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Pig >> mail # dev >> Handle NULL values in Cube dimensions

Prasanth J 2012-06-06, 21:24
Dmitriy Ryaboy 2012-06-07, 00:41
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Re: Handle NULL values in Cube dimensions
But how do the user specify custom value for "*"? In the current implementation I am passing "NULL" string to the CubeDimensions constructor. If we need to get that value from user then we need some changes in grammar like

a = CUBE b BY (x,y,z) ALL as "AllProducts";

also what should be the default value if user didn't specify anything?

-- Prasanth

On Jun 6, 2012, at 8:41 PM, Dmitriy Ryaboy wrote:

> Note that the current CubeDimensions UDF does a third thing -- instead
> of rebranding "nulls" as "unknown" and using null to mean "*" or "all
> values", the UDF allows you to specify a custom value to stand for "*"
> or "all values". That way null can be an individual valid cell value.
> This is (imho) much nicer than the other options, but it does
> complicate working with 3rd party tools.
> Does anyone have opinions on this?
> D
> On Wed, Jun 6, 2012 at 2:24 PM, Prasanth J <[EMAIL PROTECTED]> wrote:
>> Hello everyone
>> I would like to bring up this discussion about the ways for handling NULL values in dimensions specified for cubing. For example, if we have a dimension color with following values
>> red
>> blue
>> null
>> green
>> how do we differentiate if the null value represent rollup of all colors values or actual null value?
>> SQL way:
>> There are 2 ways in which SQL server analysis services handles null values in dimensions
>> 1) Throw error when it encounters null values in dimension values
>> 2) Ignore error by adding the null values to UnknownMembers. By default UnknownMembers will be named as "Unknown". The name for UnknownMembers can also be specified by the user.
>> Do we need to handle both ways in Pig? I think the first way (throwing error) is pretty straightforward.
>> For the second way (ignoring error), what is the best way to provide support for user specified name for UnknownMembers?
>> Please share your thoughts about how we can handle this scenario for different datatypes in Pig.
>> Thanks
>> -- Prasanth

Alan Gates 2012-06-08, 16:22
Prasanth J 2012-06-09, 02:00
Jonathan Coveney 2012-06-09, 03:06
Prasanth J 2012-06-12, 05:53