Question

How do we perform indexing on a datetime field in oracle. We should be able to search for a specific year

Thanks

Answer 1

To create an index in Oracle, use:

CREATE INDEX your_index_name ON your_table_name(your_column_name)

For more info about Oracle index creation, read this link.

Correction & Clarification
If you use a function to isolate a component of a date (IE: EXTRACT, or TRUNC), an index on the column will not help. But an index will help if you provide a date range:

WHERE your_date_column BETWEEN TO_DATE('2010-01-01', 'YYYY-MM-DD')
                                            AND TO_DATE('2010-12-31', 'YYYY-MM-DD')

You can however create function based indexes in Oracle:

CREATE INDEX your_index_name 
    ON your_table_name(EXTRACT(YEAR FROM your_column_name))

…which DBAs loath with a passion.