The leaks are all 40 bytes and happens in this call stack when running
mtr vcol.vcol_syntax:
alloc_root()
...
Virtual_column_info::fix_and_check_exp()
...
Delayed_insert::get_local_table()
The problem was that one copied a MEM_ROOT from THD to a TABLE without
taking into account that new blocks would be allocated through the
TABLE memroot (and would thus be leaked).
In general, one should NEVER copy MEM_ROOT from one object to another
without clearing the copied memroot!
Fixed by, at end of get_local_table(), copy all new allocated objects
to client_thd->mem_root.
Other things:
- Removed references to MEM_ROOT::total_alloc that was wrongly left
after a previous commit
move MYSQL::fields down, replacing MYSQL::unused5
this way only MYSQL::fields and MYSQL::field_alloc will still have
different offset in C/C and the server, but all other MYSQL members
will get back in sync.
luckily, plugins shouldn't need MYSQL::fields or MYSQL::field_alloc
added a check to ensure both MYSQL structures are always of
the same size.
To allow cmake -DWITH_ASAN=ON to work out of the box when using
newer compilers, we must increase the default thread stack size.
By design, AddressSanitizer will allocate some "sentinel" areas in
stack frames so that it can better catch buffer overflows, by trapping
access to memory addresses that reside between stack-allocated variables.
Apparently, some parameters related to this have been changed
recently, possibly to allow -fsanitize=address to catch more errors.
When computing vcol expression some items use current_thd and that was
not set in MyISAM repair thread. Since all the repair threads belong
to one connection and items should not write into THD we can utilize
table THD for that.
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.
Also fixes: MDEV-30050 Inconsistent results of DISTINCT with NOPAD
Problem:
Key segments for CHAR columns where compared using strnncollsp()
for engines MyISAM and Aria.
This did not work correct in case if the engine applyied trailing
space compression.
Fix:
Replacing ha_compare_text() calls to new functions:
- ha_compare_char_varying()
- ha_compare_char_fixed()
- ha_compare_word()
- ha_compare_word_prefix()
- ha_compare_word_or_prefix()
The code branch corresponding to comparison of CHAR column keys
(HA_KEYTYPE_TEXT segment type) now uses ha_compare_char_fixed()
which calls strnncollsp_nchars().
This patch does not change the behavior for the rest of the code:
- comparison of VARCHAR/TEXT column keys
(HA_KEYTYPE_VARTEXT1, HA_KEYTYPE_VARTEXT2 segments types)
- comparison in the fulltext code
(Variant#3: Allow cross-charset comparisons, use a special
CHARSET_INFO to create lookup keys. Review input addressed.)
Equalities that compare utf8mb{3,4}_general_ci strings, like:
WHERE ... utf8mb3_key_col=utf8mb4_value (MB3-4-CMP)
can now be used to construct ref[const] access and also participate
in multiple-equalities.
This means that utf8mb3_key_col can be used for key-lookups when
compared with an utf8mb4 constant, field or expression using '=' or
'<=>' comparison operators.
This is controlled by optimizer_switch='cset_narrowing=on', which is
OFF by default.
IMPLEMENTATION
Item value comparison in (MB3-4-CMP) is done using utf8mb4_general_ci.
This is valid as any utf8mb3 value is also an utf8mb4 value.
When making index lookup value for utf8mb3_key_col, we do "Charset
Narrowing": characters that are in the Basic Multilingual Plane (=BMP) are
copied as-is, as they can be represented in utf8mb3. Characters that are
outside the BMP cannot be represented in utf8mb3 and are replaced
with U+FFFD, the "Replacement Character".
In utf8mb4_general_ci, the Replacement Character compares as equal to any
character that's not in BMP. Because of this, the constructed lookup value
will find all index records that would be considered equal by the original
condition (MB3-4-CMP).
Approved-by: Monty <monty@mariadb.org>
The MDEV-29693 conflict resolution is from Monty, as well as is
a bug fix where ANALYZE TABLE wrongly built histograms for
single-column PRIMARY KEY.
Also includes a fix for safe_malloc error reporting.
Other things:
- Copied main.log_slow from 10.4 to avoid mtr issue
Disabled test:
- spider/bugfix.mdev_27239 because we started to get
+Error 1429 Unable to connect to foreign data source: localhost
-Error 1158 Got an error reading communication packets
- main.delayed
- Bug#54332 Deadlock with two connections doing LOCK TABLE+INSERT DELAYED
This part is disabled for now as it fails randomly with different
warnings/errors (no corruption).
Raise notes if indexes cannot be used:
- in case of data type or collation mismatch (diferent error messages).
- in case if a table field was replaced to something else
(e.g. Item_func_conv_charset) during a condition rewrite.
Added option to write warnings and notes to the slow query log for
slow queries.
New variables added/changed:
- note_verbosity, with is a set of the following options:
basic - All old notes
unusable_keys - Print warnings about keys that cannot be used
for select, delete or update.
explain - Print unusable_keys warnings for EXPLAIN querys.
The default is 'basic,explain'. This means that for old installations
the only notable new behavior is that one will get notes about
unusable keys when one does an EXPLAIN for a query. One can turn all
of all notes by either setting note_verbosity to "" or setting sql_notes=0.
- log_slow_verbosity has a new option 'warnings'. If this is set
then warnings and notes generated are printed in the slow query log
(up to log_slow_max_warnings times per statement).
- log_slow_max_warnings - Max number of warnings written to
slow query log.
Other things:
- One can now use =ALL for any 'set' variable to set all options at once.
For example using "note_verbosity=ALL" in a config file or
"SET @@note_verbosity=ALL' in SQL.
- mysqldump will in the future use @@note_verbosity=""' instead of
@sql_notes=0 to disable notes.
- Added "enum class Data_type_compatibility" and changing the return type
of all Field::can_optimize*() methods from "bool" to this new data type.
Reviewer & Co-author: Alexander Barkov <bar@mariadb.com>
- The code that prints out the notes comes mainly from Alexander
This patch adds support for controlling of memory allocation
done by SP/PS that could happen on second and following executions.
As soon as SP or PS has been executed the first time its memory root
is marked as read only since no further memory allocation should
be performed on it. In case such allocation takes place it leads to
the assert hit for invariant that force no new memory allocations
takes place as soon as the SP/PS has been marked as read only.
The feature for control of memory allocation made on behalf SP/PS
is turned on when both debug build is on and the cmake option
-DWITH_PROTECT_STATEMENT_MEMROOT is set.
The reason for introduction of the new cmake option
-DWITH_PROTECT_STATEMENT_MEMROOT
to control memory allocation of second and following executions of
SP/PS is that for the current server implementation there are too many
places where such memory allocation takes place. As soon as all such
incorrect allocations be fixed the cmake option
-DWITH_PROTECT_STATEMENT_MEMROOT
can be removed and control of memory allocation made on second and
following executions can be turned on only for debug build. Before
every incorrect memory allocation be fixed it makes sense to guard
the checking of memory allocation on read only memory by extra cmake
option else we would get a lot of failing test on buildbot.
Moreover, fixing of all incorrect memory allocations could take pretty
long period of time, so for introducing the feature without necessary
to wait until all places throughout the source code be fixed it makes
sense to add the new cmake option.
