Some fixes related to commit f838b2d799 and
Rows_log_event::do_apply_event() and Update_rows_log_event::do_exec_row()
for system-versioned tables were provided by Nikita Malyavin.
This was required by test versioning.rpl,trx_id,row.
Functions extracting non-negative datetime components:
- YEAR(dt), EXTRACT(YEAR FROM dt)
- QUARTER(td), EXTRACT(QUARTER FROM dt)
- MONTH(dt), EXTRACT(MONTH FROM dt)
- WEEK(dt), EXTRACT(WEEK FROM dt)
- HOUR(dt),
- MINUTE(dt),
- SECOND(dt),
- MICROSECOND(dt),
- DAYOFYEAR(dt)
- EXTRACT(YEAR_MONTH FROM dt)
did not set their max_length properly, so in the DECIMAL
context they created a too small DECIMAL column, which
led to the 'Out of range value' error.
The problem is that most of these functions historically
returned the signed INT data type.
There were two simple ways to fix these functions:
1. Add +1 to max_length.
But this would also change their size in the string context
and create too long VARCHAR columns, with +1 excessive size.
2. Preserve max_length, but change the data type from INT to INT UNSIGNED.
But this would break backward compatibility.
Also, using UNSIGNED is generally not desirable,
it's better to stay with signed when possible.
This fix implements another solution, which it makes all these functions
work well in all contexts: int, decimal, string.
Fix details:
- Adding a new special class Type_handler_long_ge0 - the data type
handler for expressions which:
* should look like normal signed INT
* but which known not to return negative values
Expressions handled by Type_handler_long_ge0 store in Item::max_length
only the number of digits, without adding +1 for the sign.
- Fixing Item_extract to use Type_handler_long_ge0
for non-negative datetime components:
YEAR, YEAR_MONTH, QUARTER, MONTH, WEEK
- Adding a new abstract class Item_long_ge0_func, for functions
returning non-negative datetime components.
Item_long_ge0_func uses Type_handler_long_ge0 as the type handler.
The class hierarchy now looks as follows:
Item_long_ge0_func
Item_long_func_date_field
Item_func_to_days
Item_func_dayofmonth
Item_func_dayofyear
Item_func_quarter
Item_func_year
Item_long_func_time_field
Item_func_hour
Item_func_minute
Item_func_second
Item_func_microsecond
- Cleanup: EXTRACT(QUARTER FROM dt) created an excessive VARCHAR column
in string context. Changing its length from 2 to 1.
These changes are submitted under the BSD 3-clause License.
The original ticket describes a server crash when using a UDF in the WHERE clause of a view. The crash also happens when using a UDF in the WHERE clause of a SELECT that uses a sub-query in the FROM clause.
When the UDF does not have a _deinit function the server crashes in udf_handler::cleanup (sql/item_func.cc:3467).
When the UDF has both an _init and a _deinit function but _init does not allocate memory for initid->ptr the server crashes in udf_handler::cleanup (sql/item_func.cc:3467).
When the UDF has both an _init and a _deinit function and allocates/deallocates memory for initid->ptr the server crashes in the memory deallocation of the _deinit function.
The sequence of events seen are:
1. A UDF, U, is created for the query.
2. The UDF _init function is called using U->initid.
3. U is cloned for the sub-query using the [default|implicit] copy constructor, resulting in V.
4. The UDF _init function is called using V->initid. U->initid and V->initid are the same value.
5. The UDF function is called.
6. The UDF _deinit function is called using U->initid. If any memory was allocated for initid->ptr it is deallocated here.
7. udf_handler::cleanup deletes the U->buffers String array.
8. The UDF _deinit function is called using V->initid. If any memory was allocated for initid->ptr it was previously deallocated and _deinit crashes the server.
9. udf_handler::cleanup deletes the V->buffers String array. V->buffers was the same values as U->buffers which was already deallocated. The server crashes.
The solution is to create a[n explicit] copy constructor for udf_handler which sets not_original to true. Later, not_original is set back to false (0) after udf_handler::fix_fields has set up a new value for initid->ptr.
This is the follow-up patch that removes explicit use of thd->stmt_arena
for memory allocation and replaces it with call of the method
THD::active_stmt_arena_to_use()
Additionally, this patch adds extra DBUG_ASSERT to check that right
query arena is in use.
The crash happened with an indexed virtual column whose
value is evaluated using a function that has a different meaning
in sql_mode='' vs sql_mode=ORACLE:
- DECODE()
- LTRIM()
- RTRIM()
- LPAD()
- RPAD()
- REPLACE()
- SUBSTR()
For example:
CREATE TABLE t1 (
b VARCHAR(1),
g CHAR(1) GENERATED ALWAYS AS (SUBSTR(b,0,0)) VIRTUAL,
KEY g(g)
);
So far we had replacement XXX_ORACLE() functions for all mentioned function,
e.g. SUBSTR_ORACLE() for SUBSTR(). So it was possible to correctly re-parse
SUBSTR_ORACLE() even in sql_mode=''.
But it was not possible to re-parse the MariaDB version of SUBSTR()
after switching to sql_mode=ORACLE. It was erroneously mis-interpreted
as SUBSTR_ORACLE().
As a result, this combination worked fine:
SET sql_mode=ORACLE;
CREATE TABLE t1 ... g CHAR(1) GENERATED ALWAYS AS (SUBSTR(b,0,0)) VIRTUAL, ...;
INSERT ...
FLUSH TABLES;
SET sql_mode='';
INSERT ...
But the other way around it crashed:
SET sql_mode='';
CREATE TABLE t1 ... g CHAR(1) GENERATED ALWAYS AS (SUBSTR(b,0,0)) VIRTUAL, ...;
INSERT ...
FLUSH TABLES;
SET sql_mode=ORACLE;
INSERT ...
At CREATE time, SUBSTR was instantiated as Item_func_substr and printed
in the FRM file as substr(). At re-open time with sql_mode=ORACLE, "substr()"
was erroneously instantiated as Item_func_substr_oracle.
Fix:
The fix proposes a symmetric solution. It provides a way to re-parse reliably
all sql_mode dependent functions to their original CREATE TABLE time meaning,
no matter what the open-time sql_mode is.
We take advantage of the same idea we previously used to resolve sql_mode
dependent data types.
Now all sql_mode dependent functions are printed by SHOW using a schema
qualifier when the current sql_mode differs from the function sql_mode:
SET sql_mode='';
CREATE TABLE t1 ... SUBSTR(a,b,c) ..;
SET sql_mode=ORACLE;
SHOW CREATE TABLE t1; -> mariadb_schema.substr(a,b,c)
SET sql_mode=ORACLE;
CREATE TABLE t2 ... SUBSTR(a,b,c) ..;
SET sql_mode='';
SHOW CREATE TABLE t1; -> oracle_schema.substr(a,b,c)
Old replacement names like substr_oracle() are still understood for
backward compatibility and used in FRM files (for downgrade compatibility),
but they are not printed by SHOW any more.
- Adding a helper function append_identifier_opt_casedn()
- Reusing it in:
Item_ident::print()
Item_func_nextval::print()
Item_func_setval::print()
This change remove six my_casedn_str() calls and reduces the code size.
Before this patch, the code in Item_field::print() used
this convention (described in sql_explain.h:ExplainDataStructureLifetime):
- By default, the table that Item_field refers to is accessible.
- ANALYZE and SHOW {EXPLAIN|ANALYZE} may print Items after some
temporary tables have been dropped. They use
QT_DONT_ACCESS_TMP_TABLES flag. When it is ON, Item_field::print
will not access the table it refers to, if it is a temp.table
The bug was that EXPLAIN statement also may compute subqueries (depending
on subquery context and @@expensive_subquery_limit setting). After the
computation, the subquery calls JOIN::cleanup(true) which drops some of
its temporary tables. Calling Item_field::print() that refer to such table
will cause an access to free'd memory.
In this patch, we take into account that query optimization can compute
a subquery and discard its temporary tables. Item_field::print() now
assumes that any temporary table might have already been dropped.
This means QT_DONT_ACCESS_TMP_TABLES flag is not needed - we imply it is
always present.
But we also make one exception: derived tables are not freed in
JOIN::cleanup() call. They are freed later in close_thread_tables(),
at the same time when regular tables are closed.
Because of that, Item_field::print may assume that temp.tables
representing derived tables are available.
Initial patch by: Rex Jonston
Reviewed by: Monty <monty@mariadb.org>
On create table tmp as select ... we exited Item_func::fix_fields()
with error. fix_fields_if_needed('foo' or 'bar') failed and we
returned true, but already changed const_item_cache. So the item is in
inconsistent state: fixed == false and const_item_cache == false.
Now we cleanup the item before the return if Item_func::fix_fields()
fails to process.
Change history in the affected code:
- Since 10.4.8 (MDEV-20397 and MDEV-23311), functions ROUND(), CEILING(),
FLOOR() return a TIME value for a TIME input.
- Since 10.4.14 (MDEV-23525), MIN() and MAX() calculate a result for a TIME
input using val_native() rather than val_str().
Problem:
The patch for MDEV-23525 did not take into account combinations like
MIN(ROUND(time)), MAX(FLOOR(time)), etc.
MIN() and MAX() with ROUND(time), CEILING(time), FLOOR(time) as an argument
call the method val_native() of the undelying classes Item_func_round and
Item_func_int_val. However these classes implemented the method val_native()
as DBUG_ASSERT(0).
Fix:
This patch adds a TIME-specific code inside:
- Item_func_round::val_native()
- Item_func_int_val::val_native()
still with DBUG_ASSERT(0) for all other data types,
as other data types do not call val_native() of these classes.
We'll need a more generic solition eventualy, e.g.
turn Item_func_round and Item_func_int_val into Item_handled_func.
However, this change would be too risky for 10.4 at this point.
'long long int'; cast to an unsigned type to negate this value ..
to itself in Item_func_mul::int_op and Item_func_round::int_op
Problems:
The code in multiple places in the following methods:
- Item_func_mul::int_op()
- longlong Item_func_int_div::val_int()
- Item_func_mod::int_op()
- Item_func_round::int_op()
did not properly check for corner values LONGLONG_MIN
and (LONGLONG_MAX+1) before doing negation.
This cuased UBSAN to complain about undefined behaviour.
Fix summary:
- Adding helper classes ULonglong, ULonglong_null, ULonglong_hybrid
(in addition to their signed couterparts in sql/sql_type_int.h).
- Moving the code performing multiplication of ulonglong numbers
from Item_func_mul::int_op() to ULonglong_hybrid::ullmul().
- Moving the code responsible for extracting absolute values
from negative numbers to Longlong::abs().
It makes sure to perform negation without undefinite behavior:
LONGLONG_MIN is handled in a special way.
- Moving negation related code to ULonglong::operator-().
It makes sure to perform negation without undefinite behavior:
(LONGLONG_MAX + 1) is handled in a special way.
- Moving signed<=>unsigned conversion code to
Longlong_hybrid::val_int() and ULonglong_hybrid::val_int().
- Reusing old and new sql_type_int.h classes in multiple
places in Item_func_xxx::int_op().
Fix details (explain how sql_type_int.h classes are reused):
- Instead of straight negation of negative "longlong" arguments
*before* performing unsigned multiplication,
Item_func_mul::int_op() now calls ULonglong_null::ullmul()
using Longlong_hybrid_null::abs() to pass arguments.
This fixes undefined behavior N1.
- Instead of straight negation of "ulonglong" result
*after* performing unsigned multiplication,
Item_func_mul::int_op() now calls ULonglong_hybrid::val_int(),
which recursively calls ULonglong::operator-().
This fixes undefined behavior N2.
- Removing duplicate negating code from Item_func_mod::int_op().
Using ULonglong_hybrid::val_int() instead.
This fixes undefinite behavior N3.
- Removing literal "longlong" negation from Item_func_round::int_op().
Using Longlong::abs() instead, which correctly handler LONGLONG_MIN.
This fixes undefinite behavior N4.
- Removing the duplicate (negation related) code from
Item_func_int_div::val_int(). Reusing class ULonglong_hybrid.
There were no undefinite behavior in here.
However, this change allowed to reveal a bug in
"-9223372036854775808 DIV 1".
The removed negation code appeared to be incorrect when
negating +9223372036854775808. It returned the "out of range" error.
ULonglong_hybrid::operator-() now handles all values correctly
and returns +9223372036854775808 as a negation for -9223372036854775808.
Re-recording wrong results for
SELECT -9223372036854775808 DIV 1;
Now instead of "out of range", it returns -9223372036854775808,
which is the smallest possible value for the expression data type
(signed) BIGINT.
- Removing "no UBSAN" branch from Item_func_splus::int_opt()
and Item_func_minus::int_opt(), as it made UBSAN happy but
in RelWithDebInfo some MTR tests started to fail.
Rewrite datetime comparison conditions into sargeable. For example,
YEAR(col) <= val -> col <= YEAR_END(val)
YEAR(col) < val -> col < YEAR_START(val)
YEAR(col) >= val -> col >= YEAR_START(val)
YEAR(col) > val -> col > YEAR_END(val)
YEAR(col) = val -> col BETWEEN YEAR_START(val) AND YEAR_END(val)
Do the same with DATE(col), for example:
DATE(col) <= val -> col <= DAY_END(val)
After such a rewrite index lookup on column "col" can be employed
This patch is the result of running
run-clang-tidy -fix -header-filter=.* -checks='-*,modernize-use-equals-default' .
Code style changes have been done on top. The result of this change
leads to the following improvements:
1. Binary size reduction.
* For a -DBUILD_CONFIG=mysql_release build, the binary size is reduced by
~400kb.
* A raw -DCMAKE_BUILD_TYPE=Release reduces the binary size by ~1.4kb.
2. Compiler can better understand the intent of the code, thus it leads
to more optimization possibilities. Additionally it enabled detecting
unused variables that had an empty default constructor but not marked
so explicitly.
Particular change required following this patch in sql/opt_range.cc
result_keys, an unused template class Bitmap now correctly issues
unused variable warnings.
Setting Bitmap template class constructor to default allows the compiler
to identify that there are no side-effects when instantiating the class.
Previously the compiler could not issue the warning as it assumed Bitmap
class (being a template) would not be performing a NO-OP for its default
constructor. This prevented the "unused variable warning".
