PG Bug reporting form <noreply@postgresql.org> writes: > Then the trigger data changes after the insert statement in the trigger > function.
Hmm. TD is defined as a global dictionary like SD, so it saves values across calls to the plpython function. So the inner INSERT operation fires the same trigger, which decides not to print anything, but nonetheless it's changed TD and the outer trigger call will see that.
There used to be similar problems in plain plpython functions if they were invoked recursively, because named function arguments are also passed as global variables. We fixed that in a rather hacky way in 1d2fe56e4, ie save and restore those globals when recursing. Probably the same thing could be done with TD.