When compiling GROUP BY Item_ref instances are dereferenced in
setup_copy_fields(), i.e. replaced with the corresponding Item_field
(if they point to one) or Item_copy_string for the other cases.
Since the Item_ref (in the Item_field case) is no longer used the information
about the aliases stored in it is lost.
Fixed by preserving the column, table and DB alias on dereferencing Item_ref
procedure variable
Second version, after review.
Keep the unsigned_flag in Item_decimal updated. Note that this also changed
the result of several old test results - creating tables from decimal
templates now gives unsigned columns and different sizes. (Several tests
had Length > Max_length before.)
not default_charset_into. It fixes the
problem that in some cases numbers where
treated as CHAR(N), not as BINARY(N), e.g.
wrong 'charsetnr' when sent to the client side.
2. IFNULL didn't aggregate argument charsets
and collations, so IFNULL(1,'a') produced
a CHAR(N). Now produces a BINARY(N).
3. SELECT PROCEDURE ANALIZE now returns
BINARY columns, which is much better than it worked
previously: CHAR with the default character set.
But in the future it's worth to fix the fields
'Field_name' and 'Optimal_fieldtype' to use UTF8,
and 'Min_value' and 'Max_value' to inherit their charsets
from the original items. But it is not important,
and BINARY(N) is OK for now.
4. Tests were fixed accordingly. No new tests were
made, as the old onces cover everything.
For numeric constants we only need to add, since the parser doesn't produce
negative numbers.
For strings we only add (we actually could substract 1 if given string is a constant
and it has '-number' form but we're not doing that because
* we set max_length bigger then necessary in other cases as well.
* the current solution is simpler and safer (bigger max_length is better then cutting out)
the result takes its charset/collation
attributes from the character string,
e.g. SELECT func(NULL, _latin2'string')
now returns a latin2 result. This is
done by introducing a new derivation
(aka coercibility) level DERIVATION_IGNORABLE,
which is used with Item_null.
2. 'Pure' NULL is now BINARY(0), not CHAR(0).
I.e. NULL is now more typeless.
TIMESTAMP columns should be unsigned to preserve compatibility with 4.0
(Or else InnoDB will return different internal TIMESTAMP values when user upgrades to 4.1).
Altough this fix will introduce problems with early 4.1 -> 4.1 upgrades (tables with
TIMESTAMP field should be reloaded using mysqldump) it will allow easy 4.0 -> 4.1
upgrade (which is more important since 4.1 is still beta).
