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feat(historian): QuestDB reads and aggregates (pushed down, shared evaluation)

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QuestDbHistorianDataSource serves Raw (LIMIT $n, no continuation, R8), AtTime
(chunked LIMIT 1 neighbour seeks, <=50 times per statement), Events and
Processed (one statement per node, bucket = (cast(ts AS LONG)*10 - start)/interval,
shared BucketPlan/AggregateEvaluator/AtTimeEvaluator). Every sample read filters
NOT deleted; every row goes through StoredSample.FromStored; RC2 long.MinValue
read repair. QuestDbConformanceBackend (seed/read-back) for the conformance suite;
writer/updater factories are T7 placeholders.

Claude-Session: https://claude.ai/code/session_01Ef2ozxS7QPanGT8uoATbTe
This commit is contained in:
Joseph Doherty
2026-10-11 02:13:00 -04:00
parent ecc0f914cc
commit c4b4b2e2bc
4 changed files with 1059 additions and 0 deletions
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tests/Drivers/ZB.MOM.WW.OtOpcUa.Driver.Historian.QuestDb.IntegrationTests/QuestDbConformanceBackend.cs
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using System.Text;
using Npgsql;
using NpgsqlTypes;
using ZB.MOM.WW.OtOpcUa.Core.Abstractions;
using ZB.MOM.WW.OtOpcUa.Driver.Historian.Conformance;
using ZB.MOM.WW.OtOpcUa.Driver.Historian.Sql.Common;
namespace ZB.MOM.WW.OtOpcUa.Driver.Historian.QuestDb.IntegrationTests;
/// <summary>
/// The QuestDB historian as a conformance backend: a fresh unique table prefix per instance (dropped on dispose),
/// seeded by plain multi-row INSERTs (never through the writer or updater) followed by the WAL visibility wait.
/// Storage resolution is 1 µs (10 ticks); <see cref="Round"/> is <see cref="QuestDbConnection.Round"/>, and
/// <see cref="SeedAsync"/> rounds the times it is given the same way before storing them.
/// </summary>
internal sealed class QuestDbConformanceBackend : IConformanceBackend
{
private const int SeedBatchRows = 1000;
private readonly QuestDbFixture _fx;
private readonly string _prefix;
private QuestDbConformanceBackend(QuestDbFixture fx, string prefix, QuestDbHistorianOptions options,
QuestDbConnection conn, QuestDbSchemaBootstrapper boot)
{
_fx = fx;
_prefix = prefix;
Options = options;
Conn = conn;
Boot = boot;
Wal = new QuestDbWalVisibility(conn, options.VisibilityTimeout);
}
/// <summary>The options of this instance's table set.</summary>
public QuestDbHistorianOptions Options { get; }
/// <summary>The connection helper.</summary>
public QuestDbConnection Conn { get; }
/// <summary>The schema bootstrapper (already run).</summary>
public QuestDbSchemaBootstrapper Boot { get; }
/// <summary>The WAL visibility wait.</summary>
public QuestDbWalVisibility Wal { get; }
/// <summary>Creates a backend over a fresh table prefix; skips the calling test when the gate is closed.</summary>
/// <param name="fx">The shared fixture.</param>
/// <returns>The backend.</returns>
public static async Task<IConformanceBackend> CreateAsync(QuestDbFixture fx) => await CreateConcreteAsync(fx);
/// <summary>As <see cref="CreateAsync"/>, typed (for QuestDB-specific tests that need the connection).</summary>
/// <param name="fx">The shared fixture.</param>
/// <returns>The backend.</returns>
public static async Task<QuestDbConformanceBackend> CreateConcreteAsync(QuestDbFixture fx)
{
fx.SkipIfUnavailable();
var prefix = fx.UniquePrefix();
var o = fx.Options(prefix);
var conn = new QuestDbConnection(o);
var boot = new QuestDbSchemaBootstrapper(conn, o);
await boot.EnsureAsync(CancellationToken.None);
return new QuestDbConformanceBackend(fx, prefix, o, conn, boot);
}
/// <inheritdoc/>
public long ResolutionTicks => 10;
/// <inheritdoc/>
public DateTime Round(DateTime t) => QuestDbConnection.Round(t);
/// <summary>A fresh tag catalog (fresh positive cache) over this table set.</summary>
public QuestDbTagCatalog NewCatalog() => new(Conn, Boot, Wal);
/// <inheritdoc/>
public IHistorianDataSource CreateDataSource(TimeProvider? clock = null) =>
new QuestDbHistorianDataSource(Conn, Boot, NewCatalog(), timeProvider: clock);
/// <inheritdoc/>
/// <remarks>TODO(T7): build the T4 <c>QuestDbHistorianValueWriter</c> here once T4 is merged.</remarks>
public IHistorianValueWriter CreateValueWriter(Func<DateTime>? utcNow = null) =>
throw new NotSupportedException("TODO(T7): the QuestDB value writer (T4) is not merged into this branch yet.");
/// <inheritdoc/>
/// <remarks>TODO(T7): build the T6 <c>QuestDbHistorianDataUpdater</c> here once T6 is merged.</remarks>
public IHistorianDataUpdater CreateUpdater() =>
throw new NotSupportedException("TODO(T7): the QuestDB history updater (T6) is not merged into this branch yet.");
/// <inheritdoc/>
/// <remarks>
/// Times are rounded to the microsecond (<see cref="Round"/>) before they are stored; the tag row is registered
/// through the catalog (data type 0, as the SQL Server seed does); every row is live (<c>deleted = false</c>);
/// <c>server_ts</c> = rounded time + 1 s. Waits for WAL visibility before returning.
/// </remarks>
public async Task SeedAsync(string tag, params (DateTime T, HistorianValue V, uint Status)[] samples)
{
await NewCatalog().EnsureAsync(tag, 0, CancellationToken.None);
await InsertRowsAsync(tag, samples.Select(s => (Round(s.T), s.V, s.Status, Deleted: false)).ToArray());
}
/// <summary>
/// Inserts raw rows (the tag must already be registered when reads should find it), including tombstones, then
/// waits for WAL visibility. A tombstone re-inserted at an existing <c>(ts, tag)</c> replaces that row (DEDUP).
/// </summary>
/// <param name="tag">The tag.</param>
/// <param name="rows">Rows: time (already rounded by the caller or not — it is bound through BindTimestamp), value, status, deleted.</param>
public async Task InsertRowsAsync(string tag, (DateTime T, HistorianValue V, uint Status, bool Deleted)[] rows)
{
if (rows.Length == 0) return;
await using (var c = await Conn.OpenAsync(CancellationToken.None))
{
for (var offset = 0; offset < rows.Length; offset += SeedBatchRows)
{
var batch = rows.Skip(offset).Take(SeedBatchRows).ToArray();
var sql = new StringBuilder(
$"INSERT INTO {Conn.SampleTable} (ts, tag, kind, num_value, int_value, str_value, status, deleted, server_ts) VALUES ");
await using var cmd = Conn.CreateCommand(c, "");
var n = 0;
for (var i = 0; i < batch.Length; i++)
{
var (t, v, status, deleted) = batch[i];
var col = SampleColumnMapper.ToColumns(v);
if (i > 0) sql.Append(", ");
sql.Append('(');
for (var j = 0; j < 9; j++) sql.Append(j == 0 ? "" : ", ").Append('$').Append(++n);
sql.Append(')');
QuestDbConnection.BindTimestamp(cmd, t);
QuestDbConnection.BindText(cmd, tag);
QuestDbConnection.BindByte(cmd, col.ValueKind);
cmd.Parameters.Add(new NpgsqlParameter { NpgsqlDbType = NpgsqlDbType.Double, Value = (object?)col.NumValue ?? DBNull.Value });
cmd.Parameters.Add(new NpgsqlParameter { NpgsqlDbType = NpgsqlDbType.Bigint, Value = (object?)col.IntValue ?? DBNull.Value });
QuestDbConnection.BindText(cmd, col.StrValue);
QuestDbConnection.BindLong(cmd, SampleColumnMapper.ToLongStatus(status));
cmd.Parameters.Add(new NpgsqlParameter { NpgsqlDbType = NpgsqlDbType.Boolean, Value = deleted });
QuestDbConnection.BindTimestamp(cmd, Round(t).AddSeconds(1));
}
cmd.CommandText = sql.ToString();
await cmd.ExecuteNonQueryAsync();
}
}
await Wal.WaitAsync(Conn.SampleTable, CancellationToken.None);
}
/// <summary>Runs a statement against this table set (test-only escape hatch for hand-made rows), then waits for WAL visibility of the sample table.</summary>
/// <param name="sql">The statement; parameters are bound positionally by <paramref name="bind"/>.</param>
/// <param name="bind">Binds the parameters.</param>
public async Task ExecuteAsync(string sql, Action<NpgsqlCommand> bind)
{
await using (var c = await Conn.OpenAsync(CancellationToken.None))
{
await using var cmd = Conn.CreateCommand(c, sql);
bind(cmd);
await cmd.ExecuteNonQueryAsync();
}
await Wal.WaitAsync(Conn.SampleTable, CancellationToken.None);
}
/// <inheritdoc/>
public async Task<IReadOnlyList<(DateTime T, HistorianValue V, uint Status)>> ReadBackAsync(string tag)
{
await using var c = await Conn.OpenAsync(CancellationToken.None);
await using var cmd = Conn.CreateCommand(c,
$"SELECT ts, kind, num_value, int_value, str_value, status FROM {Conn.SampleTable} " +
"WHERE tag = $1 AND NOT deleted ORDER BY ts");
QuestDbConnection.BindText(cmd, tag);
var list = new List<(DateTime, HistorianValue, uint)>();
await using var r = await cmd.ExecuteReaderAsync();
while (await r.ReadAsync())
{
var v = QuestDbHistorianDataSource.ToValue(QuestDbConnection.ReadKind(r, 1),
r.IsDBNull(2) ? null : r.GetDouble(2), r.IsDBNull(3) ? null : r.GetInt64(3), r.IsDBNull(4) ? null : r.GetString(4));
// Verbatim: no read-side clamp. A NULL status cannot be written by any code path; it reads as the raw 0 bits.
var status = r.IsDBNull(5) ? 0u : SampleColumnMapper.FromLongStatus(r.GetInt64(5));
list.Add((QuestDbConnection.ReadUtc(r, 0), v, status));
}
return list;
}
/// <inheritdoc/>
public async Task<bool> TagExistsAsync(string tag)
{
await using var c = await Conn.OpenAsync(CancellationToken.None);
await using var cmd = Conn.CreateCommand(c, $"SELECT count() FROM {Conn.TagTable} WHERE name = $1");
QuestDbConnection.BindText(cmd, tag);
return Convert.ToInt64(await cmd.ExecuteScalarAsync()) > 0;
}
/// <inheritdoc/>
public async Task<DriverDataType?> TagDataTypeAsync(string tag)
{
await using var c = await Conn.OpenAsync(CancellationToken.None);
await using var cmd = Conn.CreateCommand(c, $"SELECT data_type FROM {Conn.TagTable} WHERE name = $1 LIMIT 1");
QuestDbConnection.BindText(cmd, tag);
await using var r = await cmd.ExecuteReaderAsync();
return await r.ReadAsync() ? (DriverDataType)QuestDbConnection.ReadKind(r, 0) : null;
}
/// <inheritdoc/>
public async ValueTask DisposeAsync()
{
await Conn.DisposeAsync();
await _fx.DropPrefixAsync(_prefix); // early; the fixture also drops every prefix it handed out
}
}
tests/Drivers/ZB.MOM.WW.OtOpcUa.Driver.Historian.QuestDb.IntegrationTests/ReadTests.cs
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using System.Text;
using Npgsql;
using NpgsqlTypes;
using Shouldly;
using Xunit;
using ZB.MOM.WW.OtOpcUa.Core.Abstractions;
using ZB.MOM.WW.OtOpcUa.Driver.Historian.Conformance;
using ZB.MOM.WW.OtOpcUa.Driver.Historian.Sql.Common;
namespace ZB.MOM.WW.OtOpcUa.Driver.Historian.QuestDb.IntegrationTests;
/// <summary>
/// QuestDB-specific read behaviour (the shared Raw/AtTime/Processed literals run through the conformance suite):
/// tombstones, the pre-1970 / whole-range bucket math, reverse paging at one value per page, QuestDB's LONG NULL
/// sentinel, the kind-decides-the-value rule, AtTime chunking, Events and failure accounting.
/// </summary>
[Collection(QuestDbCollection.Name)]
public sealed class ReadTests(QuestDbFixture fx) : IAsyncLifetime
{
private static readonly CancellationToken Ct = CancellationToken.None;
private const uint Good = ConformanceData.Good;
private const uint Bad = ConformanceData.Bad;
private const uint GoodCalc = 0x00000401u;
private const uint UncertainCalc = 0x40A40401u;
private const uint UncertainInterpolated = 0x40A40402u;
private const uint GoodInterpolated = 0x00000402u;
private const uint NoDataCalc = 0x809B0401u;
private QuestDbConformanceBackend _b = null!;
private static DateTime At(double s) => ConformanceData.At(s);
public async ValueTask InitializeAsync() => _b = await QuestDbConformanceBackend.CreateConcreteAsync(fx);
public async ValueTask DisposeAsync()
{
if (_b is not null) await _b.DisposeAsync();
}
private static double?[] Values(HistoryReadResult r) => r.Samples.Select(s => (double?)s.Value).ToArray();
/// <summary>What T6's DeleteAtTime writes: the same (ts, tag), deleted = true, value columns NULL, status BadNoData.</summary>
private Task TombstoneAsync(string tag, DateTime t) =>
_b.InsertRowsAsync(tag, [(t, HistorianValue.Empty, HistorianStatusCodes.BadNoData, true)]);
[Fact]
public async Task Tombstoned_rows_are_invisible_to_raw_attime_and_processed()
{
await ConformanceData.SeedAAsync(_b); // +0=10, +10=20, +20=Bad 30, +30=40, +40=50
await TombstoneAsync("A", At(10)); // DEDUP replaces the +10 row with a tombstone
(await _b.ReadBackAsync("A")).Count.ShouldBe(4);
var src = _b.CreateDataSource();
var raw = await src.ReadRawAsync("A", At(0), At(100), 0, Ct);
Values(raw).ShouldBe([10d, 30d, 40d, 50d]);
raw.Samples.Select(s => s.StatusCode).ShouldBe([Good, Bad, Good, Good]);
// +10 is no longer an exact hit: previous is +0 = 10 (Good), next is the Bad +20 ⇒ held, Uncertain.
var at = (await src.ReadAtTimeAsync("A", [At(10), At(5)], Ct)).Samples;
at.Select(s => s.Value).ShouldBe([(object?)10d, 10d]);
at.ShouldAllBe(s => s.StatusCode == UncertainInterpolated);
// B0 [0,20) holds only {10}: Good, count 1. A visible tombstone would be a Bad sample ⇒ Uncertain, PercentBad 50.
async Task<DataValueSnapshot> B0(HistoryAggregateType a) =>
(await src.ReadProcessedAsync("A", At(0), At(80), TimeSpan.FromSeconds(20), a, Ct)).Samples[0];
var avg = await B0(HistoryAggregateType.Average);
avg.Value.ShouldBe(10d);
avg.StatusCode.ShouldBe(GoodCalc);
(await B0(HistoryAggregateType.Count)).Value.ShouldBe(1);
(await B0(HistoryAggregateType.PercentBad)).Value.ShouldBe(0d);
(await B0(HistoryAggregateType.End)).Value.ShouldBe(10d);
}
[Fact]
public async Task A_whole_range_processed_read_from_1601_to_9999_with_interval_zero_does_not_overflow()
{
await ConformanceData.SeedAAsync(_b);
var src = _b.CreateDataSource();
var start = new DateTime(1601, 1, 1, 0, 0, 0, DateTimeKind.Utc);
var end = new DateTime(9999, 12, 31, 0, 0, 0, DateTimeKind.Utc);
foreach (var agg in new[] { HistoryAggregateType.Average, HistoryAggregateType.Start, HistoryAggregateType.MaximumActualTime })
{
var s = (await src.ReadProcessedAsync("A", start, end, TimeSpan.Zero, agg, Ct)).Samples.Single();
s.StatusCode.ShouldBe(UncertainCalc, agg.ToString());
}
(await src.ReadProcessedAsync("A", start, end, TimeSpan.Zero, HistoryAggregateType.Average, Ct)).Samples.Single().Value.ShouldBe(30d);
(await src.ReadProcessedAsync("A", start, end, TimeSpan.Zero, HistoryAggregateType.Start, Ct)).Samples.Single().Value.ShouldBe(10d);
var max = (await src.ReadProcessedAsync("A", start, end, TimeSpan.Zero, HistoryAggregateType.MaximumActualTime, Ct)).Samples.Single();
max.Value.ShouldBe(50d);
max.SourceTimestampUtc.ShouldBe(_b.Round(At(40)));
// The extreme DateTime range: MinValue/MaxValue are nudged (never bound as ±infinity, which would match nothing).
(await src.ReadProcessedAsync("A", DateTime.MinValue, DateTime.MaxValue, TimeSpan.Zero, HistoryAggregateType.Total, Ct))
.Samples.Single().Value.ShouldBe(120d);
// A pre-1970 window holds no data and is not an error.
(await src.ReadProcessedAsync("A", start, new DateTime(1969, 1, 1, 0, 0, 0, DateTimeKind.Utc), TimeSpan.FromDays(3650),
HistoryAggregateType.Count, Ct)).Samples.ShouldAllBe(x => x.StatusCode == NoDataCalc);
src.GetHealthSnapshot().TotalFailures.ShouldBe(0);
}
/// <summary>
/// The node manager's reverse paging at <c>NumValuesPerNode = 1</c> (OtOpcUaNodeManager + HistoryPaging): resume at
/// the last timestamp inclusive and trim it; when the trimmed page stalls on that timestamp, point-read it and step
/// one tick down. One tick below a µs-aligned time rounds to the previous µs, so the walk advances.
/// </summary>
[Fact]
public async Task A_reverse_paging_walk_with_one_value_per_page_returns_every_row()
{
await ConformanceData.SeedAAsync(_b);
var src = _b.CreateDataSource();
var end = At(-1);
DateTime start = At(100);
var resumed = false;
var emitted = new List<object?>();
for (var guard = 0; guard < 50; guard++)
{
var page = (await src.ReadRawAsync("A", start, end, 1, Ct)).Samples;
var trimmed = resumed ? page.Where(s => s.SourceTimestampUtc != start).ToList() : page.ToList();
if (page.Count == 0) break;
if (resumed && (trimmed.Count == 0 || trimmed[^1].SourceTimestampUtc == start))
{
// Stalled on the boundary: the tie cluster at `start` is one sample (already emitted) ⇒ step down a tick.
(await src.ReadRawAsync("A", start, start, 2, Ct)).Samples.Count.ShouldBe(1);
if (start.AddTicks(-1) <= end) break;
start = start.AddTicks(-1);
resumed = false;
continue;
}
emitted.AddRange(trimmed.Select(s => s.Value));
start = page[^1].SourceTimestampUtc!.Value;
resumed = true;
}
emitted.ShouldBe([50d, 40d, 30d, 20d, 10d]);
}
[Fact]
public async Task An_int64_of_long_MinValue_is_served_as_long_MinValue_not_zero()
{
// QuestDB stores long.MinValue in a LONG as NULL (its NULL sentinel); num_value keeps -2^63 exactly (RC2).
await _b.SeedAsync("L",
(At(0), HistorianValue.FromInt64(long.MinValue), Good),
(At(1), HistorianValue.FromInt64(long.MinValue + 1), Good));
var src = _b.CreateDataSource();
(await src.ReadRawAsync("L", At(0), At(10), 0, Ct)).Samples.Select(s => s.Value)
.ShouldBe([(object?)long.MinValue, long.MinValue + 1]);
(await src.ReadAtTimeAsync("L", [At(0)], Ct)).Samples.Single().Value.ShouldBe(long.MinValue);
(await src.ReadProcessedAsync("L", At(0), At(10), TimeSpan.Zero, HistoryAggregateType.Start, Ct))
.Samples.Single().Value.ShouldBe(long.MinValue);
}
[Fact]
public async Task The_kind_not_the_populated_column_decides_the_value()
{
// An Int64-kind row whose num_value is NULL (a NaN-free double view lost) still serves its int_value, and a
// Double-kind row carrying a stray int_value still serves num_value.
await _b.SeedAsync("K");
await _b.ExecuteAsync(
$"INSERT INTO {_b.Conn.SampleTable} (ts, tag, kind, num_value, int_value, status, deleted, server_ts) " +
"VALUES ($1, $2, $3, NULL, $4, $5, false, $6), ($7, $2, $8, $9, $10, $5, false, $11)",
cmd =>
{
QuestDbConnection.BindTimestamp(cmd, At(0)); // $1
QuestDbConnection.BindText(cmd, "K"); // $2
QuestDbConnection.BindByte(cmd, (byte)HistorianValueKind.Int64); // $3
QuestDbConnection.BindLong(cmd, 7); // $4
QuestDbConnection.BindLong(cmd, 0); // $5 status Good
QuestDbConnection.BindTimestamp(cmd, At(1)); // $6
QuestDbConnection.BindTimestamp(cmd, At(2)); // $7
QuestDbConnection.BindByte(cmd, (byte)HistorianValueKind.Double); // $8
cmd.Parameters.Add(new NpgsqlParameter { NpgsqlDbType = NpgsqlDbType.Double, Value = 2.5 }); // $9
QuestDbConnection.BindLong(cmd, 99); // $10
QuestDbConnection.BindTimestamp(cmd, At(3)); // $11
});
var s = (await _b.CreateDataSource().ReadRawAsync("K", At(0), At(10), 0, Ct)).Samples;
s.Select(x => x.Value).ShouldBe([(object?)7L, 2.5d]);
}
[Fact]
public async Task AtTime_over_several_statement_chunks_keeps_request_length_and_order()
{
await ConformanceData.SeedAAsync(_b);
// 140 distinct times (3 statements of ≤ 50), requested in descending order, plus a duplicate of the first.
var times = Enumerable.Range(0, 140).Select(i => At((390 - i * 3) / 10.0)).ToList();
times.Add(times[0]);
var s = (await _b.CreateDataSource().ReadAtTimeAsync("A", times, Ct)).Samples;
s.Count.ShouldBe(times.Count);
s.Select(x => x.SourceTimestampUtc).ShouldBe(times.Select(t => (DateTime?)_b.Round(t)));
s[0].Value.ShouldBe(49d); // +39: 40 + 10 × 9/10
s[0].StatusCode.ShouldBe(GoodInterpolated);
s[^1].Value.ShouldBe(49d); // the duplicate
s[100].Value.ShouldBe(19d); // +9: 10 + 10 × 9/10, from the third chunk
s[139].Value.ShouldBeNull(); // -2.7 s: no previous sample
s[139].StatusCode.ShouldBe(0x809B0000u); // BadNoData
}
[Fact]
public async Task Events_are_filtered_by_source_and_window_ascending_and_limited_with_a_continuation()
{
await _b.Boot.EnsureAsync(Ct);
async Task Event(DateTime t, string id, string source, int severity, string? message)
{
await _b.ExecuteAsync(
$"INSERT INTO {_b.Conn.EventTable} (ts, event_id, source, severity, message, received_utc) VALUES ($1, $2, $3, $4, $5, $6)",
cmd =>
{
QuestDbConnection.BindTimestamp(cmd, t);
QuestDbConnection.BindText(cmd, id);
QuestDbConnection.BindText(cmd, source);
cmd.Parameters.Add(new NpgsqlParameter { NpgsqlDbType = NpgsqlDbType.Integer, Value = severity });
QuestDbConnection.BindText(cmd, message);
QuestDbConnection.BindTimestamp(cmd, t.AddSeconds(2));
});
await _b.Wal.WaitAsync(_b.Conn.EventTable, Ct);
}
await Event(At(3), "e3", "src1", 700, "three");
await Event(At(1), "e1", "src1", 70000, "one");
await Event(At(2), "e2", "src2", 500, null);
await Event(At(9), "e9", "src1", 500, "out of window");
var src = _b.CreateDataSource();
var all = await src.ReadEventsAsync(null, At(0), At(5), 0, Ct);
all.Events.Select(e => e.EventId).ShouldBe(["e1", "e2", "e3"]);
all.ContinuationPoint.ShouldBeNull();
all.Events[0].Severity.ShouldBe((ushort)65535);
all.Events[0].EventTimeUtc.ShouldBe(_b.Round(At(1)));
all.Events[0].ReceivedTimeUtc.ShouldBe(_b.Round(At(1)).AddSeconds(2));
all.Events[1].Message.ShouldBeNull();
var one = await src.ReadEventsAsync("src1", At(5), At(0), 1, Ct); // reversed window is swapped
one.Events.Select(e => e.EventId).ShouldBe(["e1"]);
Encoding.UTF8.GetString(one.ContinuationPoint!).ShouldBe(EventContinuation.Encode(_b.Round(At(3)), "e3"));
(await src.ReadEventsAsync("src1", At(0), At(5), 2, Ct)).ContinuationPoint.ShouldBeNull();
(await src.ReadEventsAsync(new string('x', 401), At(0), At(5), 0, Ct)).Events.ShouldBeEmpty();
}
[Fact]
public async Task A_failed_read_is_rethrown_and_recorded_in_health_without_counting_client_errors()
{
// A table set that does not exist, with AutoCreateSchema off: every read that reaches the database fails.
var prefix = fx.UniquePrefix();
var o = fx.Options(prefix, autoCreate: false);
await using var conn = new QuestDbConnection(o);
var boot = new QuestDbSchemaBootstrapper(conn, o);
using var src = new QuestDbHistorianDataSource(conn, boot, new QuestDbTagCatalog(conn, boot, new QuestDbWalVisibility(conn, o.VisibilityTimeout)));
await Should.ThrowAsync<HistorianSchemaMissingException>(() => src.ReadRawAsync("A", At(0), At(100), 0, Ct));
await Should.ThrowAsync<HistorianSchemaMissingException>(() => src.ReadEventsAsync(null, At(0), At(5), 0, Ct));
// Client-request errors are thrown before any I/O and are not backend failures.
await Should.ThrowAsync<HistoryAggregateNotSupportedException>(() =>
src.ReadProcessedAsync("A", At(0), At(5), TimeSpan.Zero, HistoryAggregateType.Interpolative, Ct));
await Should.ThrowAsync<ArgumentOutOfRangeException>(() =>
src.ReadProcessedAsync("A", At(0), At(100), TimeSpan.FromTicks(10), HistoryAggregateType.Count, Ct));
var h = src.GetHealthSnapshot();
h.TotalQueries.ShouldBe(2);
h.TotalFailures.ShouldBe(2);
h.ConsecutiveFailures.ShouldBe(2);
h.LastError.ShouldNotBeNull();
h.LastError.ShouldStartWith(nameof(HistorianSchemaMissingException));
h.ProcessConnectionOpen.ShouldBeFalse();
// The healthy backend's own data source is unaffected (a failure fails only its call).
await ConformanceData.SeedAAsync(_b);
(await _b.CreateDataSource().ReadRawAsync("A", At(0), At(100), 0, Ct)).Samples.Count.ShouldBe(5);
}
}