课表查询中最明显的性能优化。

将混合考场查询从“加载整个学期的考场、座位、教师、班级后在内存筛选”，改为在数据库中按班级、教师或教室直接筛选。
改为窄字段投影，避免创建大量 EF 实体和关系对象。
添加查询标签，便于后续在 MySQL 慢查询和链路追踪中定位。
保留现有 HybridCache/可选 Redis 缓存体系，无需新增依赖或数据库迁移。
增加教室、无关教室、监考教师三种回归场景。

src/Jiaowu.Api/Infrastructure/Timetables/TimetableDataService.cs

@@ -356,72 +356,49 @@ public sealed class TimetableDataService(AppDbContext db)
             MapToEntryDto(x, slotLookup)));
 
         // ── Mixed-room sessions (ExamRoomAssignment) ──
-        // Load all mixed rooms for this term into memory, then filter
+        // Start from room/session links so the resource predicate stays in SQL.
-        var allMixedRooms = await db.ExamRooms.AsNoTracking()
+        // Loading every room, seat and roster for the term made a single
-            .Where(room =>
+        // timetable request scale with the entire exam plan.
-                room.ExamPlan!.AcademicTermId == academicTermId &&
+        var mixedQuery = db.ExamRoomSessions.AsNoTracking()
-                room.ExamPlan.Status == ExamPlanStatus.Published)
+            .Where(link =>
-            .Include(room => room.ExamPlan)
+                link.ExamRoom!.ExamPlan!.AcademicTermId == academicTermId &&
-            .Include(room => room.Classroom)
+                link.ExamRoom.ExamPlan.Status == ExamPlanStatus.Published);
-                .ThenInclude(c => c!.Building)
+        mixedQuery = ApplyMixedResourceFilter(
-                    .ThenInclude(b => b!.Campus)
+            mixedQuery, resourceType, resourceId, studentId);
-            .Include(room => room.Invigilators)
+
-                .ThenInclude(i => i.Teacher)
+        var mixedSessions = await mixedQuery
-            .Include(room => room.SessionLinks)
+            .TagWith("Timetable.LoadMixedExamEntries")
-                .ThenInclude(link => link.ExamSession)
-                    .ThenInclude(s => s!.TeachingTask)
-                        .ThenInclude(t => t!.Course)
-            .Include(room => room.SessionLinks)
-                .ThenInclude(link => link.ExamSession)
-                    .ThenInclude(s => s!.TeachingTask)
-                        .ThenInclude(t => t!.Teachers)
-                            .ThenInclude(tt => tt.Teacher)
-            .Include(room => room.SessionLinks)
-                .ThenInclude(link => link.ExamSession)
-                    .ThenInclude(s => s!.TeachingTask)
-                        .ThenInclude(t => t!.Classes)
-                            .ThenInclude(tc => tc.AdministrativeClass)
-            .Include(room => room.Seats)
             .AsSplitQuery()
-            .ToListAsync(cancellationToken);
+            .OrderBy(link => link.ExamRoom!.ExamDate)
-
+            .ThenBy(link => link.ExamRoom!.StartPeriod)
-        foreach (var room in allMixedRooms)
+            .ThenBy(link => link.ExamSession!.TeachingTask!.Course!.Code)
-        {
+            .Select(link => new ExamSessionProjection(
-            foreach (var link in room.SessionLinks)
+                link.ExamRoomId,
-            {
+                link.ExamSession!.TeachingTaskId,
-                var session = link.ExamSession;
+                link.ExamSession.TeachingTask!.TaskNumber,
-                if (session == null || session.TeachingTask == null) continue;
+                link.ExamSession.TeachingTask.Name,
-
+                link.ExamSession.TeachingTask.Course!.Code,
-                // Apply resource filter in memory
+                link.ExamSession.TeachingTask.Course.Name,
-                if (!MatchesMixedResource(
+                link.ExamSession.TeachingTask.Teachers
-                        room, session, resourceType, resourceId, studentId))
-                    continue;
-
-                result.Add(MapToEntryDto(new ExamSessionProjection(
-                    room.Id,
-                    session.TeachingTaskId,
-                    session.TeachingTask.TaskNumber,
-                    session.TeachingTask.Name,
-                    session.TeachingTask.Course!.Code,
-                    session.TeachingTask.Course.Name,
-                    session.TeachingTask.Teachers
                     .OrderByDescending(t => t.IsPrimary)
                     .Select(t => t.Teacher!.Name).ToList(),
-                    session.TeachingTask.Classes
+                link.ExamSession.TeachingTask.Classes
                     .Select(c => c.AdministrativeClass!.Name).ToList(),
-                    room.Classroom!.Name,
+                link.ExamRoom!.Classroom!.Name,
-                    room.Classroom.Building!.Name,
+                link.ExamRoom.Classroom.Building!.Name,
-                    room.Classroom.Building.Campus!.Name,
+                link.ExamRoom.Classroom.Building.Campus!.Name,
-                    room.ExamDate,
+                link.ExamRoom.ExamDate,
-                    room.StartPeriod,
+                link.ExamRoom.StartPeriod,
-                    room.PeriodCount,
+                link.ExamRoom.PeriodCount,
-                    room.ExamPlan!.Name,
+                link.ExamRoom.ExamPlan!.Name,
-                    room.Invigilators
+                link.ExamRoom.Invigilators
                     .Select(i => i.Teacher!.Name).ToList(),
                 null,
-                    room.UpdatedAt), slotLookup));
+                link.ExamRoom.UpdatedAt))
-            }
+            .ToListAsync(cancellationToken);
-        }
+
+        result.AddRange(mixedSessions.Select(x =>
+            MapToEntryDto(x, slotLookup)));
 
         return result;
     }
@@ -535,9 +512,8 @@ public sealed class TimetableDataService(AppDbContext db)
         return date.AddDays(1 - dayOfWeek);
     }
 
-    private static bool MatchesMixedResource(
+    private static IQueryable<ExamRoomSession> ApplyMixedResourceFilter(
-        ExamRoomAssignment room,
+        IQueryable<ExamRoomSession> source,
-        ExamSession session,
         TimetableResourceType resourceType,
         Guid resourceId,
         Guid? studentId)
@@ -545,20 +521,28 @@ public sealed class TimetableDataService(AppDbContext db)
         switch (resourceType)
         {
             case TimetableResourceType.Classroom:
-                return room.ClassroomId == resourceId;
+                return source.Where(link =>
+                    link.ExamRoom!.ClassroomId == resourceId);
             case TimetableResourceType.Teacher:
-                return room.Invigilators.Any(i => i.TeacherId == resourceId) ||
+                return source.Where(link =>
-                       session.TeachingTask!.Teachers.Any(
+                    link.ExamRoom!.Invigilators.Any(i =>
-                           t => t.TeacherId == resourceId);
+                        i.TeacherId == resourceId) ||
+                    link.ExamSession!.TeachingTask!.Teachers.Any(t =>
+                        t.TeacherId == resourceId));
             case TimetableResourceType.Class:
                 if (studentId.HasValue)
-                    return session.TeachingTask!.Classes.Any(c =>
+                {
+                    return source.Where(link =>
+                        link.ExamSession!.TeachingTask!.Classes.Any(c =>
                             c.AdministrativeClassId == resourceId) ||
-                           room.Seats.Any(s => s.StudentId == studentId.Value);
+                        link.ExamRoom!.Seats.Any(s =>
-                return session.TeachingTask!.Classes.Any(c =>
+                            s.StudentId == studentId.Value));
-                    c.AdministrativeClassId == resourceId);
+                }
+                return source.Where(link =>
+                    link.ExamSession!.TeachingTask!.Classes.Any(c =>
+                        c.AdministrativeClassId == resourceId));
             default:
-                return true;
+                return source;
         }
     }
 

tests/Jiaowu.Api.Tests/ExamArrangementServiceTests.cs

@@ -1,6 +1,7 @@
 using Jiaowu.Api.Domain.Academic;
 using Jiaowu.Api.Infrastructure.Exams;
 using Jiaowu.Api.Infrastructure.Persistence;
+using Jiaowu.Api.Infrastructure.Timetables;
 using Microsoft.Data.Sqlite;
 using Microsoft.EntityFrameworkCore;
 
@@ -55,6 +56,48 @@ public sealed class ExamArrangementServiceTests
         Assert.Contains("1个教学班场次处理完成", result.Message);
         Assert.Contains("1名监考教师", result.Message);
         Assert.Contains("程序设计", result.Message);
+
+        plan = await db.ExamPlans.SingleAsync(x => x.Id == plan.Id);
+        plan.Status = ExamPlanStatus.Published;
+        await db.SaveChangesAsync();
+        db.ChangeTracker.Clear();
+
+        var timetableService = new TimetableDataService(db);
+        var classroomTimetable = await timetableService.BuildAsync(
+            TimetableResourceType.Classroom,
+            seed.LargeClassroom.Id,
+            seed.Term.Id,
+            null,
+            false,
+            null,
+            null,
+            CancellationToken.None);
+        var unrelatedClassroomTimetable = await timetableService.BuildAsync(
+            TimetableResourceType.Classroom,
+            seed.SmallClassroom.Id,
+            seed.Term.Id,
+            null,
+            false,
+            null,
+            null,
+            CancellationToken.None);
+        var invigilatorTimetable = await timetableService.BuildAsync(
+            TimetableResourceType.Teacher,
+            room.Invigilators.Single().TeacherId,
+            seed.Term.Id,
+            null,
+            false,
+            null,
+            null,
+            CancellationToken.None);
+
+        Assert.Equal(
+            "程序设计",
+            Assert.Single(classroomTimetable!.ExamEntries).CourseName);
+        Assert.Empty(unrelatedClassroomTimetable!.ExamEntries);
+        Assert.Contains(
+            "监考：监考教师",
+            Assert.Single(invigilatorTimetable!.ExamEntries).TeacherNames);
     }
 
     [Fact]