group concat tree is allocated in a memroot, so the only way to free
memory is to copy a part of the tree into a new memroot.
track the accumilated length of the result, and when it crosses
the threshold - copy the result into a new tree, free the old one.
Adding an intermediate volatile variable to avoid using co-processor registers
on some platforms (e.g. 32-bit x86).
This change makes test results stable accross all platforms.
Added support for usual agreggate UDF (UDAF)
Added remove() call support for more efficient window function processing
Added example of aggregate UDF with efficient windows function support
The problem described in the bug report happened because the code
did not test check_cols(1) after fix_fields() in a few places.
Additionally, fix_fields() could be called multiple times for SP variables,
because they are all fixed at a early stage in append_for_log().
Solution:
1. Adding a few helper methods
- fix_fields_if_needed()
- fix_fields_if_needed_for_scalar()
- fix_fields_if_needed_for_bool()
- fix_fields_if_needed_for_order_by()
and using it in many cases instead of fix_fields() where
the "fixed" status is not definitely known to be "false".
2. Adding DBUG_ASSERT(!fixed) into Item_splocal*::fix_fields()
to catch double execution.
3. Adding tests.
As a good side effect, the patch removes a lot of duplicate code (~60 lines):
if (!item->fixed &&
item->fix_fields(..) &&
item->check_cols(1))
return true;
Detailed: changes:
1. Moving Field specific code into new methods on Field:
- Field *Field::create_tmp_field(...)
- virtual void init_for_tmp_table(...)
2. Removing virtual Item::create_tmp_field().
Adding instead a new virtual method Item::create_tmp_field_ex().
Note, a virtual create_tmp_field() still exists, but only for Item_sum.
This resembles 10.0 code structure. Perhaps create_tmp_field() should
be removed from Item_sum and Item_sum descendants should override
create_tmp_field_ex() directly. This can be done in a separate commit.
3. Adding helper classes Tmp_field_src and Tmp_field_param,
to make the API for Item::create_tmp_field_ex() smaller
and easier to extend in the future.
4. Decomposing the public function create_tmp_field() into
virtual implementations for Item and a number of its descendants:
- Item_basic_value
- Item_sp_variable
- Item_name_const
- Item_result_field
- Item_field
- Item_ref
- Item_type_holder
- Item_row
- Item_func_sp
- Item_func_user_var
- Item_sum
- Item_sum_field
- Item_proc
5. Adding DBUG_ASSERT-only virtual implementations for
Item types that should not appear in create_tmp_table_ex(),
for easier debugging:
- Item_nodeset_func
- Item_nodeset_to_const_comparator
- Item_null_result
- Item_copy
- Item_ident_for_show
- Item_user_var_as_out_param
6. Moving public function create_tmp_field_from_field()
as a method to Item_field.
7. Removing Item::set_result_field(). It's not needed any more.
8. Cleanup: Removing the enum value "EXPR_CACHE_ITEM",
as it's not used for a very long time.
Original problem reported by Wlad: re-compilation of 10.3 on top of 10.2
build would cache undefined HAVE_ISINF from 10.2, whereas it is expected
to be 1 in 10.3.
std::isinf() seem to be available on all supported platforms.
Queries involving rollup need all aggregate function to have copy_or_same function where we create a copy
of item_sum items for each sum level.
Implemented copy_or_same function for the custom aggregate function class (Item_sum_sp)
