Florian G. Pflug wrote:
Because the _whole_ _point_ of an index is to find matching rows _without_ scanning the whole table. IF you have to look at every row
anyway, then just might as well to an sequential scan.
I am sorry it took me this long to understand this, but I think I got it now thanks to all Your (all in this thread) efforts to make me :-)
What confuses me was the difference between what controls a query and what filters a row in a selected data set, I just could not see the difference, but that have changed :-) I think the problem was I just could not see the general principles from the special case where I thought I had the use for this index lookup.
Thanks to anyone for there effort to make me understand, hope I will be a faster learner next time :-)
/BL
---------------------------(end of broadcast)--------------------------- TIP 9: the planner will ignore your desire to choose an index scan if your joining column's datatypes do not match
