Fix OpenTelemetry: db.name reports the configured database, not the database sent with the request

ClickHouse.Driver.Tests/ActivitySourceHelperTests.cs

@@ -1,4 +1,7 @@
+using System.Collections.Generic;
 using System.Diagnostics;
+using System.Linq;
+using System.Threading.Tasks;
 using ClickHouse.Driver.Diagnostic;
 
 namespace ClickHouse.Driver.Tests;
@@ -66,4 +69,83 @@ public void SetQuery_AttachesTruncatedSql_WhenEnabled()
         ClassicAssert.That(tagValue, Is.EqualTo("SELEC"));
         activity.Stop();
     }
+
+    [TestCase("", null, "")]
+    [TestCase("system", null, "system")]
+    [TestCase("", "system", "system")]
+    [TestCase("system", "default", "default")]
+    [TestCase("system", "", "")]
+    public async Task ExecuteScalarAsync_ConfiguredAndQueryOptionsDatabase_SetsDbNameToDatabaseSentWithRequest(
+        string configuredDatabase, string queryDatabase, string expectedDbName)
+    {
+        var settings = TestUtilities.GetTestClickHouseClientSettings();
+        settings.Database = configuredDatabase;
+        using var queryClient = new ClickHouseClient(settings);
+
+        var spans = new List<Activity>();
+        using var listener = ListenToDriverSpans(spans);
+
+        await queryClient.ExecuteScalarAsync("SELECT 1", options: new QueryOptions { Database = queryDatabase });
+
+        Assert.That(spans.Single().GetTagItem("db.name"), Is.EqualTo(expectedDbName));
+    }
+
+    [Test]
+    public async Task InsertBinaryAsync_WithInsertOptionsDatabase_SetsDbNameToInsertDatabaseOnEverySpan()
+    {
+        var table = CreateTableName();
+        await client.ExecuteNonQueryAsync($"CREATE TABLE {table} (x UInt32) ENGINE = Memory");
+        var bareTable = TestUtilities.BareTableName(table);
+
+        var spans = new List<Activity>();
+        using var listener = ListenToDriverSpans(spans);
+
+        await client.InsertBinaryAsync(
+            bareTable,
+            ["x"],
+            [[1u]],
+            new InsertOptions { Database = TestUtilities.TestDatabase });
+
+        Assert.That(
+            spans.Select(s => (s.OperationName, s.GetTagItem("db.name"))),
+            Is.EqualTo(new[]
+            {
+                ("PostSqlQueryAsync", (object)TestUtilities.TestDatabase),
+                ("PostStreamAsync", TestUtilities.TestDatabase),
+            }));
+    }
+
+    [Test]
+    public async Task ExecuteScalarAsync_AfterChangeDatabase_SetsDbNameToSelectedDatabase()
+    {
+        using var conn = client.CreateConnection();
+        await conn.OpenAsync();
+        conn.ChangeDatabase("system");
+        using var command = conn.CreateCommand("SELECT currentDatabase()");
+
+        var spans = new List<Activity>();
+        using var listener = ListenToDriverSpans(spans);
+
+        var serverDatabase = await command.ExecuteScalarAsync();
+
+        Assert.That(serverDatabase, Is.EqualTo("system"));
+        Assert.That(spans.Single().GetTagItem("db.name"), Is.EqualTo("system"));
+    }
+
+    private static ActivityListener ListenToDriverSpans(List<Activity> spans)
+    {
+        var listener = new ActivityListener
+        {
+            ShouldListenTo = s => s.Name == ClickHouseDiagnosticsOptions.ActivitySourceName,
+            SampleUsingParentId = (ref ActivityCreationOptions<string> _) => ActivitySamplingResult.AllDataAndRecorded,
+            Sample = (ref ActivityCreationOptions<ActivityContext> _) => ActivitySamplingResult.AllDataAndRecorded,
+            ActivityStopped = a =>
+            {
+                lock (spans)
+                    spans.Add(a);
+            },
+        };
+        ActivitySource.AddActivityListener(listener);
+        return listener;
+    }
 }

ClickHouse.Driver/ClickHouseClient.cs

@@ -298,10 +298,10 @@ internal async Task<QueryResult> PostSqlQueryAsync(
         bool rawBody = false,
         CancellationToken cancellationToken = default)
     {
-        using var activity = this.StartActivity("PostSqlQueryAsync");
-
         var uriBuilder = CreateUriBuilder(queryOverride: options);
 
+        using var activity = this.StartActivity("PostSqlQueryAsync", uriBuilder.Database);
+
         var logger = GetLogger(ClickHouseLogCategories.Command);
         var isDebugLoggingEnabled = logger?.IsEnabled(LogLevel.Debug) ?? false;
         Stopwatch stopwatch = null;
@@ -931,11 +931,11 @@ private Task<HttpResponseMessage> PostStreamAsync(string sql, Func<Stream, Cance
 
     private async Task<HttpResponseMessage> PostStreamAsync(string sql, HttpContent content, string contentEncoding, QueryOptions queryOptions, CancellationToken token)
     {
-        using var activity = this.StartActivity("PostStreamAsync");
-        activity.SetQuery(sql);
-
         var builder = CreateUriBuilder(sql, queryOptions);
 
+        using var activity = this.StartActivity("PostStreamAsync", builder.Database);
+        activity.SetQuery(sql);
+
         using var postMessage = CreatePostStreamRequest(builder, queryOptions);
         // rawBody: this method returns the HttpResponseMessage itself — PostStreamAsync and
         // InsertRawStreamAsync are public — so its body belongs to the caller, exactly like a raw result,

ClickHouse.Driver/Diagnostic/ActivitySourceHelper.cs

@@ -26,7 +26,11 @@ internal static class ActivitySourceHelper
 
     internal static ActivitySource ActivitySource { get; } = CreateActivitySource();
 
-    internal static Activity StartActivity(this ClickHouseClient client, string name)
+    /// <summary>
+    /// Starts a client activity. <paramref name="database"/> is the database sent with the request, reported as
+    /// <c>db.name</c>; when it is <c>null</c>, the client's configured database is reported.
+    /// </summary>
+    internal static Activity StartActivity(this ClickHouseClient client, string name, string database = null)
     {
         if (client is null) throw new ArgumentNullException(nameof(client));
         if (string.IsNullOrEmpty(name)) throw new ArgumentNullException(nameof(name));
@@ -38,7 +42,7 @@ internal static Activity StartActivity(this ClickHouseClient client, string name
             activity.SetTag(TagThreadId, Environment.CurrentManagedThreadId.ToString(CultureInfo.InvariantCulture));
             activity.SetTag(TagDbSystem, "clickhouse");
             activity.SetTag(TagDbConnectionString, client.RedactedConnectionString);
-            activity.SetTag(TagDbName, client.Settings.Database);
+            activity.SetTag(TagDbName, database ?? client.Settings.Database);
             activity.SetTag(TagUser, client.Settings.Username);
             activity.SetTag(TagService, $"{client.ServerUri.Host}:{client.ServerUri.Port}{client.ServerUri.AbsolutePath}");
         }

changelog.d/685-otel-db-name.fixes.md

@@ -0,0 +1,4 @@
+* Fixed the OpenTelemetry `db.name` span tag reporting the client's configured database when a query is
+  sent to a different one ([#685](https://github.com/ClickHouse/clickhouse-cs/issues/685)). The tag now
+  reports the database sent with the request: `QueryOptions.Database` / `InsertOptions.Database` when
+  set, or the database selected with `ClickHouseConnection.ChangeDatabase` for `ClickHouseCommand`.

docs/http.mdx

@@ -2371,7 +2371,7 @@ Each span includes standard OpenTelemetry database attributes plus ClickHouse-sp
 | Attribute | Description |
 |-----------|-------------|
 | `db.system` | Always `"clickhouse"` |
-| `db.name` | Database name |
+| `db.name` | Database sent with the request: `QueryOptions.Database` / `InsertOptions.Database` when set (for `ClickHouseCommand`, the database selected with `ClickHouseConnection.ChangeDatabase`), otherwise the client's `Database` setting. Empty when neither is set |
 | `db.user` | Username |
 | `db.statement` | SQL query (if enabled) |
 | `db.clickhouse.read_rows` | Rows read by the query |