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Fix Bug#11333 "Stored Procedure: Memory blow up on repeated SELECT ... INTO query"

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mysql-test/r/sp.result:
  update result
mysql-test/t/sp.test:
  Add test for Bug #11333 "Stored Procedure: Memory blow up on repeated SELECT ... INTO query"
sql/item.cc:
  we should call destructors for Items before reuse
sql/item.h:
  Add new method and constructor for Item_string.
sql/sp_head.cc:
  String allocation should be done on the system heap for now.
This commit is contained in:
unknown
2005-08-25 15:34:14 +04:00
parent 141a36c31b
commit d29df5645b
5 changed files with 91 additions and 4 deletions
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23
sql/sp_head.cc
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@@ -249,10 +249,25 @@ sp_eval_func_item(THD *thd, Item **it_addr, enum enum_field_types type,
DBUG_PRINT("info",("default result: %*s",
s->length(), s->c_ptr_quick()));
CREATE_ON_CALLERS_ARENA(it= new(reuse, &rsize)
Item_string(thd->strmake(s->ptr(),
s->length()), s->length(),
it->collation.collation),
use_callers_arena, &backup_current_arena);
Item_string(it->collation.collation),
use_callers_arena, &backup_current_arena);
/*
We have to use special constructor and allocate string
on system heap here. This is because usual Item_string
constructor would allocate memory in the callers arena.
This would lead to the memory leak in SP loops.
See Bug #11333 "Stored Procedure: Memory blow up on
repeated SELECT ... INTO query" for sample of such SP.
TODO: Usage of the system heap gives significant overhead,
however usual "reuse" mechanism does not work here, as
Item_string has no max size. That is, if we have a loop, which
has string variable with constantly increasing size, we would have
to allocate new pieces of memory again and again on each iteration.
In future we should probably reserve some area of memory for
not-very-large strings and reuse it. But for large strings
we would have to use system heap anyway.
*/
((Item_string*) it)->set_str_with_copy(s->ptr(), s->length());
}
break;
}