when the column is to be read from a derived table column which
was specified as a concatenation of string literals.
The bug happened because the Item_string::append did not adjust the
value of Item_string::max_length. As a result of it the temporary
table column defined to store the concatenation of literals was
not wide enough to hold the whole value.
after single-row table substitution could lead to a wrong result set.
The bug happened because the function Item_field::replace_equal_field
erroniously assumed that any field included in a multiple equality
with a constant has been already substituted for this constant.
This not true for fields becoming constant after row substitutions
for constant tables.
When the SUBSTRING() function was used over a LONGTEXT field the max_length of
the SUBSTRING() result was wrongly calculated and set to 0. As the max_length
parameter is used while tmp field creation it limits the length of the result
field and leads to printing an empty string instead of the correct result.
Now the Item_func_substr::fix_length_and_dec() function correctly calculates
the max_length parameter.
When rand() is called multiple times inside a stored procedure, the server does
not binlog the correct random seed values.
This patch corrects the problem by resetting rand_used= 0 in
THD::cleanup_after_query() allowing the system to save the random seeds if needed
for each command in a stored procedure body.
However, rand_used is not reset if executing in a stored function or trigger
because these operations are binlogged by call and thus only the calling statement
need detect the call to rand() made by its substatements. These substatements must
not set rand_used to 0 because it would remove the detection of rand() by the
calling statement.
construct references invalid name.
Derived tables currently cannot use outer references.
Thus there is no outer context for them.
The 4.1 code takes this fact into account while the
Item_field::fix_outer_field code of 5.0 lost the check that blocks
any attempts to resolve names in outer context for derived tables.
incorrect key file for table
In certain cases it could happen that deleting a row could
corrupt an RTREE index.
According to Guttman's algorithm, page underflow is handled
by storing the page in a list for later re-insertion. The
keys from the stored pages have to be inserted into the
remaining pages of the same level of the tree. Hence the
level number is stored in the re-insertion list together
with the page.
In the MySQL RTree implementation the level counts from zero
at the root page, increasing numbers for levels down the tree.
If during re-insertion of the keys the tree height grows, all
level numbers become invalid. The remaining keys will be
inserted at the wrong level.
The fix is to increment the level numbers stored in the
reinsert list after a split of the root block during reinsertion.
result.
For built-in functions like sqrt() function names are hard-coded and can be
compared by pointer. But this isn't the case for a used-defined stored
functions - names there are dynamical and should be compared as strings.
Now the Item_func::eq() function employs my_strcasecmp() function to compare
used-defined stored functions names.
away.
During optimization stage the WHERE conditions can be changed or even
be removed at all if they know for sure to be true of false. Thus they aren't
showed in the EXPLAIN EXTENDED which prints conditions after optimization.
Now if all elements of an Item_cond were removed this Item_cond is substituted
for an Item_int with the int value of the Item_cond.
If there were conditions that were totally optimized away then values of the
saved cond_value and having_value will be printed instead.
DATE/DATETIME values are out of the currently supported
4 basic value types (INT,STRING,REAL and DECIMAL).
So expressions (not fields) of compile type DATE/DATETIME are
generally considered as STRING values. This is not so
when they are compared : then they are compared as
INTEGER values.
But the rule for comparison as INTEGERS must be checked
explicitly each time when a comparison is to be performed.
filesort is one such place. However there the check was
not done and hence the expressions (not fields) of type
DATE/DATETIME were sorted by their string representation.
Fixed to compare them as INTEGER values for filesort.
