Dear hackers:
Is it reasonable or possible to have the optimizer filter out impossible
string/numeric matches because of length/overflow conditions?
For example: (on 7.4.1)
select * from t where f = '1234567' -- f = char(6)
explain says index/seq scan, depending on presence of index, when
obviously there can be no matches.
also, for the typical case for indexed field f,select * from t where f = f' or false
generates an index scan
but select * from t where f = f' or f = f''
generates a seq. scan with default settings. If f'' is not in the
domain of f, the first case should apply. Is this really as simple as
it seems?
Merlin
