Guidelines for adding non-unique indices to a standard table

When adding non-unique indices, use a naming convention that differs from the convention.

The naming convention is tablename_i<1+n>. Using your own naming convention prevents your indices from accidentally being dropped during upgrades. The following considerations are also recommended:

Adding a prefix that doesn't start with Y.
Prefix your non-unique indices with EXTN_ for easier identification.
Unique indices are not allowed for tables.
Column names for indices must be valid.
Index names should not exceed 18 characters.