Fix for bug 7894 replaces a field(s) in a non-aggregate function with a item
reference if such a field was specified in the GROUP BY clause in order to
get a correct result.
When ROLLUP is involved this lead to a wrong result due to value of a such
field is got through a copy function and copying happens after the function
evaluation.
Such replacement isn't needed if grouping is also done by such a function.
The change_group_ref() function now isn't called for a function present in
the group list.
After the patch for big 21698 equality propagation stopped
working for BETWEEN and IN predicates with STRING arguments.
This changeset completes the solution of the above patch.
RTree keys are really different from BTree and need specific
paramters to be set by optimizer to work.
Sometimes optimizer doesn't set those properly.
Here we decided just to add code to check that the parameters
are correct. Hope to fix optimizer sometimes.
Fix: "mysql --xml" now print NULL values the same way that "mysqldump --xml" does:
<field name="name" xsi:nil="true" />
to distinguish from empty strings:
<field name="name"></field>
and from string "NULL":
<field name="name">NULL</field>
Problem: for character sets having mbmaxlen==2,
any ALTER TABLE changed TEXT column type to MEDIUMTEXT,
due to wrong "internal length to create length" formula.
Fix: removing rounding code introduced in early 4.1 time,
which is not correct anymore.
Adding a multibyte-aware VARCHAR copying function, to put correct column prefix,
taking in account number of characters (instead just limiting on number of bytes).
For example, for a KEY(col(3)) on a UTF8 column when copying the string 'foo bar foo',
we should put only 3 leftmost characters: 'foo'.
9 characters were incorrectly put before this fix.
We use the condition from CHECK OPTION twice handling UPDATE command.
First we construnct 'update_cond' AND 'option_cond'
condition to select records to be updated, then we check the
'option_cond' for the updated row.
The problem is that first 'AND' condition is optimized during the 'select'
which can break 'option_cond' structure, so it will be unusable for
the sectond use - to check the updated row.
Possible soultion is either use copy of the condition in the first
use or to make optimization less traumatic for the operands.
I picked the first one.
On an INSERT into an updatable but non-insertable view an error message was
issued stating the view being not updatable. This can lead to a confusion of a
user.
A new error message is introduced. Is is showed when a user tries to insert
into a non-insertable view.
while space allocation
Under some circumstances DISTINCT clause can be converted to grouping.
In such cases grouping is performed by all items in the select list.
If an ORDER clause is present then items from it is prepended to group list.
But the case with ORDER wasn't taken into account when allocating the
array for sum functions. This leads to memory corruption and crash.
The JOIN::alloc_func_list() function now allocates additional space if there
is an ORDER by clause is specified and DISTINCT -> GROUP BY optimization is
possible.
Crash may happen when selecting from a merge table that has underlying
tables with less indexes than in a merge table itself.
If number of keys in merge table is not bigger than requested key number,
return error.
