Hi Swapna,
The return type is typically derived from looking at the return types of
each of the input arguments and choosing what'll work without losing
precision. For example, take a look at this loop in ExpressionCompiler that
determines this for expressions that are added together:
new ArithmeticExpressionFactory() {
@Override
public Expression create(ArithmeticParseNode node,
List<Expression> children) throws SQLException {
boolean foundDate = false;
Determinism determinism = Determinism.ALWAYS;
PDataType theType = null;
for(int i = 0; i < children.size(); i++) {
Your probably already doing this, but make sure you don't assume the
arguments are column references, but allow them to be any expression.
Also, it'd be great to see what you've got so far without handling multiple
arguments to your function (in the form of a pull request) so folks can get
you feedback on your work so far.
Thanks, and we appreciate the contributions!
James
On Tue, May 3, 2016 at 12:59 PM, Swapna Swapna <[email protected]>
wrote:
> Sure,
>
> Hbase data that I have is:
>
> rowkey us uk
> 20161001 3 4
> 20161002 1 2
>
>
> select myaggFunc(us) from table : // this is returning output as :
> 4
> select myaggFunc(uk) from table : // this is returning output as :
> 6
>
> In similar to that, i'm visualizing the query like: select
> myaggFunc1(us,uk)
> from table; //with multiple columns
>
> to return output: (based on the aggregation logic, below results are for
> sum aggregation)
> us 4
> uk 6
>
>
>
> On Tue, May 3, 2016 at 11:33 AM, James Taylor <[email protected]>
> wrote:
>
> > Removing user list (please don't cross post)
> >
> > Can you give us a full example of the query you have in mind?
> >
> > Thanks,
> > James
> >
> > On Tue, May 3, 2016 at 11:14 AM, Swapna Swapna <[email protected]>
> > wrote:
> >
> > > Hi,
> > >
> > > I'm trying to implement aggregate function on multiple columns (as an
> > > arguments) like:
> > >
> > > myaggFunc(col1,col2)
> > >
> > > And I would want to return the results by each column after applying
> > > aggregate operation.
> > >
> > > The output would be something like:
> > >
> > > col1, count ( aggregate of all records for col1)
> > > col2, count
> > >
> > > Inorder to return the results in the above format, what is the return
> > data
> > > type (of the method) should I have to choose?
> > >
> > > Thanks
> > >
> >
>
