perf: index form data exports

src/modules/workflow/Infrastructure/Persistence/Configurations/FormDataConfiguration.cs

@@ -26,7 +26,7 @@ public class FormDataConfiguration : IEntityTypeConfiguration<FormData>
         builder.Property(e => e.OperatorIP).HasMaxLength(500).HasComment("操作人IP地址");
 
         builder.HasIndex(e => e.InstanceId);
-        builder.HasIndex(e => e.FormDefinitionId);
+        builder.HasIndex(e => new { e.FormDefinitionId, e.CreatedAt, e.Id });
 
         // GIN 索引支持对 DataJson 内容的 @> 包含查询
         builder.HasIndex(e => e.DataJson)

src/modules/workflow/Infrastructure/Persistence/Migrations/20260724030743_AddFormDataExportKeysetIndex.cs

@@ -0,0 +1,36 @@
+using Microsoft.EntityFrameworkCore.Migrations;
+
+#nullable disable
+
+namespace Workflow.Infrastructure.Persistence.Migrations
+{
+    /// <inheritdoc />
+    public partial class AddFormDataExportKeysetIndex : Migration
+    {
+        /// <inheritdoc />
+        protected override void Up(MigrationBuilder migrationBuilder)
+        {
+            migrationBuilder.DropIndex(
+                name: "ix_b_form_data_form_definition_id",
+                table: "b_form_data");
+
+            migrationBuilder.CreateIndex(
+                name: "ix_b_form_data_form_definition_id_created_at_id",
+                table: "b_form_data",
+                columns: new[] { "form_definition_id", "created_at", "id" });
+        }
+
+        /// <inheritdoc />
+        protected override void Down(MigrationBuilder migrationBuilder)
+        {
+            migrationBuilder.DropIndex(
+                name: "ix_b_form_data_form_definition_id_created_at_id",
+                table: "b_form_data");
+
+            migrationBuilder.CreateIndex(
+                name: "ix_b_form_data_form_definition_id",
+                table: "b_form_data",
+                column: "form_definition_id");
+        }
+    }
+}

src/modules/workflow/Infrastructure/Persistence/Migrations/WorkflowDbContextModelSnapshot.cs

@@ -873,12 +873,12 @@ namespace BuildFlow.Workflow.Infrastructure.Persistence.Migrations
                     NpgsqlIndexBuilderExtensions.HasMethod(b.HasIndex("DataJson"), "GIN");
                     NpgsqlIndexBuilderExtensions.HasOperators(b.HasIndex("DataJson"), new[] { "jsonb_path_ops" });
 
-                    b.HasIndex("FormDefinitionId")
-                        .HasDatabaseName("ix_b_form_data_form_definition_id");
-
                     b.HasIndex("InstanceId")
                         .HasDatabaseName("ix_b_form_data_instance_id");
 
+                    b.HasIndex("FormDefinitionId", "CreatedAt", "Id")
+                        .HasDatabaseName("ix_b_form_data_form_definition_id_created_at_id");
+
                     b.ToTable("b_form_data", (string)null);
                 });
 

tests/BuildFlow.Workflow.Tests/Performance/FormDataExportIndexTests.cs

@@ -0,0 +1,30 @@
+using FluentAssertions;
+using Microsoft.EntityFrameworkCore;
+using Workflow.Domain.Entities;
+using Xunit;
+
+namespace BuildFlow.Workflow.Tests.Performance;
+
+/// <summary>表单数据导出 keyset 查询的 EF 索引模型测试。</summary>
+public class FormDataExportIndexTests
+{
+    [Fact]
+    public void FormDataShouldHaveExportKeysetCompositeIndex()
+    {
+        var options = new DbContextOptionsBuilder<WorkflowDbContext>()
+            .UseInMemoryDatabase($"form-data-export-index-{Guid.NewGuid():N}")
+            .Options;
+        using var db = new WorkflowDbContext(options);
+        var entity = db.Model.FindEntityType(typeof(FormData));
+
+        entity.Should().NotBeNull();
+        entity!.GetIndexes().Should().Contain(index => index.Properties
+            .Select(property => property.Name)
+            .SequenceEqual(new[]
+            {
+                nameof(FormData.FormDefinitionId),
+                nameof(FormData.CreatedAt),
+                nameof(FormData.Id),
+            }));
+    }
+}