Update's very slow

Hi all,
I translate statements From SQLServer To
Oracle ,
In SQLSERVER :

Update A
set ...
FROM conditions

in Oracle this statement is very slow :

Update A
set ... =
(select ..)
where conditions and Exists (select ...);

Who know an optimization for this ?

Thanks in avance.

The short answer is use an index.

The long answer is: Depends, what's the query plan say?

Yeah, some more information would be helpful towards crafting a better statement.

You will find this to be one of the more painful parts of a conversion from SQLServer to Oracle - Oracle, quite frankly, sucks at multi-table updates, whereas SQLServer handles them very eloquently.

Give us an actual statement (and plan, preferably) and we'll see what we can do for you.

- Chris