>> Backend crashes at some queries involving views of aggregate queries.
> 7.0beta3 is fixed in this area.
The particular query shown here may work in 7.0, but it's important to
know that views using grouping or aggregates are still not implemented
right in 7.0. It's not going to be possible to make all these cases
work properly until we redesign querytrees, which is currently planned
for 7.1. In the meantime I'd have to recommend avoiding GROUP BY in
views.
regards, tom lane