"michel rosa" <mrosa@geomatic.ch> writes:
> ...
> and upload_date<='2010-03-02'
> give as result
> 2010-03-02 | 0 | 837
> 2010-03-02 | 0.5 | 136
> 2010-03-02 | 1.5 | 138
> but when upload_date<='2010-03-03', I get extras rows for 2010-03-02
Is the upload_date column actually a date? I think maybe it's a
timestamp and the "extra" rows correspond to times after midnight.
Your cutoff conditions are being interpreted as
upload_date<='2010-03-02 00:00:00'
etc.
regards, tom lane