Storage sizes for datatypes

The storage sizes for datatypes are shown in Table 16-2:

**Table 16-2: Storage sizes for Adaptive Server datatypes**
Datatype	Size
char	Defined size
nchar	Defined size * @@ncharsize
unichar	n*@@unicharsize (@@unicharsize equals 2)
univarchar	the actual number of characters*@@unicharsize
varchar	Actual number of characters
nvarchar	Actual number of characters * @@ncharsize
binary	Defined size
varbinary	Data size
int	4
smallint	2
tinyint	1
float	4 or 8, depending on precision
double precision	8
real	4
numeric	2–17, depending on precision and scale
decimal	2–17, depending on precision and scale
money	8
smallmoney	4
datetime	8
smalldatetime	4
bit	1
text	16 bytes + 2K * number of pages used
image	16 bytes + 2K * number of pages used
timestamp	8

The storage size for a numeric or decimal column depends on its precision. The minimum storage requirement is 2 bytes for a 1- or 2-digit column. Storage size increases by 1 byte for each additional 2 digits of precision, up to a maximum of 17 bytes.

Any columns defined as NULL are considered variable-length columns, since they involve the overhead associated with variable-length columns.

All calculations in the examples that follow are based on the maximum size for varchar, univarchar, nvarchar, and varbinary data—the defined size of the columns. They also assume that the columns were defined as NOT NULL. If you want to use average values instead, see “Using average sizes for variable fields”.