Re: graph representation of data structures in optimizer

Hi,

The patch attached is an implementation for graph generation of data
structures in postgres. The file debuggraph.c is a simple library that
generate graphs in the format supported by graphviz. Example:

#include "nodes/debuggraph.h"
...
DebugGraph *graph;
DebugNode *node;

graph = createDebugGraph();
node = newDebugNode( graph, "node1", "Node 1" );
addDebugNodeAttribute( node, "Attribute 1", "Value 1" );
newDebugNode( graph, "node2", "Node 2" );
newDebugEdge( graph, "node1", "node2", "Edge 1" );

printGraphvizToFile( graph, stderr );
destroyDebugGraph( graph );

I've also made a reimplementation of outfuncs.c to outfuncs_graph.c for
an entire node output support.

#include "nodes/outfuncs_graph.h"
...
printGraphNodes( node, stderr );

I hope that this may be useful for somebody.

--
Adriano Lange
C3SL/UFPR - www.c3sl.ufpr.br