How Can I Efficiently Store Time Values Without Dates in Oracle?

Storing Time Values Without Date Values in Oracle

In cases where only time values need to be stored, Oracle provides an alternative to standard datetime pairs which can result in space savings and improved processing speed.

To store time alone, consider using Oracle's INTERVAL DAY TO SECOND data type. Unlike datetime values, which combine both date and time, INTERVAL DAY TO SECOND stores only the time component:

CREATE TABLE t1 (time_of_day INTERVAL DAY (0) TO SECOND(0));

INSERT INTO t1 VALUES (TO_DSINTERVAL('0 23:59:59'));

SELECT DATE '2009-05-13'+time_of_day FROM t1;

The INTERVAL DAY TO SECOND data type consumes 11 bytes, compared to the standard datetime value's size of 26 bytes. This can provide significant disk space savings when dealing with large datasets.

One important consideration is that INTERVAL DAY TO SECOND values are stored internally as a number of milliseconds. Therefore, precision is limited to milliseconds, which may not be suitable for all applications. However, for cases where only general time information is required, the INTERVAL DAY TO SECOND data type offers a convenient and space-efficient way to store time values.

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