Hi,
Below is my code for the trigger for  duplicate prevention on the account . It works well, but if I have 50k records this impacts scalability and not feasible.
So please any one can help to code in better way.
thanks in advance.
trigger AccountDuplicate on Account (before insert) {
 List<Account> dup = new List<Account>();
 dup = [Select id, Name from Account];
 for(Account a:Trigger.New){
 for(Account a1:dup){
 if(a.Name==a1.Name){
 a.Name.addError('Name already Exist ');
 }
 }
 }   
 }