I get this error:
"ORA-01743: only pure functions can be indexed"
when I try to do this:
create index date_index
on mytable(to_date(date_column, 'MM/DD/RR'))
See, this "date_column" is not of "date" datatype, rather of varchar, and, it's not consistent...meaning sometimes it's '8/6/02' and sometimes it's '8/06/02'...so implicit conversion doesn't work, therefore I have to use the to_date function in my queries.
I need to index this column becasue there's over 20 million rows in this table, but when I try to create a function based index with the above statement, I get the error.