TABLE DATA IF DUMPS MYSQL DATABA
Problem: If mysqldump is run without --events (or with --skip-events)
it will not dump the mysql.event table's data. This behaviour is inconsistent
with that of --routines option, which does not affect the dumping of
mysql.proc table. According to the Manual, --events (--skip-events) defines,
if the Event Scheduler events for the dumped databases should be included
in the mysqldump output and this has nothing to do with the mysql.event table
itself.
Solution: A warning has been added when mysqldump is used without --events
(or with --skip-events) and a separate patch with the behavioral change
will be prepared for 5.6/trunk.
TABLE DATA IF DUMPS MYSQL DATABA
Problem: If mysqldump is run without --events (or with --skip-events)
it will not dump the mysql.event table's data. This behaviour is inconsistent
with that of --routines option, which does not affect the dumping of
mysql.proc table. According to the Manual, --events (--skip-events) defines,
if the Event Scheduler events for the dumped databases should be included
in the mysqldump output and this has nothing to do with the mysql.event table
itself.
Solution: A warning has been added when mysqldump is used without --events
(or with --skip-events) and a separate patch with the behavioral change
will be prepared for 5.6/trunk.
THREAD POOLING STRESS TEST
PROBLEM:
Connection stress tests which consists of concurrent
kill connections interleaved with mysql ping queries
cause the mysqld server which uses thread pool scheduler
to crash.
FIX:
Killing a connection involves shutdown and close of client
socket and this can cause EPOLLHUP(or EPOLLERR) events to be
to be queued and handled after disarming and cleanup of
of the connection object (THD) is being done.We disarm the
the connection by modifying the epoll mask to zero which
ensure no events come and release the ownership of waiting
thread that collect events and then do the cleanup of THD.
object.As per the linux kernel epoll source code (
http://lxr.linux.no/linux+*/fs/eventpoll.c#L1771), EPOLLHUP
(or EPOLLERR) can't be masked even if we set EPOLL mask
to zero. So we disarm the connection and thus prevent
execution of any query processing handler/queueing to
client ctx. queue by removing the client fd from the epoll
set via EPOLL_CTL_DEL. Also there is a race condition which
involve the following threads:
1) Thread X executing KILL CONNECTION Y and is in THD::awake
and using mysys_var (holding LOCK_thd_data).
2) Thread Y in tp_process_event executing and is being killed.
3) Thread Z receives KILL flag internally and possible call
the tp_thd_cleanup function which set thread session variable
and changing mysys_var.
The fix for the above race is to set thread session variable
under LOCK_thd_data.
We also do not call THD::awake if we found the thread in the
thread list that is to be killed but it's KILL_CONNECTION flag
set thus avoiding any possible concurrent cleanup. This patch
is approved by Mikael Ronstrom via email review.
The patch "mysql-chain-certs.patch" needs to be adapted
to code changes in "vio/viosslfactories.c" which were
done in MySQL 5.5.
Then, the patch can be re-enabled in the spec file.
When a new primary key is added to an InnoDB table, then the following
steps are taken by InnoDB plugin:
. let t1 be the original table.
. a temporary table t1@00231 will be created by cloning t1.
. all data will be copied from t1 to t1@00231.
. rename t1 to t1@00232.
. rename t1@00231 to t1.
. drop t1@00232.
The rename and drop operations involve file operations. But file operations
cannot be rolled back. So in row_merge_rename_tables(), just after doing data
dictionary update and before doing any file operations, generate redo logs
for file operations and commit the transaction. This will ensure that any
crash after this commit, the table is still recoverable by moving .ibd and
.frm files. Manual recovery is required.
During recovery, the rename file operation redo logs are processed.
Previously this was being ignored.
rb://1460 approved by Marko Makela.
Analysis
---------
my_stat() calls stat() and if the stat() call fails we try to set
the variable my_errno which is actually a thread specific data .
We try to get the address of this thread specific data using
my_pthread_getspecifc(),but for the purge thread we have not defined
any thread specific data so it returns null and when dereferencing
null we get a segmentation fault.
init_available_charsets() seen in the core stack is invoked
through pthread_once() .pthread_once is used for one time
initialization.Since free_charsets() is called before innodb plugin
shutdown ,purge thread calls init_avaliable_charsets() which leads
to the crash.
Fix
---
Call free_charsets() after the innodb plugin shutdown,since purge
threads are still using the charsets.
Analysis
---------
my_stat() calls stat() and if the stat() call fails we try to set
the variable my_errno which is actually a thread specific data .
We try to get the address of this thread specific data using
my_pthread_getspecifc(),but for the purge thread we have not defined
any thread specific data so it returns null and when dereferencing
null we get a segmentation fault.
init_available_charsets() seen in the core stack is invoked
through pthread_once() .pthread_once is used for one time
initialization.Since free_charsets() is called before innodb plugin
shutdown ,purge thread calls init_avaliable_charsets() which leads
to the crash.
Fix
---
Call free_charsets() after the innodb plugin shutdown,since purge
threads are still using the charsets.
A change to "vio/viosslfactories.c" in August, 2012,
broke a patch which is to be applied during the build
of ULN RPMs.
The patch file is
"packaging/rpm-uln/mysql-chain-certs.patch"
This change bypasses the problem by not trying to apply
the patch.
This is a regression and must be fixed, not bypassed.
VARIABLES
Analysis:
-------------
After executing the query, new value of the user defined
variables are set in the function "select_dumpvar::send_data".
"select_dumpvar::send_data" first calls function
"Item_func_set_user_var::save_item_result()". This function
checks the nullness of the Item_field passed as parameter
to it and saves it. The nullness of item is stored with
arg[0]'s null_value flag. Then "select_dumpvar::send_data" calls
"Item_func_set_user_var::update()" which notices null
result that was saved and calls "Item_func_set_user_var::
update_hash". But here null_value is not set and args[0]
is different from that given to function "Item_func_set_user_var::
set_item_result()". This causes "Item_func_set_user_var::
update_hash" function to believe that its getting non-null value.
"user_var_entry::length" set to 0 and hence "user_var_entry::value"
is made to point to extra_area allocated in "user_var_entry".
And "Item_func_set_user_var::update_hash" tries to write
at memory beyond extra_area for result type DECIMAL. Because of
this invalid write issue is reported by Valgrind.
Before this bug was introduced, we avoided this problem by
creating "Item_func_set_user_var" object with the same
Item_field as arg[0] and as parameter to
Item_func_set_user_var::save_item_result(). But now
they are refering to different args[0]. Because of this
null_value flag set in parameter Item_field in function
"Item_func_set_user_var::save_item_result()" is not
reflected in "Item_func_set_user_var" object.
Fix:
------------
This issue is reported on versions 5.5.24. Issue does not exists
in 5.5.23, 5.1, 5.6 and trunk.
This issue was introduced by
revid:georgi.kodinov@oracle.com-20120309130449-82e3bs5v3et1x0ef (fix for
bug #12408412), which was pushed into 5.5 and later releases. This patch
has later been reversed in 5.6 and trunk by
revid:norvald.ryeng@oracle.com-20121010135242-xj34gg73h04hrmyh (fix for
bug #14664077). Backported this patch in 5.5 also to fix this issue.
Brief description: After insert some rows to MEMORY table with HASH key some
rows can't be deleted in one step.
Problem Analysis/solution: info->current_ptr will have the information about the
current hash pointer from where we can traverse to the list to get all the
remaining tuples.
In hp_delete_key we are updating info->current_ptr with the last_pos based on
the flag parameter(which is the keydef and last index are same). As part of the
fix we are making it to zero only when the code flow reaches to the end of the
function hp_delete_key() it means that the next record which has to get deleted
will be at the starting of the list so, that in the next call to
read record(heap_rnext()) will take line number 100 path instead of 102 path,
please see the below code in file hp_rnext.c, function heap_rnext().
99 else if (!info->current_ptr) /* Deleted or first call */
100 pos= hp_search(info, keyinfo, info->lastkey, 0);
101 else
102 pos= hp_search(info, keyinfo, info->lastkey, 1);
with that change the hp_search() will update the info->current_ptr with the
record which needs to be deleted.
PROBLEM
-------
optimize on partiton will recreate the whole table
instead of just partition.
ANALYSIS
--------
At present innodb doesn't support optimize option ,so we do a rebuild of the
whole table and then call analyze() on the table.Presently for any optimize()
option (on table or partition) we display the following info to the user
"Table does not support optimize, doing recreate + analyze instead".
FIX
---
It was decided for GA versions(5.1 and 5.5) whenever the user tries to
optimize a partition(s) we will will display the following info the user
"Table does not support optimize on partitions.
All partitions will be rebuilt and analyzed."
Earlier partitions were not analyzed.Now all partitions will be analyzed.
If the user wants to optimize the whole table ,we will display the
previous info to the user. i.e
"Table does not support optimize, doing recreate + analyze instead"
For 5.6+ versions we will raise a new bug to support optimize() options
in innodb.
PROBLEM
-------
optimize on partiton will recreate the whole table
instead of just partition.
ANALYSIS
--------
At present innodb doesn't support optimize option ,so we do a rebuild of the
whole table and then call analyze() on the table.Presently for any optimize()
option (on table or partition) we display the following info to the user
"Table does not support optimize, doing recreate + analyze instead".
FIX
---
It was decided for GA versions(5.1 and 5.5) whenever the user tries to
optimize a partition(s) we will will display the following info the user
"Table does not support optimize on partitions.
All partitions will be rebuilt and analyzed."
Earlier partitions were not analyzed.Now all partitions will be analyzed.
If the user wants to optimize the whole table ,we will display the
previous info to the user. i.e
"Table does not support optimize, doing recreate + analyze instead"
For 5.6+ versions we will raise a new bug to support optimize() options
in innodb.
- improve the logic that decides when ndbcluster should be enabled and the extra
test suites for MySQL Cluster should be added. Should be consistent and logical now ;)
Problem description:
mysql server crashes when we run repair table on currupted table.
Analysis:
The problem with this bug seem to be key_reflength out of bounds
(186 according to debugger). We read this value from meta-data
segment of .MYI file while doing mi_open().
If you look into _mi_kpointer() you can see that the upper limit
for key_reflength is 7.
Solution:
In mi_open() there is a line like:
if (share->base.keystart > 65535 || share->base.rec_reflength > 8)
we should verify key_reflength here as well.
DISABLE AND ENABLED DURING DDL OPERATION
PROBLEM: Same thread trying to acquire the same mutex
second time leads to hang/server crash.
While [un]installing audit_log plugin
a thread acquires the LOCK_plugin mutex
and after successful initialization tries
to write in mysql.plugin table. It holds
this mutex for a long time. If some how
plugin table is corrupted then a write to
plugin table will throw an error, thread try
to log this error in the audit_log plugin,
doing so it tries to acquire the mutex
again and results is server hang/crash.
SOLUTION: Releasing the LOCK_plugin mutex before
writing in mysql.plugin table. We dont
need to hold this mutex as thread already
acquired a TL_WRITE lock on mysql.plugin
table.
TO 'MYISAM_SORT_BUFFER_SIZE'
Problem: 'myisam_sort_buffer_size' is a parameter used by
mysqld program only whereas 'sort_buffer_size' is used by
mysqld and myisamchk programs. But the error message printed
when myisamchk program is run with insufficient buffer size
is myisam_sort_buffer_size is too small which may mislead to the
server parameter myisam_sort_buffer_size.
SOLUTION: A parameter 'myisam_sort_buffer_size' is added as an
alias for 'sort_buffer_size' and the 'sort_buffer_size' parameter
is marked as deprecated. So myisamchk also has both the parameters
with the same role.
TO 'MYISAM_SORT_BUFFER_SIZE'
Problem: 'myisam_sort_buffer_size' is a parameter used by
mysqld program only whereas 'sort_buffer_size' is used by
mysqld and myisamchk programs. But the error message printed
when myisamchk program is run with insufficient buffer size
is myisam_sort_buffer_size is too small which may mislead to the
server parameter myisam_sort_buffer_size.
SOLUTION: A parameter 'myisam_sort_buffer_size' is added as an
alias for 'sort_buffer_size' and the 'sort_buffer_size' parameter
is marked as deprecated. So myisamchk also has both the parameters
with the same role.
main.mysqlbinlog_row_innodb are skipped by mtr
=== Problem ===
The following tests are wrongly placed in main suite and as a
result these are not run with proper binlog format combinations.
Some are always skipped by mtr.
1) mysqlbinlog_row_myisam
2) mysqlbinlog_row_innodb
3) mysqlbinlog_row.test
4) mysqlbinlog_row_trans.test
5) mysqlbinlog-cp932
6) mysqlbinlog2
7) mysqlbinlog_base64
=== Background ===
mtr runs the tests placed in main suite with binlog format=stmt.
Those that need to be tested against binlog format=row or mixed
or more than one binlog format and require only one mysql server
are placed in binlog suite. mtr runs tests in binlog suite with
all three binlog formats(stmt,row and mixed).
=== Fix ===
1) Moved the test listed in problem section above to binlog suite.
2) Added prefix "binlog_" to the name of each test case moved.
Renamed the coresponding result files and option files accordingly.
IN ALTER TABLE ... ADD UNIQUE KEY
A bogus debug assertion failure occurred when reporting a duplicate
key on a column prefix of a CHAR column.
This is a regression from Bug#14729221 IN-PLACE ALTER TABLE REPORTS ''
INSTEAD OF REAL DUPLICATE VALUE FOR PREFIX KEYS. The assertion is only
present when UNIV_DEBUG is defined (which it is in debug builds
starting from MySQL 5.5). It is a case of overasserting.
Fix approved by Inaam Rana on IM.
