After merge fix

into moonbone.local:/home/evgen/bk-trees/mysql-4.1-opt

into  mysql.com:/home/kgeorge/mysql/5.0/B18895

into  mysql.com:/home/kgeorge/mysql/5.0/B18895

into moonbone.local:/home/evgen/bk-trees/mysql-5.0-opt

The Field::eq() considered instances of Field_bit that differ only in 
bit_ptr/bit_ofs equal. This caused equality conditions optimization 
(build_equal_items_for_cond()) to make bad field substitutions that result
in wrong predicates. 
Field_bit requires an overloaded eq() function that checks the bit_ptr/bit_ofs
in addition to Field::eq().

into moonbone.local:/work/15962-bug-5.0-opt-mysql

into  mysql.com:/home/kgeorge/mysql/5.0/B20195

into moonbone.local:/home/evgen/bk-trees/mysql-4.1-opt

The INSERT DELAYED should not maintain its own private auto-increment
counter, because this is assuming that other threads cannot insert
into the table while the INSERT DELAYED thread is inserting, which is
a wrong assumption.

So the start of processing of a batch of INSERT rows in the 
INSERT DELAYED thread must be treated as a start of a new statement
and cached next_insert_id must be cleared.

into moonbone.local:/work/16377-bug-4.1-opt-mysql

can lead to a wrong result.

All date/time functions has the STRING result type thus their results are
compared as strings. The string date representation allows a user to skip 
some of leading zeros. This can lead to wrong comparison result if a date/time 
function result is compared to such a string constant.

The idea behind this bug fix is to compare results of date/time functions
and data/time constants as ints, because that date/time representation is 
more exact. To achieve this the agg_cmp_type() is changed to take in the
account that a date/time field or an date/time item should be compared 
as ints.

This bug fix is partially back ported from 5.0.

The agg_cmp_type() function now accepts THD as one of parameters. 
In addition, it now checks if a date/time field/function is present in the
list. If so, it tries to coerce all constants to INT to make date/time
comparison return correct result. The field for the constant coercion is
taken from the Item_field or constructed from the Item_func. In latter case
the constructed field will be freed after conversion of all constant items.
Otherwise the result is same as before - aggregated with help of the
item_cmp_type() function.

From the Item_func_between::fix_length_and_dec() function removed the part
which was converting date/time constants to int if possible. Now this is 
done by the agg_cmp_type() function.

The new function result_as_longlong() is added to the Item class. 
It indicates that the item is a date/time item and result of it can be
compared as int. Such items are date/time fields/functions.

Correct val_int() methods are implemented for classes Item_date_typecast, 
Item_func_makedate, Item_time_typecast, Item_datetime_typecast. All these
classes are derived from Item_str_func and Item_str_func::val_int() converts
its string value to int without regard to the date/time type of these items.

Arg_comparator::set_compare_func() and Arg_comparator::set_cmp_func()
functions are changed to substitute result type of an item with the INT_RESULT
if the item is a date/time item and another item is a constant. This is done
to get a correct result of comparisons like date_time_function() = string_constant.

into moonbone.local:/home/evgen/bk-trees/mysql-4.1-opt

into moonbone.local:/work/16716-bug-4.1-opt-mysql

into  rurik.mysql.com:/home/igor/mysql-5.0-opt

into  mysql.com:/home/kgeorge/mysql/5.0/B15355

  query
Problem:
There was a wrong context assigned to the columns that were added in insert_fields()
when expanding a '*'. When this is done in a prepared statement it causes 
fix_fields() to fail to find the table that these columns reference.
Actually the right context is set in setup_natural_join_row_types() called at the 
end of setup_tables(). However when executed in a context of a prepared statement
setup_tables() resets the context, but setup_natural_join_row_types() was not
setting it to the correct value assuming it has already done so.

Solution:
The top-most, left-most NATURAL/USING join must be set as a 
first_name_resolution_table in context even when operating on prepared statements.

To calculate its max_length the CONCAT() function is simply sums max_lengths
of its arguments but when the collation of an argument differs from the 
collation of the CONCAT() max_length will be wrong. This may lead to a data
truncation when a tmp table is used, in UNIONS for example.

The Item_func_concat::fix_length_and_dec() function now recalculates the 
max_length of an argument when the mbmaxlen of the argument differs from the
mbmaxlen of the CONCAT().

into  rurik.mysql.com:/home/igor/mysql-5.0-opt

into  rurik.mysql.com:/home/igor/mysql-4.1-opt

The bug report revealed two problems related to min/max optimization:
1. If the length of a constant key used in a SARGable condition for
for the MIN/MAX fields is greater than the length of the field an 
unwanted warning on key truncation is issued;
2. If MIN/MAX optimization is applied to a partial index, like INDEX(b(4))
than can lead to returning a wrong result set.

into  mysql.com:/home/kgeorge/mysql/5.0/B4981

        3.23 regression test failure

The member SEL_ARG::min_flag was not initialized, 
due to which the condition for no GEOM_FLAG in function 
key_or did not choose "Range checked for each record" as 
the correct access method.

  After merge fix

into moonbone.local:/work/18360-bug-4.1-mysql-opt

The IN() function uses agg_cmp_type() to aggregate all types of its arguments
to find out some common type for comparisons. In this particular case the 
char() and the int was aggregated to double because char() can contain values
like '1.5'. But all strings which do not start from a digit are converted to
0. thus 'a' and 'z' become equal. 
This behaviour is reasonable when all function arguments are constants. But 
when there is a field or an expression this can lead to false comparisons. In
this case it makes more sense to coerce constants to the type of the field
argument.

The agg_cmp_type() function now aggregates types of constant and non-constant
items separately. If some non-constant items will be found then their
aggregated type will be returned. Thus after the aggregation constants will be
coerced to the aggregated type. 

into  neptunus.(none):/home/msvensson/mysql/mysql-5.0

into  neptunus.(none):/home/msvensson/mysql/mysql-5.0

into  devsrv-b.mysql.com:/users/msvensson/mysql-5.0

into  neptunus.(none):/home/msvensson/mysql/mysql-5.0

into  neptunus.(none):/home/msvensson/mysql/mysql-5.0