Use the following equation to determine the amount of usable data space for Field mode:
Usable Data Space = a(RO + RP + n(PH + NF + CF)) + b(SNF + SCF)
The following parameter definitions are used with this equation:
| Parameter | Definition |
|---|---|
| a | Number of rows being selected. |
| RO | Row overhead (22 bytes per row). |
| RP | Row parcel indicators; 8 bytes per row (rec start, rec end). |
| n | Number of columns being selected. |
| PH | Parcel headers (4 bytes per field). |
| NF | Formatted size of each numeric column (spaces, dollar signs, and commas must be included). |
| CF | Formatted size of each character column. For example, a selected column defined as VARCHAR(200) takes up 200 characters even with only 3 nonblank characters. The value for CF can be less than the CREATE TABLE definition of the string only if there is a FORMAT phrase. |
| b | Number of numeric columns in the ORDER BY clause (sort key). |
| SNF | Sorted numeric fields (8 bytes each). |
| SCF | Formatted size of each character column in the ORDER BY clause. If an order operation is done on a column defined as VARCHAR(200), 200 characters are allowed, even if there are only 3 nonblank characters. The value for CF can be less than the CREATE TABLE definition of the string only if there is a FORMAT phrase. The formatted length of the character string must be rounded up to the next even value, then 2 more bytes must be added to the number. |