egg-mysql 迁移 mysql 8.0 charset=utf8mb4 不生效

[uqeq]

在此输入你需要反馈的 Bug 具体信息（Bug in Detail）：

由于业务机房调整，数据库从mysql 5.7 迁移到 mysql 8.0.35，迁移数据库后发现数据库查询出现了中文乱码。
（直接在数据库set names utf8 查询中文返回正常，程序读取乱码）

1. 通过egg-mysql 底层依赖查询，发现依赖的是ali-rds 的底层框架，如果不指定charset则默认为utf8mb4
2. 迁移到mysql 8.0.35 之后，通过debug日志打点，直接通过sql查询程序的连接charset 发生了改变

class AppBootHook {
  constructor(app) {
    this.app = app;
    console.log(`app pid: ${process.pid}`);
    const requestLogger = this.app.getLogger('requestLogger');
    UTILS.setHttpClientLog(app.httpclient, requestLogger);
  }
  // async didLoad() {
  //   // 请将你的插件项目中 app.beforeStart 中的代码置于此处。
  // }
  async willReady() {
    // 请将你的应用项目中 app.beforeStart 中的代码置于此处。
    const charset = await this.app.mysql.query(`
    SELECT 
      @@character_set_database AS database_charset,
      @@character_set_server AS server_charset,
      @@character_set_connection AS connection_charset,
      @@character_set_client AS client_charset,
      @@character_set_results AS results_charset
    `)
    this.app.coreLogger.info(`mysql charset: ${JSON.stringify(charset[0])}`);
    await this.app.mysql.query(`set names utf8mb4`)
    const charset_after = await this.app.mysql.query(`
    SELECT 
      @@character_set_database AS database_charset,
      @@character_set_server AS server_charset,
      @@character_set_connection AS connection_charset,
      @@character_set_client AS client_charset,
      @@character_set_results AS results_charset
    `)
    this.app.coreLogger.info(`mysql charset: ${JSON.stringify(charset_after[0])}`);
  }
}

print

2025-12-03 20:24:55,813 INFO 60 mysql charset: {"database_charset":"latin1","server_charset":"latin1","connection_charset":"latin1","client_charset":"latin1","results_charset":"latin1"}
2025-12-03 20:24:55,816 INFO 60 mysql charset: {"database_charset":"latin1","server_charset":"latin1","connection_charset":"utf8mb4","client_charset":"utf8mb4","results_charset":"utf8mb4"}

3. 即默认的编码从 utf8mb4 变成了latin1编码，通过配置强制设置charset = utf8mb4也不生效

  config.mysql = {
    client: {
      // host
      host: process.env.DB_HOST,
      // 端口号
      port: process.env.DB_PORT,
      // 用户名
      user: process.env.DB_USER,
      // 密码
      password: process.env.DB_USER_PASSWORD,
      // 数据库名
      database: process.env.DB_DATABASE,
      // 连接池大小
      connectionLimit: 20,
      // 字符集
      charset: process.env.DB_CHARSET || 'utf8mb4',
    },
  };

4. 翻越源码得知egg-mysql会创建数据库连接池，如果set names utf8mb4的话，只能对连接池的某一个连接生效，其余的仍然是latin1编码。升级egg-mysql 版本到 5.0.0 问题仍然存在

代码依赖

{
  "name": "unipay-api-manager-server",
  "version": "1.0.0",
  "description": "",
  "private": true,
  "dependencies": {
    "crypto-js": "^3.1.9-1",
    "date-fns": "^2.0.0-alpha.27",
    "date-fns-tz": "^1.0.7",
    "diff-match-patch": "^1.0.4",
    "egg": "^2.25.0",
    "egg-mysql": "^3.0.0",
    "egg-proxy": "^1.0.6",
    "egg-redis": "^2.4.0",
    "egg-scripts": "^2.11.1",
    "egg-validate": "^2.0.1",
    "form-data": "^2.4.0",
    "ioredis": "^4.11.1",
    "jaeger-client": "^3.15.0",
    "lodash": "^4.17.11",
    "md5": "^2.2.1",
    "mysql": "^2.17.1",
    "ncp": "^2.0.0",
    "openid": "^2.0.6",
    "rimraf": "^2.6.3",
    "unidiff": "^1.0.2",
    "unzipper": "^0.10.1",
    "uuid": "^3.3.2"
  },
  "devDependencies": {
    "autod": "^3.1.0",
    "autod-egg": "^1.0.0",
    "cross-env": "^6.0.3",
    "egg-bin": "^4.14.0",
    "egg-ci": "^1.13.1",
    "egg-mock": "^3.24.2",
    "eslint": "^6.0.1",
    "eslint-config-egg": "^7.3.1"
  },
  "engines": {
    "node": ">=8.9.0"
  },
  "scripts": {
    "start": "egg-scripts start --title=unipay-api-manager-server",
    "stop": "egg-scripts stop --title=unipay-api-manager-server",
    "dev": "egg-bin dev",
    "debug": "cross-env EGG_AGENT_DEBUG_PORT=5900 egg-bin debug",
    "test": "egg-bin test",
    "test-lint": "npm run lint -- --fix && npm run test",
    "cov": "egg-bin cov",
    "lint": "eslint .",
    "ci": "npm run lint && npm run cov",
    "autod": "autod"
  },
  "prettier": {
    "printWidth": 150,
    "singleQuote": true,
    "trailingComma": "all",
    "arrowParens": "always",
    "jsxSingleQuote": true,
    "endOfLine": "lf"
  },
  "ci": {
    "version": "8"
  },
  "repository": {
    "type": "git",
    "url": ""
  },
  "author": "zhoucong",
  "license": "MIT"
}

可复现问题的仓库地址（Reproduction Repo）

nope

Node 版本号：

node12

Eggjs 版本号：

2.25.0

相关插件名称与版本号（PlugIn and Name）：

egg-mysql 3.0.0

操作平台与版本号（Platform and Version）：

linux