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MDEV-36047 Package body variables are not allowed as FETCH targets

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It was not possible to use a package body variable as a
fetch target:

CREATE PACKAGE BODY pkg AS
  vc INT := 0;
  FUNCTION f1 RETURN INT AS
    CURSOR cur IS SELECT 1 AS c FROM DUAL;
  BEGIN
    OPEN cur;
    FETCH cur INTO vc; -- this returned "Undeclared variable: vc" error.
    CLOSE cur;
    RETURN vc;
  END;
END;

FETCH assumed that all fetch targets reside of the same sp_rcontext
instance with the cursor. This patch fixes the problem.
Now a cursor and its fetch target can reside in different sp_rcontext
instances.

Details:

- Adding a helper class sp_rcontext_addr
  (a combination of Sp_rcontext_handler pointer and an offset in the rcontext)

- Adding a new class sp_fetch_target deriving from sp_rcontext_addr.
  Fetch targets in "FETCH cur INTO target1, target2 ..." are now collected
  into this structure instead of sp_variable.
  sp_variable cannot be used any more to store fetch targets,
  because it does not have a pointer to Sp_rcontext_handler
  (it only has the current rcontext offset).

- Removing members sp_instr_set members m_rcontext_handler and m_offset.
  Deriving sp_instr_set from sp_rcontext_addr instead.

- Renaming sp_instr_cfetch member  "List<sp_variable> m_varlist"
  to "List<sp_fetch_target> m_fetch_target_list".

- Fixing LEX::sp_add_cfetch() to return the pointer to the
  created sp_fetch_target instance (instead of returning bool).
  This helps to make the grammar in sql_yacc.c simpler

- Renaming LEX::sp_add_cfetch() to LEX::sp_add_instr_cfetch(),
  as `if(sp_add_cfetch())` changed its meaning to the opposite,
  to avoid automatic wrong merge from earlier versions.

- Chaning the "List<sp_variable> *vars" parameter to sp_cursor::fetch
  to have the data type "List<sp_fetch_target> *".

- Changing the data type of "List<sp_variable> &vars" in
  sp_cursor::Select_fetch_into_spvars::send_data_to_variable_list()
  to "List<sp_fetch_target> &".

- Adding THD helper methods get_rcontext() and get_variable().

- Moving the code from sql_yacc.yy into a new LEX method
  LEX::make_fetch_target().

- Simplifying the grammar in sql_yacc.yy using the new LEX method.
  Changing the data type of the bison rule sp_fetch_list from "void"
  to "List<sp_fetch_target> *".
This commit is contained in:
Alexander Barkov
2025-02-08 17:39:27 +04:00
parent 6be0940f10
commit b7d67ceb5f
25 changed files with 731 additions and 72 deletions
Download Patch File Download Diff File Expand all files Collapse all files

12
sql/sp_instr.cc
View File

@@ -1923,7 +1923,7 @@ sp_instr_cfetch::execute(THD *thd, uint *nextp)
Query_arena backup_arena;
DBUG_ENTER("sp_instr_cfetch::execute");
res= c ? c->fetch(thd, &m_varlist, m_error_on_no_data) : -1;
res= c ? c->fetch(thd, &m_fetch_target_list, m_error_on_no_data) : -1;
*nextp= m_ip+1;
DBUG_RETURN(res);
@@ -1933,8 +1933,8 @@ sp_instr_cfetch::execute(THD *thd, uint *nextp)
void
sp_instr_cfetch::print(String *str)
{
List_iterator_fast<sp_variable> li(m_varlist);
sp_variable *pv;
List_iterator_fast<sp_fetch_target> li(m_fetch_target_list);
sp_fetch_target *pv;
const LEX_CSTRING *cursor_name= m_ctx->find_cursor(m_cursor);
/* cfetch name@offset vars... */
@@ -1953,12 +1953,14 @@ sp_instr_cfetch::print(String *str)
str->qs_append(m_cursor);
while ((pv= li++))
{
if (str->reserve(pv->name.length+SP_INSTR_UINT_MAXLEN+2))
const LEX_CSTRING *prefix= pv->rcontext_handler()->get_name_prefix();
if (str->reserve(pv->name.length+prefix->length+SP_INSTR_UINT_MAXLEN+2))
return;
str->qs_append(' ');
str->qs_append(prefix);
str->qs_append(&pv->name);
str->qs_append('@');
str->qs_append(pv->offset);
str->qs_append(pv->offset());
}
}