This statement enlarges the area for retrieval statements.
Definition
A lower-level DBH option of SYSTEM-LIMITS
Function
The DBH option COLUMNS allows you to enlarge the area for retrieval statements.
The area for retrieval statements is normally limited to 256 columns. In the case of large retrieval statements that address more than 256 columns, you must increase the size of this area up to 1024 columns.
You can adjust the value of the option during the DBH session by means of the RECONFIGURE-DBH-SESSION administration statement (see "RECONFIGURE-DBH-SESSION").
COLUMNS |
= 256 / <integer 256..1024> |
Operands
COLUMNS = 256 / <integer 256..1024>
Area size in columns for retrieval statements.
Calculating the length of a retrieval statement
You base your entry for the COLUMNS option on the length of the longest retrieval statement in an application. This is determined by the number of columns (attributes in the case of CALL DML) or the number of conditions attached to columns. In the case of SQL applications, the number of operators in arithmetic expressions is also included in the calculation.
To calculate the length of a retrieval statement, proceed as follows:
Count each column whenever it is addressed in the retrieval statement.
In the case of SQL applications, count also the operators in arithmetic expressions.
In the case of multiple columns, add the number of occurrences addressed in the retrieval statement.
If one or more conditions are attached to one and the same column, add the number of conditions for this column.
In the case of CALL DML, the value calculated corresponds to the area specified in the COLUMNS option. In the case of SQL DML, the calculated length of the longest retrieval statement represents a maximum value for the area specified in the COLUMNS option. As a result of internal optimization, the optimal value can be lower than the calculated value.
Space required to save the temporary work file
The space required to store internal statement formats in the temporary work file depends on the COLUMNS option. The space required can be seen in the following list (see also the description of WORK-CONTAINER on "WORK-CONTAINER").
COLUMNS = | Space required for storing average internal statement formats (Kbytes) |
up to 260 | 28 |
up to 325 | 32 |
up to 366 | 36 |
up to 408 | 40 |
up to 449 | 44 |
up to 512 | 48 |
up to 553 | 52 |
up to 594 | 56 |
up to 636 | 60 |
up to 1024 | 64 |
Table 9: Space required for storing internal statement formats