The semisync code does a fast-but-unsafe check for enabled or not without lock,
followed by a slow-but-safe check under lock. However, if the slow check failed,
the code still referenced not valid data (in an assert() expression), causing a
crash.

Fixed by not running the incorrect assert when semisync is disabled.

This is XtraDB bug lp:1015109, introduced by innodb_split_buf_pool_mutex.patch

Comment the offending assertion, until the fixed XtraDB is available

MySQL introduced a class Deferred_log_events. This class keeps a pointer
last_added. The code was keeping this pointer around even after the memory
pointed to was freed, and later comparing the bogus pointer against other
allocated memory. This is illegal, and can randomly produce false equal
comparisons depending on whatever the malloc() subsystem decides to return.

- put back the result encoding in func_in.result (messed up by kdiff3)
- update .result for other tests (checked)

Attempt to make it easier to upgrade mysql->mariadb on Ubuntu precise.
It looks like we were missing conflicts: and replaces: on packages
mysql-server-5.5 and mysql-client-5.5.

make sure that find_date_time_item() is called before agg_arg_charsets_for_comparison().
optimize Item_func_conv_charset to avoid conversion if no string result is needed

On localized Windows versions, Windows uses localized time zone names and contain non-ASCII characters.  non-ASCII characters appear broken when displayed by clients
The fix is to declare system_time_zone variable to have UTF8 encoding and to convert tzname to UTF8.

mysql-test/suite/sphinx/sphinx.result:
  Removed sphinx_time, as it was depending on timing.
mysql-test/suite/sphinx/sphinx.test:
  Removed sphinx_time, as it was depending on timing.

mysqldump with --include-master-host-port putting quotes around port number
Patch from Stewart Smith

client/mysqldump.c:
  Remove quotes from MASTER_PORT

Fixed MDEV-306 / LP:1007967 - Assertion `table->file->stats.records > 0 || error' failed join_read_const_table on concurrent SELECT and DROP/ADD INDEX


sql/sql_table.cc:
  Added comment
storage/maria/ma_close.c:
  Don't store history if it's visible to all.
  This fixed the MDEV-306 bug
storage/maria/ma_delete_table.c:
  Removed old comment
  Delete history state for deleted tables
storage/maria/ma_info.c:
  More DBUG_PRINT
storage/maria/ma_open.c:
  More DBUG_PRINT

Analysis:
The fix for bug lp:985667 implements the method Item_subselect::no_rows_in_result()
for all main kinds of subqueries. The purpose of this method is to be called from
return_zero_rows() and set Items to some default value in the case when a query
returns no rows. Aggregates and subqueries require special treatment in this case.

Every implementation of Item_subselect::no_rows_in_result() called
Item_subselect::make_const() to set the subquery predicate to its default value
irrespective of where the predicate was located in the query. Once the predicate
was set to a constant it was never executed.

At the same time, the JOIN object of the fake select for UNIONs (the one used for
the final result of the UNION), was set after all subqueries in the union were
executed. Since we set the subquery as constant, it was never executed, and the
corresponding JOIN was never created.

In order to decide whether the result of NOT IN is NULL or FALSE, Item_in_optimizer
needs to check if the subquery result was empty or not. This is where we got the
crash, because subselect_union_engine::no_rows() checks for
unit->fake_select_lex->join->send_records, and the join object was NULL.

Solution:
If a subquery is in the HAVING clause it must be evaluated in order to know its
result, so that we can properly filter the result records. Once subqueries in the
HAVING clause are executed even in the case of no result rows, this specific
crash will be solved, because the UNION will be executed, and its JOIN will be
constructed. Therefore the fix for this crash is to narrow the fix for lp:985667,
and to apply Item_subselect::no_rows_in_result() only when the subquery predicate
is in the SELECT clause.

Percona-Server 5.5.24-rel26.0

The class Item_func missed an implementation of the virtual 
function update_null_value.
Back-ported the fix for bug 62125 from mysql 5.6 code line.
The test case was also back-ported. 

Analysis:
Queries with implicit grouping (there is aggregate, but no group by)
follow some non-obvious semantics in the case of empty result set.
Aggregate functions produce some special "natural" value depending on
the function. For instance MIN/MAX return NULL, COUNT returns 0.

The complexity comes from non-aggregate expressions in the select list.
If the non-aggregate expression is a constant, it can be computed, so
we should return its value, however if the expression is non-constant,
and depends on columns from the empty result set, then the only meaningful
value is NULL.

The cause of the wrong result was that for subqueries the optimizer didn't
make a difference between constant and non-constant ones in the case of
empty result for implicit grouping.

Solution:
In all implementations of Item_subselect::no_rows_in_result() check if the
subquery predicate is constant. If it is constant, do not set it to the
default value for implicit grouping, instead let it be evaluated.

One of the reported problems manifested itself in the scenario when one
thread tried to to get statistics on a key cache while the second thread
had not finished initialization of the key cache structure yet. 
The problem was resolved by forcing serialization of such operations
on key caches.

To serialize function calls to perform certain operations over a key cache
a new mutex associated with the key cache now is used. It is stored in the
field op_lock of the KEY_CACHE structure. It is locked when the operation
is performed. Some of the serialized key cache operations utilize calls 
for other key cache operations. To avoid recursive locking of op_lock
the new functions that perform the operations of key cache initialization,
destruction and re-partitioning with an additional parameter were introduced.
The parameter says whether the operation over op_lock are to be performed or
are to be omitted. The old functions for the operations of key cache 
initialization, destruction,and  re-partitioning  now just call the
corresponding new functions with the additional parameter set to true
requesting to use op_lock while all other calls of these new function
have this parameter set to false. 

Another problem reported in the bug entry concerned the operation of
assigning an index to a key cache. This operation can be called
while the key cache structures are not initialized yet. In this
case any call of flush_key_blocks() should return without any actions.

No test case is provided with this patch.