Marco Vezzoli <[EMAIL PROTECTED]> writes:
> ewsweb_test=> \d measures_product
> Index "measures_product"
> Attribute | Type
> ------------+----------
> product_id | smallint
^^^^^^^^
> ewsweb_test=> explain select zero_yield, gross from measures where
> product_id=29 and date between '2003-03-12' and '2003-08-14';
^^^^^^^^^^^^^
"29" is taken as an integer (int4). To get an indexscan on an int2
column, you need to explicitly cast it to int2:
product_id = 29::smallint
or you can put it in quotes and let the parser figure out the right
type:
product_id = '29'
Yes, we'd like to make this better, but there are surprisingly many
pitfalls in tinkering with the assignment of datatypes to constants...
regards, tom lane
PS: you could also consider whether it's really saving you any space to
store product_id as a smallint instead of int. Because of alignment
considerations, it very possibly isn't.
---------------------------(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
