Enable Index To Search For NULLs By Adding Constant to Index List. But Some Constants Better Than Others (Never Let Me Down)

By default, Oracle doesn’t index an entry if all columns within the index are NULL. However, (as I’ve blogged previously), it’s possible to index all possible NULL values by simply adding a constant value to the index column list. Importantly, the CBO knows when a column has all it’s NULL values indexed and can potentially […]