Yang 2012-11-02, 22:09
Alan Gates 2012-11-02, 22:33
Cheolsoo Park 2012-11-02, 22:40
Yang 2012-11-05, 17:15
Alan Gates 2012-11-05, 16:16
-Re: CONCAT(null, "something") == NULL ?
Jonathan Coveney 2012-11-05, 18:01
I agree with Alan on all counts. I think the confusing part is that null is
2012/11/5 Alan Gates <[EMAIL PROTECTED]>
> Better in terms of semantics or terms of documentation? We can't change
> the semantics of null in Pig; it's been that way the whole time. Plus this
> concept of unknown data is important in data processing. If we had it to
> do over again we could name it 'unknown' instead of null, but it seems late
> for that now.
> On Nov 2, 2012, at 3:40 PM, Cheolsoo Park wrote:
> > Hi Alan,
> > Recently, I have seen several similar confusions about nulls in Pig. For
> > example, here is another discussion:
> > https://issues.apache.org/jira/browse/PIG-3021.
> > We are documenting them, but apparently, many users find it confusing. I
> > wondering if there is anything that we can do better.
> > Thanks,
> > Cheolsoo
> > On Fri, Nov 2, 2012 at 3:33 PM, Alan Gates <[EMAIL PROTECTED]>
> >> To give some context, the null semantics in Pig follow SQL's. In SQL,
> >> null is viral, so any operation with null results in null. The idea is
> >> that null means unknown, not empty. So concat('x', unknown) = unknown.
> >> Alan.
> >> On Nov 2, 2012, at 3:09 PM, Yang wrote:
> >>> looks a more intuitive result should be "something" , right?
> >>> but on my system it gave null
Cheolsoo Park 2012-11-02, 22:14