Records:1000000
Width:10
Depth:5

Tree..d:".((`child;c);(`parent;,/0,{(#x)#y}':(0,+\\_ Width^!Depth-1)_ c:!+/_ Width^!Depth))"	
Trans..d:".((`leaf;c Records _draw#c:Tree[`child]_dvl?Tree`parent);(`value;Records _draw 0))"

Rollup..d:"
 p:Tree[`parent]\\'!#Tree`parent                  
 g:Tree[`child]?/:Trans`leaf
 f:{@[x;p;y;@[x;g;y;z]]}
 s:f[(#p)#0.;+;Trans`value]
 c:f[(#p)#0;+;1]          			   
 .((`node;Tree`child);(`sum;s);(`count;c);(`avg;s%c))"

.k..c:`form
.k..a:(`Depth`Width`Records;`Tree`Trans`Rollup)
`show$`.k