strange behaviour of merge statement using native dynamic sql

Is someone able to explain to me the following behaviour (Oracle 9.0.1.3 on SuSE Linux):

SQL> create table x (

   2 pk integer primary key,
   3 data varchar2(4000)
   4 ) ;

Table created.

SQL> create table y (

   2 pk integer primary key,
   3 data varchar2(4000)
   4 ) ;

Table created.

SQL> insert into x values(1,'aaa') ;

1 row created.

SQL> insert into x values(2,'bbb') ;

1 row created.

SQL> insert into x values(3,'ccc') ;

1 row created.

• now I do create the following file and call it p.sql: ***

  ---

  declare dsql varchar2(32767) ; begin dsql :=
  ' merge into ' ||
  ' y tbl ' ||
  ' using ( ' ||
  ' select ' ||
  ' x.pk, ' ||
  ' x.data ' ||
  ' from ' ||
  ' x ' ||
  ' where ' ||
  ' x.pk = :1 ' ||
  ' ) qry ' ||
  ' on ( ' ||
  ' tbl.pk = qry.pk ' ||
  ' ) ' ||
  ' when matched then ' ||
  ' update ' ||
  ' set ' ||
  ' tbl.data = qry.data ' ||
  ' when not matched then ' ||
  ' insert ( ' ||
  ' tbl.pk, ' ||
  ' tbl.data ' ||
  ' ) values ( ' ||
  ' qry.pk, ' ||
  ' qry.data ' ||
  ' ) ' ;
  execute immediate dsql using 1 ; end ; /

  ---

SQL> @p
declare
*
ERROR at line 1:
ORA-01008: not all variables bound
ORA-06512: at line 31

• now I do create the following file and call it p2.sql. ***
• the difference is in the "using" clause only ***

  ---

  declare dsql varchar2(32767) ; begin dsql :=
  ' merge into ' ||
  ' y tbl ' ||
  ' using ( ' ||
  ' select ' ||
  ' x.pk, ' ||
  ' x.data ' ||
  ' from ' ||
  ' x ' ||
  ' where ' ||
  ' x.pk = :1 ' ||
  ' ) qry ' ||
  ' on ( ' ||
  ' tbl.pk = qry.pk ' ||
  ' ) ' ||
  ' when matched then ' ||
  ' update ' ||
  ' set ' ||
  ' tbl.data = qry.data ' ||
  ' when not matched then ' ||
  ' insert ( ' ||
  ' tbl.pk, ' ||
  ' tbl.data ' ||
  ' ) values ( ' ||
  ' qry.pk, ' ||
  ' qry.data ' ||
  ' ) ' ;
  execute immediate dsql using 'why do I need this?', 1 ; end ; /

  ---

SQL> @p2

PL/SQL procedure successfully completed.

If I increase the number of "real" bind variables by 1,2,3,... I have to increase the number of "bogus" bind variables by 1,2,3,....

Bug or feature? :)

Kind regards,

-- 
Cris Carampa (spamto:cris119_at_operamail.com)
"Welcome to the new world order
  Families sleepin' in their cars in the southwest
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