Re: Index on immutable function call

2010/1/19 Philippe Lang <philippe.lang@attiksystem.ch>:
> That works just fine, but is there maybe a way of creating a slighly
> more "generic" index? If I change the ">" with a "<" in the query, index
> cannot of course be used. According to documentation, answer seems to be
> "no"...
>

You could create an index on the difference:

create index long_transformation_index on indexed_table
((data1-this_is_a_long_transformation(data2)));

then rewrite your queries accordingly:

... WHERE data1-this_is_a_long_transformation(data2) > some const (or
< some const)

HTH,
Dean