Is querying over a view slower than executing SQL directly?

Question

Scenario:

I have 3 tables needing to be joined together, a where clause to limit the result set, and only a few columns from each table being selected. Simple. Howev

Answer 1

In Oracle, the performance is the same. A view is really a named sql statement. But fancier.

When you start nesting views, and joining views with other table or views, things get complicated real quick. If Oracle can't push your filters down the view to the table, it often has to materialize (build a temp table of) parts of the query, and this is when you get the bad performance.