commit 47771637cefa8a283b23bb3b1ba692cbd560403b
Author: okbob@github.com <pavel.stehule@gmail.com>
Date:   Tue Aug 18 14:00:58 2020 +0200

    enhancing dbg plpgsql API

diff --git a/src/pl/plpgsql/src/pl_exec.c b/src/pl/plpgsql/src/pl_exec.c
index d4a3d58daa..294008af88 100644
--- a/src/pl/plpgsql/src/pl_exec.c
+++ b/src/pl/plpgsql/src/pl_exec.c
@@ -4078,6 +4078,8 @@ plpgsql_estate_setup(PLpgSQL_execstate *estate,
 	{
 		(*plpgsql_plugin_ptr)->error_callback = plpgsql_exec_error_callback;
 		(*plpgsql_plugin_ptr)->assign_expr = exec_assign_expr;
+		(*plpgsql_plugin_ptr)->eval_datum = exec_eval_datum;
+		(*plpgsql_plugin_ptr)->cast_value = do_cast_value;

 		if ((*plpgsql_plugin_ptr)->func_setup)
 			((*plpgsql_plugin_ptr)->func_setup) (estate, func);
diff --git a/src/pl/plpgsql/src/plpgsql.h b/src/pl/plpgsql/src/plpgsql.h
index 0c3d30fb13..bec2429555 100644
--- a/src/pl/plpgsql/src/plpgsql.h
+++ b/src/pl/plpgsql/src/plpgsql.h
@@ -1142,8 +1142,11 @@ typedef struct PLpgSQL_execstate
  *
  * Also, immediately before any call to func_setup, PL/pgSQL fills in the
  * error_callback and assign_expr fields with pointers to its own
- * plpgsql_exec_error_callback and exec_assign_expr functions.  This is
- * a somewhat ad-hoc expedient to simplify life for debugger plugins.
+ * plpgsql_exec_error_callback and exec_assign_expr functions. eval_datum
+ * is assigned to function exec_eval_datum, and cast_value to function
+ * do_cast_value. With last two functions is easy to get content of
+ * any PLpgSQL_datum in any expected type. This is a somewhat ad-hoc
+ * expedient to simplify life for debugger plugins.
  */
 typedef struct PLpgSQL_plugin
 {
@@ -1158,6 +1161,13 @@ typedef struct PLpgSQL_plugin
 	void		(*error_callback) (void *arg);
 	void		(*assign_expr) (PLpgSQL_execstate *estate, PLpgSQL_datum *target,
 								PLpgSQL_expr *expr);
+	void		(*eval_datum) (PLpgSQL_execstate *estate, PLpgSQL_datum *datum,
+								Oid *typeid, int32 *typetypmod, Datum *value,
+								bool *isnull);
+	Datum		(*cast_value) (PLpgSQL_execstate *estate,
+								Datum value, bool *isnull,
+								Oid valtype, int32 valtypmod,
+								Oid reqtype, int32 reqtypmod);
 } PLpgSQL_plugin;

 /*