Bug #49910: Behavioural change in SELECT/WHERE on YEAR(4) data type                                  
(Original patch by Sinisa Milivojevic)

The YEAR(4) value of 2000 was equal to the "bad" YEAR(4) value of 0000.                              

The get_year_value() function has been modified to not adjust bad                                    
YEAR(4) value to 2000.

comments to rpl_show_slave_running test are added to ease merging

The problem is that when we make conditon for
grouped result const part of condition is cut off.
It happens because some parts of 'having' condition
which refer to outer join become const after
make_join_statistics. These parts may be lost
during further having condition transformation
in JOIN::exec. The fix is adding 'having'
condition check for const tables after
make_join_statistics is performed.

DBUG_SYNC_POINT has at least one strong limitation that it's not defined
on all platforms. It has issues cooperating with @@debug.
All in all its functionality is superseded by DEBUG_SYNC facility and
there is no reason to maintain the old less flexible one.

Fixed with adding debug_sync_set_action() function as a facility to set up
a sync-action in the server sources code and re-writing existing simulations
(found 3) to use it.
Couple of tests have been reworked as well.

The patch offers a pattern for setting sync-points in replication threads
where the standard DEBUG_SYNC does not suffice to reach goals.

This has been back-ported from 6.0 as the problems proved to afflict 
5.1 as well.
The fix exposed two new bugs. They were reported as follows.
      
Bug no 52174: Sometimes wrong plan when reading a MAX value 
from non-NULL index
      
Bug no 52173: Reading NULL value from non-NULL index gives wrong 
result in embedded server 
      
Both bugs taken together affect a much smaller class of queries than #47762, 
so the fix stays for now.

Optimizer erroneously translated LEFT JOIN into INNER JOIN.
It leads to cutting rows with NULL right side. It happens
because Item_row uses not_null_tables() method form the
base(Item) class and does not calculate 'null tables'
properly. The fix is adding calculation of 'not null tables'
to Item_row.

The crash happens because of discrepancy between values of
conts_tables and join->const_table_map(make_join_statisctics).
Calculation of conts_tables used condition with
HA_STATS_RECORDS_IS_EXACT flag check. Calculation of
join->const_table_map does not use this flag check.
In case of MERGE table without union with index
the table does not become const table and
thus join_read_const_table() is not called
for the table. join->const_table_map supposes
this table is const and later in make_join_select
this table is used for making&calculation const
condition. As table record buffer is not populated
it leads to crash.
The fix is adding a check if an engine supports
HA_STATS_RECORDS_IS_EXACT flag before updating
join->const_table_map.

for general use.

           for InnoDB
            
The class Field_bit_as_char stores the metadata for the
field incorrecly because bytes_in_rec and bit_len are set
to (field_length + 7 ) / 8 and 0 respectively, while
Field_bit has the correct values field_length / 8 and
field_length % 8.
            
Solved the problem by re-computing the values for the
metadata based on the field_length instead of using the
bytes_in_rec and bit_len variables.
            
To handle compatibility with old server, a table map
flag was added to indicate that the bit computation is
exact. If the flag is clear, the slave computes the
number of bytes required to store the bit field and
compares that instead, effectively allowing replication
*without conversion* from any field length that require
the same number of bytes to store.

   definition at engine

If a single ALTER TABLE contains both DROP INDEX and ADD INDEX using 
the same index name (a.k.a. index modification) we need to disable 
in-place alter table because we can't ask the storage engine to have 
two copies of the index with the same name even temporarily (if we 
first do the ADD INDEX and then DROP INDEX) and we can't modify 
indexes that are needed by e.g. foreign keys if we first do 
DROP INDEX and then ADD INDEX.
Fixed the problem by disabling in-place ALTER TABLE for these cases.

SunStudio
      
SunStudio compilers of late warn about methods that might hide
methods in base classes due to the use of overloading combined
with overriding. SunStudio also warns about variables defined
in local socpe or method arguments that have the same name as
a member attribute of the class.
      
This patch renames methods that might hide base class methods,
to make it easier both for humans and compilers to see what is
actually called. It also renames variables in local scope.

The problem was that killing a query during the optimization
phase of a subselect would lead to crashes. The root of the
problem is that the subselect execution engine ignores failures
(eg: killed) during the optimization phase (JOIN::optimize),
leading to a crash once the subquery is executed due to
partially initialized structures (in this case a join tab).

The optimal solution would be to cleanup certain optimizer
structures if the optimization phase fails, but currently
there is no infrastructure to properly to track and cleanup
the structures. To workaround the whole problem one somewhat
good solution is to avoid executing a subselect if the query
has been killed. Cutting short any problems caused by failures
during the optimization phase.

NULL column for NULL

The optimization to read MIN() and MAX() values from an
index did not properly handle comparisons with NULL
values. Fixed by giving up the particular optimization step
if there are non-NULL safe comparisons with NULL values, as 
the result is NULL anyway.

Also, Oracle copyright notice was added to all files.

via I_S.PLUGINS, not via SHOW PLUGINS.

Base Tables

The type inferrence of a view column caused the result to be
interpreted as the wrong type: DATE colums were interpreted
as TIME and TIME as DATETIME. This happened because view
columns are represented by Item_ref objects as opposed to
Item_field's. Item_ref had no method for retrieving a TIME
value and thus was forced to depend on the default
implementation for any expression, which caused the
expression to be evaluated as a string and then parsed into
a TIME/DATETIME value.

Fixed by letting Item_ref classes forward the request for a
TIME value to the referred Item - which is a field in this
case - this reads the TIME value directly without
conversion.

Fix up function return value, it must return a double.

            index cardinalities=1

Parallel repair didn't poroperly update index cardinality
in certain cases.

When myisam_sort_buffer_size is not enough to store all
keys, index cardinality was updated before index was
actually written, when no index statistic is available.

Additional result file update

      
Applied a path from Jim Winstead : Added a GPL notice.
Added the missing '(c)' and 'v2'. 

join view in sql_safe_updates mode. 

This bug was unexpectedly fixed along with bug 
number 49534. This patch contains only the test
case.

BUG#51342 - more xid crashing

Restore autocommit variable by supplying explicit value.