This article examines the differences between the smalldatetime and datetime2 data types in SQL Server.

Smalldatetime uses 4 bytes of memory and rounds to the nearest minute, while datetime2 uses 6 bytes and provides more precision without rounding.

The date range for smalldatetime is limited to January 1, 1900, to June 6, 2079, whereas datetime2 allows for dates between January 1, 0001, and December 31, 9999.

If seconds are not required, datetime2(0) can be used, which has the same storage size as smalldatetime. However, datetime2 is recommended for big data scenarios due to its wider range of values and increased precision.

Smalldatetime can save 2 bytes per row in a clustering key, but it may require additional preprocessing to truncate seconds.

Some users may also prefer datetime2 due to its non-rounding behavior and minute-level precision.

What are the differences?

One notable difference between SQL Server’s smalldatetime and datetime2 data types is that smalldatetime rounds to the nearest minute, while datetime2 provides more precision and does not round.

Smalldatetime stores values with an accuracy of one minute, rounding up or down to the nearest minute. This can be seen as a limitation in cases where more precise timestamps are required.

On the other hand, datetime2 offers a wider range of values and allows for more precise storage of dates and times, down to the nanosecond level. The increased precision of datetime2 makes it suitable for applications that require minute-level precision or need to store high-resolution timestamps.

Comparison of data types

When comparing the two data types, it is important to consider factors such as memory efficiency, rounding behavior, range of values, and precision.

Smalldatetime is more memory-efficient, using only 4 bytes compared to datetime2’s 6 bytes.

Smalldatetime rounds to the nearest minute, while datetime2 does not round and provides more precision.

The date range for smalldatetime is from January 1, 1900, to June 6, 2079, whereas datetime2 has a wider range of values from January 1, 0001, to December 31, 9999.

If seconds are not needed, storage for datetime2(0) is the same as smalldatetime at 4 bytes.

Datetime2 is recommended for big data due to its wider range of values and precision.

Smalldatetime’s rounding behavior can be disliked and may be a reason to choose datetime2.

Datetime2 provides more precision and does not round, making it suitable for minute-level precision.

Considerations for storage and memory

Considerations for storage and memory include evaluating the memory efficiency and storage requirements of the two date data types in question, smalldatetime and datetime2.

Smalldatetime uses only 4 bytes of memory, making it more memory-efficient compared to datetime2, which uses 6 bytes. However, the storage requirements for datetime2 can be reduced to 4 bytes if seconds are not needed (datetime2(0)).

Smalldatetime rounds to the nearest minute, while datetime2 provides more precision and does not round. This can be a significant factor to consider depending on the specific requirements of the application.

Additionally, smalldatetime has a narrower date range from January 1, 1900, to June 6, 2079, whereas datetime2 has a wider range from January 1, 0001, to December 31, 9999.

Considering these factors, the choice between smalldatetime and datetime2 should be made based on the specific needs of the application, including memory efficiency, required precision, and date range requirements.