fix: MySQL DDL+DML同批EXPLAIN预检bug + Redis集群MOVED重定向 + 清晰错误提示

MySQL修复:
- 批次含DDL时跳过整个EXPLAIN预检(避免CREATE TABLE未执行时INSERT的EXPLAIN失败)
- 纯DML批次仍正常做EXPLAIN预检

Redis集群修复:
- 单节点客户端遇到MOVED时自动映射外部IP+端口重试
- 重试失败给出清晰提示(Docker端口未暴露)
- 新增 isClusterInstance/parseMovedTarget 辅助函数

测试验证通过:
- MySQL 5条DDL+DML ✅ (建表+INSERT+UPDATE+加索引)
- MySQL 纯DML+EXPLAIN预检 ✅
- MySQL dba(logan)执行 ✅
- Redis单机 SET写入 ✅
- Redis集群 ⚠️ Docker内部端口未暴露(基础设施限制)

backend/internal/handler/ticket.go

@@ -14,6 +14,7 @@ import (
 	"sql-platform/internal/model"
 
 	"github.com/gin-gonic/gin"
+	"github.com/redis/go-redis/v9"
 )
 
 // SqlExecItem records the execution result of a single SQL statement
@@ -571,6 +572,33 @@ func ExecuteTicket(c *gin.Context) {
 				}
 				execStart := time.Now()
 				result, err := client.Do(ctx, args...).Result()
+				// Cluster MOVED redirect: retry on the correct node with external IP mapping
+				if err != nil && isClusterInstance(&instance) {
+					errStr := err.Error()
+					if moved := parseMovedTarget(errStr); moved != "" {
+						// Map internal IP to external host: replace host part, keep port
+						if idx := strings.LastIndex(moved, ":"); idx >= 0 {
+							port := moved[idx+1:]
+							externalAddr := instance.Host + ":" + port
+							password := instance.Password
+							if strings.HasPrefix(password, "enc:") {
+								if dec, e := decryptPassword(strings.TrimPrefix(password, "enc:")); e == nil {
+									password = dec
+								}
+							}
+							targetClient := redis.NewClient(&redis.Options{
+								Addr:     externalAddr,
+								Username: instance.Username,
+								Password: password,
+							})
+							defer targetClient.Close()
+							result, err = targetClient.Do(ctx, args...).Result()
+							if err != nil {
+								err = fmt.Errorf("集群节点重定向失败(MOVED→%s): %w — 集群节点端口(%s)可能未暴露给外部，需检查Docker端口映射", moved, err, port)
+							}
+						}
+					}
+				}
 				stmtMs := time.Since(execStart).Milliseconds()
 				execRes := SqlExecResult{
 					Status:    "success",
@@ -659,10 +687,26 @@ func ExecuteTicket(c *gin.Context) {
 			execTimeout := getSettingInt("executor_timeout", 300)
 			ctx, cancel := context.WithTimeout(context.Background(), time.Duration(execTimeout)*time.Second)
 			defer cancel()
-			// Dry-run: EXPLAIN pre-check (skip DDL statements)
+			// Dry-run: EXPLAIN pre-check
 			if getSetting("executor_dry_run", "true") == "true" {
 				ddlPrefixes := []string{"CREATE", "ALTER", "DROP", "TRUNCATE", "RENAME"}
 				statements := splitSQL(ticket.SQLContent)
+				// If batch contains ANY DDL, skip EXPLAIN precheck entirely —
+				// DDL changes the schema so subsequent DML can't be EXPLAINed beforehand
+				hasDDL := false
+				for _, stmt := range statements {
+					upper := strings.ToUpper(strings.TrimSpace(stmt))
+					for _, prefix := range ddlPrefixes {
+						if strings.HasPrefix(upper, prefix) {
+							hasDDL = true
+							break
+						}
+					}
+					if hasDDL {
+						break
+					}
+				}
+				if !hasDDL {
 					for _, stmt := range statements {
 						stmt = strings.TrimSpace(stmt)
 						if stmt == "" {
@@ -672,17 +716,6 @@ func ExecuteTicket(c *gin.Context) {
 						if strings.HasPrefix(upperStmt, "EXPLAIN") {
 							continue
 						}
-					// Skip DDL — EXPLAIN does not work on DDL statements
-					isDDL := false
-					for _, prefix := range ddlPrefixes {
-						if strings.HasPrefix(upperStmt, prefix) {
-							isDDL = true
-							break
-						}
-					}
-					if isDDL {
-						continue
-					}
 						rows, err := db.QueryContext(ctx, "EXPLAIN "+stmt)
 						if err != nil {
 							execErr = fmt.Sprintf("预检查失败(EXPLAIN): %v", err)
@@ -690,6 +723,7 @@ func ExecuteTicket(c *gin.Context) {
 						}
 						rows.Close()
 					}
+				}
 				if execErr != "" {
 					failStatus := "failed"
 					ticket.Status = &failStatus
@@ -1026,3 +1060,22 @@ func getApplicantName(userID int) string {
 	}
 	return ""
 }
+
+// isClusterInstance checks if a Redis instance is configured as cluster mode
+func isClusterInstance(instance *model.Instance) bool {
+	return instance.ClusterMode != nil && *instance.ClusterMode
+}
+
+// parseMovedTarget extracts the target address from a MOVED response
+// Input: "MOVED 8480 172.19.0.4:9002" → Output: "172.19.0.4:9002"
+func parseMovedTarget(errMsg string) string {
+	// MOVED <slot> <host>:<port>
+	if !strings.HasPrefix(errMsg, "MOVED ") {
+		return ""
+	}
+	parts := strings.SplitN(errMsg, " ", 3)
+	if len(parts) == 3 {
+		return parts[2]
+	}
+	return ""
+}