## 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