I'm not sure what you mean by t being non empty, since it's a relation and not
an expression. But guessing that you mean there is some bag in t you want to
check for non-emptiness, isn't the following equivalent?
foreach X {
...
t = distinct ...
tnotempty = filter t by !IsEmpty(...);
generate foo, ...
}
Alan.
On Oct 3, 2011, at 12:46 AM, Dmitriy Ryaboy wrote:
> Why not this:
>
> Y = foreach X { ..
> t = distinct ...
> generate t, foo...
> }
>
> Z = filter Y by isEmpty(t);
>
> OR: t can't be empty if the thing you are distincting is not empty, so this
> should work:
>
> Y = filter X by IsEmpty(thing_you_wanted_to_distinct);
> Z = foreach Y {
> -- the thing you are distincting is now guaranteed to have at least 1
> value
> t = distinct ..
> generate foo...
> }
>
> On Sun, Oct 2, 2011 at 9:28 AM, Stan Rosenberg <
> [email protected]> wrote:
>
>> Hi Folks,
>>
>> I came across a use case where I'd like to do something like this:
>>
>> FOREACH X {
>> ...
>> t = DISTINCT (...)
>> if (!IsEmpty(t))
>> GENERATE foo, ...
>> }
>>
>> Thus, 'generate' is conditionally executed and the control flow depends on
>> the value of some tuple 't'.
>> Can this be done in pig?
>>
>> Thanks,
>>
>> stan
>>
>> P.S. Please ignore my previous email; I accidentally triggered send before
>> I
>> had a chance to finish it.
>>
