Post-fix for MDEV-35144.
Cannot allocate options values on the statement arena, because
HA_CREATE_INFO is shallow-copied for every execution, so if the
option_list was initially empty, it will be reset for every execution
and any values allocated on the statement arena will be lost.
Cannot allocate option values on the execution arena, because
HA_CREATE_INFO is shallow-copied for every execution, so if the
option_list was initially NOT empty, any values appended to the
end will be preserved and if they're on the execution arena their
content will be destroyed.
Let's use thd->change_item_tree() to save and restore necessary pointers
for every execution.
followup for 3da565c41d87
Replication of non-transactional engines is experimental and
uses TOI. This naturally means that if there is open transaction
with transactional engine it's changes will be rolled back.
Fixed by adding error message if non-transactional engine
is part of multi-engine transaction with warning.
Signed-off-by: Julius Goryavsky <julius.goryavsky@mariadb.com>
If semi-sync is switched off then on while a transaction is
in-between binlogging and waiting for an ACK, the semi-sync state of
the transaction is removed, leading to a debug assertion that
indicates the transaction tried to wait, but cannot receive an ACK
signal. More specifically, when semi-sync is switched off, the
Active_tranx list is cleared (where a transaction adds an entry to
this list during binlogging), and each entry in this list saves the
thread which will wait for an ACK, and the thread has the COND
variable to signal to wake itself. So if the entry is lost, the
Ack_receiver thread won’t be able to find the thread to wake up when
an ACK comes in
The fix is to ensure that the entry exists before awaiting the ACK,
and if there is no entry, skip the wait. In debug builds, an
informative message is written explaining that the transaction is
skipping its wait. Additional debug-build only logic is added to
ensure that the cause of the missing entry is due to semi-sync being
turned off and on
Reviewed By:
============
Kristian Nielsen <knielsen@knielsen-hq.org>
The problem was that when using clang + asan, we do not get a correct value
for the thread stack as some local variables are not allocated at the
normal stack.
It looks like that for example clang 18.1.3, when compiling with
-O2 -fsanitize=addressan it puts local variables and things allocated by
alloca() in other areas than on the stack.
The following code shows the issue
Thread 6 "mariadbd" hit Breakpoint 3, do_handle_one_connection
(connect=0x5080000027b8,
put_in_cache=<optimized out>) at sql/sql_connect.cc:1399
THD *thd;
1399 thd->thread_stack= (char*) &thd;
(gdb) p &thd
(THD **) 0x7fffedee7060
(gdb) p $sp
(void *) 0x7fffef4e7bc0
The address of thd is 24M away from the stack pointer
(gdb) info reg
...
rsp 0x7fffef4e7bc0 0x7fffef4e7bc0
...
r13 0x7fffedee7060 140737185214560
r13 is pointing to the address of the thd. Probably some kind of
"local stack" used by the sanitizer
I have verified this with gdb on a recursive call that calls alloca()
in a loop. In this case all objects was stored in a local heap,
not on the stack.
To solve this issue in a portable way, I have added two functions:
my_get_stack_pointer() returns the address of the current stack pointer.
The code is using asm instructions for intel 32/64 bit, powerpc,
arm 32/64 bit and sparc 32/64 bit.
Supported compilers are gcc, clang and MSVC.
For MSVC 64 bit we are using _AddressOfReturnAddress()
As a fallback for other compilers/arch we use the address of a local
variable.
my_get_stack_bounds() that will return the address of the base stack
and stack size using pthread_attr_getstack() or NtCurrentTed() with
fallback to using the address of a local variable and user provided
stack size.
Server changes are:
- Moving setting of thread_stack to THD::store_globals() using
my_get_stack_bounds().
- Removing setting of thd->thread_stack, except in functions that
allocates a lot on the stack before calling store_globals(). When
using estimates for stack start, we reduce stack_size with
MY_STACK_SAFE_MARGIN (8192) to take into account the stack used
before calling store_globals().
I also added a unittest, stack_allocation-t, to verify the new code.
Reviewed-by: Sergei Golubchik <serg@mariadb.org>
Implement variable legacy_xa_rollback_at_disconnect to support
backwards compatibility for applications that rely on the pre-10.5
behavior for connection disconnect, which is to rollback the
transaction (in violation of the XA specification).
Signed-off-by: Kristian Nielsen <knielsen@knielsen-hq.org>
Field_blob::store() has special code for GROUP_CONCAT temporary table
(to store blob values in Blob_mem_storage - this prevents them
from being freed/overwritten when a next row is read).
Field_geom and Field_blob_compressed inherit from Field_blob but they
have their own ::store() method without this special Blob_mem_storage
support.
Considering that non-grouping CONCAT() of such fields converts
them to plain BLOB, let's do the same for GROUP_CONCAT. To do it,
Item_func_group_concat::setup will signal that it's creating
a temporary table for GROUP_CONCAT, and Field_blog::make_new_field()
override will create base Field_blob when under group concat.
Fixed by checking handler_stats if it's active instead of
thd->variables.log_slow_verbosity & LOG_SLOW_VERBOSITY_ENGINE.
Reviewed-by: Sergei Petrunia <sergey@mariadb.com>
We have found that my_errno can be "passed" to the next commad in some cases.
It is practically impossible to check/fix all cases of my_errno in the server,
plugins and engines so we will reset it as we reset other errors.
The test case will be fixed by CSV engine fix so will be added with it
(see part2).
(Variant 2b: call greedy_search() twice, correct handling for limited
search_depth)
Modify the join optimizer to specifically try to produce join orders that
can short-cut their execution for ORDER BY..LIMIT clause.
The optimization is controlled by @@optimizer_join_limit_pref_ratio.
Default value 0 means don't construct short-cutting join orders.
Other value means construct short-cutting join order, and prefer it only
if it promises speedup of more than #value times.
In Optimizer Trace, look for these names:
* join_limit_shortcut_is_applicable
* join_limit_shortcut_plan_search
* join_limit_shortcut_choice
(With trivial fixes by sergey@mariadb.com)
Added option fix_innodb_cardinality to optimizer_adjust_secondary_key_costs
Using fix_innodb_cardinality disables the 'divide by 2' of rec_per_key_int
in InnoDB that in effect doubles the Cardinality for secondary keys.
This has the biggest effect for indexes where a few rows has the same key
value. Using this may also cause table scans for very small tables (which
in some cases may be better than an index scan).
The user visible effect is that 'SHOW INDEX FROM table_name' will for
InnoDB show the true Cardinality (and not 2x the real value). It will
also allow the optimizer to chose a better index in some cases as the
division by 2 could have a bad effect for tables with 2-5 identical values
per key.
A few notes about using fix_innodb_cardinality:
- It has direct affect for SHOW INDEX FROM table_name. SHOW INDEX
will also update the statistics in table share.
- The effect of fix_innodb_cardinality for query plans or EXPLAIN
is only visible after first open of the table. This is why one must
do a flush tables or use SHOW INDEX for the option to take effect.
- Using fix_innodb_cardinality can thus affect all user in their query
plans if they are using the same tables.
Because of this, it is strongly recommended that one uses
optimizer_adjust_secondary_key_costs=fix_innodb_cardinality mainly
in configuration files to not cause issues for other users.
Trivial batch, using the handler statistics already collected for
the slow query log.
The reason for the changes in test cases was mainly to change to use
select TABLE_SCHEMA ... from information_schema.table_statistics instead
of 'show table_statistics' to avoid future changes to test results
if we add more columns to table_statistics.
Improve performance of queries like
SELECT * FROM t1 WHERE field = NAME_CONST('a', 4);
by, in this example, replacing the WHERE clause with field = 4
in the case of ref access.
The rewrite is done during fix_fields and we disambiguate this
case from other cases of NAME_CONST by inspecting where we are
in parsing. We rely on THD::where to accomplish this. To
improve performance there, we change the type of THD::where to
be an enumeration, so we can avoid string comparisons during
Item_name_const::fix_fields. Consequently, this patch also
changes all usages of THD::where to conform likewise.
