From c2fc4e10cd266bd0f5c93b50b9036136769b8210 Mon Sep 17 00:00:00 2001
From: Erik Darling <2136037+erikdarlingdata@users.noreply.github.com>
Date: Tue, 24 Feb 2026 21:40:44 -0500
Subject: [PATCH] Issue #274: Query Store Regressions drill-down + TVF rewrite

Rewrite report.query_store_regressions TVF with bounded baseline (mirror
window instead of unbounded), execution-count weighted averages, multi-metric
detection (duration/CPU/reads >25%), absolute minimum thresholds, and total
impact ranking (additional_duration_ms). Deployed to sql2017-sql2025.

Add double-click drill-down from regressions grid to QueryExecutionHistoryWindow.
Add new grid columns: Total Impact, Base/Recent Exec Counts, Base/Recent Plan Counts.

Fix chart:grid ratio to 3*:2* with MinHeight 300 across all drill-down windows.
Lower sparse data threshold from 10 to 1 so lines always connect with 2+ points.
Fix QueryExecutionHistoryWindow sparse threshold to use total count not per-plan count.
Fix tooltip registration to collect scatters in loop instead of GetPlottables().

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>
---
 .../Controls/QueryPerformanceContent.xaml     | 43 ++++++++++++++++++-
 .../Controls/QueryPerformanceContent.xaml.cs  | 32 ++++++++++++++
 Dashboard/Models/QueryStoreRegressionItem.cs  |  5 +++
 Dashboard/ProcedureHistoryWindow.xaml         |  4 +-
 Dashboard/ProcedureHistoryWindow.xaml.cs      |  2 +-
 Dashboard/QueryExecutionHistoryWindow.xaml    |  4 +-
 Dashboard/QueryExecutionHistoryWindow.xaml.cs | 14 +++---
 Dashboard/QueryStatsHistoryWindow.xaml        |  4 +-
 Dashboard/QueryStatsHistoryWindow.xaml.cs     |  2 +-
 .../DatabaseService.QueryPerformance.cs       | 30 +++++++++----
 10 files changed, 117 insertions(+), 23 deletions(-)

diff --git a/Dashboard/Controls/QueryPerformanceContent.xaml b/Dashboard/Controls/QueryPerformanceContent.xaml
index 46d4d4ea..948c6cde 100644
--- a/Dashboard/Controls/QueryPerformanceContent.xaml
+++ b/Dashboard/Controls/QueryPerformanceContent.xaml
@@ -1417,7 +1417,8 @@
             <DataGrid x:Name="QueryStoreRegressionsDataGrid" AutoGenerateColumns="False" IsReadOnly="True"
                       RowHeight="35" GridLinesVisibility="Horizontal" CanUserResizeColumns="True"
                       ScrollViewer.CanContentScroll="True" ScrollViewer.HorizontalScrollBarVisibility="Auto" ScrollViewer.VerticalScrollBarVisibility="Auto"
-                      RowStyle="{DynamicResource DefaultRowStyle}">
+                      RowStyle="{DynamicResource DefaultRowStyle}"
+                      MouseDoubleClick="QueryStoreRegressionsDataGrid_MouseDoubleClick">
                 <DataGrid.Columns>
                     <DataGridTextColumn Binding="{Binding LastExecutionTime, StringFormat='{}{0:yyyy-MM-dd HH:mm:ss}'}" Width="150">
                         <DataGridTextColumn.Header>
@@ -1451,6 +1452,46 @@
                             </StackPanel>
                         </DataGridTextColumn.Header>
                     </DataGridTextColumn>
+                    <DataGridTextColumn Binding="{Binding AdditionalDurationMs, StringFormat='{}{0:N0}'}" ElementStyle="{StaticResource NumericCell}" Width="110">
+                        <DataGridTextColumn.Header>
+                            <StackPanel Orientation="Horizontal">
+                                <Button Style="{DynamicResource ColumnFilterButtonStyle}" Tag="AdditionalDurationMs" Click="QsRegressionsFilter_Click" Margin="0,0,4,0"/>
+                                <TextBlock Text="Total Impact (ms)" FontWeight="Bold" VerticalAlignment="Center"/>
+                            </StackPanel>
+                        </DataGridTextColumn.Header>
+                    </DataGridTextColumn>
+                    <DataGridTextColumn Binding="{Binding BaselineExecCount, StringFormat='{}{0:N0}'}" ElementStyle="{StaticResource NumericCell}" Width="90">
+                        <DataGridTextColumn.Header>
+                            <StackPanel Orientation="Horizontal">
+                                <Button Style="{DynamicResource ColumnFilterButtonStyle}" Tag="BaselineExecCount" Click="QsRegressionsFilter_Click" Margin="0,0,4,0"/>
+                                <TextBlock Text="Base Execs" FontWeight="Bold" VerticalAlignment="Center"/>
+                            </StackPanel>
+                        </DataGridTextColumn.Header>
+                    </DataGridTextColumn>
+                    <DataGridTextColumn Binding="{Binding RecentExecCount, StringFormat='{}{0:N0}'}" ElementStyle="{StaticResource NumericCell}" Width="90">
+                        <DataGridTextColumn.Header>
+                            <StackPanel Orientation="Horizontal">
+                                <Button Style="{DynamicResource ColumnFilterButtonStyle}" Tag="RecentExecCount" Click="QsRegressionsFilter_Click" Margin="0,0,4,0"/>
+                                <TextBlock Text="Recent Execs" FontWeight="Bold" VerticalAlignment="Center"/>
+                            </StackPanel>
+                        </DataGridTextColumn.Header>
+                    </DataGridTextColumn>
+                    <DataGridTextColumn Binding="{Binding BaselinePlanCount}" ElementStyle="{StaticResource NumericCell}" Width="80">
+                        <DataGridTextColumn.Header>
+                            <StackPanel Orientation="Horizontal">
+                                <Button Style="{DynamicResource ColumnFilterButtonStyle}" Tag="BaselinePlanCount" Click="QsRegressionsFilter_Click" Margin="0,0,4,0"/>
+                                <TextBlock Text="Base Plans" FontWeight="Bold" VerticalAlignment="Center"/>
+                            </StackPanel>
+                        </DataGridTextColumn.Header>
+                    </DataGridTextColumn>
+                    <DataGridTextColumn Binding="{Binding RecentPlanCount}" ElementStyle="{StaticResource NumericCell}" Width="80">
+                        <DataGridTextColumn.Header>
+                            <StackPanel Orientation="Horizontal">
+                                <Button Style="{DynamicResource ColumnFilterButtonStyle}" Tag="RecentPlanCount" Click="QsRegressionsFilter_Click" Margin="0,0,4,0"/>
+                                <TextBlock Text="Recent Plans" FontWeight="Bold" VerticalAlignment="Center"/>
+                            </StackPanel>
+                        </DataGridTextColumn.Header>
+                    </DataGridTextColumn>
                     <DataGridTextColumn Binding="{Binding DurationRegressionPercent, StringFormat='{}{0:N2}%'}" ElementStyle="{StaticResource NumericCell}" Width="110">
                         <DataGridTextColumn.Header>
                             <StackPanel Orientation="Horizontal">
diff --git a/Dashboard/Controls/QueryPerformanceContent.xaml.cs b/Dashboard/Controls/QueryPerformanceContent.xaml.cs
index 584b0069..b792292e 100644
--- a/Dashboard/Controls/QueryPerformanceContent.xaml.cs
+++ b/Dashboard/Controls/QueryPerformanceContent.xaml.cs
@@ -1200,6 +1200,38 @@ private void QueryStoreDataGrid_MouseDoubleClick(object sender, MouseButtonEvent
             }
         }
 
+        private void QueryStoreRegressionsDataGrid_MouseDoubleClick(object sender, MouseButtonEventArgs e)
+        {
+            if (!TabHelpers.IsDoubleClickOnRow((DependencyObject)e.OriginalSource)) return;
+            if (_databaseService == null) return;
+
+            if (QueryStoreRegressionsDataGrid.SelectedItem is QueryStoreRegressionItem item)
+            {
+                if (string.IsNullOrEmpty(item.DatabaseName) || item.QueryId <= 0)
+                {
+                    MessageBox.Show(
+                        "Unable to show history: missing database name or query ID.",
+                        "Information",
+                        MessageBoxButton.OK,
+                        MessageBoxImage.Information
+                    );
+                    return;
+                }
+
+                var historyWindow = new QueryExecutionHistoryWindow(
+                    _databaseService,
+                    item.DatabaseName,
+                    item.QueryId,
+                    "Query Store",
+                    _queryStoreHoursBack,
+                    _queryStoreFromDate,
+                    _queryStoreToDate
+                );
+                historyWindow.Owner = Window.GetWindow(this);
+                historyWindow.ShowDialog();
+            }
+        }
+
         private void ProcStatsDataGrid_MouseDoubleClick(object sender, MouseButtonEventArgs e)
         {
             if (!TabHelpers.IsDoubleClickOnRow((DependencyObject)e.OriginalSource)) return;
diff --git a/Dashboard/Models/QueryStoreRegressionItem.cs b/Dashboard/Models/QueryStoreRegressionItem.cs
index 1a706ba2..be76a2dc 100644
--- a/Dashboard/Models/QueryStoreRegressionItem.cs
+++ b/Dashboard/Models/QueryStoreRegressionItem.cs
@@ -18,6 +18,11 @@ public class QueryStoreRegressionItem
         public decimal BaselineReads { get; set; }
         public decimal RecentReads { get; set; }
         public decimal IoRegressionPercent { get; set; }
+        public decimal AdditionalDurationMs { get; set; }
+        public long BaselineExecCount { get; set; }
+        public long RecentExecCount { get; set; }
+        public int BaselinePlanCount { get; set; }
+        public int RecentPlanCount { get; set; }
         public string Severity { get; set; } = string.Empty;
         public string QueryTextSample { get; set; } = string.Empty;
         public DateTime? LastExecutionTime { get; set; }
diff --git a/Dashboard/ProcedureHistoryWindow.xaml b/Dashboard/ProcedureHistoryWindow.xaml
index 3fcebee0..9bb68bb1 100644
--- a/Dashboard/ProcedureHistoryWindow.xaml
+++ b/Dashboard/ProcedureHistoryWindow.xaml
@@ -31,8 +31,8 @@
     <Grid>
         <Grid.RowDefinitions>
             <RowDefinition Height="Auto"/>
-            <RowDefinition Height="2*" MinHeight="250"/>
-            <RowDefinition Height="3*"/>
+            <RowDefinition Height="3*" MinHeight="300"/>
+            <RowDefinition Height="2*"/>
             <RowDefinition Height="Auto"/>
         </Grid.RowDefinitions>
 
diff --git a/Dashboard/ProcedureHistoryWindow.xaml.cs b/Dashboard/ProcedureHistoryWindow.xaml.cs
index b632280e..8bf6243e 100644
--- a/Dashboard/ProcedureHistoryWindow.xaml.cs
+++ b/Dashboard/ProcedureHistoryWindow.xaml.cs
@@ -191,7 +191,7 @@ private void UpdateChart()
             scatter.Color = color;
 
             // Sparse data: show only markers to avoid misleading interpolated lines
-            if (dates.Length <= 10)
+            if (dates.Length <= 1)
             {
                 scatter.LineWidth = 0;
                 scatter.MarkerSize = 8;
diff --git a/Dashboard/QueryExecutionHistoryWindow.xaml b/Dashboard/QueryExecutionHistoryWindow.xaml
index 27508f29..5a9f410d 100644
--- a/Dashboard/QueryExecutionHistoryWindow.xaml
+++ b/Dashboard/QueryExecutionHistoryWindow.xaml
@@ -31,8 +31,8 @@
     <Grid>
         <Grid.RowDefinitions>
             <RowDefinition Height="Auto"/>
-            <RowDefinition Height="2*" MinHeight="250"/>
-            <RowDefinition Height="3*"/>
+            <RowDefinition Height="3*" MinHeight="300"/>
+            <RowDefinition Height="2*"/>
             <RowDefinition Height="Auto"/>
         </Grid.RowDefinitions>
 
diff --git a/Dashboard/QueryExecutionHistoryWindow.xaml.cs b/Dashboard/QueryExecutionHistoryWindow.xaml.cs
index d5b9f414..06f4fb7c 100644
--- a/Dashboard/QueryExecutionHistoryWindow.xaml.cs
+++ b/Dashboard/QueryExecutionHistoryWindow.xaml.cs
@@ -183,6 +183,7 @@ private void UpdateChart()
             };
 
             int colorIndex = 0;
+            var scatterSeries = new List<(ScottPlot.Plottables.Scatter Scatter, string Label)>();
 
             foreach (var planGroup in planGroups)
             {
@@ -197,10 +198,12 @@ private void UpdateChart()
                 var color = colors[colorIndex % colors.Length];
                 var scatter = HistoryChart.Plot.Add.Scatter(dates, values);
                 scatter.Color = color;
-                scatter.LegendText = $"Plan {planGroup.Key}";
+                var label = $"Plan {planGroup.Key}";
+                scatter.LegendText = label;
 
-                // Sparse data: show only markers to avoid misleading interpolated lines
-                if (dates.Length <= 10)
+                // Sparse data: use total dataset size, not per-plan size, since
+                // data is split across plan groups
+                if (_historyData.Count <= 1)
                 {
                     scatter.LineWidth = 0;
                     scatter.MarkerSize = 8;
@@ -211,6 +214,7 @@ private void UpdateChart()
                     scatter.MarkerSize = 4;
                 }
 
+                scatterSeries.Add((scatter, label));
                 colorIndex++;
             }
 
@@ -228,8 +232,8 @@ private void UpdateChart()
             else
                 _chartHover.Unit = unit;
             _chartHover.Clear();
-            foreach (var p in HistoryChart.Plot.GetPlottables().OfType<ScottPlot.Plottables.Scatter>())
-                _chartHover.Add(p, p.LegendText ?? "");
+            foreach (var (s, l) in scatterSeries)
+                _chartHover.Add(s, l);
 
             // Update legend text
             ChartLegendText.Text = planGroups.Count > 1
diff --git a/Dashboard/QueryStatsHistoryWindow.xaml b/Dashboard/QueryStatsHistoryWindow.xaml
index c71c1026..16847101 100644
--- a/Dashboard/QueryStatsHistoryWindow.xaml
+++ b/Dashboard/QueryStatsHistoryWindow.xaml
@@ -31,8 +31,8 @@
     <Grid>
         <Grid.RowDefinitions>
             <RowDefinition Height="Auto"/>
-            <RowDefinition Height="2*" MinHeight="250"/>
-            <RowDefinition Height="3*"/>
+            <RowDefinition Height="3*" MinHeight="300"/>
+            <RowDefinition Height="2*"/>
             <RowDefinition Height="Auto"/>
         </Grid.RowDefinitions>
 
diff --git a/Dashboard/QueryStatsHistoryWindow.xaml.cs b/Dashboard/QueryStatsHistoryWindow.xaml.cs
index 8ab35744..4e1b0145 100644
--- a/Dashboard/QueryStatsHistoryWindow.xaml.cs
+++ b/Dashboard/QueryStatsHistoryWindow.xaml.cs
@@ -183,7 +183,7 @@ private void UpdateChart()
             scatter.Color = color;
 
             // Sparse data: show only markers to avoid misleading interpolated lines
-            if (dates.Length <= 10)
+            if (dates.Length <= 1)
             {
                 scatter.LineWidth = 0;
                 scatter.MarkerSize = 8;
diff --git a/Dashboard/Services/DatabaseService.QueryPerformance.cs b/Dashboard/Services/DatabaseService.QueryPerformance.cs
index 7ad138df..3a15189e 100644
--- a/Dashboard/Services/DatabaseService.QueryPerformance.cs
+++ b/Dashboard/Services/DatabaseService.QueryPerformance.cs
@@ -1284,9 +1284,12 @@ public async Task<List<QueryStoreRegressionItem>> GetQueryStoreRegressionsAsync(
                     var connection = tc.Connection;
 
                     /*
-                    report.query_store_regressions is now an inline TVF requiring parameters:
-                    - @start_date: divides baseline from recent (baseline = data BEFORE this date)
-                    - @end_date: end of recent period (recent = data between start_date and end_date)
+                    report.query_store_regressions inline TVF:
+                    - Bounded baseline (mirror window before @start_date, same duration as recent)
+                    - Weighted averages (execution-count weighted)
+                    - Multi-metric detection (duration, CPU, or reads >25%)
+                    - Absolute minimums (baseline >= 1ms duration or >= 100 reads)
+                    - Ranked by additional_duration_ms (total extra time = delta * exec count)
                     */
                     string query = @"
         SET TRANSACTION ISOLATION LEVEL READ UNCOMMITTED;
@@ -1303,17 +1306,22 @@ public async Task<List<QueryStoreRegressionItem>> GetQueryStoreRegressionsAsync(
             qsr.baseline_reads,
             qsr.recent_reads,
             qsr.io_regression_percent,
+            qsr.additional_duration_ms,
+            qsr.baseline_exec_count,
+            qsr.recent_exec_count,
+            qsr.baseline_plan_count,
+            qsr.recent_plan_count,
             qsr.severity,
             qsr.query_text_sample,
             qsr.last_execution_time
         FROM report.query_store_regressions(@start_date, @end_date) AS qsr
         ORDER BY
-            qsr.duration_regression_percent DESC;";
+            qsr.additional_duration_ms DESC;";
 
                     using var command = new SqlCommand(query, connection);
                     command.CommandTimeout = 120;
 
-                    /*Calculate the time window - baseline is everything before start_date, recent is start_date to end_date*/
+                    /*Calculate the time window - baseline is mirror window before start_date, recent is start_date to end_date*/
                     DateTime startDate;
                     DateTime endDate;
 
@@ -1337,7 +1345,6 @@ ORDER BY
                     using var reader = await command.ExecuteReaderAsync();
                     while (await reader.ReadAsync())
                     {
-                        /*Use Convert.ToDecimal for robustness - TVF may return bigint or decimal depending on query store aggregations*/
                         items.Add(new QueryStoreRegressionItem
                         {
                             DatabaseName = reader.GetString(0),
@@ -1351,9 +1358,14 @@ ORDER BY
                             BaselineReads = reader.IsDBNull(8) ? 0 : Convert.ToDecimal(reader.GetValue(8), CultureInfo.InvariantCulture),
                             RecentReads = reader.IsDBNull(9) ? 0 : Convert.ToDecimal(reader.GetValue(9), CultureInfo.InvariantCulture),
                             IoRegressionPercent = reader.IsDBNull(10) ? 0 : Convert.ToDecimal(reader.GetValue(10), CultureInfo.InvariantCulture),
-                            Severity = reader.IsDBNull(11) ? string.Empty : reader.GetString(11),
-                            QueryTextSample = reader.IsDBNull(12) ? string.Empty : reader.GetString(12),
-                            LastExecutionTime = reader.IsDBNull(13) ? null : reader.GetDateTime(13)
+                            AdditionalDurationMs = reader.IsDBNull(11) ? 0 : Convert.ToDecimal(reader.GetValue(11), CultureInfo.InvariantCulture),
+                            BaselineExecCount = reader.IsDBNull(12) ? 0 : Convert.ToInt64(reader.GetValue(12)),
+                            RecentExecCount = reader.IsDBNull(13) ? 0 : Convert.ToInt64(reader.GetValue(13)),
+                            BaselinePlanCount = reader.IsDBNull(14) ? 0 : Convert.ToInt32(reader.GetValue(14)),
+                            RecentPlanCount = reader.IsDBNull(15) ? 0 : Convert.ToInt32(reader.GetValue(15)),
+                            Severity = reader.IsDBNull(16) ? string.Empty : reader.GetString(16),
+                            QueryTextSample = reader.IsDBNull(17) ? string.Empty : reader.GetString(17),
+                            LastExecutionTime = reader.IsDBNull(18) ? null : reader.GetDateTime(18)
                         });
                     }