- Add function Item_param::fix_fields which will update any subselect they are part of and indicate that the subsleect is not const during prepare phase, and thus should not be executed during prepare.
Added a test case for bug #8616.
item.h:
Fixed bug #8616.
Added class Item_null_result used in rollup processing.
sql_select.h, sql_select.cc:
Fixed bug #8616.
Added JOIN::rollup_write_data to cover rollup queries
with DISTINCT. Modified other rollup methods.
fixing test results accordingly.
func_system.test:
New test that illegal mix of collations does not happen anymore.
item_strfunc.h:
safe_charset_converter() was added for system constants.
item_strfunc.cc:
safe_charset_converter() was added for system constants.
item_func.cc, item.h, item.cc:
Bug#8291: Illegal collation mix with USER() function.
After discussion with PeterG and Serge, a new coercibility
level for "system constants" was introduced, between
COERRIBLE and IMPLICIT. Thus:
SELECT col1 = USER() FROM t1; - is done according to col1 collation.
SELECT 'string' = USER(); - is done according to USER() collation.
At the same time, "nagg" and "strong" members were removed as unused.
item_create.cc:
Version is a system constant too.
Change string->float conversion to delay division as long as possible.
This gives us more exact integer->float conversion for numbers of type '123.45E+02' (Bug #7740)
Revised the fix for bug #7098.
Corrected the method Item_string::new_item.
sql_select.cc:
Revised the fix for bug #7098.
Aborted the previous modifications.
delete is declared. As we don't use exceptions placement delete is never
called and the fix only affects numerous warnings when
compiling with MS Visual C++.
For more info see http://www.gotw.ca/gotw/010.htm.
Ensure that references in HAVING, ORDER BY or GROUP BY are calculated after fields in SELECT.
This will ensure that any reference to these has a valid value.
Generalized the code for split_sum_func()
* Added Item_ref::set_properties
* Item_ref::Item_ref now expects to get in *item either
NULL - then fix_fields() will be called later or
ptr to Item it will refer to - then an equivalent of fix_fields() call is performed
The problem in 4.1 was the same as in 4.0 - fix_fields() not called for created Item_ref.
The fix is similar too - initialize Item_refs in ctor (but don't interfere with cases when
Item_ref is used by subselects).
of <parameter> IS NULL":
we must not only set Item::null_value in Item_param, but implement
Item_param::is_null() to work well with IS NULL/IS NOT NULL clauses.
the result takes its charset/collation
attributes from the character string,
e.g. SELECT func(NULL, _latin2'string')
now returns a latin2 result. This is
done by introducing a new derivation
(aka coercibility) level DERIVATION_IGNORABLE,
which is used with Item_null.
2. 'Pure' NULL is now BINARY(0), not CHAR(0).
I.e. NULL is now more typeless.
constant with a column. The string is converted into the column
character set. It conversion doesn't lose data, then operation
is possible. Otherwise, give an error, as it was earlier.
A fix for Bug#6042 "constants propogation works olny once (prepared
statements)": reset item->marker in Item::cleanup, as it's used
in propogate_cond_constants. No test case as the only way I could
come up with to show the problem is EXPLAIN, and EXPLAIN is painful
to use in the test suite.
crashes server (prepared statements)": the bug was that all boolean
items always recovered its original arguments at statement cleanup
stage.
This collided with Item_subselect::select_transformer, which tries to
permanently change the item tree to use a transformed subselect instead of
original one.
So we had this call sequence for prepare:
mysql_stmt_prepare -> JOIN::prepare ->
Item_subselect::fix_fields -> the item tree gets transformed ->
Item_bool_rowready_func2::cleanup, item tree is recovered to original
state, while it shouldn't have been;
mysql_stmt_execute -> attempts to execute a broken tree -> crash.
Now instead of bluntly recovering all arguments of bool functions in
Item_bool_rowready_func2::cleanup, we recover only those
which were changed, and do it in one place.
There still would exist a possibility for a collision with subselect
tranformation, if permanent and temporary changes were performed at the
same stage.
But fortunately subselect transformation is always done first, so it
doesn't conflict with the optimization done by propogate_cond_constants.
Now we have:
mysql_stmt_prepare -> JOIN::prepare -> subselect transformation
permanently changes the tree -> cleanup doesn't recover anything,
because nothing was registered for recovery.
mysql_stmt_execute -> JOIN::prepare (the tree is already transformed,
so it doesn't change), JOIN::optimize ->
propogate_cond_constants -> temporary changes the item tree
with constants -> JOIN::execute -> cleanup ->
the changes done by propogate_cond_constants are recovered, as
they were registered for recovery.
crashes mysqld": implementation for a generic item tree modifications
registry. Every item tree modification which should be rolled back for
subsequent execution of a prepared statement or stored procedure should
be saved in the registry. All such modifications are rolled back at once
during cleanup stage of PS.
Actual fix for the bug just adds a call to register modifications to
convert_constant_item.
Post review fixes implemented.
character set introducer": add new item type to be returned before from
Item_param until it's value is set.
This way items like Item_bool_func2 and udf_handler won't treat this item
as constant literal when statement is prepared.
