Set duckdb_api config option for connections

Author: Giorgi

DuckDB.NET.Data/DuckDBConnectionStringBuilder.cs

@@ -19,6 +19,7 @@ public class DuckDBConnectionStringBuilder : DbConnectionStringBuilder
     public const string InMemorySharedConnectionString = "DataSource=:memory:?cache=shared";
 
     private const string DataSourceKey = "DataSource";
+    private const string DuckDBApiConfigKey = "duckdb_api";
 
     static DuckDBConnectionStringBuilder()
     {
@@ -38,6 +39,11 @@ internal static DuckDBConnectionString Parse(string connectionString)
             ConnectionString = connectionString
         };
 
+        if (!builder.ContainsKey(DuckDBApiConfigKey))
+        {
+            builder[DuckDBApiConfigKey] = "DuckDB.NET";
+        }
+
         var dataSource = builder.DataSource;
 
         var configurations = new Dictionary<string, string>();

DuckDB.NET.Test/DuckDBConnectionTests.cs

@@ -536,4 +536,17 @@ void Assert(object sender, StateChangeEventArgs args)
             handlerCalled = true;
         }
     }
+
+    [Fact]
+    public void ConnectionSetsDuckDBApiConfigOption()
+    {
+        using (var connection = new DuckDBConnection(DuckDBConnectionStringBuilder.InMemoryConnectionString))
+        {
+            connection.Open();
+            using var command = connection.CreateCommand();
+            command.CommandText = "SELECT current_setting('duckdb_api');";
+            var value = command.ExecuteScalar();
+            value.Should().Be("DuckDB.NET");
+        }
+    }
 }