use for join by different db getDerivedStructs shouldn't return paginated result encourage to sort according given ids in getDerivedStructs, it will improve processing speed because inner join so getMainStructs will run 2 times and second time will return derivedIds to filter again filterUnusedDerivedStruct is used to relief stress of nested loop filterUnusedDerivedStruct can just simply return true or function below func(derivedStruct J, ids []U) { arrayhelper.Includes(ids, derivedStruct.<fk>) }.

use for join by different db getDerivedStructs shouldn't return paginated result encourage to sort according given ids in getDerivedStructs, it will improve processing speed.

oriPreFix: can use for prefix ori table name (e.x: oriPreFix = "data_baidu" become select `data_baidu`.xx).