SLOW/CRASHES SEMAPHORE

Problem:

There are 2 lakh tables - fk_000001, fk_000002 ... fk_200000.  All of them
are related to the same parent_table through a foreign key constraint.
When the parent_table is loaded into the dictionary cache, all the child table
will also be loaded.  This is taking lot of time.  Since this operation happens
when the dictionary latch is taken, the scenario leads to "long semaphore wait"
situation and the server gets killed.

Analysis:

A simple performance analysis showed that the slowness is because of the
dict_foreign_find() function.  It does a linear search on two linked list
table->foreign_list and table->referenced_list, looking for a particular
foreign key object based on foreign->id as the key.  This is called two
times for each foreign key object.

Solution:

Introduce a rb tree in table->foreign_rbt and table->referenced_rbt, which
are some sort of index on table->foreign_list and table->referenced_list
respectively, using foreign->id as the key.  These rbt structures will be
solely used by dict_foreign_find().  

rb#5599 approved by Vasil

For charsets with no binary collation: use my_charset_bin.

                                IN
                                SSL_CTX_LOAD_VERIFY_
                                LOCATIONS()
                                and
                                OFF-BY-ONE PROBLEM IN
                                VOID CERTDECODER::
                                GETDATE(DATETYPE DT)
                                IN ASN.CPP

Description : Fixes corner cases in yassl code.
              Refer to bug page for details.

Item_func_ltrim::val_str did not handle multibyte charsets.
Fix: factor out common code for Item_func_trim and Item_func_ltrim.

              MYSQLADMIN IN PROCESSES LIST

Description: Checking the process status (with ps -ef)  
while executing "mysqladmin" with old password and new 
password via command-line will show the new password in the
process list sporadically.

Analysis: The old password is being masked by "mysqladmin".
So masking the new password in the similar manner would 
reduce hitting the bug. But this would not completely fix
the bug, because if "ps -ef " command hits the mysqladmin
before it masks the passwords it will show both the old and
new passwords in the process list. But the chances of
hitting this is very less.

Fix: The new password also masked in the similar manner
that of the --password argument.

Problem:
Load_log_event::print_query() function does not put escape character in file name 
for "LOAD DATA INFILE" statement.

Analysis:
When we have "'" in our file name for "LOAD DATA INFILE" statement,
Load_log_event::print_query() function does not put escape character 
in our file name.

This one result that when we show binary-log, we get file name without 
escape character.

Solution:
To put escape character when we have "'" in file name, for this instead of using 
simple memcpy() to put file-name, we will use pretty_print_str().

               "HAVING SUM(DISTINCT)": WRONG RESULTS.
ISSUE:
------
If a query uses loose index scan and it has both
AGG(DISTINCT) and MIN()/MAX()functions. Then, result values
of MIN/MAX() is set improperly.
When query has AGG(DISTINCT) then end_select is set to
end_send_group. "end_send_group" keeps doing aggregation
until it sees a record from next group. And, then it will
send out the result row of that group.
Since query also has MIN()/MAX() and loose index scan is
used, values of MIN/MAX() are set as part of loose index
scan itself. Setting MIN()/MAX() values as part of loose
index scan overwrites values computed in end_send_group.
This caused invalid result.
For such queries to work loose index scan should stop
performing MIN/MAX() aggregation. And, let end_send_group to
do the same. But according to current design loose index
scan can produce only one row per group key. If we have both
MIN() and MAX() then it has to give two records out. This is
not possible as interface has to use common buffer
record[0]! for both records at a time.

SOLUTIONS:
----------
For such queries to work we need a new interface for loose
index scan. Hence, do not choose loose_index_scan for such
cases. So a new rule SA7 is introduced to take care of the
same.

SA7: "If Q has both AGG_FUNC(DISTINCT ...) and
      MIN/MAX() functions then loose index scan access
      method is not used."

mysql-test/r/group_min_max.result:
  Expected result.
mysql-test/t/group_min_max.test:
  1. Test with various combination of AGG(DISTINCT) and
  MIN(), MAX() functions.
  2. Corrected the plan for old queries.
sql/opt_range.cc:
  A new rule SA7 is introduced.

Bug #18382225 MYSQL_CONFIG CAN'T HANDLE RELOCABLE PACKAGES THAT USES "LIB64" OR "-64" SUFFIX
  
'lib' is hardcoded into mysql_config, so 'cmake -DINSTALL_LIBDIR=lib64' will not work.
Use INSTALL_LIBDIR when generating mysql_config.
  
mysql_config may be renamed to e.g. mysql_config-32, fix the basedir pattern matching.

SHOW PROCESSLIST, SHOW BINLOGS

Fixing post push test failure (MTR does not like giving
127.0.0.1 for localhost incase of --embedded run, it thinks
it is an external ip address)

SHOW PROCESSLIST, SHOW BINLOGS

Problem:  A deadlock was occurring when 4 threads were
involved in acquiring locks in the following way
Thread 1: Dump thread ( Slave is reconnecting, so on
              Master, a new dump thread is trying kill
              zombie dump threads. It acquired thread's
              LOCK_thd_data and it is about to acquire
              mysys_var->current_mutex ( which LOCK_log)
Thread 2: Application thread is executing show binlogs and
               acquired LOCK_log and it is about to acquire
               LOCK_index.
Thread 3: Application thread is executing Purge binary logs
               and acquired LOCK_index and it is about to
               acquire LOCK_thread_count.
Thread 4: Application thread is executing show processlist
               and acquired LOCK_thread_count and it is
               about to acquire zombie dump thread's
               LOCK_thd_data.
Deadlock Cycle:
     Thread 1 -> Thread 2 -> Thread 3-> Thread 4 ->Thread 1

The same above deadlock was observed even when thread 4 is
executing 'SELECT * FROM information_schema.processlist' command and
acquired LOCK_thread_count and it is about to acquire zombie
dump thread's LOCK_thd_data.

Analysis:
There are four locks involved in the deadlock.  LOCK_log,
LOCK_thread_count, LOCK_index and LOCK_thd_data.
LOCK_log, LOCK_thread_count, LOCK_index are global mutexes
where as LOCK_thd_data is local to a thread.
We can divide these four locks in two groups.
Group 1 consists of LOCK_log and LOCK_index and the order
should be LOCK_log followed by LOCK_index.
Group 2 consists of other two mutexes
LOCK_thread_count, LOCK_thd_data and the order should
be LOCK_thread_count followed by LOCK_thd_data.
Unfortunately, there is no specific predefined lock order defined
to follow in the MySQL system when it comes to locks across these
two groups. In the above problematic example,
there is no problem in the way we are acquiring the locks
if you see each thread individually.
But If you combine all 4 threads, they end up in a deadlock.

Fix: 
Since everything seems to be fine in the way threads are taking locks,
In this patch We are changing the duration of the locks in Thread 4
to break the deadlock. i.e., before the patch, Thread 4
('show processlist' command) mysqld_list_processes()
function acquires LOCK_thread_count for the complete duration
of the function and it also acquires/releases
each thread's LOCK_thd_data.

LOCK_thread_count is used to protect addition and
deletion of threads in global threads list. While show
process list is looping through all the existing threads,
it will be a problem if a thread is exited but there is no problem
if a new thread is added to the system. Hence a new mutex is
introduced "LOCK_thd_remove" which will protect deletion
of a thread from global threads list. All threads which are
getting exited should acquire LOCK_thd_remove
followed by LOCK_thread_count. (It should take LOCK_thread_count
also because other places of the code still thinks that exit thread
is protected with LOCK_thread_count. In this fix, we are changing
only 'show process list' query logic )
(Eg: unlink_thd logic will be protected with
LOCK_thd_remove).

Logic of mysqld_list_processes(or file_schema_processlist)
will now be protected with 'LOCK_thd_remove' instead of
'LOCK_thread_count'.

Now the new locking order after this patch is:
LOCK_thd_remove -> LOCK_thd_data -> LOCK_log ->
LOCK_index -> LOCK_thread_count

ISSUE:
------
For UNION of selects, rows examined by the query will be sum
of rows examined by individual select operations and rows
examined for union operation. The value of session level
global counter that is used to count the rows examined by a
select statement should be accumulated and reset before it
is used for next select statement. But we have missed to
reset the same. Because of this examined row count of a
select query is accounted more than once.

SOLUTION:
---------
In union reset the session level global counter used to
accumulate count of examined rows after its value is saved.

mysql-test/r/union.result:
  Expected output of testcase added.
mysql-test/t/union.test:
  Test to verify examined row count of Union operations.
sql/sql_union.cc:
  Reset the value of thd->examined_row_count after
  accumulating the value.

Description: Using the temporary file vulnerability an
attacker can create a file with arbitrary content at a
location of his choice. This can be used to create the
file /var/lib/mysql/my.cnf, which will be read as a
configuration file by MySQL, because it is located in the
home directory of the mysql user. With this configuration
file, the attacker can specify his own plugin_dir variable,
which then allows him to load arbitrary code via
"INSTALL PLUGIN...".

Analysis: While creating the ".TMD" file we are not checking
if the file is already exits or not in mi_repair() function.
And we are truncating if the ".TMD" file exits and going ahead
This is creating the security breach.

Fix: We need to use O_EXCL flag along with O_RDWR and O_TRUNC
which will make sure if any user creates ".TMD" file, will
fails the repair table with "cannot create ".TMD" file error".
Actually we are initialing "param.tmpfile_createflag" member
with O_RDWR | O_TRUNC | O_EXCL in myisamchk_init(). And we
are modifying it in ha_myisam::repair() to O_RDWR | O_TRUNC.
So, we need to remove the line which is modifying the
"param.tmpfile_createflag".

Bug#18187290 ISSUE WITH BUILDING MYSQL USING CMAKE 2.8.12

We want to upgrade to VS2013 on Windows.
In order to do this, we need to upgrade to cmake 2.8.12
This has introduced some incompatibilities for .pdb files,
and "make install" no longer works.

To reproduce:
  cmake --build . --target package --config debug

The fix:
Rather than installing .pdb files for static libraries, we use the /Z7 flag
to store symbolic debugging information in the .obj files.

Problem:
If there is a predicate on a column referenced by MIN/MAX and
that predicate is not present in all the disjunctions on
keyparts earlier in the compound index, Loose Index Scan will
not return correct result.

Analysis:
When loose index scan is chosen, range optimizer currently
groups all the predicates that contain group parts separately
and minmax parts separately. It therefore applies all the
conditions on the group parts first to the fetched row.
Then in the call to next_max, it processes the conditions
which have min/max keypart.

For ex in the following query:
Select f1, max(f2) from t1 where (f1 = 10 and f2 = 13) or
(f1 = 3) group by f1;
Condition (f2 = 13) would be applied even for rows that
satisfy (f1 = 3) thereby giving wrong results.

Solution:
Do not choose loose_index_scan for such cases. So a new rule
WA2 is introduced to take care of the same.

WA2: "If there are predicates on C, these predicates must
be in conjuction to all predicates on all earlier keyparts
in I."

Todo the same, fix reuses the function get_constant_key_infix().
Since this funciton will fail for all multi-range conditions, it
is re-written to recognize that if the sub-conditions are
equivalent across the disjuncts: it will now succeed.
And to achieve this a new helper function is introduced called
all_same().

The fix also moves the test of NGA3 up to the former only
caller, get_constant_key_infix().


mysql-test/r/group_min_max_innodb.result:
  Added test result change for Bug#17909656
mysql-test/t/group_min_max_innodb.test:
  Added test cases for Bug#17909656
sql/opt_range.cc:
  Introduced Rule WA2 because of Bug#17909656

Fixing post push failure

Typo leading to not including the last list values (partition).

Also improved pruning to skip last partition if not used.

rb#4762 approved by Aditya and Marko.

Fixing post push failure

Problem: Uninstallation of semi sync plugin causes replication to
break.

Analysis: A semisync enabled replication is mutual agreement between
Master and Slave when the connection (I/O thread) is established.
Once I/O thread is started and if semisync is enabled on both
master and slave, master appends special magic header to events
using semisync plugin functions and sends it to slave. And slave
expects that each event will have that special magic header format
and reads those bytes using semisync plugin functions.

When semi sync replication is in use if users execute
uninstallation of the plugin on master, slave gets confused while
interpreting that event's content because it expects special 
magic header at the beginning of the event. Slave SQL thread will
be stopped with "Missing magic number in the header" error.

Similar problem will happen if uninstallation of the plugin happens
on slave when semi sync replication is in in use. Master sends
the events with magic header and slave does not know about the
added magic header and thinks that it received a corrupted event.
Hence slave SQL thread stops with "Found  corrupted event" error.

Fix: Uninstallation of semisync plugin will be blocked when semisync
replication is in use and will throw 'ER_UNKNOWN_ERROR' error.
To detect that semisync replication is in use, this patch uses
semisync status variable values.
 > On Master, it checks for 'Rpl_semi_sync_master_status' to be OFF
    before allowing the uninstallation of rpl_semi_sync_master plugin.
    >> Rpl_semi_sync_master_status is OFF when
        >>> there is no dump thread running
        >>> there are no semisync slaves
 > On Slave, it checks for 'Rpl_semi_sync_slave_status' to be OFF
    before allowing the uninstallation of rpl_semi_sync_slave plugin.
    >> Rpl_semi_sync_slave_status is OFF when
       >>> there is no I/O thread running
       >>> replication is asynchronous replication.

Bug #18593044 COMPILE FLAGS NOT PASSED TO DTRACE, BREAKS CROSS BUILD

ARE PERMANENTLY SKIPPED IN 5.5/5.6).

The problem was that some result files were not updated,
so the tests were skipped.

The fix is to record updated result files.

               WHERE ONE OF SELECT* IS DISTINCT FAILS.
ISSUE:
------
There are 2 issues related to explain union.
1. If we have subquery with union of selects. And, one of
   the select need temp table to materialize its results
   then it will replace its query structure with a simple
   select from temporary table. Trying to display new
   internal temporary table scan resulted in crash. But to
   display the query plan, we should save the original
   query structure.
2. Multiple execution of prepared explain statement which
   have union of subqueries resulted in crash. If we have
   constant subqueries, fake select used in union operation
   will be evaluated once before using it for explain.
   During first execution we have set fake select options to
   SELECT_DESCRIBE, but did not reset after the explain.
   Hence during next execution of prepared statement during
   first time evaluation of fake select we had our select
   options as SELECT_DESCRIBE this resulted in improperly
   initialized data structures and crash.

SOLUTION:
---------
1. If called by explain now we save the original query
   structure. And this will be used for displaying.
2. Reset the fake select options after it is called for
   explain of union.

sql/sql_select.cc:
  Reset the fake select options after it is called for explain of union
sql/sql_union.cc:
  If called by explain but not from select_describe and we
  need a temp table, then we create a temp join to preserve
  original query structure.

              BREAKS RBR

Analysis:
--------
A table created using a query of the format:
CREATE TABLE t1 AS SELECT REPEAT('A',1000) DIV 1 AS a;
breaks the Row Based Replication.

The query above creates a table having a field of datatype
'bigint' with a display width of 3000 which is beyond the
maximum acceptable value of 255.

In the RBR mode, CREATE TABLE SELECT statement is
replicated as a combination of CREATE TABLE statement
equivalent to one the returned by SHOW CREATE TABLE and
row events for rows inserted. When this CREATE TABLE event
is executed on the slave, an error is reported:
Display width out of range for column 'a' (max = 255)

The following is the output of 'SHOW CREATE TABLE t1':
CREATE TABLE t1(`a` bigint(3000) DEFAULT NULL)
                  ENGINE=InnoDB DEFAULT CHARSET=latin1;

The problem is due to the combination of two facts:

1) The above CREATE TABLE SELECT statement uses the display
   width of the result of DIV operation as the display width
   of the column created without validating the width for out
   of bound condition.
2) The DIV operation incorrectly returns the length of its first
   argument as the display width of its result; thus allowing
   creation of a table with an incorrect display width of 3000
   for the field.

Fix:
----
This fix changes the DIV operation implementation to correctly
evaluate the display width of its result. We check if DIV's
results estimated width crosses maximum width for integer
value (21) and if yes set it to this maximum value.

This patch also fixes fixes maximum display width evaluation
for DIV function when its first argument is in UCS2.

- Upgrade from MySQL-* packages
- Fix Cflags for el7

              INTO CLIENT_ERRORS ARRAY
              
Analysis:
--------
The client may crash while executing a statement due to
the missing mapping of the server error to it's equivalent
client error.

When trying to reallocate memory for the packet buffer, if
the system is out of memory or the packet buffer is large,
the server errors 'ER_OUT_OF_RESOURCES' or 'ER_PACKET_TOO_LARGE'
is returned respectively. The client error number calculated is
negative and when trying to dereference the array of client 
error messages with the calculated error number, the client
crashes.

Fix:
----
Map the server error returned to it's equivalent client error
prior to dereferencing the array of client error messages.

Note: Test case is not added since it is difficult to simulate
the error condition.

  Bug#18396916 MAIN.OUTFILE_LOADDATA TEST FAILS ON ARM, AARCH64, PPC/PPC64
  
  The recorded results for the failing tests were wrong.
  They were introduced by the patch for
  Bug#30946 mysqldump silently ignores --default-character-set when used with --tab
  
  Correct results were returned for platforms where 'char' is implemented as unsigned.
  This was reported as 
  Bug#46895 Test "outfile_loaddata" fails (reproducible)
  Bug#11755168 46895: TEST "OUTFILE_LOADDATA" FAILS (REPRODUCIBLE)
  The patch for that bug fixed only parts of the problem,
  leaving the incorrect results in the .result file.
  
  Solution: use 'uchar' for field_terminator and line_terminator on all platforms.
  Also: remove some un-necessary casts, leaving the ones we actually need.

It is error to call mysql_thread_init() before libmysql is initialized with mysql_library_init(). Thus to fix this bug we need to detect if library was initialized and return error result if mysql_thread_init() is called with uninitialized library.

Fixed by checking my_thread_global_init_done and returning nonzero if the library is not initialized.

When there is no connection mysql_get_server_version() will return 0
and report CR_COMMANDS_OUT_OF_SYNC error.

WRITTEN WHILE ROWS REMAINS

Problem:
========
When truncate table fails while using transactional based
engines even though the operation errors out we still
continue and log it to binlog. Because of this master has
data but the truncate will be written to binary log which
will cause inconsistency.

Analysis:
========
Truncate table can happen either through drop and create of
table or by deleting rows. In the second case the existing
code is written in such a way that even if an error occurs
the truncate statement will always be binlogged. Which is not
correct.

Binlogging of TRUNCATE TABLE statement should check whether
truncate is executed "transactionally or not". If the table
is transaction based we log the TRUNCATE TABLE only on
successful completion.

If table is non transactional there are possibilities that on
error we could have partial changes done hence in such cases
we do log in spite of errors as some of the lines might have
been removed, so the statement has to be sent to slave.

Fix:
===
Using table handler whether truncate table is being executed
in transaction based mode or not is identified and statement
is binlogged accordingly.

mysql-test/suite/binlog/r/binlog_truncate_kill.result:
  Added test case to test the fix for Bug#17942050.
mysql-test/suite/binlog/t/binlog_truncate_kill.test:
  Added test case to test the fix for Bug#17942050.
sql/sql_truncate.cc:
  Check if truncation is successful or not and retun appropriate
  return values so that binlogging can be done based on that.
sql/sql_truncate.h:
  Added a new enum.

Removed unused variable.
Fixed long (>80 lines)

The problem was in the validation of the input data for blob types.
When assigned binary data, the character blob types were only checking if 
the length of these data is a multiple of the minimum char length for the 
destination charset. 
And since e.g. UTF-8's minimum character length is 1 (becuase it's 
variable length) even byte sequences that are invalid utf-8 strings (e.g. 
wrong leading byte etc) were copied verbatim into utf-8 columns when
coming from binary strings or fields.
Storing invalid data into string columns was having all kinds of ill effects 
on code that assumed that the encoding data are valid to begin with.

Fixed by additionally checking the incoming binary string for validity when 
assigning it to a non-binary string column.
Made sure the conversions to charsets with no known "invalid" ranges 
are not covered by the extra check.
Removed trailing spaces.

Test case added.

archive table which is using an auto increment column, the
server hangs. In order to recover the mysqld process, it
has to be terminated abnormally using SIGKILL. The problem
is observed in mysql-5.5.
Bug #18065452 "PREPARING" STATE HOGS CPU WITH ARCHIVE
               + SUBQUERY

Analysis: This happens because the server is trapped inside
an infinite loop in the function,
"subselect_indexsubquery_engine::exec()". This function
resolves the correlated suquery by doing an index lookup
for the appropriate engine. In  case of archive engine,
after reaching the end of records, "table->status" is not
set to STATUS_NOT_FOUND. As a result the loop is not 
terminated.

Fix: The "table->status" is set to STATUS_NOT_FOUND when
the end of records is reached.