feat(historian): ServerHistorian:MaxRawValuesPerRead caps raw pages and backend reads

Review R08:1.1: an uncapped HistoryRead-Raw (NumValuesPerNode = 0) read a tag's whole window into memory on every backend (SQL TOP(int.MaxValue), QuestDB LIMIT, Gateway max_values = int.MaxValue + a second snapshot copy). New ServerHistorian:MaxRawValuesPerRead (default 10 000; <= 0 unbounded with a Validate() warning; 1 raised to 2). Each backend data source takes it, reports it as IHistorianDataSource.MaxRawValuesPerRead (the Gateway: min with a strict gateway's learned ceiling), so the node manager's existing RawPageLimit paging serves N = 0 and N > cap as pages of at most the cap with a continuation point. Independently, a backend raw read asking for 0 or more than the cap reads cap + 1 rows and is REFUSED (HistoryReadLimitExceededException => BadTooManyOperations) when the window holds more - never answered truncated, since the server's paging reads a short answer as the last page. Bound through the Host registry, the SqlServer/QuestDb providers and GatewayHistorian.CreateDataSource. Tests: options (default/binding/warnings), provider binding, Gateway unit + through a real SDK node manager (uncapped -> 999/998/998/605 + CPs), and a conformance case for the SQL backends. Refs #736 Claude-Session: https://claude.ai/code/session_01Ub9hGmYLQvn9XETzw7CMsT
2026-10-22 06:29:10 -04:00
parent ad2b5c4044
commit 6669fae7e5
17 changed files with 621 additions and 33 deletions
@@ -67,6 +67,12 @@ public sealed class GatewayHistorianDataSource : IHistorianDataSource, IAsyncDis
    /// <summary>The tie-cluster limit the crowding re-reads honour — exposed so the factory wiring is testable.</summary>
    internal int MaxPreWindowRows => _maxPreWindowRows;

+    /// <summary>
+    ///     The server raw cap (<c>ServerHistorian:MaxRawValuesPerRead</c>, R08:1.1): the most samples one raw read may
+    ///     return; 0 = none. See <see cref="MaxRawValuesPerRead"/> and <see cref="ReadRawWindowAsync"/>.
+    /// </summary>
+    private readonly int _maxRawValuesPerRead;
+
    /// <summary>A strict gateway's row ceiling, learned from its first refusal.</summary>
    private readonly GatewayRowCeiling _ceiling;
    private readonly GatewayTagPresenceCache _tags;
@@ -96,11 +102,19 @@ public sealed class GatewayHistorianDataSource : IHistorianDataSource, IAsyncDis
    ///     The most rows before a raw window a crowding re-read makes room for (<c>ServerHistorian:MaxTieClusterOverfetch</c>,
    ///     values below 1 count as 1). More ⇒ <see cref="HistoryReadLimitExceededException"/> (<c>BadTooManyOperations</c>).
    /// </param>
+    /// <param name="maxRawValuesPerRead">
+    ///     The server raw cap (<c>ServerHistorian:MaxRawValuesPerRead</c>, R08:1.1): the most samples one
+    ///     <see cref="ReadRawAsync"/> may return — reported as <see cref="MaxRawValuesPerRead"/> (bounded further by a strict
+    ///     gateway's learned ceiling), so the server pages at it. A read asking for more (or for everything) asks the gateway
+    ///     for cap + 1 rows and is refused when the window holds more, never truncated. &lt;= 0 = unbounded (the pre-#736
+    ///     behaviour: an uncapped read is sent as <see cref="int.MaxValue"/>).
+    /// </param>
    public GatewayHistorianDataSource(IHistorianGatewayClient client, ILogger<GatewayHistorianDataSource> logger,
        int maxRawRows = TimeWeightedAggregator.DefaultMaxWindowRows, TimeProvider? timeProvider = null,
-        bool atTimeFromRaw = true, int maxPreWindowRows = DefaultMaxPreWindowRows)
+        bool atTimeFromRaw = true, int maxPreWindowRows = DefaultMaxPreWindowRows, int maxRawValuesPerRead = 0)
    {
        _maxPreWindowRows = Math.Max(1, maxPreWindowRows);
+        _maxRawValuesPerRead = Math.Max(0, maxRawValuesPerRead);
        _atTimeFromRaw = atTimeFromRaw;
        ArgumentNullException.ThrowIfNull(client);
        ArgumentNullException.ThrowIfNull(logger);
@@ -203,6 +217,13 @@ public sealed class GatewayHistorianDataSource : IHistorianDataSource, IAsyncDis
    ///         a cancelled gateway stream evicts its pooled historian session). <c>ReturnBounds</c> is not plumbed to the
    ///         data source on any backend, so bounding values are never synthesised here.
    ///     </para>
+    ///     <para>
+    ///         <b>The server raw cap</b> (R08:1.1, #736). With a cap, a read asking for everything (<c>0</c>) or for more than
+    ///         the cap runs as a capped read of cap + 1 — one more than it may return — so an over-cap window is DETECTED and
+    ///         refused (<see cref="HistoryReadLimitExceededException"/>) rather than answered truncated (the server's paging
+    ///         reads a short answer as the last page) and never sent as <see cref="int.MaxValue"/>. The server itself never asks
+    ///         for more than the cap (it pages at <see cref="MaxRawValuesPerRead"/>); this bounds a caller that bypasses it.
+    ///     </para>
    /// </remarks>
    private async Task<List<HistorianSample>> ReadRawWindowAsync(
        string fullReference, DateTime startUtc, DateTime endUtc, uint maxValuesPerNode,
@@ -210,6 +231,9 @@ public sealed class GatewayHistorianDataSource : IHistorianDataSource, IAsyncDis
    {
        // The gateway seam caps with an int; OPC UA hands us a uint, so clamp to int range.
        var cap = (int)Math.Min(maxValuesPerNode, int.MaxValue);
+        var serverCap = _maxRawValuesPerRead;
+        var probe = serverCap > 0 && (cap == 0 || cap > serverCap);
+        if (probe) cap = (int)Math.Min(int.MaxValue, (long)serverCap + 1);
        if (cap == 0)
        {
            var all = await PassAsync(int.MaxValue).ConfigureAwait(false);
@@ -225,7 +249,7 @@ public sealed class GatewayHistorianDataSource : IHistorianDataSource, IAsyncDis

        var asked = (int)Math.Min(int.MaxValue, (long)cap + RawAggregateReader.PreWindowAllowance);
        var pass = await PassAsync(asked).ConfigureAwait(false);
-        if (pass.Result.Complete) return pass.Result.Samples;
+        if (pass.Result.Complete) return Bounded(pass.Result.Samples);

        // A strict gateway's ceiling already bounded that read: a larger budget would only be refused again. The
        // refusal carries the pre-window rows it saw: the server re-reads the page that many values smaller.
@@ -256,7 +280,7 @@ public sealed class GatewayHistorianDataSource : IHistorianDataSource, IAsyncDis
            }
            if (budget <= pass.Budget) break; // no more room, never retry the same full read
            pass = await PassAsync(budget).ConfigureAwait(false);
-            if (pass.Result.Complete) return pass.Result.Samples;
+            if (pass.Result.Complete) return Bounded(pass.Result.Samples);
            preWindow = Math.Max(preWindow, pass.Result.PreWindowRows);
            if (pass.Budget < budget) break; // bounded by a ceiling learned meanwhile
            if (room >= _maxPreWindowRows) break; // the limit's worth of room did not suffice
@@ -271,6 +295,16 @@ public sealed class GatewayHistorianDataSource : IHistorianDataSource, IAsyncDis
        // Pre-window rows the allowance did not cover are what crowded the read; fewer are not the cause.
        static int Crowding(int preWindowRows) => preWindowRows > RawAggregateReader.PreWindowAllowance ? preWindowRows : 0;

+        // The cap + 1 probe came back with one sample too many: the window holds more than the server raw cap.
+        List<HistorianSample> Bounded(List<HistorianSample> samples)
+        {
+            if (probe && samples.Count > serverCap)
+                throw new HistoryReadLimitExceededException(serverCap,
+                    $"The raw read of '{fullReference}' holds more than ServerHistorian:MaxRawValuesPerRead ({serverCap}) " +
+                    "samples; set NumValuesPerNode at or below it to page, or narrow the window.");
+            return samples;
+        }
+
        // One drained pass; a strict gateway's refusal of the budget is retried once at the ceiling it names.
        Task<((List<HistorianSample> Samples, int PreWindowRows, bool Complete) Result, int Budget)> PassAsync(int budget) =>
            _ceiling.ReadAsync(budget,
@@ -531,13 +565,20 @@ public sealed class GatewayHistorianDataSource : IHistorianDataSource, IAsyncDis
    public bool SupportsReverseRaw => false;

    /// <inheritdoc />
-    // 0 until a strict gateway (AllowStreamingBeyondCeiling=false) has refused a budget and
-    // named its ceiling (GatewayRowCeiling); then that ceiling less the
-    // RawAggregateReader.PreWindowAllowance a capped read adds for AVEVA's boundary row — so a page of this
-    // size asks for exactly the ceiling. Back to 0 when a re-probe finds the gateway streaming again.
-    public int MaxRawValuesPerRead => _ceiling.Learned is var c and > 0
-        ? Math.Max(1, c - RawAggregateReader.PreWindowAllowance)
-        : 0;
+    // The server raw cap (ServerHistorian:MaxRawValuesPerRead; 0 = none), bounded further by a strict gateway's
+    // (AllowStreamingBeyondCeiling=false) learned ceiling once a refusal has named it (GatewayRowCeiling) — that
+    // ceiling less the RawAggregateReader.PreWindowAllowance a capped read adds for AVEVA's boundary row, so a page of
+    // this size asks for exactly the ceiling. The learned part is forgotten when a re-probe finds the gateway streaming
+    // again; the cap stays. 0 only with no cap and no learned ceiling.
+    public int MaxRawValuesPerRead
+    {
+        get
+        {
+            var learned = _ceiling.Learned is var c and > 0 ? Math.Max(1, c - RawAggregateReader.PreWindowAllowance) : 0;
+            var cap = _maxRawValuesPerRead;
+            return cap > 0 && learned > 0 ? Math.Min(cap, learned) : cap > 0 ? cap : learned;
+        }
+    }

    /// <inheritdoc />
    // false: the gateway's ReadEvents streams ascending only. The server never sends it a
@@ -44,7 +44,9 @@ public static class GatewayHistorian
            // AtTime from raw reads + the shared evaluator; false = AVEVA's own interpolation (kill switch).
            atTimeFromRaw: options.GatewayAtTimeFromRaw,
            // A crowding re-read never makes room for more pre-window rows than the tie-cluster limit.
-            maxPreWindowRows: options.MaxTieClusterOverfetch);
+            maxPreWindowRows: options.MaxTieClusterOverfetch,
+            // The server raw cap (R08:1.1): the page limit the server reads at, and the bound on every raw read.
+            maxRawValuesPerRead: options.EffectiveMaxRawValuesPerRead);
    }

    /// <summary>
@@ -66,6 +66,7 @@ public sealed class QuestDbHistorianDataSource : IHistorianDataSource
    private readonly TimeProvider _time;
    private readonly HistorianHealthCounters _health = new();
    private readonly int _maxTimeWeightedRawRows;
+    private readonly int _maxRawValuesPerRead;

    /// <summary>Creates the data source over the provider's shared connection, bootstrapper and tag catalog.</summary>
    /// <param name="conn">Connection helper.</param>
@@ -74,11 +75,19 @@ public sealed class QuestDbHistorianDataSource : IHistorianDataSource
    /// <param name="log">Optional logger.</param>
    /// <param name="timeProvider">Clock for "now" (AtTime beyond the last sample, server timestamps); system by default.</param>
    /// <param name="maxTimeWeightedRawRows">Raw in-window row cap of one time-weighted read (&lt;= 0 = unbounded).</param>
+    /// <param name="maxRawValuesPerRead">
+    ///     The server raw cap (<c>ServerHistorian:MaxRawValuesPerRead</c>, R08:1.1): the most samples one
+    ///     <see cref="ReadRawAsync"/> may return — reported as <see cref="MaxRawValuesPerRead"/>, so the server pages at it.
+    ///     A read asking for more (or for everything) is refused when the window holds more, never truncated.
+    ///     &lt;= 0 = unbounded (the pre-#736 behaviour).
+    /// </param>
    internal QuestDbHistorianDataSource(
        QuestDbConnection conn, QuestDbSchemaBootstrapper bootstrap, QuestDbTagCatalog catalog, ILogger? log = null,
-        TimeProvider? timeProvider = null, int maxTimeWeightedRawRows = TimeWeightedAggregator.DefaultMaxWindowRows)
+        TimeProvider? timeProvider = null, int maxTimeWeightedRawRows = TimeWeightedAggregator.DefaultMaxWindowRows,
+        int maxRawValuesPerRead = 0)
    {
        _maxTimeWeightedRawRows = maxTimeWeightedRawRows;
+        _maxRawValuesPerRead = Math.Max(0, maxRawValuesPerRead);
        _conn = conn ?? throw new ArgumentNullException(nameof(conn));
        _bootstrap = bootstrap ?? throw new ArgumentNullException(nameof(bootstrap));
        _catalog = catalog ?? throw new ArgumentNullException(nameof(catalog));
@@ -93,12 +102,21 @@ public sealed class QuestDbHistorianDataSource : IHistorianDataSource
    // (int.MaxValue); larger values clamp. At most top samples, ContinuationPoint always null: the node
    // manager pages by re-reading from the last returned timestamp inclusive, which the (ts, tag) dedup
    // key makes exact.
+    // The server raw cap (R08:1.1, #736): with a cap, a read asking for everything or for more than the cap reads
+    // cap + 1 rows — one more than it may return — so an over-cap window is DETECTED and refused
+    // (HistoryReadLimitExceededException ⇒ BadTooManyOperations) rather than answered truncated: the server's paging
+    // reads a short answer as the last page, so a silent LIMIT would lose data. The server itself never asks for more
+    // than the cap (it pages at MaxRawValuesPerRead); this bounds a caller that bypasses it.
    /// <inheritdoc />
    public async Task<HistoryReadResult> ReadRawAsync(
        string fullReference, DateTime startUtc, DateTime endUtc, uint maxValuesPerNode, CancellationToken cancellationToken)
    {
        ArgumentNullException.ThrowIfNull(fullReference);
-        var top = maxValuesPerNode == 0 ? int.MaxValue : (int)Math.Min(maxValuesPerNode, int.MaxValue);
+        var cap = _maxRawValuesPerRead;
+        var probe = cap > 0 && (maxValuesPerNode == 0 || maxValuesPerNode > (uint)cap);
+        var top = probe
+            ? (int)Math.Min(int.MaxValue, (long)cap + 1)
+            : maxValuesPerNode == 0 ? int.MaxValue : (int)Math.Min(maxValuesPerNode, int.MaxValue);
        try
        {
            var samples = new List<DataValueSnapshot>();
@@ -129,9 +147,19 @@ public sealed class QuestDbHistorianDataSource : IHistorianDataSource
                }
            }

+            if (probe && samples.Count > cap)
+                throw new HistoryReadLimitExceededException(cap,
+                    $"The raw read of '{fullReference}' holds more than ServerHistorian:MaxRawValuesPerRead ({cap}) samples; " +
+                    "set NumValuesPerNode at or below it to page, or narrow the window.");
+
            RecordSuccess();
            return new HistoryReadResult(samples, ContinuationPoint: null);
        }
+        catch (HistoryReadLimitExceededException)
+        {
+            // A client-request limit (the server raw cap), not a backend fault: not counted as a failure.
+            throw;
+        }
        catch (Exception ex)
        {
            RecordFailure(ex);
@@ -360,9 +388,11 @@ public sealed class QuestDbHistorianDataSource : IHistorianDataSource
    /// <inheritdoc />
    public bool SupportsReverseRaw => true;

-    // 0: a capped raw read is one bounded statement - no backend row ceiling.
+    // The server raw cap (ServerHistorian:MaxRawValuesPerRead; 0 = none): the server pages every raw read at it, so a
+    // client's NumValuesPerNode = 0 is served as pages of at most this many values. QuestDB itself has no row ceiling -
+    // a capped raw read is one bounded statement.
    /// <inheritdoc />
-    public int MaxRawValuesPerRead => 0;
+    public int MaxRawValuesPerRead => _maxRawValuesPerRead;

    // Reverse events reads are served natively (ORDER BY ... DESC).
    /// <inheritdoc />
@@ -35,14 +35,17 @@ public sealed class QuestDbHistorianProvider : IHistorianBackendProvider, IAsync
    /// <summary>Creates the provider over the <c>ServerHistorian:QuestDb</c> options (validated elsewhere).</summary>
    /// <param name="options">The <c>ServerHistorian:QuestDb</c> options.</param>
    /// <param name="maxTimeWeightedRawRows">The shared <c>ServerHistorian:MaxTimeWeightedRawRows</c> cap (&lt;= 0 = unbounded).</param>
+    /// <param name="maxRawValuesPerRead">The shared <c>ServerHistorian:MaxRawValuesPerRead</c> raw cap (&lt;= 0 = unbounded; R08:1.1).</param>
    public QuestDbHistorianProvider(QuestDbHistorianOptions options,
-        int maxTimeWeightedRawRows = TimeWeightedAggregator.DefaultMaxWindowRows)
+        int maxTimeWeightedRawRows = TimeWeightedAggregator.DefaultMaxWindowRows, int maxRawValuesPerRead = 0)
    {
        _options = options ?? throw new ArgumentNullException(nameof(options));
        _maxTimeWeightedRawRows = maxTimeWeightedRawRows;
+        _maxRawValuesPerRead = maxRawValuesPerRead;
    }

    private readonly int _maxTimeWeightedRawRows;
+    private readonly int _maxRawValuesPerRead;

    /// <inheritdoc />
    public string Name => "QuestDb";
@@ -75,7 +78,8 @@ public sealed class QuestDbHistorianProvider : IHistorianBackendProvider, IAsync
    {
        var s = Get(sp);
        return new QuestDbHistorianDataSource(s.Conn, s.Bootstrap, s.Catalog,
-            Loggers(sp).CreateLogger<QuestDbHistorianDataSource>(), maxTimeWeightedRawRows: _maxTimeWeightedRawRows);
+            Loggers(sp).CreateLogger<QuestDbHistorianDataSource>(), maxTimeWeightedRawRows: _maxTimeWeightedRawRows,
+            maxRawValuesPerRead: _maxRawValuesPerRead);
    }

    /// <inheritdoc />
@@ -61,6 +61,7 @@ public sealed class SqlServerHistorianDataSource : IHistorianDataSource

    private readonly HistorianHealthCounters _health = new();
    private readonly int _maxTimeWeightedRawRows;
+    private readonly int _maxRawValuesPerRead;

    /// <summary>Creates the data source over the provider's shared connection, bootstrapper and tag catalog.</summary>
    /// <param name="conn">Connection helper.</param>
@@ -69,11 +70,19 @@ public sealed class SqlServerHistorianDataSource : IHistorianDataSource
    /// <param name="log">Optional logger.</param>
    /// <param name="timeProvider">Clock for "now" (AtTime beyond the last sample, server timestamps); system by default.</param>
    /// <param name="maxTimeWeightedRawRows">Raw in-window row cap of one time-weighted read (&lt;= 0 = unbounded).</param>
+    /// <param name="maxRawValuesPerRead">
+    ///     The server raw cap (<c>ServerHistorian:MaxRawValuesPerRead</c>, R08:1.1): the most samples one
+    ///     <see cref="ReadRawAsync"/> may return — reported as <see cref="MaxRawValuesPerRead"/>, so the server pages at it.
+    ///     A read asking for more (or for everything) is refused when the window holds more, never truncated.
+    ///     &lt;= 0 = unbounded (the pre-#736 behaviour).
+    /// </param>
    internal SqlServerHistorianDataSource(
        SqlHistorianConnection conn, SqlServerSchemaBootstrapper bootstrap, SqlServerTagCatalog catalog, ILogger? log = null,
-        TimeProvider? timeProvider = null, int maxTimeWeightedRawRows = TimeWeightedAggregator.DefaultMaxWindowRows)
+        TimeProvider? timeProvider = null, int maxTimeWeightedRawRows = TimeWeightedAggregator.DefaultMaxWindowRows,
+        int maxRawValuesPerRead = 0)
    {
        _maxTimeWeightedRawRows = maxTimeWeightedRawRows;
+        _maxRawValuesPerRead = Math.Max(0, maxRawValuesPerRead);
        _conn = conn ?? throw new ArgumentNullException(nameof(conn));
        _bootstrap = bootstrap ?? throw new ArgumentNullException(nameof(bootstrap));
        _catalog = catalog ?? throw new ArgumentNullException(nameof(catalog));
@@ -90,13 +99,22 @@ public sealed class SqlServerHistorianDataSource : IHistorianDataSource
    //     <c>0</c> is the node manager's "unbounded" sentinel; values above <see cref="int.MaxValue"/> clamp.
    //     The node manager pages by re-reading from the last returned timestamp inclusive and trimming it; the
    //     <c>(TagId, SourceTimeUtc)</c> primary key rules out tie clusters, so that is exact.
+    //     The server raw cap (R08:1.1, #736): with a cap, a read asking for everything or for more than the cap reads
+    //     cap + 1 rows — one more than it may return — so an over-cap window is DETECTED and refused
+    //     (HistoryReadLimitExceededException ⇒ BadTooManyOperations) rather than answered truncated: the server's paging
+    //     reads a short answer as the last page, so a silent TOP would lose data. The server itself never asks for more than
+    //     the cap (it pages at MaxRawValuesPerRead); this bounds a caller that bypasses it.
    // </remarks>
    /// <inheritdoc />
    public async Task<HistoryReadResult> ReadRawAsync(
        string fullReference, DateTime startUtc, DateTime endUtc, uint maxValuesPerNode, CancellationToken cancellationToken)
    {
        ArgumentNullException.ThrowIfNull(fullReference);
-        var top = maxValuesPerNode == 0 ? int.MaxValue : (int)Math.Min(maxValuesPerNode, int.MaxValue);
+        var cap = _maxRawValuesPerRead;
+        var probe = cap > 0 && (maxValuesPerNode == 0 || maxValuesPerNode > (uint)cap);
+        var top = probe
+            ? (int)Math.Min(int.MaxValue, (long)cap + 1)
+            : maxValuesPerNode == 0 ? int.MaxValue : (int)Math.Min(maxValuesPerNode, int.MaxValue);
        try
        {
            var tagId = await ResolveAsync(fullReference, cancellationToken).ConfigureAwait(false);
@@ -126,9 +144,19 @@ public sealed class SqlServerHistorianDataSource : IHistorianDataSource
                }
            }

+            if (probe && samples.Count > cap)
+                throw new HistoryReadLimitExceededException(cap,
+                    $"The raw read of '{fullReference}' holds more than ServerHistorian:MaxRawValuesPerRead ({cap}) samples; " +
+                    "set NumValuesPerNode at or below it to page, or narrow the window.");
+
            RecordSuccess();
            return new HistoryReadResult(samples, ContinuationPoint: null);
        }
+        catch (HistoryReadLimitExceededException)
+        {
+            // A client-request limit (the server raw cap), not a backend fault: not counted as a failure.
+            throw;
+        }
        catch (Exception ex)
        {
            RecordFailure(ex);
@@ -319,9 +347,13 @@ public sealed class SqlServerHistorianDataSource : IHistorianDataSource
    /// <inheritdoc />
    public bool SupportsReverseRaw => true;

-    // <remarks><c>0</c>: a capped raw read is one bounded statement — no backend row ceiling.</remarks>
+    // <remarks>
+    //     The server raw cap (ServerHistorian:MaxRawValuesPerRead; 0 = none): the server pages every raw read at it, so a
+    //     client's NumValuesPerNode = 0 is served as pages of at most this many values. SQL Server itself has no row
+    //     ceiling — a capped raw read is one bounded statement.
+    // </remarks>
    /// <inheritdoc />
-    public int MaxRawValuesPerRead => 0;
+    public int MaxRawValuesPerRead => _maxRawValuesPerRead;

    // <remarks>Reverse events reads are served natively (<c>ORDER BY … DESC</c>).</remarks>
    /// <inheritdoc />
@@ -31,14 +31,17 @@ public sealed class SqlServerHistorianProvider : IHistorianBackendProvider
    /// <summary>Creates the provider over the <c>ServerHistorian:SqlServer</c> options (validated elsewhere).</summary>
    /// <param name="options">The <c>ServerHistorian:SqlServer</c> options.</param>
    /// <param name="maxTimeWeightedRawRows">The shared <c>ServerHistorian:MaxTimeWeightedRawRows</c> cap (&lt;= 0 = unbounded).</param>
+    /// <param name="maxRawValuesPerRead">The shared <c>ServerHistorian:MaxRawValuesPerRead</c> raw cap (&lt;= 0 = unbounded; R08:1.1).</param>
    public SqlServerHistorianProvider(SqlServerHistorianOptions options,
-        int maxTimeWeightedRawRows = TimeWeightedAggregator.DefaultMaxWindowRows)
+        int maxTimeWeightedRawRows = TimeWeightedAggregator.DefaultMaxWindowRows, int maxRawValuesPerRead = 0)
    {
        _options = options ?? throw new ArgumentNullException(nameof(options));
        _maxTimeWeightedRawRows = maxTimeWeightedRawRows;
+        _maxRawValuesPerRead = maxRawValuesPerRead;
    }

    private readonly int _maxTimeWeightedRawRows;
+    private readonly int _maxRawValuesPerRead;

    /// <inheritdoc />
    public string Name => "SqlServer";
@@ -69,7 +72,8 @@ public sealed class SqlServerHistorianProvider : IHistorianBackendProvider
    {
        var s = Get(sp);
        return new SqlServerHistorianDataSource(s.Conn, s.Bootstrap, s.Catalog,
-            Loggers(sp).CreateLogger<SqlServerHistorianDataSource>(), maxTimeWeightedRawRows: _maxTimeWeightedRawRows);
+            Loggers(sp).CreateLogger<SqlServerHistorianDataSource>(), maxTimeWeightedRawRows: _maxTimeWeightedRawRows,
+            maxRawValuesPerRead: _maxRawValuesPerRead);
    }

    /// <inheritdoc />