mariadb-columnstore-engine/utils/udfsdk/docs/source/reference/UDAFMap.rst

.. _udafmap:

UDAFMap
=======

The UDAFMap is where we tell the system about our function. For Columnstore 1.2, you must manually place your function into this map.

* open mcsv1_udaf.cpp
* add your header to the #include list
* add a new line to the UDAFMap::getMap() function

::

 #include "allnull.h"
 #include "ssq.h"
 #include "median.h"
 #include "avg_mode.h"
 UDAF_MAP& UDAFMap::getMap()
 {
    if (fm.size() > 0)
    {
        return fm;
	}
    // first: function name
    // second: Function pointer
    // please use lower case for the function name. Because the names might be 
    // case-insensitive in MySQL depending on the setting. In such case, 
    // the function names passed to the interface is always in lower case.
    fm["allnull"] = new allnull();
    fm["ssq"] = new ssq();
    fm["median"] = new median();
    fm["avg_mode"] = new avg_mode();
	
    return fm;
 }

An alternative method added for 1.2 is to put the following in your .cpp file.
replace "median" with the name of your function:

::

 class Add_median_ToUDAFMap
 {
 public:
     Add_median_ToUDAFMap()
     {
         UDAFMap::getMap()["median"] = new median();
     }
 };

 static Add_median_ToUDAFMap addToMap;

This defines an object whose constructor adds the entry to the UDAFMap. The 
static declaration instatiates an object at runtime, thus adding the entry
at startup.