Item::val_xxx() may be called by the server several times at execute time
for a single query. Calls to val_xxx() may be very expensive and sometimes
(count(distinct), sum(distinct), avg(distinct)) not possible.
To avoid that problem the results of calculation for these aggregate
functions are cached so that val_xxx() methods just return the calculated
value for the second and subsequent calls.
wrong results
Mark the containing Item(s) (Item_subselect descendant usually) of
a subselect as containing aggregate functions if it has references
to aggregates functions that are calculated outside its context.
This tels end_send_group() not to make an Item_subselect descendant in
select list a copy and causes the correct value being returned.
make st_select_lex::setup_ref_array() take into account that
Item_sum-descendant objects located within descendant SELECTs
may be added into ref_pointer_array.
when calculating GROUP_CONCAT all blob fields are transformed
to varchar when making the temp table.
However a varchar has at max 2 bytes for length.
This fix makes the conversion only for blobs whose max length
is below that limit.
Otherwise blob field is created by make_string_field() call.
In some functions dealing with strings and character sets, the wrong
pointers were saved for restoration in THD::rollback_item_tree_changes().
This could potentially cause random corruption or crashes.
Fixed by passing the original Item ** locations, not local stack copies.
Also remove unnecessary use of default arguments.
Server crashed in some cases when a query required a MIN/MAX
agrregation for a 'ucs2' field.
In these cases the aggregation caused calls of the function
update_tmptable_sum_func that indirectly invoked
the method Item_sum_hybrid::min_max_update_str_field()
containing a call to strip_sp for a ucs2 character set.
The latter led directly to the crash as it used my_isspace
undefined for the ucs2 character set.
Actually the call of strip_sp is not needed at all in this
situation and has been removed by the fix.
The GROUP_CONCAT uses its own temporary table. When ROLLUP is present
it creates the second copy of Item_func_group_concat. This copy receives the
same list of arguments that original group_concat does. When the copy is
set up the result_fields of functions from the argument list are reset to the
temporary table of this copy.
As a result of this action data from functions flow directly to the ROLLUP copy
and the original group_concat functions shows wrong result.
Since queries with COUNT(DISTINCT ...) use temporary tables to store
the results the COUNT function they are also affected by this bug.
The idea of the fix is to copy content of the result_field for the function
under GROUP_CONCAT/COUNT from the first temporary table to the second one,
rather than setting result_field to point to the second temporary table.
To achieve this goal force_copy_fields flag is added to Item_func_group_concat
and Item_sum_count_distinct classes. This flag is initialized to 0 and set to 1
into the make_unique() member function of both classes.
To the TMP_TABLE_PARAM structure is modified to include the similar flag as
well.
The create_tmp_table() function passes that flag to create_tmp_field().
When the flag is set the create_tmp_field() function will set result_field
as a source field and will not reset that result field to newly created
field for Item_func_result_field and its descendants. Due to this there
will be created copy func to copy data from old result_field to newly
created field.
Bad examples of usage of a string with its length fixed.
The incorrect length in the trigger file configuration descriptor
fixed (BUG#14090).
A hook for unknown keys added to the parser to support old .TRG files.
The problem was in that the MIN/MAX optimization in opt_sum_query was
replacing MIN/MAX functions with their constant argument without
taking into account that a query has no result rows.
Added flag to Field::store(longlong) to specify if value is unsigned.
This fixes bug #12750: Incorrect storage of 9999999999999999999 in DECIMAL(19, 0)
Fixed warning from valgrind in CREATE ... SELECT
Fixed double free of mysql.options if reconnect failed
Added test cases for bug #12863.
item_sum.cc, item_sum.h:
Fixed bug #12863.
Added a flag to Item_func_group_concat set to FALSE after
concatenation of the first element of a group.
Item_func_group_concat::fix_fields() set maybe_null flag to 0, and set it to
1 only if some of it's arguments may be null. When used in subquery in tmp
table created field which can't be null. When no data retireved result field
have to be set to null and error mentioned in bug report occurs. Also this
bug can occur if selecting from not null field in empty table.
Function group_concat now marked maybe_null from the very beginning not only
if some of it's argument may be null.
Cannot convert the charset of a GROUP_CONCAT result:
item_sum.cc:
"result" character set was not set into proper value.
func_gconcat.result, func_gconcat.test:
Fixing tests accordingly.
Item_type_holder doesn't store information about length and exact type of
original item which results in redefining length to max_length and geometry
type to longtext.
Changed the way derived tables except unions are built. Now they are created
from original field list instead of list of Item_type_holder.
Adding test
item_sum.cc:
Adding a call for collation/charset aggregation,
to collect attributes from the arguments. The actual bug fix.
item_func.h, item_func.cc, item.h, item.cc:
- Removing collation aggrgation functions from Item_func class
in item.cc, and adding it as non-class functions in item.cc
to be able to reuse this code for group_concat.
- Adding replacement for these functions into Item_func class
as wrappers for moved functions, to minizize patch size,
