Controls how conservative the optimizer’s join result estimates are in unusually complex situations.
Can be set temporary for an individual connection or for the PUBLIC group. Takes effect immediately.
This option controls how conservative the join optimizer’s result size estimates are in situations where an input to a specific join has already passed through at least one intermediate join that can result in multiple copies of rows projected from the table being joined.
A level of zero indicates that the optimizer should use the same estimation method above intermediate expanding joins as it would if there were no intermediate expanding joins.
This results in the most aggressive (small) join result size estimates.
A level of 100 indicates that the optimizer should be much more conservative in its estimates whenever there are intermediate expanding joins, and this results in the most conservative (large) join result size estimates.
Normally, you should not need to change this value. If you do, Sybase recommends setting JOIN_EXPANSION_FACTOR as a temporary or user option.