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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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src/Drivers/ZB.MOM.WW.OtOpcUa.Driver.Historian.QuestDb/QuestDbAggregateQueries.cs
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using System.Globalization;
using ZB.MOM.WW.OtOpcUa.Core.Abstractions;
using ZB.MOM.WW.OtOpcUa.Driver.Historian.Sql.Common;
namespace ZB.MOM.WW.OtOpcUa.Driver.Historian.QuestDb;
/// <summary>
/// Push-down QuestDB SQL for processed (aggregate) reads (spec §3 "Processed", T0 Q8-confirmed forms), one query
/// per <see cref="AggregateFamily"/>, mirroring the SQL Server backend's <c>SqlAggregateQueries</c> family split and
/// column order. Every query takes five positional parameters:
/// <list type="number">
/// <item><c>$1</c> — the (rounded) window start in 100 ns ticks since the Unix epoch
/// (<see cref="BucketPlan.StartUnixTicks"/>, <c>Bigint</c>);</item>
/// <item><c>$2</c> — the bucket width in ticks (<see cref="BucketPlan.IntervalTicks"/>, <c>Bigint</c>);</item>
/// <item><c>$3</c> — the tag (<c>Varchar</c>);</item>
/// <item><c>$4</c>/<c>$5</c> — the forward window <c>[start, end)</c> (<c>TimestampTz</c> via
/// <see cref="QuestDbConnection.BindTimestamp"/>).</item>
/// </list>
/// Each returns one row per <b>non-empty</b> bucket; the caller fills the empty ones.
/// </summary>
/// <remarks>
/// <para>
/// <b>Bucketing.</b> <c>b = (cast(ts AS LONG) * 10 − $1) / $2</c>. <c>cast(ts AS LONG)</c> is µs since 1970, so
/// <c>× 10</c> is ticks since 1970; both it and <c>$1</c> are µs-aligned (R6), so the integer division is
/// start-inclusive / end-exclusive to the tick, exactly like SQL Server's. Every row is at or after the start,
/// so the dividend is never negative (no truncation-toward-zero surprise), and nothing overflows before 9999.
/// <c>SAMPLE BY</c> is deliberately not used: its alignment rules differ from ours.
/// </para>
/// <para>
/// <b>Sample classes (S6).</b> The status is stored as the <b>unsigned</b> 32-bit code in a <c>LONG</c>, so
/// "not Bad" is <c>status &lt; 0x80000000</c> (not T-SQL's sign test). <i>usable</i> = not Bad AND
/// <c>kind &lt;&gt; 0</c> (an Empty sample is an outage marker and counts as Bad whatever its code);
/// <i>good</i> = usable AND <c>status &lt; 0x40000000</c>; <i>bad</i> = not usable; <i>non-numeric</i> = usable
/// String/DateTime. The literals are generated from <see cref="StatusBits"/> and <see cref="HistorianValueKind"/>.
/// </para>
/// <para>Common result columns (ordinals 0–5): <c>b, total_count, usable_count, good_count, bad_count,
/// non_numeric_count</c>. Family columns follow from <see cref="FirstFamilyColumn"/>.</para>
/// </remarks>
internal static class QuestDbAggregateQueries
{
/// <summary>Ordinal of the first family-specific column.</summary>
public const int FirstFamilyColumn = 6;
/// <summary><c>status &lt; SeverityBadBit</c>, as a decimal LONG literal.</summary>
internal static readonly string NotBadLimit = StatusBits.SeverityBadBit.ToString(CultureInfo.InvariantCulture);
/// <summary><c>status &lt; SeverityUncertainBit</c>, as a decimal LONG literal.</summary>
internal static readonly string GoodLimit = StatusBits.SeverityUncertainBit.ToString(CultureInfo.InvariantCulture);
/// <summary>The <c>kind</c> values of String and DateTime: usable but not numeric.</summary>
internal static readonly string NonNumericKinds =
((byte)HistorianValueKind.String).ToString(CultureInfo.InvariantCulture) + ", " +
((byte)HistorianValueKind.DateTime).ToString(CultureInfo.InvariantCulture);
private static readonly string EmptyKind = ((byte)HistorianValueKind.Empty).ToString(CultureInfo.InvariantCulture);
/// <summary>
/// Average / Minimum / Maximum / Total / Count / Range / PercentGood / PercentBad.
/// Family columns: <c>6 avg_value, 7 min_value, 8 max_value, 9 sum_value</c> (DOUBLE, NULL when no usable sample).
/// </summary>
/// <param name="sample">Prefixed sample table name.</param>
/// <returns>The SQL text.</returns>
public static string Simple(string sample) =>
"SELECT b, " + CommonCounts() + ", " +
"avg(CASE WHEN u = 1 THEN num_value END) AS avg_value, " +
"min(CASE WHEN u = 1 THEN num_value END) AS min_value, " +
"max(CASE WHEN u = 1 THEN num_value END) AS max_value, " +
"sum(CASE WHEN u = 1 THEN num_value END) AS sum_value " +
"FROM (" + Classified(sample) + ") GROUP BY b ORDER BY b";
/// <summary>
/// Start / End / Delta: the first and last usable sample of each bucket by <c>ts</c>.
/// Family columns: <c>6..10</c> first sample (<c>kind, num_value, int_value, str_value, ts</c>), <c>11..15</c> last
/// sample (same order). A bucket without a usable sample has NULL <c>ts</c> but <c>kind = 0</c> (BYTE has no NULL),
/// so the reader keys absence on the NULL time.
/// </summary>
/// <param name="sample">Prefixed sample table name.</param>
/// <returns>The SQL text.</returns>
public static string StartEnd(string sample) =>
"WITH s AS (" + Classified(sample) + "), " +
"st AS (SELECT b, " + CommonCounts() + " FROM s GROUP BY b), " +
"f AS (SELECT b, kind, num_value, int_value, str_value, ts, " +
"row_number() OVER (PARTITION BY b ORDER BY ts ASC) AS rf, " +
"row_number() OVER (PARTITION BY b ORDER BY ts DESC) AS rl FROM s WHERE u = 1) " +
"SELECT st.*, " +
"x.kind, x.num_value, x.int_value, x.str_value, x.ts, " +
"y.kind, y.num_value, y.int_value, y.str_value, y.ts " +
"FROM st LEFT JOIN (SELECT * FROM f WHERE rf = 1) x ON x.b = st.b " +
"LEFT JOIN (SELECT * FROM f WHERE rl = 1) y ON y.b = st.b ORDER BY st.b";
/// <summary>
/// MinimumActualTime / MaximumActualTime: the usable sample with the smallest (largest) <c>num_value</c>, ties
/// broken by the earliest <c>ts</c>. Family columns: <c>6 num_value, 7 ts</c> (NULL when the bucket has no usable
/// numeric sample).
/// </summary>
/// <param name="sample">Prefixed sample table name.</param>
/// <param name="maximum">True for MaximumActualTime.</param>
/// <returns>The SQL text.</returns>
public static string ActualTime(string sample, bool maximum) =>
"WITH s AS (" + Classified(sample) + "), " +
"st AS (SELECT b, " + CommonCounts() + " FROM s GROUP BY b), " +
"r AS (SELECT b, num_value, ts, " +
"row_number() OVER (PARTITION BY b ORDER BY num_value " + (maximum ? "DESC" : "ASC") + ", ts ASC) AS rn " +
"FROM s WHERE u = 1 AND num_value IS NOT NULL) " +
"SELECT st.*, r.num_value, r.ts " +
"FROM st LEFT JOIN (SELECT * FROM r WHERE rn = 1) r ON r.b = st.b ORDER BY st.b";
/// <summary>The bucket-index expression (exposed for tests).</summary>
internal const string BucketExpression = "(cast(ts AS LONG) * 10 - $1) / $2";
/// <summary>The classified subquery <c>s</c>: the window's live samples with bucket index and the usable/good flags.</summary>
private static string Classified(string sample) =>
"SELECT " + BucketExpression + " AS b, ts, kind, num_value, int_value, str_value, " +
$"CASE WHEN status < {NotBadLimit} AND kind <> {EmptyKind} THEN 1 ELSE 0 END AS u, " +
$"CASE WHEN status < {GoodLimit} AND kind <> {EmptyKind} THEN 1 ELSE 0 END AS g " +
$"FROM {sample} WHERE tag = $3 AND ts >= $4 AND ts < $5 AND NOT deleted";
/// <summary>The five common count columns (after <c>b</c>).</summary>
private static string CommonCounts() =>
"count() AS total_count, sum(u) AS usable_count, sum(g) AS good_count, count() - sum(u) AS bad_count, " +
$"sum(CASE WHEN u = 1 AND kind IN ({NonNumericKinds}) THEN 1 ELSE 0 END) AS non_numeric_count";
}