DROP USER 
RENAME USER CURRENT_USER() ...
GRANT ... TO CURRENT_USER()
REVOKE ... FROM CURRENT_USER()
ALTER DEFINER = CURRENT_USER() EVENTbut, When these statements are binlogged, CURRENT_USER() just is binlogged
as 'CURRENT_USER()', it is not expanded to the real user name. When slave 
executes the log event, 'CURRENT_USER()' is expand to the user of slave 
SQL thread, but SQL thread's user name always NULL. This breaks the replication.

After this patch, session's user will be written into query log events 
if these statements call CURREN_USER() or 'ALTER EVENT' does not assign a definer.


mysql-test/include/diff_tables.inc:
  Expend its abilities.
  Now it can diff not only in sessions of 'master' and 'slave', but 
  other sessions as well.
mysql-test/include/rpl_diff_tables.inc:
  Diff the same table between master and slaves.
sql/log_event.cc:
  session's user will be written into Query_log_event, if is_current_user_used() is TRUE.
  On slave SQL thread, Only thd->variables.current_user is written into Query_log_event,
  if it exists.
sql/sql_acl.cc:
  On slave SQL thread, grantor should copy from thd->variables.current_user, if it exists
sql/sql_class.h:
  On slave SQL thread, thd->variables.current_user is used to store the applying event's
  invoker.

This deadlock happened if DROP DATABASE was blocked due to an open
HANDLER table from a different connection. While DROP DATABASE
is blocked, it holds the LOCK_mysql_create_db mutex. This results
in a deadlock if the connection with the open HANDLER table tries
to execute a CREATE/ALTER/DROP DATABASE statement as they all
try to acquire LOCK_mysql_create_db.

This patch makes this deadlock scenario very unlikely by closing and
marking for re-open all HANDLER tables for which there are pending
conflicing locks, before LOCK_mysql_create_db is acquired.
However, there is still a very slight possibility that a connection
could access one of these HANDLER tables between closing/marking for
re-open and the acquisition of LOCK_mysql_create_db.

This patch is for 5.1 only, a separate and complete fix will be
made for 5.5+.

Test case added to schema.test.

During creation of the table list of
processed tables hidden I_S table 'VARIABLES'
is erroneously added into the table list.
it leads to ER_UNKNOWN_TABLE error in
TABLE_LIST::add_table_to_list() function.
The fix is to skip addition of hidden I_S
tables into the table list.


mysql-test/r/information_schema.result:
  test case
mysql-test/t/information_schema.test:
  test case
sql/sql_show.cc:
  The fix is to skip addition of hidden I_S
  tables into the table list.

require O(#scans) memory

When an index merge operation was restarted, it would
re-allocate the Unique object controlling the duplicate row
ID elimination. Fixed by making the Unique object a member
of QUICK_INDEX_MERGE_SELECT and thus reusing it throughout
the lifetime of this object.

file .\filesort.cc, line 149 (part II)

Problem: the server didn't disregard sort order 
for some zero length tuples.

Fix: skip sort order in such a case 
(zero length NOT NULL string functions).


mysql-test/r/select.result:
  Fix for bug #54459: Assertion failed: param.sort_length, 
  file .\filesort.cc, line 149 (part II)
    - test result.
mysql-test/t/select.test:
  Fix for bug #54459: Assertion failed: param.sort_length, 
  file .\filesort.cc, line 149 (part II)
    - test case.
sql/sql_select.cc:
  Fix for bug #54459: Assertion failed: param.sort_length, 
  file .\filesort.cc, line 149 (part II)
    - disregard sort order for zero length NOT NULL string functions
  along with zero length NOT NULL fields.

Incorrect handling of NULL arguments could lead to a crash on
the IN or CASE operations when either NULL arguments were
passed explicitly as arguments (IN) or implicitly generated by
the WITH ROLLUP modifier (both IN and CASE).

Item_func_case::find_item() assumed all necessary comparators
to be instantiated in fix_length_and_dec(). However, in the
presence of WITH ROLLUP modifier, arguments could be
substituted with an Item_null leading to an "unexpected"
STRING_RESULT comparator being invoked.

In addition to the problem identical to the above,
Item_func_in::val_int() could crash even with explicitly passed
NULL arguments due to an optimization in fix_length_and_dec()
leading to NULL arguments being ignored during comparators
creation.


mysql-test/r/func_in.result:
  Test cases for bug#54477.
mysql-test/t/func_in.test:
  Test cases for bug#54477.
sql/item_cmpfunc.cc:
  Added additional checks for Item_nulls in 
  Item_func_case::find_item() and Item_func_in::val_int().

mysql-test/suite/perfschema/t/no_threads-master.opt:
  Innodb will start multiple threads, which is
  not compatible with --one-thread.   Disable
  innodb to be able to run the test case.

In process of record search it is not taken into account
that inital quick->file->ref value could be inapplicable
to range interval. After proper row is found this value is
stored into the record buffer and later the record is
filtered out at condition evaluation stage.
The fix is store a refernce of found row to the handler ref field.


mysql-test/r/innodb_mysql.result:
  test case
mysql-test/std_data/intersect-bug50389.tsv:
  test case
mysql-test/t/innodb_mysql.test:
  test case
sql/opt_range.cc:
  store a refernce of found row to the handler ref field.

InnoDB came in a new version "simultanously" with the
commit.  This patch is a minor change to the new innodb
regression test suite. 

Problem: a flaw (derefencing a NULL pointer) in the LIKE optimization
code may lead to a server crash in some rare cases.

Fix: check the pointer before its dereferencing.


mysql-test/r/func_like.result:
  Fix for bug #54575: crash when joining tables with unique set column
    - test result.
mysql-test/t/func_like.test:
  Fix for bug #54575: crash when joining tables with unique set column
    - test case.
sql/item_cmpfunc.cc:
  Fix for bug #54575: crash when joining tables with unique set column
    - check res2 buffer pointer before its dereferencing 
  as it may be NULL in some cases.

mysql_client_binlog_statement

Problem: server may read from unassigned memory performing
"wrong" BINLOG queries.

Fix: never read from unassigned memory.


mysql-test/suite/binlog/r/binlog_base64_flag.result:
  Fix for bug #54393: crash and/or valgrind errors in
  mysql_client_binlog_statement
    - test result.
mysql-test/suite/binlog/t/binlog_base64_flag.test:
  Fix for bug #54393: crash and/or valgrind errors in
  mysql_client_binlog_statement
    - test case.
sql/sql_binlog.cc:
  Fix for bug #54393: crash and/or valgrind errors in
  mysql_client_binlog_statement
    - coded_len should not count trailing '/0';
    - never read from unassigned memory.