If you do:

Schema s1 = Utils.getSchemaFromString(
"b:bag{t:tuple(name:chararray,age:int)}");
then it will all be -1'd out. It doesn't seem to be used anywhere, I was
just wondering, since in other case, it will be populated properly.
Thanks

Jon

Santosh is the best person to answer this, as he wrote that code.  But, IIRC its purpose is to store the "full" name of a column after cogroups and joins.  For example,

A = load 'foo' as (u, v);
B = load 'bar' as (x, y);
C = join A by u, B by x;

I believe the canonicalname will now hold A::u, etc.

Alan.

On Nov 16, 2011, at 7:25 PM, Jonathan Coveney wrote:

> If you do:
>
> Schema s1 = Utils.getSchemaFromString(
> "b:bag{t:tuple(name:chararray,age:int)}");
>
>
> then it will all be -1'd out. It doesn't seem to be used anywhere, I was
> just wondering, since in other case, it will be populated properly.
>
>
> Thanks
>
> Jon

Alan is right. Its meant to help with disambiguation when the column name is the same across relations. In Alan's example, if you had u instead of x in B, then the columns in the C (join) would be (A::u, v, B::u, y). A::v and B::y are also valid column names.

Santhosh

-----Original Message-----
From: Alan Gates [mailto:[EMAIL PROTECTED]]
Sent: Friday, November 18, 2011 8:58 AM
To: [EMAIL PROTECTED]
Cc: Santhosh Srinivasan
Subject: Re: What is the canonicalname field in a Schema object used for?

Santosh is the best person to answer this, as he wrote that code.  But, IIRC its purpose is to store the "full" name of a column after cogroups and joins.  For example,

A = load 'foo' as (u, v);
B = load 'bar' as (x, y);
C = join A by u, B by x;

I believe the canonicalname will now hold A::u, etc.

Alan.

On Nov 16, 2011, at 7:25 PM, Jonathan Coveney wrote:

> If you do:
>
> Schema s1 = Utils.getSchemaFromString(
> "b:bag{t:tuple(name:chararray,age:int)}");
>
>
> then it will all be -1'd out. It doesn't seem to be used anywhere, I
> was just wondering, since in other case, it will be populated properly.
>
>
> Thanks
>
> Jon

Ah, ok, that makes sense. I only asked because in some UDFs it was being
ignored, and that would explain why: they didn't need to be disambiguated
in that particular case.

2011/11/20 Santhosh Srinivasan <[EMAIL PROTECTED]>

> Alan is right. Its meant to help with disambiguation when the column name
> is the same across relations. In Alan's example, if you had u instead of x
> in B, then the columns in the C (join) would be (A::u, v, B::u, y). A::v
> and B::y are also valid column names.
>
> Santhosh
>
> -----Original Message-----
> From: Alan Gates [mailto:[EMAIL PROTECTED]]
> Sent: Friday, November 18, 2011 8:58 AM
> To: [EMAIL PROTECTED]
> Cc: Santhosh Srinivasan
> Subject: Re: What is the canonicalname field in a Schema object used for?
>
> Santosh is the best person to answer this, as he wrote that code.  But,
> IIRC its purpose is to store the "full" name of a column after cogroups and
> joins.  For example,
>
> A = load 'foo' as (u, v);
> B = load 'bar' as (x, y);
> C = join A by u, B by x;
>
> I believe the canonicalname will now hold A::u, etc.
>
> Alan.
>
> On Nov 16, 2011, at 7:25 PM, Jonathan Coveney wrote:
>
> > If you do:
> >
> > Schema s1 = Utils.getSchemaFromString(
> > "b:bag{t:tuple(name:chararray,age:int)}");
> >
> >
> > then it will all be -1'd out. It doesn't seem to be used anywhere, I
> > was just wondering, since in other case, it will be populated properly.
> >
> >
> > Thanks
> >
> > Jon
>
>