when there was one NULL value, AVG(DISTINCT) could forget about other values.
See commit comment of item_sum.cc.

mysql-test/r/func_group.result:
  before the code fix, both SELECTs would return NULL
sql/item_sum.cc:
  Assume we are executing "SELECT AVG([DISTINCT] some_field) FROM some_table".
  and some_field is the single field of some_table for simplicity.
  Each time a row is processed (evaluate_join_record()->
  end_send_group()->update_sum_func()) an aggregator is notified,
  which itself notifies an Item_sum_avg.
  Without DISTINCT, this Item_sum_avg immediately increments its
  internal "sum of values" and "count of values" (the latter being
  Item_sum_avg::count). The count is incremented only if the row's value
  is not NULL (in Item_sum_avg::add()), per AVG() semantices. This row's value
  is available in args[0] of Item_sum_avg ("args[0]" stands for
  "the first argument of the item": it's an Item_field which automatically
  receives the row's value when a row is read from the table).
  bool Item_sum_avg::add()
  {
    if (Item_sum_sum::add()) << calculates the sum (ignores NULL)
      return TRUE;
    if (!args[0]->null_value)<<if added value is not NULL
      count++;       <<increment "count"
    return FALSE;
  }
  and everything works.
  With DISTINCT, when a row is processed by evaluate_join_record(),
  Item_sum_avg does no immediate computation, rather stores
  the row's value in a tree (to throw the value away if it is a duplicate
  of previous value, otherwise to remember all
  distinct values). It's only when it's time to send the average to the
  user (at end of the query:
  sub_select(end_of_records=true)->end_send_group()->
  select_send->send_data()->Protocol::send_result_set_row()->
  Item::send()->Item_sum_avg->val_str()), that we iterate over the tree,
  compute the sum and count: for this, for each element of the tree,
  Item_sum_avg::add() is called and has the same two steps as before:
  * Item_sum_sum::add() updates the sum (finding the tree element's value
  correctly, and determining correctly its NULLness - look for "arg_is_null"
  in that function)
  * the "if (!args[0]->null_value)" test right after, breaks: it uses args[0],
  which isn't the tree's element but rather the value for the last row
  processed by evaluate_join_record(). So if that last row was NULL,
  "count" stays 0 for each row, and AVG() then returns NULL (count==0 =>
  NULL, per AVG() semantics).
  The fix is to let the aggregator tell whether the value
  it just saw was NULL. The aggregator knows where to get the info
  thanks to virtual functions. Item_sum_sum::add() now asks
  the aggregator. Item_sum_avg() also asks the aggregator
  and then knows it shouldn't increment "count".
sql/item_sum.h:
  Aggregator can now tell about value/NULLness of just-aggregated value

Null merge to from mysql-5.1-bugteam to mysql-5.5-bugteam.
Test case does not exist in 5.5 tree.

Automerging bzr bundle from bug report into latest 
mysql-5.1-bugteam.

            command line clients.

Command line tools like mysqladmin and mysqldump did not recognize
default-auth and plugin-dir options.

Support for these options was found missing in these command line
tools.

Fixed by adding support for the same.


client/mysqladmin.cc:
  Bug#58139 : default-auth option not recognized in MySQL standard
              command line clients.
  
  Introduced two new variables to hold values from default-auth and
  plugin-dir options and further pushed them to client's st_mysql
  instance.
client/mysqldump.c:
  Bug#58139 : default-auth option not recognized in MySQL standard
              command line clients.
  
  Introduced two new variables to hold values from default-auth and
  plugin-dir options and further pushed them to client's st_mysql
  instance.
mysql-test/r/plugin_auth.result:
  Added test case for Bug#58139.
mysql-test/t/plugin_auth.test:
  Added test case for Bug#58139.

Re-enable fast mutexes on Linux for release builds.

to_binlog -> binlog_stmt.

Adding symbol FN_DIRSEP to Windows as well.

Fixing test case that fails on Windows because .dll is used.

           but the statement is written to binlog

TRUNCATE PARTITION was written to the binlog
even if it failed before calling any partition's
truncate function.

Solved by adding an argument to truncate_partition,
to flag if it should be written to the binlog or not.

It should be written to the binlog when a call to any
partitions truncate function is done.

mysql-test/r/partition_binlog.result:
  New result file
mysql-test/t/partition_binlog.test:
  New test file, including DROP PARTITION binlog test
sql/ha_partition.cc:
  Added argument to avoid binlogging failed truncate_partition that
  have not yet changed any data.
sql/ha_partition.h:
  Added argument to avoid excessive binlogging
sql/sql_partition_admin.cc:
  Avoid to binlog TRUNCATE PARTITION if it fails before
  any partition has tried to truncate.

When installing plugins, there is a missing check
for slash (/) in the path on Windows. Note that on
Windows, both / and \ can be used to separate
directories.

This patch fixes the issue by:
- Adding a FN_DIRSEP symbol for all platforms
  consisting of a string of legal directory
  separators.
- Adding a charset-aware version of strcspn().
- Adding a check_valid_path() function that uses
  my_strcspn() to check if any FN_DIRSEP character
  is in the supplied string.
- Using the check_valid_path() function in
  sql_plugin.cc and sql_udf.cc (which means
  replacing the existing test there).

include/config-netware.h:
  Adding FN_DIRSEP
  ******
  Adding FN_DIRSEP
include/config-win.h:
  Adding FN_DIRSEP
  ******
  Adding FN_DIRSEP
include/m_ctype.h:
  Adding my_strspn() and my_strcspn().
  
  ******
  Adding my_strspn() and my_strcspn().
include/my_global.h:
  Adding FN_DIRSEP
  ******
  Adding FN_DIRSEP
mysql-test/t/plugin_not_embedded.test:
  Adding test that file names containing / is
  disallowed on *all* platforms.
  ******
  Adding test that file names containing / is
  disallowed on *all* platforms.
sql/sql_plugin.cc:
  Introducing check_if_path() function for
  checking if filename is a path to include
  / on Windows.
  ******
  Introducing check_if_path() function for
  checking if filename is a path to include
  / on Windows.
sql/sql_udf.cc:
  Switching to use check_if_path() function.
  ******
  Switching to use check_if_path() function.
strings/my_strchr.c:
  Adding my_strspn() and my_strcspn().
  ******
  Adding my_strspn() and my_strcspn().

This is a code cleanup.

The implementation of a storage engine (subclasses of handler) is not supposed
to call my_error() directly inside the engine implementation, 
but only return error codes, and report errors later at the demand
of the sql layer only (if needed), using handler::print_error().

This fix removes misplaced calls to my_error(),
and provide an implementation of print_error() instead.

Given that the sql layer implementation of create table, ha_create_table(),
does not use print_error() but returns ER_CANT_CREATE_TABLE directly,
the return code for create table statements using the performance schema
has changed to ER_CANT_CREATE_TABLE.

Adjusted the test suite accordingly.

Before this fix, the test thread_cache failed with spurious failures.

The test used:
-- disconnect X
-- connect Y

while assuming that connection Y would reuse connection X slot in the thread cache.

For this to happen, the disconnect X operation must be given enough time to complete,
otherwise connect Y can be executed in the server before X actually finishes.

This fix uses wait conditions to make the test execution more controlled,
and more reproductible.

Before this fix, the test myisam_file_io executed:
- (a) an update on setup_instrument to disable non myisam file io instruments
- (b) a truncate on events_waits_history_long
and later
- (c) a select on events_waits_history_long

Surprisingly, events that were supposed to be disabled in (a) and removed in (b)
still were found in (c).

This happened for events such as 
  wait/io/file/innodb/innodb_data_file fil0fil.c: sync  
because the sync was started before (a) and completed after (b),
and as a consequence was added in the performance schema history, as expected.

Presence of these records in the history made the test fail. 

This fix makes the test script more robust to account for extra spill waits records in (c).

This fix affects the test suite only.

Before this fix, performance schema tests dml_*.test could
fail with spurious failure, depending on the table content.

This fix simplifies the SELECT tests in the dml_*.test scripts,
to only verify that the SELECT operation passed the security checks
and succeeded, which was the original intent of the test.

Usage of 
  --replace_column 1 # 2 # 3 # 4 # ...
to discard the test output was replaced by a simpler and more maintainable 
  --disable_result_log
which also work for empty tables.

Fixing the testcase to use the database name
as connected_db instead of 'test' database.

mysql-test/r/mysql.result:
  Additional fix in the test for bug#54899.
mysql-test/t/mysql.test:
  Additional fix in the test for bug#54899.

The problem was due to a misuse of GCC asm constraints used to
implement a atomic load. On x86_64, the load was implemented
as a cmpxchg which implicitly uses the eax register as a
source and destination operand, yet the dummy value used for
comparison wasn't being properly loaded into eax (and other
problems).

The core problem is that cmpxchg is unnecessary as a load
on x86_64 as there are other simpler instructions such
as xadd. Even though, such instructions are only used to
have a memory barrier as load and stores are atomic by
definition. Hence, the solution is to explicitly issue the
required CPU and compiler barriers.

include/atomic/x86-gcc.h:
  Issue a synchronizing instruction before loading the value.
  Afterwards, issue a compiler barrier to prevent reordering.

integral type. Use intptr which is designed to hold pointer values
and pass it to off_t.

mysys/stacktrace.c:
  Add a compile time assert to ensure that off_t is large enough
  to hold the pointer value.