RAND() must accept scalar expressions regardless of their kind.
That includes both constant expressions and expressions that
depend on column values.
When the expression is constant the random seed can be initialized
at compile time.
However when the expression is not constant the random seed must be
initialized at each invocation (while it still can be allocated at
compile time).
Implemented the above rules by extending Item_func_rand::val_real()
to initialize the random seed at the correct place.
st_table::const_key_parts member is used in determining if
certain key has a prefix that is compared to constant(s) in
the query predicates.
If there's such prefix the index can be used to get the data
from the remaining suffix columns in sorted order.
However if a field is compared to another field from a "const"
table the const_key_parts is not amended.
This makes the optimizer unable to detect that the key can be
used for sorting and adds an extra filesort.
Fixed by updating const_key_parts after reading in the "const"
table.
Subselect's engine checks table->status field to determine if the
record was properly found when we use keyread upon the table.
Partition engine checks all the partitions for given key
before return. So if matching record was found in the first
partition and no matching records were found in the second,
we have table->status == NOT_FOUND after the function, what
makes subselects to skip matching records.
The patch adds table->status= 0 if we actually found something.
aliases ignored
When a column reference to a column in JOIN USING is resolved and a new
Item is created for this column the user defined name was lost.
This fix preserves the alias by setting the name of the new Item to the
original alias.
In the method Item_field::fix_fields we try to resolve the name of
the field against the names of the aliases that occur in the select
list. This is done by a call of the function find_item_in_list.
When this function finds several occurrences of the field name
it sends an error message to the error queue and returns 0.
Yet the code did not take into account that find_item_in_list
could return 0 and tried to dereference the returned value.
used.
The Item::save_in_field() function is called from fill_record() to fill the
new row with data while execution of the CREATE TABLE ... SELECT statement.
Item::save_in_field() calls val_xxx() methods in order to get values.
val_xxx() methods do not take into account the result field. Due to this
Item_func_set_user_var::val_xxx() methods returns values from the original
table, not from the temporary one.
The save_in_field() member function is added to the Item_func_set_user_var
class. It detects whether the result field should be used and properly updates
the value of the user variable.
A BINARY field is represented by the Field_string class. The space character
is used as the filler for unused characters in such a field. But a BINARY field
should use \x00 instead.
Field_string:reset() now detects whether the current field is a BINARY one
and if so uses the \x00 character as a default value filler.
The optimizer removes expressions from GROUP BY/DISTINCT
if they happen to participate in a <expression> = <const>
predicates of the WHERE clause (the idea being that if
it's always equal to a constant it can't have multiple
values).
However for predicates where the expression and the
constant item are of different result type this is not
valid (e.g. a string column compared to 0).
Fixed by additional check of the result types of the
expression and the constant and if they differ the
expression don't get removed from the group by list.
This bug appeared after the patch for bug 21390 that had added some code
to handle outer joins with no matches after substitution of a const
table in an efficient way. That code as it is cannot be applied to the case
of nested outer join operations. Being applied to the queries with
nested outer joins the code can cause crashes or wrong result sets.
The fix blocks row substitution for const inner tables of an outer join
if the inner operand is not a single table.
5.1-related fixes
libmysqld/Makefile.am fixed to recompile and link ha_*.cc files that
keep dependance on THD structure.
Minor fixes to make tests working.
