This change takes into account a column's GENERATED ALWAYS AS
expression dependcy on sql_mode's PAD_CHAR_TO_FULL_LENGTH and
NO_UNSIGNED_SUBTRACTION flags.
Indexed virtual columns as well as persistent generated columns are
now not allowed to have such dependencies to avoid inconsistent data
or index files on sql_mode changes.
So an error is now returned in cases like this:
CREATE OR REPLACE TABLE t1
(
a CHAR(5),
v VARCHAR(5) AS (a) PERSISTENT -- CHAR->VARCHAR or CHAR->TEXT = ERROR
);
Functions RPAD() and RTRIM() can now remove dependency on
PAD_CHAR_TO_FULL_LENGTH. So this can be used instead:
CREATE OR REPLACE TABLE t1
(
a CHAR(5),
v VARCHAR(5) AS (RTRIM(a)) PERSISTENT
);
Note, unlike CHAR->VARCHAR and CHAR->TEXT this still works,
not RPAD(a) is needed:
CREATE OR REPLACE TABLE t1
(
a CHAR(5),
v CHAR(5) AS (a) PERSISTENT -- CHAR->CHAR is OK
);
More sql_mode flags may affect values of generated columns.
They will be addressed separately.
See comments in sql_mode.h for implementation details.
The bug occurs because Item_func_set_user var is allowed to be pushed
into materialized derived table/view.
To fix it excl_dep_on_table() as added to Item_func_set_user_var class
to prevent pushdown.
The problem was originally stated in
http://bugs.mysql.com/bug.php?id=82212
The size of an base64-encoded Rows_log_event exceeds its
vanilla byte representation in 4/3 times.
When a binlogged event size is about 1GB mysqlbinlog generates
a BINLOG query that can't be send out due to its size.
It is fixed with fragmenting the BINLOG argument C-string into
(approximate) halves when the base64 encoded event is over 1GB size.
The mysqlbinlog in such case puts out
SET @binlog_fragment_0='base64-encoded-fragment_0';
SET @binlog_fragment_1='base64-encoded-fragment_1';
BINLOG @binlog_fragment_0, @binlog_fragment_1;
to represent a big BINLOG.
For prompt memory release BINLOG handler is made to reset the BINLOG argument
user variables in the middle of processing, as if @binlog_fragment_{0,1} = NULL
is assigned.
Notice the 2 fragments are enough, though the client and server still may
need to tweak their @@max_allowed_packet to satisfy to the fragment
size (which they would have to do anyway with greater number of
fragments, should that be desired).
On the lower level the following changes are made:
Log_event::print_base64()
remains to call encoder and store the encoded data into a cache but
now *without* doing any formatting. The latter is left for time
when the cache is copied to an output file (e.g mysqlbinlog output).
No formatting behavior is also reflected by the change in the meaning
of the last argument which specifies whether to cache the encoded data.
Rows_log_event::print_helper()
is made to invoke a specialized fragmented cache-to-file copying function
which is
copy_cache_to_file_wrapped()
that takes care of fragmenting also optionally wraps encoded
strings (fragments) into SQL stanzas.
my_b_copy_to_file()
is refactored to into my_b_copy_all_to_file(). The former function
is generalized
to accepts more a limit argument to constraint the copying and does
not reinitialize anymore the cache into reading mode.
The limit does not do any effect on the fully read cache.
The problem happened in the derived condition pushdown code:
- When Item_func_regex::build_clone() was called, it created a copy of
the original Item_func_regex, and this copy got registered in free_list.
Class specific additional dynamic members (such as "re") made
a shallow copy, rather than a deep copy, in the cloned Item_func_regex.
As a result, the Regexp_processor_pcre::m_pcre of the cloned Item_func_regex
and of the original Item_func_regex pointed to the same compiled regular
expression.
- On cleanup_items(), both original and cloned copies of Item_func_regex
called re.cleanup(), which called pcre_free(m_pcre). So the same compiled
regular expression was freed two times, which was noticed by ASAN.
The same problem was repeatable for Item_func_regexp_instr.
A similar problem happened for Item_func_sp, for the sp_result_field member.
Both original and cloned copies of Item_func_sp pointed the same Field instance
and both deleted it on cleanup().
A possible solution would be to fix build_clone() to create deep
(instead of shallow) copies for the dynamic members of the affected classes
(Item_func_regex, Item_func_regexp_instr, Item_func sp).
However, this would be too complex.
As agreed with Galina and Igor, this patch disallows using using these
affected classes in derived condition pushdown by overriding get_clone()
to return NULL.
preserve positions if the multi-update join is using tmp table:
* store positions in the tmp table if needed
JOIN::add_fields_for_current_rowid()
* take positions from the tmp table, not from file->position():
multi_update::prepare2()
multiple times with different arguments.
If the ON expression of an outer join is an OR formula with one
of the disjunct being a constant formula then the expression
cannot be null-rejected if the constant formula is true. Otherwise
it can be null-rejected and if so the outer join can be converted
into inner join. This optimization was added in the patch for
mdev-4817. Yet the code had a defect: if the query was used in
a stored procedure with parameters and the constant item contained
some of them then the value of this constant item depended on the
values of the parameters. With some parameters it may be true,
for others not. The validity of conversion to inner join is checked
only once and it happens only for the first call of procedure.
So if the parameters in the first call allowed the conversion it
was done and next calls used the transformed query though there
could be calls whose parameters made the conversion invalid.
Fixed by cheking whether the constant disjunct in the ON expression
originally contained an SP parameter. If so the expression is not
considered as null-rejected. For this check a new item's attribute
was intruduced: Item::with_param. It is calculated for each item
by fix fields() functions.
Also moved the call of optimize_constant_subqueries() in
JOIN::optimize after the call of simplify_joins(). The reason
for this is that after the optimization introduced by the patch
for mdev-4817 simplify_joins() can use the results of execution
of non-expensive constant subqueries and this is not valid.
Problems:
1. Unlike Item_field::fix_fields(),
Item_sum_sp::fix_length_and_dec() and Item_func_sp::fix_length_and_dec()
did not run the code which resided in adjust_max_effective_column_length(),
therefore they did not extend max_length for the integer return data types
from the user-specified length to the maximum length according to
the data type capacity.
2. The code in adjust_max_effective_column_length() was not correct
for TEXT data, because Field_blob::max_display_length()
multiplies to mbmaxlen. So TEXT variants were unintentionally
promoted to the next longer data type for multi-byte character
sets: TINYTEXT->TEXT, TEXT->MEDIUMTEXT, MEDIUMTEXT->LONGTEXT.
3. Item_sum_sp::create_table_field_from_handler()
Item_func_sp::create_table_field_from_handler()
erroneously called tmp_table_field_from_field_type(),
which converted VARCHAR(>512) to TEXT variants.
So "CREATE..SELECT spfunc()" erroneously converted
VARCHAR to TEXT. This was wrong, because stored
functions have explicitly declared data types,
which should be preserved.
Solution:
- Removing Type_std_attributes(const Field *)
and using instead Type_std_attributes::set() in combination
with field->type_str_attributes() all around the code, e.g.:
Type_std_attributes::set(field->type_std_attributes())
These two ways of copying attributes from a Field
to an Item duplicated each other, and were slightly
different in how to mix max_length and mbmaxlen.
- Removing adjust_max_effective_column_length() and
fixing Field::type_std_attributes() to do all necessary
type-specific calculations , so no further adjustments
is needed.
Field::type_std_attributes() is now called from all affected methods:
Item_field::fix_fields()
Item_sum_sp::fix_length_and_dec()
Item_func_sp::fix_length_and_dec()
This fixes the problem N1.
- Making Field::type_std_attributes() virtual, to make
sure that type-specific adjustments a properly done
by individual Field_xxx classes. Implementing
Field_blob::type_std_attributes() in the way that
no TEXT promotion is done.
This fixes the problem N2.
- Fixing Item_sum_sp::create_table_field_from_handler()
Item_func_sp::create_table_field_from_handler() to
call create_table_field_from_handler() instead of
tmp_table_field_from_field_type() to avoid
VARCHAR->TEXT conversion on "CREATE..SELECT spfunc()".
- Recording mysql-test/suite/compat/oracle/r/sp-param.result
as "CREATE..SELECT spfunc()" now correctly
preserve the data type as specified in the RETURNS clause.
- Adding new tests
Renaming methods:
- Field::make_field(Send_field*) to make_send_field(..)
- Item::make_field(THD *,Send_field *) to make_send_field(..)
- Item::init_make_field(Send_field *, enum_field_type) to init_make_send_field(..)
These names looked similar to other functions that are used
for a very different purpose (creating Field instances):
- Public function "Field * make_field(..)"
- Method "Field *Column_defitinion::make_field(..)"
The rename makes it's easier to search the code using "grep".
