Merge feat/668-modified-values: Part 11 modified-value history (IsReadModified) on SqlServer + QuestDB (#668)

2026-10-11 09:32:13 -04:00
parent 699871040a cfd403710e
commit 062086f9a6
51 changed files with 2173 additions and 195 deletions
@@ -140,6 +140,101 @@ public sealed class QuestDbHistorianDataSource : IHistorianDataSource
        }
    }

+    // ------------------------------------------------------------------------------------------ Modified (Part 11, #668)
+
+    /// <inheritdoc />
+    /// <remarks>
+    ///     Reads <c>{prefix}sample_modified</c>, the append-only trail <see cref="QuestDbHistorianDataUpdater"/> writes
+    ///     BEFORE each change. Windows follow <see cref="ReadRawAsync"/> (bounds rounded to µs); rows are ordered by
+    ///     <c>(ts, modified_id)</c>; <c>maxValues + 1</c> rows are fetched to report
+    ///     <see cref="HistoryModifiedReadResult.HasMore"/> exactly. A row whose <c>status</c> is NULL had no prior value
+    ///     (an insert) and is served <c>null</c> / <c>BadNoData</c>. Because the trail row lands first, a crash between it and
+    ///     the sample write leaves an orphan row describing a change that never applied (documented).
+    /// </remarks>
+    public async Task<HistoryModifiedReadResult> ReadModifiedAsync(
+        string fullReference, DateTime startUtc, DateTime endUtc, uint maxValues, HistoryModifiedCursor? resumeAfter,
+        CancellationToken cancellationToken)
+    {
+        ArgumentNullException.ThrowIfNull(fullReference);
+        var bounded = maxValues > 0 && maxValues < int.MaxValue;
+        try
+        {
+            var values = new List<HistoryModifiedValue>();
+            var hasMore = false;
+            if (await ResolveAsync(fullReference, cancellationToken).ConfigureAwait(false))
+            {
+                var start = QuestDbConnection.Round(startUtc);
+                var end = QuestDbConnection.Round(endUtc);
+                var reverse = start > end;
+                string where;
+                if (start == end) where = "ts = $2 AND ts = $3";
+                else if (!reverse) where = "ts >= $2 AND ts < $3";
+                else where = "ts > $2 AND ts <= $3";
+                var next = 4;
+                if (resumeAfter is not null)
+                {
+                    where += reverse
+                        ? " AND (ts < $4 OR (ts = $4 AND modified_id < $5))"
+                        : " AND (ts > $4 OR (ts = $4 AND modified_id > $5))";
+                    next = 6;
+                }
+                var order = reverse ? "DESC" : "ASC";
+                var (lo, hi) = start <= end ? (start, end) : (end, start);
+
+                await using var conn = await _conn.OpenAsync(cancellationToken).ConfigureAwait(false);
+                await using var cmd = _conn.CreateCommand(conn,
+                    $"SELECT {SampleColumns}, modified_id, modification_ts, update_type, principal FROM {_conn.SampleModifiedTable} " +
+                    $"WHERE tag = $1 AND {where} ORDER BY ts {order}, modified_id {order}" + (bounded ? $" LIMIT ${next}" : ""));
+                QuestDbConnection.BindText(cmd, fullReference);
+                QuestDbConnection.BindTimestamp(cmd, lo);
+                QuestDbConnection.BindTimestamp(cmd, hi);
+                if (resumeAfter is not null)
+                {
+                    QuestDbConnection.BindTimestamp(cmd, resumeAfter.SourceTimeUtc);
+                    QuestDbConnection.BindLong(cmd, resumeAfter.ModifiedId);
+                }
+                if (bounded)
+                    cmd.Parameters.Add(new NpgsqlParameter { NpgsqlDbType = NpgsqlDbType.Integer, Value = (int)maxValues + 1 });
+
+                await using var reader = await cmd.ExecuteReaderAsync(cancellationToken).ConfigureAwait(false);
+                while (await reader.ReadAsync(cancellationToken).ConfigureAwait(false))
+                {
+                    if (bounded && values.Count == maxValues)
+                    {
+                        hasMore = true;
+                        break;
+                    }
+
+                    var sourceTime = QuestDbConnection.ReadUtc(reader, 0);
+                    var modifiedAt = QuestDbConnection.ReadUtc(reader, 8);
+                    DataValueSnapshot prior;
+                    if (reader.IsDBNull(5))
+                    {
+                        prior = new DataValueSnapshot(null, HistorianStatusCodes.BadNoData, sourceTime, modifiedAt);
+                    }
+                    else
+                    {
+                        var s = ReadStored(reader, 0);
+                        prior = new DataValueSnapshot(s.Value.ToObject(), s.Status, s.TimeUtc, ReadServerTime(reader, 6, modifiedAt));
+                    }
+
+                    values.Add(new HistoryModifiedValue(prior, modifiedAt,
+                        (HistoryModificationType)QuestDbConnection.ReadKind(reader, 9),
+                        reader.IsDBNull(10) ? string.Empty : reader.GetString(10),
+                        reader.GetInt64(7)));
+                }
+            }
+
+            RecordSuccess();
+            return new HistoryModifiedReadResult(values, hasMore);
+        }
+        catch (Exception ex)
+        {
+            RecordFailure(ex);
+            throw;
+        }
+    }
+
    // ------------------------------------------------------------------------------------------ AtTime

    /// <inheritdoc />