On Thu, 28 Mar, 2019, 4:33 PM Steve Atkins, <steve@blighty.com> wrote:
> On Mar 28, 2019, at 8:29 AM, Ron <ronljohnsonjr@gmail.com> wrote: > > On 3/28/19 3:23 AM, Sameer Kumar wrote: > [snip] >> You can write a query with upper function: >> >> select * from emp where upper(ename)=upper('aaa'); > > That's a guaranteed table scan.
Unless you have an index on upper(ename).
Yup, with this or overloading "=", one can create an expression based index and benefit from it.