Per-database exclusions for collectors — Dashboard side (#887)

Dashboard/ExcludedDatabasesDialog.xaml

@@ -0,0 +1,49 @@
+<Window x:Class="PerformanceMonitorDashboard.ExcludedDatabasesDialog"
+        xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
+        xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
+        Title="Excluded Databases"
+        Height="500" Width="500"
+        WindowStartupLocation="CenterOwner"
+        ResizeMode="CanResizeWithGrip"
+        Background="{DynamicResource BackgroundBrush}">
+    <Grid Margin="16">
+        <Grid.RowDefinitions>
+            <RowDefinition Height="Auto"/>
+            <RowDefinition Height="Auto"/>
+            <RowDefinition Height="*"/>
+            <RowDefinition Height="Auto"/>
+            <RowDefinition Height="Auto"/>
+        </Grid.RowDefinitions>
+
+        <TextBlock Grid.Row="0" x:Name="HeaderText" FontWeight="Bold" FontSize="14"
+                   Foreground="{DynamicResource ForegroundBrush}" Margin="0,0,0,8"/>
+
+        <TextBlock Grid.Row="1" TextWrapping="Wrap" FontSize="11"
+                   Foreground="{DynamicResource ForegroundMutedBrush}" Margin="0,0,0,12"
+                   Text="Databases marked here are skipped by per-database collectors (query_store, file_io_stats, etc.) on this server. System databases (master/tempdb/model/msdb) are always excluded."/>
+
+        <Border Grid.Row="2" BorderBrush="{DynamicResource BorderBrush}" BorderThickness="1" CornerRadius="4">
+            <ScrollViewer VerticalScrollBarVisibility="Auto" Padding="8">
+                <ItemsControl x:Name="DatabasesItemsControl">
+                    <ItemsControl.ItemTemplate>
+                        <DataTemplate>
+                            <CheckBox Content="{Binding DisplayName}"
+                                      IsChecked="{Binding IsExcluded, Mode=TwoWay}"
+                                      IsEnabled="{Binding IsEnabled}"
+                                      Foreground="{Binding ForegroundBrush}"
+                                      Margin="2,3"/>
+                        </DataTemplate>
+                    </ItemsControl.ItemTemplate>
+                </ItemsControl>
+            </ScrollViewer>
+        </Border>
+
+        <TextBlock Grid.Row="3" x:Name="StatusText" FontSize="10" FontStyle="Italic"
+                   Foreground="{DynamicResource ForegroundMutedBrush}" Margin="0,8,0,0"/>
+
+        <StackPanel Grid.Row="4" Orientation="Horizontal" HorizontalAlignment="Right" Margin="0,12,0,0">
+            <Button Content="Save" Width="80" Height="28" Margin="0,0,8,0" Click="Save_Click"/>
+            <Button Content="Cancel" Width="80" Height="28" Click="Cancel_Click" IsCancel="True"/>
+        </StackPanel>
+    </Grid>
+</Window>

Dashboard/ExcludedDatabasesDialog.xaml.cs

@@ -0,0 +1,150 @@
+/*
+ * Copyright (c) 2026 Erik Darling, Darling Data LLC
+ *
+ * This file is part of the SQL Server Performance Monitor.
+ *
+ * Licensed under the MIT License. See LICENSE file in the project root for full license information.
+ */
+
+using System;
+using System.Collections.Generic;
+using System.Collections.ObjectModel;
+using System.ComponentModel;
+using System.Linq;
+using System.Windows;
+using System.Windows.Media;
+using PerformanceMonitorDashboard.Models;
+using PerformanceMonitorDashboard.Services;
+
+namespace PerformanceMonitorDashboard
+{
+    public partial class ExcludedDatabasesDialog : Window
+    {
+        private readonly ServerManager _serverManager;
+        private readonly ServerConnection _server;
+        private ObservableCollection<DatabaseExclusionItem> _items = new();
+
+        public bool ExclusionsModified { get; private set; }
+
+        public ExcludedDatabasesDialog(ServerManager serverManager, ServerConnection server)
+        {
+            InitializeComponent();
+            _serverManager = serverManager;
+            _server = server;
+            HeaderText.Text = $"Excluded Databases — {server.DisplayNameWithIntent}";
+            Loaded += async (_, _) => await LoadAsync();
+        }
+
+        private async System.Threading.Tasks.Task LoadAsync()
+        {
+            StatusText.Text = "Loading databases…";
+            DatabasesItemsControl.ItemsSource = null;
+
+            try
+            {
+                var liveDatabases = await _serverManager.GetUserDatabasesAsync(_server);
+                var existingExclusions = await _serverManager.GetCollectorDatabaseExclusionsAsync(_server);
+
+                var liveSet = new HashSet<string>(liveDatabases, StringComparer.OrdinalIgnoreCase);
+
+                _items = new ObservableCollection<DatabaseExclusionItem>();
+
+                /* Live databases: sortable, checkable */
+                foreach (var name in liveDatabases.OrderBy(n => n, StringComparer.OrdinalIgnoreCase))
+                {
+                    _items.Add(new DatabaseExclusionItem
+                    {
+                        Name = name,
+                        DisplayName = name,
+                        IsExcluded = existingExclusions.Contains(name, StringComparer.OrdinalIgnoreCase),
+                        IsEnabled = true,
+                        IsStale = false
+                    });
+                }
+
+                /* Stale entries: in exclusion list but not present on the server. Show greyed, disabled, pre-checked. */
+                foreach (var name in existingExclusions
+                             .Where(n => !liveSet.Contains(n))
+                             .OrderBy(n => n, StringComparer.OrdinalIgnoreCase))
+                {
+                    _items.Add(new DatabaseExclusionItem
+                    {
+                        Name = name,
+                        DisplayName = $"{name}  (missing)",
+                        IsExcluded = true,
+                        IsEnabled = false,
+                        IsStale = true
+                    });
+                }
+
+                DatabasesItemsControl.ItemsSource = _items;
+                StatusText.Text = $"{liveDatabases.Count} database(s) on this server, {existingExclusions.Count} currently excluded.";
+            }
+            catch (Exception ex)
+            {
+                StatusText.Text = $"Failed to load: {ex.Message}";
+                MessageBox.Show(this,
+                    $"Could not read database list from '{_server.DisplayNameWithIntent}':\n\n{ex.Message}",
+                    "Load Failed",
+                    MessageBoxButton.OK,
+                    MessageBoxImage.Error);
+            }
+        }
+
+        private async void Save_Click(object sender, RoutedEventArgs e)
+        {
+            /* Collect every checked item (live + stale). Stale ones can't be unchecked, so they stay if they were excluded. */
+            var checkedNames = _items
+                .Where(i => i.IsExcluded)
+                .Select(i => i.Name)
+                .ToList();
+
+            Cursor = System.Windows.Input.Cursors.Wait;
+            try
+            {
+                await _serverManager.SaveCollectorDatabaseExclusionsAsync(_server, checkedNames);
+                ExclusionsModified = true;
+                DialogResult = true;
+            }
+            catch (Exception ex)
+            {
+                MessageBox.Show(this,
+                    $"Failed to save exclusions on '{_server.DisplayNameWithIntent}':\n\n{ex.Message}",
+                    "Save Failed",
+                    MessageBoxButton.OK,
+                    MessageBoxImage.Error);
+            }
+            finally
+            {
+                Cursor = null;
+            }
+        }
+
+        private void Cancel_Click(object sender, RoutedEventArgs e)
+        {
+            DialogResult = false;
+        }
+    }
+
+    public class DatabaseExclusionItem : INotifyPropertyChanged
+    {
+        public string Name { get; set; } = "";
+        public string DisplayName { get; set; } = "";
+        private bool _isExcluded;
+        public bool IsExcluded
+        {
+            get => _isExcluded;
+            set { _isExcluded = value; OnPropertyChanged(nameof(IsExcluded)); }
+        }
+        public bool IsEnabled { get; set; } = true;
+        public bool IsStale { get; set; }
+
+        public Brush ForegroundBrush => IsStale
+            ? (Brush)Application.Current.FindResource("ForegroundMutedBrush")
+            : (Brush)Application.Current.FindResource("ForegroundBrush");
+
+        public event PropertyChangedEventHandler? PropertyChanged;
+        private void OnPropertyChanged(string propertyName)
+            => PropertyChanged?.Invoke(this, new PropertyChangedEventArgs(propertyName));
+    }
+}

Dashboard/ManageServersWindow.xaml

@@ -2,7 +2,7 @@
         xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
         xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
         Title="Manage Servers"
-        Height="450" Width="780"
+        Height="450" Width="960"
         WindowStartupLocation="CenterOwner"
         ResizeMode="CanResizeWithGrip"
         Background="{DynamicResource BackgroundBrush}">
@@ -12,6 +12,7 @@
             <MenuItem Header="Edit..." Click="EditServer_Click"/>
             <MenuItem Header="Toggle Favorite" Click="ToggleFavorite_Click"/>
             <MenuItem Header="Check Server Version" Click="CheckForUpdates_Click"/>
+            <MenuItem Header="Excluded Databases" Click="ExcludedDatabases_Click"/>
             <MenuItem Header="Purge Now" Click="PurgeNow_Click"/>
             <MenuItem Header="Remove" Click="RemoveServer_Click"
                       Foreground="{DynamicResource ErrorBrush}"/>
@@ -98,6 +99,7 @@
                 <Button Content="Edit..." Width="80" Height="30" Margin="0,0,8,0" Click="EditServer_Click"/>
                 <Button x:Name="ToggleFavoriteButton" Content="Toggle Favorite" Width="110" Height="30" Margin="0,0,8,0" Click="ToggleFavorite_Click"/>
                 <Button x:Name="CheckUpdatesButton" Content="Check Server Version" Width="140" Height="30" Margin="0,0,8,0" Click="CheckForUpdates_Click"/>
+                <Button Content="Excluded Databases" Width="140" Height="30" Margin="0,0,8,0" Click="ExcludedDatabases_Click"/>
                 <Button Content="Purge Now" Width="100" Height="30" Margin="0,0,8,0" Click="PurgeNow_Click"/>
                 <Button Content="Remove" Width="80" Height="30" Margin="0,0,8,0" Click="RemoveServer_Click"
                         Foreground="{DynamicResource ErrorBrush}"/>

Dashboard/ManageServersWindow.xaml.cs

@@ -297,6 +297,25 @@ string Normalize(string v)
             }
         }
 
+        private void ExcludedDatabases_Click(object sender, RoutedEventArgs e)
+        {
+            if (ServersDataGrid.SelectedItem is not ServerConnection server)
+            {
+                MessageBox.Show(
+                    "Please select a server to configure excluded databases.",
+                    "No Server Selected",
+                    MessageBoxButton.OK,
+                    MessageBoxImage.Information);
+                return;
+            }
+
+            var dialog = new ExcludedDatabasesDialog(_serverManager, server) { Owner = this };
+            if (dialog.ShowDialog() == true && dialog.ExclusionsModified)
+            {
+                ServersModified = true;
+            }
+        }
+
         private async void PurgeNow_Click(object sender, RoutedEventArgs e)
         {
             if (ServersDataGrid.SelectedItem is not ServerConnection server)

Dashboard/Services/ServerManager.cs

@@ -284,6 +284,115 @@ FROM config.collection_log AS cl
             return result;
         }
 
+        /// <summary>
+        /// Returns user database names (excluding system DBs and PerformanceMonitor) on the target server,
+        /// for use in the Excluded Databases dialog.
+        /// </summary>
+        public async Task<List<string>> GetUserDatabasesAsync(ServerConnection server)
+        {
+            var connectionString = server.GetConnectionString(_credentialService);
+            var builder = new SqlConnectionStringBuilder(connectionString)
+            {
+                InitialCatalog = "master",
+                ConnectTimeout = 10
+            };
+
+            using var connection = new SqlConnection(builder.ConnectionString);
+            await connection.OpenAsync();
+
+            using var cmd = new SqlCommand(@"
+SELECT d.name
+FROM sys.databases AS d
+WHERE d.database_id > 4
+AND   d.state_desc = N'ONLINE'
+AND   d.name <> N'PerformanceMonitor'
+AND   d.database_id < 32761 /*exclude contained AG system databases*/
+ORDER BY d.name;", connection);
+            cmd.CommandTimeout = 30;
+
+            var names = new List<string>();
+            using var reader = await cmd.ExecuteReaderAsync();
+            while (await reader.ReadAsync())
+            {
+                names.Add(reader.GetString(0));
+            }
+            return names;
+        }
+
+        /// <summary>
+        /// Returns the current per-database exclusion list from config.collector_database_exclusions on the target.
+        /// </summary>
+        public async Task<List<string>> GetCollectorDatabaseExclusionsAsync(ServerConnection server)
+        {
+            var connectionString = server.GetConnectionString(_credentialService);
+            var builder = new SqlConnectionStringBuilder(connectionString)
+            {
+                InitialCatalog = "PerformanceMonitor",
+                ConnectTimeout = 10
+            };
+
+            using var connection = new SqlConnection(builder.ConnectionString);
+            await connection.OpenAsync();
+
+            using var cmd = new SqlCommand(@"
+SELECT e.database_name
+FROM config.collector_database_exclusions AS e
+ORDER BY e.database_name;", connection);
+            cmd.CommandTimeout = 30;
+
+            var names = new List<string>();
+            using var reader = await cmd.ExecuteReaderAsync();
+            while (await reader.ReadAsync())
+            {
+                names.Add(reader.GetString(0));
+            }
+            return names;
+        }
+
+        /// <summary>
+        /// Replaces the contents of config.collector_database_exclusions with the supplied list, transactionally.
+        /// </summary>
+        public async Task SaveCollectorDatabaseExclusionsAsync(ServerConnection server, IEnumerable<string> databaseNames)
+        {
+            var connectionString = server.GetConnectionString(_credentialService);
+            var builder = new SqlConnectionStringBuilder(connectionString)
+            {
+                InitialCatalog = "PerformanceMonitor",
+                ConnectTimeout = 10
+            };
+
+            using var connection = new SqlConnection(builder.ConnectionString);
+            await connection.OpenAsync();
+
+            using var transaction = connection.BeginTransaction();
+            try
+            {
+                using (var deleteCmd = new SqlCommand("DELETE FROM config.collector_database_exclusions;", connection, transaction))
+                {
+                    deleteCmd.CommandTimeout = 30;
+                    await deleteCmd.ExecuteNonQueryAsync();
+                }
+
+                foreach (var name in databaseNames.Distinct(StringComparer.OrdinalIgnoreCase))
+                {
+                    using var insertCmd = new SqlCommand(
+                        "INSERT INTO config.collector_database_exclusions (database_name) VALUES (@name);",
+                        connection, transaction);
+                    insertCmd.CommandTimeout = 30;
+                    insertCmd.Parameters.Add(new SqlParameter("@name", System.Data.SqlDbType.NVarChar, 128) { Value = name });
+                    await insertCmd.ExecuteNonQueryAsync();
+                }
+
+                transaction.Commit();
+                Logger.Info($"Saved collector database exclusions on '{server.DisplayName}'");
+            }
+            catch
+            {
+                transaction.Rollback();
+                throw;
+            }
+        }
+
         public void UpdateLastConnected(string id)
         {
             lock (_serversLock)