Memory Requirements of a Column Value According to Data Type

In the column definition (column_definition),  the memory requirement of a column value depends on the data_type. You can get a rough idea of the memory requirement using the following table.  Please note that these values are intended as guidance values and are applicable in most cases but may vary depending on your system configuration.

If the database parameter COLUMNCOMPRESSION=YES is set, then the space that is actually required is often smaller than the maximum memory requirement. This difference depends on the actual size of the saved column value.
See: Concepts of the Database System, Support Database Parameters

If, however, the lead column is not the last lead column, then the maximum space requirement is in fact required.

If the column is the last lead column then the actual required space is smaller than the maximum space requirement.

Data Type

Maximum Space Requirement in the Database (Bytes)
COLUMNCOMPRESSION=YES

Maximum Space Requirement in the Database (Bytes)
COLUMNCOMPRESSION=NO

Space Requirement in Communication (Bytes) when an ASCII Client is Used

Space Requirement in Communication (Bytes) when a UNICODE Client is Used

FIXED(p,s)

(p+1) DIV 2 + 3

(p+1) DIV 2 + 2

(p+1) DIV 2 + 2

(p+1) DIV 2 + 2

FLOAT(p)

(p+1) DIV 2 + 3

(p+1) DIV 2 + 2

(p+1) DIV 2 + 2

(p+1) DIV 2 + 2

BOOLEAN

3

2

2

2

DATE

10

9

11

21

TIME

10

9

9

19

TIMESTAMP

22

21

27

53

LONG

9

9

41

41

CHAR(n) ASCII
0<n<=1023
key column

n+1

n+1

n+1

2*n+1

CHAR(n) ASCII
n<=30
no key column

n+2

n+1

n+1

2*n+1

CHAR(n) ASCII
30<n<=254
no key column

n+2

n+2

n+1

2*n+1

CHAR(n) ASCII
254<n
no key column

n+3

n+3

n+1

2*n+1

CHAR(n) BYTE
0<n<=1023
key column

n+1

n+1

n+1

n+1

CHAR(n) BYTE
n<=30
no key column

n+2

n+1

n+1

n+1

CHAR(n) BYTE
30<n<=254
no key column

n+2

n+2

n+1

n+1

CHAR(n) BYTE
254<n
no key column

n+3

n+3

n+1

n+1

CHAR(n) UNICODE
0<n<=511
key column

2*n+1

2*n+1

2*n+1

2*n+1

CHAR(n) UNICODE
n<=15
no key column

2*n+2

2*n+1

2*n+1

2*n+1

CHAR(n) UNICODE
15<n<=127
no key column

2*n+2

2*n+2

2*n+1

2*n+1

CHAR(n) UNICODE
127<n
no key column

2*n+3

2*n+3

2*n+1

2*n+1

VARCHAR(n) ASCII
0<n<=1023
key column

n+1

n+1

n+1

2*n+1

VARCHAR(n) ASCII
n<=30
no key column

n+2

n+2

n+1

2*n+1

VARCHAR(n) ASCII
30<n<=254
no key column

n+2

n+2

n+1

2*n+1

VARCHAR(n) ASCII
254<n
no key column

n+3

n+3

n+1

2*n+1

VARCHAR(n) BYTE
0<n<=1023
key column

n+1

n+1

n+1

n+1

VARCHAR(n) BYTE
n<=30
no key column

n+2

n+2

n+1

n+1

VARCHAR(n) BYTE
30<n<=254
no key column

n+2

n+2

n+1

n+1

VARCHAR(n) BYTE
254<n
no key column

n+3

n+3

n+1

n+1

VARCHAR(n) UNICODE
0<n<=511
key column

2*n+1

2*n+1

2*n+1

2*n+1

VARCHAR(n) UNICODE
n<=15
no key column

2*n+2

2*n+2

2*n+1

2*n+1

VARCHAR(n) UNICODE
15<n<=127
no key column

2*n+2

2*n+2

2*n+1

2*n+1

VARCHAR(n) UNICODE
127<n
no key column

2*n+3

2*n+3

2*n+1

2*n+1