发布课表投影改为数据库端删除旧数据、每 2,000 条分批写入并及时释放 EF 跟踪对象，避免大规模发布时内存持续增长。

为“空闲教室/预约占用”新增 学期 + 周次 + 星期 + 节次 + 场地 查询索引；新发布课表的该查询已优先走课次明细投影。

src/Jiaowu.Api/Infrastructure/Persistence/AppDbContext.cs

@@ -543,6 +543,14 @@ public sealed class AppDbContext(DbContextOptions<AppDbContext> options)
         builder.Entity<PublishedScheduleOccurrence>(entity =>
         {
             entity.HasIndex(x => new { x.AcademicTermId, x.TeachingTaskId, x.Week });
+            entity.HasIndex(x => new
+            {
+                x.AcademicTermId,
+                x.Week,
+                x.DayOfWeek,
+                x.StartPeriod,
+                x.ClassroomId
+            });
             entity.HasIndex(x => new { x.SchedulePlanId, x.ClassroomId, x.Week, x.DayOfWeek, x.StartPeriod });
             entity.HasIndex(x => new { x.ScheduleEntryId, x.Week }).IsUnique();
             entity.HasOne(x => x.ScheduleEntry).WithMany().HasForeignKey(x => x.ScheduleEntryId).OnDelete(DeleteBehavior.Cascade);

src/Jiaowu.Api/Infrastructure/Persistence/Migrations/MySql/20260809080519_OptimizePublishedTimetableOccurrenceLookup.cs

@@ -0,0 +1,27 @@
+using Microsoft.EntityFrameworkCore.Migrations;
+
+#nullable disable
+
+namespace Jiaowu.Api.Infrastructure.Persistence.Migrations.MySql
+{
+    /// <inheritdoc />
+    public partial class OptimizePublishedTimetableOccurrenceLookup : Migration
+    {
+        /// <inheritdoc />
+        protected override void Up(MigrationBuilder migrationBuilder)
+        {
+            migrationBuilder.CreateIndex(
+                name: "IX_PublishedScheduleOccurrences_AcademicTermId_Week_DayOfWeek_S~",
+                table: "PublishedScheduleOccurrences",
+                columns: new[] { "AcademicTermId", "Week", "DayOfWeek", "StartPeriod", "ClassroomId" });
+        }
+
+        /// <inheritdoc />
+        protected override void Down(MigrationBuilder migrationBuilder)
+        {
+            migrationBuilder.DropIndex(
+                name: "IX_PublishedScheduleOccurrences_AcademicTermId_Week_DayOfWeek_S~",
+                table: "PublishedScheduleOccurrences");
+        }
+    }
+}