We've started to test more of our queries that involve the view and we
believe we may have come across a possible reason for the poor
performance in our views.
The view is pulling data from many tables as said before, one of them
has a varchar(255) column (ColA) that is copied over into the view.
However, in the view column definition, it is a varchar(2147483647).
In the query we tested, we are running an equivalence check against this
column, along with another varchar column of size 1 (ColB). When we
remove the check against ColA the query returns in 2.5 seconds. When
included it talks 200 seconds. There is almost no difference when the
ColB check is removed (2.5s vs 2.3s).
It is of our belief that this varchar(2147483647) could be causing
performance problems. ColA might be defaulting to 2147483647 because it
is being union-ed with the same column a couple of times in different
circumstances. So we are wondering if there a way to set the column's
varchar size in a view definition?
