any faster select count(*)

[Antony Lai]

Dear All,

I just want to check a piece of data is exist in a table or not. Someone told me this:
1) select count(*) from table1 where index_column = 'xxx'; // is slow

it should be:
2) select count(index_column) from table1 where index_column = 'xxx';

OR
3) select 1 from table1 where index_column = 'xxx';

OR
4) select count(1) from table1 where index_column = 'xxx';


Is it true? Thank you very much!

Best Regards,
Antony