How Can I Store Only the Time Portion of a Timestamp in Oracle Database?

Storing Time Only in Oracle Database

When working with timestamps, it may be necessary to isolate and store only the time portion of the datetime value, omitting the date. This optimization can potentially save storage space and enhance processing performance when dealing with large datasets.

Using the INTERVAL Data Type

One approach to storing time without date is to utilize Oracle's INTERVAL DAY TO SECOND data type. This data type represents a duration between two points in time and can be easily converted to and from a TIMESTAMP value.

Example:

-- Create a table to store time values
CREATE TABLE My_Times (time_value INTERVAL DAY TO SECOND);

-- Insert a time value
INSERT INTO My_Times (time_value) VALUES (TO_DSINTERVAL('0 23:59:59'));

-- Retrieve the time portion from a timestamp
SELECT DATE '2009-05-13' + time_value FROM My_Times;

Output:

2009-05-13 23:59:59

Disk Space and Processing Considerations

While using the INTERVAL DAY TO SECOND data type won't result in reduced storage space compared to using a TIMESTAMP, it offers a more compact representation than storing the full datetime value. Additionally, working with time intervals may provide better performance for tasks that involve time-based calculations or comparisons.

Summary

Storing only time in Oracle Database can be achieved using the INTERVAL DAY TO SECOND data type. This data type provides a compact representation of time values and offers performance benefits for time-related operations. Whether it leads to significant space savings or performance enhancements depends on the specific context and dataset size.

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