Server Administration :: Multiple Plans For A Particular SQL

Lately, there has been a handful of intermittent performance issues and it all boiled down to the fact that Oracle happened to choose a "bad" plan to execute them for a just a set of bind variables.

I understand Oracle must be doing it for a good reason but it just worked for us when we ensured a single plan is always used. We did it either by creating indexes or sometimes out of no other choice forcing a particular plan (manual plan).

Now, as a proactive measure, I am interested in identifying if there are more such cases. I managed to find about 23 such cases by using the query below. I am planning to regularly check the report generated by the below query.

Select Sql_Id,Count(*) From
(Select Distinct Sql_Id,Plan_Hash_Value From Dba_Hist_Sqlstat where plan_hash_value <> 0 )
Group By Sql_Id
having count(*) > 1

But before we really start addressing them I wanted to know if it is correct to consider that it is always a bad thing to happen if Oracle chooses multiple plans? I am not saying all such cases are giving problems but we did see that a handful of such problems boiled down to this case.