorianOptions.cs

@@ -22,6 +22,21 @@ public sealed partial class SqlServerHistorianOptions
     /// </summary>
     public bool AutoCreateSchema { get; set; } = true;
 
+    /// <summary>
+    ///     Days of history to keep, measured on source time. <c>null</c> (default) keeps everything. When set,
+    ///     a driver node deletes older <c>hist.Sample</c>/<c>hist.Event</c> rows every <see cref="PurgeInterval"/>.
+    /// </summary>
+    public int? RetentionDays { get; set; }
+
+    /// <summary>How often the retention purge runs. Must be positive.</summary>
+    public TimeSpan PurgeInterval { get; set; } = TimeSpan.FromHours(1);
+
+    /// <summary>
+    ///     Rows per <c>DELETE TOP(n)</c> batch. Default 4000 stays under SQL Server's 5000-lock escalation
+    ///     threshold so a purge never escalates to a table lock.
+    /// </summary>
+    public int PurgeBatchSize { get; set; } = 4000;
+
     [GeneratedRegex("^[A-Za-z_][A-Za-z0-9_]{0,127}$")]
     private static partial Regex IdentifierRegex();
 
@@ -41,6 +56,12 @@ public sealed partial class SqlServerHistorianOptions
             errors.Add("ServerHistorian:SqlServer:Schema must be a SQL identifier matching ^[A-Za-z_][A-Za-z0-9_]{0,127}$.");
         if (CommandTimeout <= TimeSpan.Zero)
             errors.Add("ServerHistorian:SqlServer:CommandTimeout must be greater than zero.");
+        if (RetentionDays is < 1)
+            errors.Add("ServerHistorian:SqlServer:RetentionDays must be at least 1 when set (omit it to keep history forever).");
+        if (PurgeInterval <= TimeSpan.Zero)
+            errors.Add("ServerHistorian:SqlServer:PurgeInterval must be greater than zero.");
+        if (PurgeBatchSize < 1)
+            errors.Add("ServerHistorian:SqlServer:PurgeBatchSize must be at least 1.");
         return errors;
     }
 }