There were two problems related to the bug report:
1. Item_datetime::get_date() was not implemented.
So execution went through val_int() followed
by int-to-datetime or int-to-time conversion.
This was the reason why the optimizer did not
work well on data with fractional seconds.
2. Item_datetime::set() did not have a TIME specific code
to mix months and days to hours after unpack_time().
This is why the optimizer did not work well with negative
TIME values, as well as huge time values.
Changes:
1. Overriding Item_datetime::get_date(), to return ltime.
This fixes the problem N1.
2. Cleanup: Moving pack_time() and unpack_time() from
sql-common/my_time.c and include/my_time.h to
sql/sql_time.cc and sql/sql_time.h, as they are not needed
on the client side.
3. Adding a new "enum_mysql_timestamp_type ts_type" parameter
to unpack_time() and moving the TIME specific code to mix
months and days with hours inside unpack_time().
Adding a new "ts_type" parameter to Item_datetime::set(),
to pass it from the caller down to unpack_time().
So now the TIME specific code is automatically called
from Item_datetime::set(). This fixes the problem N2.
This change also helped to get rid of duplicate TIME specific code
from other three places, where mixing month/days to hours
was done immediately after unpack_time().
Moving the DATE specific code to zero hhmmssff
from Item_func_min_max::get_date_native to inside unpack_time(),
for symmetry.
4. Removing the virtual method in_vector::result_type(),
adding in_vector::type_handler() instead.
This helps to get result_type(), field_type(),
mysql_timestamp_type() of an in_vector easier.
Passing type_handler()->mysql_timestamp_type() as
a new parameter to Item_datetime::set() inside
in_temporal::value_to_item().
5. Cleaup: Removing separate implementations of in_datetime::get_value()
and in_time::get_value(). Adding a single implementation
in_temporal::get_value() instead.
Passing type_handler()->field_type() to get_value_internal().
c17a06abf8