The bug caused a crash of the server if a subquery with
ORDER BY DESC used the range access method.
The bug happened because the method QUICK_SELECT_DESC::reset
was not reworked after MRR interface had been introduced.
may return a wrong result.
An Item_sum_hybrid object has the was_values flag which indicates whether any
values were added to the sum function. By default it is set to true and reset
to false on any no_rows_in_result() call. This method is called only in
return_zero_rows() function. An ALL/ANY subquery can be optimized by MIN/MAX
optimization. The was_values flag is used to indicate whether the subquery
has returned at least one row. This bug occurs because return_zero_rows() is
called only when we know that the select will return zero rows before
starting any scans but often such information is not known.
In the reported case the return_zero_rows() function is not called and
the was_values flag is not reset to false and yet the subquery return no rows
Item_func_not_all and Item_func_nop_all functions return a wrong
comparison result.
The end_send_group() function now calls no_rows_in_result() for each item
in the fields_list if there is no rows were found for the (sub)query.
The ALL/ANY subqueries are the subject of MIN/MAX optimization. The matter
of this optimization is to embed MIN() or MAX() function into the subquery
in order to get only one row by which we can tell whether the expression
with ALL/ANY subquery is true or false.
But when it is applied to a subquery like 'select a_constant' the reported bug
occurs. As no tables are specified in the subquery the do_select() function
isn't called for the optimized subquery and thus no values have been added
to a MIN()/MAX() function and it returns NULL instead of a_constant.
This leads to a wrong query result.
For the subquery like 'select a_constant' there is no reason to apply
MIN/MAX optimization because the subquery anyway will return at most one row.
Thus the Item_maxmin_subselect class is more appropriate for handling such
subqueries.
The Item_in_subselect::single_value_transformer() function now checks
whether tables are specified for the subquery. If no then this subselect is
handled like a UNION using an Item_maxmin_subselect object.
The convert_constant_item() function converts constant items to ints on
prepare phase to optimize execution speed. In this case it tries to evaluate
subselect which contains a derived table and is contained in a derived table.
All derived tables are filled only after all derived tables are prepared.
So evaluation of subselect with derived table at the prepare phase will
return a wrong result.
A new flag with_subselect is added to the Item class. It indicates that
expression which this item represents is a subselect or contains a subselect.
It is set to 0 by default. It is set to 1 in the Item_subselect constructor
for subselects.
For Item_func and Item_cond derived classes it is set after fixing any argument
in Item_func::fix_fields() and Item_cond::fix_fields accordingly.
The convert_constant_item() function now doesn't convert a constant item
if the with_subselect flag set in it.
When a view statement is compiled on CREATE VIEW time, most of the
optimizations should not be done. Finding the right optimization
for a subquery is one of them.
Unfortunately the optimizer is resolving the column references of
the left expression of IN subqueries in the process of deciding
witch optimization to use (if needed). So there should be a
special case in Item_in_subselect::fix_fields() : check the
validity of the left expression of IN subqueries in CREATE VIEW
mode and then proceed as normal.
When there is conjunction of conds, the substitute_for_best_equal_field()
will call the eliminate_item_equal() function in loop to build final
expression. But if eliminate_item_equal() finds that some cond will always
evaluate to 0, then that cond will be substituted by Item_int with value ==
0. In this case on the next iteration eliminate_item_equal() will get that
Item_int and treat it as Item_cond. This is leads to memory corruption and
server crash on cleanup phase.
To the eliminate_item_equal() function was added DBUG_ASSERT for checking
that all items treaten as Item_cond are really Item_cond.
The substitute_for_best_equal_field() now checks that if
eliminate_item_equal() returns Item_int and it's value is 0 then this
value is returned as the result of whole conjunction.
A subquery transformation changes the HAVING clause of the embedding query if the subquery contains
a GROUP BY clause. Yet the split_sum_func2 function was not applied to the modified HAVING clause.
This could result in wrong answers.
Bug #10308: Parse 'purge master logs' with subselect correctly.
subselect.test:
Bug #10308: Test for 'purge master logs' with subselect.
subselect.result:
Bug #10308: Test result for 'purge master logs' with subselect.
* Provide backwards compatibility extension to name resolution of
coalesced columns. The patch allows such columns to be qualified
with a table (and db) name, as it is in 4.1.
Based on a patch from Monty.
* Adjusted tests accordingly to test both backwards compatible name
resolution of qualified columns, and ANSI-style resolution of
non-qualified columns.
For this, each affected test has two versions - one with qualified
columns, and one without.
Fixed bug #11479.
The JOIN::reinit method cannot call setup_tables
after the optimization phase since this function
removes some optimization settings for joined
tables. E.g. it resets values of the null_row flag to 0.
subselect.result, subselect.test:
Added a test case for bug #11479.
"Process NATURAL and USING joins according to SQL:2003".
* Some of the main problems fixed by the patch:
- in "select *" queries the * expanded correctly according to
ANSI for arbitrary natural/using joins
- natural/using joins are correctly transformed into JOIN ... ON
for any number/nesting of the joins.
- column references are correctly resolved against natural joins
of any nesting and combined with arbitrary other joins.
* This patch also contains a fix for name resolution of items
inside the ON condition of JOIN ... ON - in this case items must
be resolved only against the JOIN operands. To support such
'local' name resolution, the patch introduces a stack of
name resolution contexts used at parse time.
NOTICE:
- This patch is not complete in the sense that
- there are 2 test cases that still do not pass -
one in join.test, one in select.test. Both are marked
with a comment "TODO: WL#2486".
- it does not include a new test specific for the task
Added a test case for bug #12392.
item_cmpfunc.cc:
Fixed bug #12392.
Missing handling of rows containing NULL components
when evaluating IN predicates caused a crash.
- Fixed some error condtion when handling dates with 'T'
- Added extra test for bug #11867 (Wrong result with "... WHERE ROW( a, b ) IN ( SELECT DISTINCT a, b WHERE ...)" to show it's not yet fixed
- Safety fixes and cleanups
Added test case for bug #11867.
Fixed results for two existing test cases.
subselect.test:
Added test case for bug #11867.
item_subselect.cc:
Fixed bug #11867.
Added missing code in Item_in_subselect::row_value_transformer
that caused problems for queries with
ROW(elems) IN (SELECT DISTINCT cols FROM ...).
Fixed buf #11487.
Added a call of QUICK_RANGE_SELECT::init to the
QUICK_RANGE_SELECT::reset method. Without it the second
evaluation of a subquery employing the range access failed.
subselect.result, subselect.test:
Added a test case for bug #11487.
Added a test case for bug #9516.
item_subselect.h:
Fixed bug #9516.
The bug was due to that fact that the class Item_subselect
inherited the generic implementation of the function
not_null_tables that was not valid for the objects
of this class. As a result evaluation of the
not_null_tables attribute was not correct for subqueries.
This caused invalid transformations of outer joins into
inner joins.
Added a test case for bug #9338.
sql_select.cc:
Fixed bug #9338.
When an occurence of a field reference has to be replaced
by another field reference the whole Item_field must be
replaced.
item.cc:
Fixed bug #9338.
The method Item_field::replace_equal_field_processor was
replaced by Item_field::replace_equal_field. The new method
is used to replace the occurences of Item_field objects.
item.h:
Fixed bug #9338.
The virtual function replace_equal_field_processor was replaced
by replace_equal_field. The latter is supposed to be used as a
callback function in calls of the method transform.
CAST() now produces warnings when casting a wrong INTEGER or CHAR values. This also applies to implicite string to number casts. (Bug #5912)
ALTER TABLE now fails in STRICT mode if it generates warnings.
Inserting a zero date in a DATE, DATETIME or TIMESTAMP column during TRADITIONAL mode now produces an error. (Bug #5933)
