Regular Expression

You cannot put non-deterministic functions into virtual columns or function-based index.  Regular expressions have always been sensitive to National Language Support (NLS) settings because what is a character is different in different languages.  However, from Oracle 12.2. regular expressions are considered to be non-deterministic because Oracle has fixed bug 20804063.

Background 

A developer came to me with the following query, complaining it was slow.

#eeeeee; border: 0px solid #000000; font-family: courier new; font-size: 100%; overflow: auto; padding-left: 4px; padding-right: 4px; width: 95%;">SELECT …
FROM   …
AND    LOWER(REGEXP_REPLACE(ASCIISTR(my_column), '[^a-zA-Z0-9]')) ='2732018'