The optimizer transforms DISTINCT into a GROUP BY
when possible.
It does that by constructing the same structure
(a list of ORDER instances) the parser makes when
parsing GROUP BY.
While doing that it also eliminates duplicates.
But if a duplicate is found it doesn't advance the
pointer to ref_pointer array, so the next
(and subsequent) ORDER structures point to the wrong
element in the SELECT list.
Fixed by advancing the pointer in ref_pointer_array
even in the case of a duplicate.
Problem: setting/displaying @@LC_TIME_NAMES didn't distinguish between
GLOBAL and SESSION variable types - always SESSION variable
was set/shonw.
Fix: set either global or session value.
Also, "mysqld --lc-time-names" was added to set "global default" value.
NO_AUTO_VALUE_ON_ZERO mode.
The table->auto_increment_field_not_null variable wasn't reset after
reading a row which may lead to inserting a wrong value to the auto-increment
field to the following row.
The table->auto_increment_field_not_null variable is reset now right after a
row is being written in the read_fixed_length() and the read_sep_field()
functions.
Removed wrong setting of the table->auto_increment_field_not_null variable in
the read_sep_field() function.
In certain cases AFTER UPDATE/DELETE triggers on NDB tables that referenced
subject table didn't see the results of operation which caused invocation
of those triggers. In other words AFTER trigger invoked as result of update
(or deletion) of particular row saw version of this row before update (or
deletion).
The problem occured because NDB handler in those cases postponed actual
update/delete operations to be able to perform them later as one batch.
This fix solves the problem by disabling this optimization for particular
operation if subject table has AFTER trigger for this operation defined.
To achieve this we introduce two new flags for handler::extra() method:
HA_EXTRA_DELETE_CANNOT_BATCH and HA_EXTRA_UPDATE_CANNOT_BATCH.
These are called if there exists AFTER DELETE/UPDATE triggers during a
statement that potentially can generate calls to delete_row()/update_row().
This includes multi_delete/multi_update statements as well as insert statements
that do delete/update as part of an ON DUPLICATE statement.
IN/BETWEEN predicates in sorting expressions.
Wrong results may occur when the select list contains an expression
with IN/BETWEEN predicate that differs from a sorting expression by
an additional NOT only.
Added the method Item_func_opt_neg::eq to compare correctly expressions
containing [NOT] IN/BETWEEN.
The eq method inherited from the Item_func returns TRUE when comparing
'a IN (1,2)' with 'a NOT IN (1,2)' that is not, of course, correct.
