Storage sizes for datatypes

The storage sizes for datatypes are shown in Table 11-2:

Table 11-2: 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”.