FROM I_S
Issue:
------
There is a difference in the field type created when the
following DDLs are used:
1) CREATE TABLE t0 AS SELECT NULL;
2) CREATE TABLE t0 AS SELECT GREATEST(NULL,NULL);
The first statement creates field of type Field_string and
the second one creates a field of type Field_null.
This creates a problem when the query mentioned in this bug
is used. Since the null_ptr is calculated differently for
Field_null.
Solution:
---------
When there is a function returning null in the select list
as mentioned above, the field should be of type
Field_string.
This was fixed in 5.6+ as part of Bug#14021323. This is a
backport to mysql-5.5.
An incorrect comment in innodb_bug54044.test has been
corrected in all versions.
NAME_CONST QUERY
ISSUE:
------
Using NAME_CONST with a non-constant negated expression as
value can result in incorrect behavior.
SOLUTION:
---------
The problem can be avoided by checking whether the argument
is a constant value.
The fix is a backport of Bug#12735545.
1. Fixing Field_time::get_equal_const_item() to pass TIME_FUZZY_DATES
and TIME_INVALID_DATES to get_time_with_conversion().
This is needed to make the recursively called Item::get_date() return
non-NULL values on garbage input. This makes Field_time::get_equal_const_item()
work consistently with how Item::val_time_packed() works.
2. Fixing Item::get_date() to return TIME'00:00:00' rather than
DATE'0000-00-00' on empty or garbage input when:
- TIME_FUZZY_DATES is enabled
- The caller requested a TIME value (by passing TIME_TIME_ONLY).
This is needed to avoid conversion of DATE'0000-00-00' to TIME
in get_time_with_conversion(), which would erroneously try to subtract
CURRENT_DATE from DATE'0000-00-00' and return TIME'-838:59:59' rather than
the desired zero value TIME'00:00:00'.
#1 and #2 fix these type of scripts to return one row with both
MyISAM and InnoDB, with and without an index on t1.b:
CREATE TABLE t1 (a ENUM('a'), b TIME, c INT, KEY(b));
INSERT INTO t1 VALUES ('','00:00:00',0);
SELECT * FROM t1 WHERE b='';
SELECT * FROM t1 WHERE a=b;
SELECT * FROM t1 IGNORE INDEX(b) WHERE b='';
SELECT * FROM t1 IGNORE INDEX(b) WHERE a=b;
Additionally, #1 and #2 fix the originally reported in MDEV-9604 crash
in Item::save_in_field(), because now execution goes through a different
path, so save_in_field() is called for a Item_time_literal instance
(which is non-NULL) rather than a Item_cache_str instance (which could
return NULL without setting null_value).
3. Fixing Field_temporal::get_equal_const_item_datetime() to enable
equal field propagation for DATETIME and TIMESTAMP in case of
comparison (e.g. when ANY_SUBST), for symmetry with
Field_newdate::get_equal_const_item(). This fixes a number of problems
with empty set returned on comparison to empty/garbage input.
Now all SELECT queries in this script return one row for MyISAM and InnoDB,
with and without an index on t1.b:
CREATE TABLE t1 (a ENUM('a'), b DATETIME, c INT, KEY(b));
INSERT INTO t1 VALUES ('','0000-00-00 00:00:00',0);
SELECT * FROM t1 WHERE b='';
SELECT * FROM t1 WHERE a=b;
SELECT * FROM t1 IGNORE INDEX(b) WHERE b='';
SELECT * FROM t1 IGNORE INDEX(b) WHERE a=b;
INTERVALS
ISSUE:
------
Some string functions return one or a combination of the
parameters as their result. Here the resultant string's
charset could be incorrectly set to that of the chosen
parameter.
This results in incorrect behavior when an ascii string is
expected.
SOLUTION:
---------
Since an ascii string is expected, val_str_ascii should
explicitly convert the string.
Part of the fix is a backport of Bug#22340858 for mysql-5.5
and mysql-5.6.
when doing set_field_to_new_field (from switch_to_nullable_trigger_fields())
make sure that the field we're about to change actually belongs
to the right table (otherwise we cannot dereference new_field[]
array as the wrong table might have more fields than
new_field[] has elements)
Case: table with a NOT NULL field, BEFORE UPDATE trigger,
and UPDATE with a subquery that uses GROUP BY on that
NOT NULL field, and needs a temporary table for it.
Because of the BEFORE trigger, the field becomes nullable
temporarily. But its Item_field (used in GROUP BY) doesn't.
When working with the temptable some code looked at
item->maybe_null, some - at field->null_ptr.
The fix: make Item_field nullable when its field is.
This triggers an assert. The group key size is calculated
before the item is made nullable, so the group key doesn't
have a null byte. The fix: make fields/items nullable
before the group key size is calculated.
ITEM_PARAM::SAFE_CHARSET_CONVERTER
ISSUE:
------
Charset conversion on a null parameter is not handled
correctly.
SOLUTION:
---------
Item_param's charset converter does not handle the case
where it might have to deal with a null value. This is
fine for other charset converters since the value is not
supplied to them at runtime.
The fix is to check if the parameter is now set to null and
return an Item_null object. Also, there is no need to
initialize Item_param's cnvitem in the constructor to a
string. This can be done in
ITEM_PARAM::SAFE_CHARSET_CONVERTER itself.
Members of Item_param, cnvbuf and cnvstr, have been removed
and cnvitem has been made a local variable in
ITEM_PARAM::SAFE_CHARSET_CONVERTER.
GENERATED BY THE EXP() FUNCTION
When generating the error message for numeric overflow, pass a flag to
Item::print() that prevents it from expanding constant expressions and
parameters to the values they evaluate to.
For consistency, also pass the flag to Item::print() when
Item_func_spatial_collection::fix_length_and_dec() generates an error
message. It doesn't make any difference at the moment, since constant
expressions haven't been evaluated yet when this function is called.
NOT NULL constraint must be checked *after* the BEFORE triggers.
That is for INSERT and UPDATE statements even NOT NULL fields
must be able to store a NULL temporarily at least while
BEFORE INSERT/UPDATE triggers are running.
* move common code to a new set_bad_null_error() function
* move repeated comparison out of the loop
* remove unused code
* unused method Table_triggers_list::set_table
* redundant condition (if (table) after table was dereferenced)
* add an assert
Problem:
At the end of first execution select_lex->prep_where is pointing to
a runtime created object (temporary table field). As a result
server exits trying to access a invalid pointer during second
execution.
Analysis:
While optimizing the join conditions for the query, after the
permanent transformation, optimizer makes a copy of the new
where conditions in select_lex->prep_where. "prep_where" is what
is used as the "where condition" for the query at the start of execution.
W.r.t the query in question, "where" condition is actually pointing
to a field in the temporary table. As a result, for the second
execution the pointer is no more valid resulting in server exit.
Fix:
At the end of the first execution, select_lex->where will have the
original item of the where condition.
Make prep_where the new place where the original item of select->where
has to be rolled back.
Fixed in 5.7 with the wl#7082 - Move permanent transformations from
JOIN::optimize to JOIN::prepare
Patch for 5.5 includes the following backports from 5.6:
Bugfix for Bug12603141 - This makes the first execute statement in the testcase
pass in 5.5
However it was noted later in in Bug16163596 that the above bugfix needed to
be modified. Although Bug16163596 is reproducible only with changes done for
Bug12582849, we have decided include the fix.
Considering that Bug12582849 is related to Bug12603141, the fix is
also included here. However this results in Bug16317817, Bug16317685,
Bug16739050. So fix for the above three bugs is also part of this patch.
The problem was that GROUP BY code created Item_field objects
that referred to fields in the temp. tables used for GROUP BY.
Item_ref and set_items_ref_array() call caused pointers to temp.
table fields to occur in many places.
This patch introduces Item_temptable_field, which can handle
item->print() calls made after the underlying table is freed.
Item_string::clone_item() creates a new Item_string that
points exactly to the same buffer that the original one does.
Later, Item_string::print() uses c_ptr() for the original Item_string,
which reallocs the original buffer, and the clone remain with
the old freed buffer.
Refactoring the code not to use c_ptr() in Item_string::print().
1. Removing the legacy code that disabled equal field propagation in cases
when comparison is done as VARBINARY. This is now correctly handled by
the new propagation code in Item_xxx::propagate_equal_fields() and
Field_str::can_be_substituted_to_equal_item (the bug fix).
2. Also, removing legacy (pre-MySQL-4.1) Arg_comparator methods
compare_binary_string() and compare_e_binary_string(), as VARBINARY
comparison is correcty handled in compare_string() and compare_e_string() by
the corresponding VARBINARY collation handler implemented in my_charset_bin.
(not really a part of the bug fix)
WHERE COALESCE(time_column)=TIME('00:00:00')
AND COALESCE(time_column)=DATE('2015-09-11')
MDEV-8814 Wrong result for WHERE datetime_column > TIME('00:00:00')
MDEV-8754 Wrong result for SELECT..WHERE year_field=2020 AND NULLIF(year_field,2010)='2020'
Problems:
1. Item_func_nullif stored a copy of args[0] in a private member m_args0_copy,
which was invisible for the inherited Item_func menthods, like
update_used_tables(). As a result, after equal field propagation
things like Item_func_nullif::const_item() could return wrong result
and a non-constant NULLIF() was erroneously treated as a constant
at optimize_cond() time.
Solution: removing m_args0_copy and storing the return value item
in args[2] instead.
2. Equal field propagation did not work well for Item_fun_nullif.
Solution: using ANY_SUBST for args[0] and args[1], as they are in
comparison, and IDENTITY_SUBST for args[2], as it's not in comparison.
