GPDB 6.x GDB commands

GDB commands making debugging Greenplum internals easier. Currently this provides a single command 'pgprint' that understand the 'Node' structures used internally, can can print them semi-intelligently.

Forked from PostgreSQL debugging tool found here:

https://github.com/tvondra/gdbpg

Usage

Copy the gdbpg.py script somewhere, and load it from gdb:

$ gdb ... 
(gdb) source /...path.../gdbpg.py 

and then just use pgprint command to print variables from gdb console. E.g. if plan is pointing to (PlannedStmt *), you may do this:

(gdb) pgprint plan

and you'll get something like this:

          type: CMD_SELECT
      query ID: 0
    param exec: 0
     returning: False
 modifying CTE: False
   can set tag: True
     transient: False
  row security: False
           
     plan tree: 
        -> HashJoin (cost=202.125...342.812 rows=2550 width=16)
                target list:
                        TargetEntry (resno=1 resname="id" ...
                        TargetEntry (resno=2 resname="id" ...
                        TargetEntry (resno=3 resname="id" ...
                        TargetEntry (resno=4 resname="id" ...
                ...

Limitations

Not all Node types are supported (only the subset I recently needed). It's rather trivial to add support for more nodes though - just hack the format_node function a bit.