Field BWSel
Index selectivity factors. Index selectivity factors used by Zim’s strategy optimizer.
Valid Values
A number from 0 to 1.000 (DEFAULT = 1.000)
Remarks
The index selectivity factors are relevant for indexed fields only.
Each number represents the fraction of records that you would typically expect to retrieve using an indexed lookup with a particular operator or operators.
|
BWSel |
selectivity factor for BETWEEN |
|
EQSel |
selectivity factor for the equals (=) operator |
|
LGSel |
selectivity factor for all other operators (i.e., less than (<), greater than (>), less than or equals (<=), greater than or equals (>=)) |
Values closer to 0 imply a very selective index, while values closer to 1 imply an index with poor selectivity. A value of 1.000 instructs Zim to use its internal selectivity factors.