Can't connect to MySQL server on '****' (10061 "Unknown error")

GangShen · 2020 年8 月 8 日 11:29

看报错是 tidb-server 之间在等待 schema version 同步的时候报错了

pingcap/tidb/blob/07c6788ef2addca2931aa8de3ccdccc0007c9ea3/domain/domain.go#L543


      
          			logutil.BgLogger().Info("reload schema in loop, schema syncer need restart")
          			// The etcd is responsible for schema synchronization, we should ensure there is at most two different schema version
          			// in the TiDB cluster, to make the data/schema be consistent. If we lost connection/session to etcd, the cluster
          			// will treats this TiDB as a down instance, and etcd will remove the key of `/tidb/ddl/all_schema_versions/tidb-id`.
          			// Say the schema version now is 1, the owner is changing the schema version to 2, it will not wait for this down TiDB syncing the schema,
          			// then continue to change the TiDB schema to version 3. Unfortunately, this down TiDB schema version will still be version 1.
          			// And version 1 is not consistent to version 3. So we need to stop the schema validator to prohibit the DML executing.
          			do.SchemaValidator.Stop()
          			err := do.mustRestartSyncer(ctx)
          			if err != nil {
          				logutil.BgLogger().Error("reload schema in loop, schema syncer restart failed", zap.Error(err))
          				break
          			}
          			// The schema maybe changed, must reload schema then the schema validator can restart.
          			exitLoop := do.mustReload()
          			// domain is cosed.
          			if exitLoop {
          				logutil.BgLogger().Error("domain is closed, exit loadSchemaInLoop")
          				return
          			}
          			do.SchemaValidator.Restart()

TiDB 中 DDL 相关介绍：

可以通过 admin show ddl jobs 命令确认一下，执行 SQL 当时有没有 DDL 语句正在执行。是否可以在无 DDL 执行的情况下，在尝试进行表关联查询，看是否还会出现一样的报错。