⚡️ perf(sync): 优化大表同步分页与批量写入

- 同步分析和预览改为分页扫描差异，避免一次性加载源表和目标表

- 直接导入与源查询同步支持分页读取和分批提交，降低低内存机器 OOM 风险

- 各数据库 ApplyChanges 统一使用参数化批量 INSERT，减少大表同步 SQL 超时

- MySQL 批量写入按行数和参数数量拆分，兼容超宽表场景

- 补充批量插入、分页差异和源查询同步回归测试

internal/sync/source_query_sync.go

@@ -68,7 +68,7 @@ func resolveSinglePKColumn(cols []connection.ColumnDefinition) (string, error) {
 	return pkCols[0], nil
 }
 
-func loadSourceQuerySyncContext(config SyncConfig, sourceDB db.Database, targetDB db.Database, needTargetRows bool, requirePK bool) (sourceQuerySyncContext, error) {
+func loadSourceQuerySyncContext(config SyncConfig, sourceDB db.Database, targetDB db.Database, needSourceRows bool, needTargetRows bool, requirePK bool) (sourceQuerySyncContext, error) {
 	tableName, err := validateSourceQuerySyncConfig(config)
 	if err != nil {
 		return sourceQuerySyncContext{}, err
@@ -83,11 +83,6 @@ func loadSourceQuerySyncContext(config SyncConfig, sourceDB db.Database, targetD
 		return sourceQuerySyncContext{}, fmt.Errorf("目标表 %s 不存在或未读取到字段定义", tableName)
 	}
 
-	sourceRows, _, err := sourceDB.Query(strings.TrimSpace(config.SourceQuery))
-	if err != nil {
-		return sourceQuerySyncContext{}, fmt.Errorf("执行源查询失败: %w", err)
-	}
-
 	ctx := sourceQuerySyncContext{
 		TableName:        tableName,
 		TargetSchema:     targetSchema,
@@ -95,10 +90,18 @@ func loadSourceQuerySyncContext(config SyncConfig, sourceDB db.Database, targetD
 		TargetQueryTable: targetQueryTable,
 		TargetType:       targetType,
 		TargetCols:       targetCols,
-		SourceRows:       sourceRows,
+		SourceRows:       make([]map[string]interface{}, 0),
 		TargetRows:       make([]map[string]interface{}, 0),
 	}
 
+	if needSourceRows {
+		sourceRows, _, err := sourceDB.Query(strings.TrimSpace(config.SourceQuery))
+		if err != nil {
+			return sourceQuerySyncContext{}, fmt.Errorf("执行源查询失败: %w", err)
+		}
+		ctx.SourceRows = sourceRows
+	}
+
 	if requirePK {
 		pkColumn, err := resolveSinglePKColumn(targetCols)
 		if err != nil {
@@ -226,7 +229,40 @@ func (s *SyncEngine) analyzeSourceQuery(config SyncConfig) SyncAnalyzeResult {
 		Table:   tableName,
 		CanSync: false,
 	}
-	ctx, err := loadSourceQuerySyncContext(config, sourceDB, targetDB, true, true)
+	ctx, err := loadSourceQuerySyncContext(config, sourceDB, targetDB, false, false, true)
+	if err != nil {
+		summary.Message = err.Error()
+		result.Tables = append(result.Tables, summary)
+		result.Message = "已完成 1 个目标表的差异分析"
+		s.progress(config.JobID, totalTables, totalTables, tableName, "差异分析完成")
+		return result
+	}
+
+	sourceType := resolveMigrationDBType(config.SourceConfig)
+	handled, counts, scanErr := scanSourceQueryDiffInPages(sourceDB, targetDB, sourceType, ctx.TargetType, strings.TrimSpace(config.SourceQuery), ctx.TargetQueryTable, ctx.TargetCols, ctx.PKColumn, true, nil)
+	if handled {
+		if scanErr != nil {
+			summary.Message = scanErr.Error()
+			result.Tables = append(result.Tables, summary)
+			result.Message = "已完成 1 个目标表的差异分析"
+			s.progress(config.JobID, totalTables, totalTables, tableName, "差异分析完成")
+			return result
+		}
+		summary.CanSync = true
+		summary.PKColumn = ctx.PKColumn
+		summary.Inserts = counts.Inserts
+		summary.Updates = counts.Updates
+		summary.Deletes = counts.Deletes
+		summary.Same = counts.Same
+		summary.TargetTableExists = true
+		summary.Message = "SQL 结果集差异分析完成"
+		result.Tables = append(result.Tables, summary)
+		result.Message = "已完成 1 个目标表的差异分析"
+		s.progress(config.JobID, totalTables, totalTables, tableName, "差异分析完成")
+		return result
+	}
+
+	ctx, err = loadSourceQuerySyncContext(config, sourceDB, targetDB, true, true, true)
 	if err != nil {
 		summary.Message = err.Error()
 		result.Tables = append(result.Tables, summary)
@@ -270,13 +306,83 @@ func (s *SyncEngine) previewSourceQuery(config SyncConfig, limit int) (TableDiff
 	}
 	defer targetDB.Close()
 
-	ctx, err := loadSourceQuerySyncContext(config, sourceDB, targetDB, true, true)
+	ctx, err := loadSourceQuerySyncContext(config, sourceDB, targetDB, false, false, true)
+	if err != nil {
+		return TableDiffPreview{}, err
+	}
+
+	sourceType := resolveMigrationDBType(config.SourceConfig)
+	out := TableDiffPreview{
+		Table:         ctx.TableName,
+		PKColumn:      ctx.PKColumn,
+		ColumnTypes:   make(map[string]string, len(ctx.TargetCols)),
+		SchemaSummary: "SQL 结果集同步预览",
+		Inserts:       make([]PreviewRow, 0, limit),
+		Updates:       make([]PreviewUpdateRow, 0, limit),
+		Deletes:       make([]PreviewRow, 0, limit),
+	}
+	for _, col := range ctx.TargetCols {
+		name := strings.ToLower(strings.TrimSpace(col.Name))
+		typ := strings.TrimSpace(col.Type)
+		if name == "" || typ == "" {
+			continue
+		}
+		out.ColumnTypes[name] = typ
+	}
+
+	handled, _, scanErr := scanSourceQueryDiffInPages(sourceDB, targetDB, sourceType, ctx.TargetType, strings.TrimSpace(config.SourceQuery), ctx.TargetQueryTable, ctx.TargetCols, ctx.PKColumn, true, func(page pagedDiffPage) error {
+		out.TotalInserts += len(page.Inserts)
+		out.TotalUpdates += len(page.Updates)
+		out.TotalDeletes += len(page.Deletes)
+		for _, row := range page.Inserts {
+			if len(out.Inserts) >= limit {
+				break
+			}
+			pk := strings.TrimSpace(fmt.Sprintf("%v", row[ctx.PKColumn]))
+			if pk != "" && pk != "<nil>" {
+				out.Inserts = append(out.Inserts, PreviewRow{PK: pk, Row: row})
+			}
+		}
+		for _, update := range page.Updates {
+			if len(out.Updates) >= limit {
+				break
+			}
+			pk := strings.TrimSpace(fmt.Sprintf("%v", update.UpdateRow.Keys[ctx.PKColumn]))
+			if pk == "" || pk == "<nil>" {
+				continue
+			}
+			out.Updates = append(out.Updates, PreviewUpdateRow{
+				PK:             pk,
+				ChangedColumns: append([]string(nil), update.ChangedColumns...),
+				Source:         update.Source,
+				Target:         update.Target,
+			})
+		}
+		for _, row := range page.Deletes {
+			if len(out.Deletes) >= limit {
+				break
+			}
+			pk := strings.TrimSpace(fmt.Sprintf("%v", row[ctx.PKColumn]))
+			if pk != "" && pk != "<nil>" {
+				out.Deletes = append(out.Deletes, PreviewRow{PK: pk, Row: row})
+			}
+		}
+		return nil
+	})
+	if handled {
+		if scanErr != nil {
+			return TableDiffPreview{}, scanErr
+		}
+		return out, nil
+	}
+
+	ctx, err = loadSourceQuerySyncContext(config, sourceDB, targetDB, true, true, true)
 	if err != nil {
 		return TableDiffPreview{}, err
 	}
 
 	inserts, updates, deletes, _ := diffRowsByPK(ctx.PKColumn, ctx.SourceRows, ctx.TargetRows)
-	out := TableDiffPreview{
+	out = TableDiffPreview{
 		Table:         ctx.TableName,
 		PKColumn:      ctx.PKColumn,
 		ColumnTypes:   make(map[string]string, len(ctx.TargetCols)),
@@ -389,7 +495,7 @@ func (s *SyncEngine) runSourceQuerySync(config SyncConfig) SyncResult {
 
 	needTargetRows := tableMode == "insert_update"
 	requirePK := tableMode == "insert_update"
-	ctx, err := loadSourceQuerySyncContext(config, sourceDB, targetDB, needTargetRows, requirePK)
+	ctx, err := loadSourceQuerySyncContext(config, sourceDB, targetDB, false, false, requirePK)
 	if err != nil {
 		return s.fail(config.JobID, totalTables, result, err.Error())
 	}
@@ -397,6 +503,33 @@ func (s *SyncEngine) runSourceQuerySync(config SyncConfig) SyncResult {
 	inserts := make([]map[string]interface{}, 0)
 	updates := make([]connection.UpdateRow, 0)
 	deletes := make([]map[string]interface{}, 0)
+	applyTableName := ctx.TargetTable
+	switch ctx.TargetType {
+	case "postgres", "kingbase", "highgo", "vastbase", "opengauss", "sqlserver":
+		applyTableName = ctx.TargetQueryTable
+	}
+
+	if handled, counts, err := s.tryApplySourceQueryInPages(config, &result, tableName, sourceDB, targetDB, ctx, opts, tableMode, applyTableName); handled {
+		if err != nil {
+			return s.fail(config.JobID, totalTables, result, "分页同步 SQL 结果集失败: "+err.Error())
+		}
+		result.TablesSynced++
+		result.RowsInserted += counts.Inserts
+		result.RowsUpdated += counts.Updates
+		result.RowsDeleted += counts.Deletes
+		if counts.Inserts == 0 && counts.Updates == 0 && counts.Deletes == 0 {
+			s.appendLog(config.JobID, &result, "info", "SQL 结果集与目标表一致，无需应用变更")
+		} else {
+			s.appendLog(config.JobID, &result, "info", fmt.Sprintf("SQL 结果集分页同步完成：插入=%d 更新=%d 删除=%d", counts.Inserts, counts.Updates, counts.Deletes))
+		}
+		s.progress(config.JobID, totalTables, totalTables, tableName, "同步完成")
+		return result
+	}
+
+	ctx, err = loadSourceQuerySyncContext(config, sourceDB, targetDB, true, needTargetRows, requirePK)
+	if err != nil {
+		return s.fail(config.JobID, totalTables, result, err.Error())
+	}
 	if tableMode == "insert_update" {
 		inserts, updates, deletes, _ = diffRowsByPK(ctx.PKColumn, ctx.SourceRows, ctx.TargetRows)
 		inserts = filterRowsByPKSelection(ctx.PKColumn, inserts, opts.Insert, opts.SelectedInsertPKs)
@@ -431,16 +564,11 @@ func (s *SyncEngine) runSourceQuerySync(config SyncConfig) SyncResult {
 		return result
 	}
 
-	applyTableName := ctx.TargetTable
-	switch ctx.TargetType {
-	case "postgres", "kingbase", "highgo", "vastbase", "opengauss", "sqlserver":
-		applyTableName = ctx.TargetQueryTable
-	}
 	applier, ok := targetDB.(db.BatchApplier)
 	if !ok {
 		return s.fail(config.JobID, totalTables, result, "目标驱动不支持应用数据变更 (ApplyChanges)")
 	}
-	if err := applier.ApplyChanges(applyTableName, changeSet); err != nil {
+	if err := s.applyChangesInBatches(config.JobID, &result, applyTableName, applier, changeSet); err != nil {
 		return s.fail(config.JobID, totalTables, result, "应用 SQL 结果集变更失败: "+err.Error())
 	}