The `SELECT 'r' INTO OUTFILE ... FIELDS ENCLOSED BY 'r' ' statement
encoded the 'r' string to a 4 byte string of value x'725c7272'
(sequence of 4 characters: r\rr).
The LOAD DATA statement decoded this string to a 1 byte string of
value x'0d' (ASCII Carriage Return character) instead of the original
'r' character.
The same error also happened with the FIELDS ENCLOSED BY clause
followed by special characters: 'n', 't', 'r', 'b', '0', 'Z' and 'N'.
NOTE 1: This is a result of the undocumented feature: the LOAD DATA INFILE
recognises 2-byte input sequences like \n, \t, \r and \Z in addition
to documented 2-byte sequences: \0 and \N. This feature should be
documented (here backspace character is a default ESCAPED BY character,
in the real-life example it may be any ESCAPED BY character).
NOTE 2, changed behaviour:
Now the `SELECT INTO OUTFILE' statement with the `FIELDS ENCLOSED BY'
clause followed by one of: 'n', 't', 'r', 'b', '0', 'Z' or 'N' characters
encodes this special character itself by doubling it ('r' --> 'rr'),
not by prepending it with an escape character.
This bug may manifest itself not only with the queries for which
the index-merge access method is chosen. It also may display
itself for queries with DISTINCT.
The bug was in how the Unique::get method used the merge_buffers
function. To compare elements in the the queue employed by
merge_buffers() it must use the buffpek_compare function rather
than the function for binary comparison.
When a UNION statement forced conversion of an UTF8
charset value to a binary charset value, the byte
length of the result values was truncated to the
CHAR_LENGTH of the original UTF8 value.
spaces.
When the my_strnncollsp_simple function compares two strings and one is a prefix
of another then this function compares characters in the rest of longer key
with the space character to find whether the longer key is greater or less.
But the sort order of the collation isn't used in this comparison. This may
lead to a wrong comparison result, wrongly created index or wrong order of the
result set of a query with the ORDER BY clause.
Now the my_strnncollsp_simple function uses collation sort order to compare
the characters in the rest of longer key with the space character.
query / no aggregate of subquery
The optimizer counts the aggregate functions that
appear as top level expressions (in all_fields) in
the current subquery. Later it makes a list of these
that it uses to actually execute the aggregates in
end_send_group().
That count is used in several places as a flag whether
there are aggregates functions.
While collecting the above info it must not consider
aggregates that are not aggregated in the current
context. It must treat them as normal expressions
instead. Not doing that leads to incorrect data about
the query, e.g. running a query that actually has no
aggregate functions as if it has some (and hence is
expected to return only one row).
Fixed by ignoring the aggregates that are not aggregated
in the current context.
One other smaller omission discovered and fixed in the
process : the place of aggregation was not calculated for
user defined functions. Fixed by calling
Item_sum::init_sum_func_check() and
Item_sum::check_sum_func() as it's done for the rest of
the aggregate functions.
SHOW CREATE TABLE or SELECT FROM I_S.
Actually, the bug discovers two problems:
- the original query is not preserved properly. This is the problem
of BUG#16291;
- the resultset of SHOW CREATE TABLE statement is binary.
This patch fixes the second problem for the 5.0.
Both problems will be fixed in 5.1.
Problem: like_range() returned wrong ranges for contractions (like 'ch' in Czech').
Fix: adding a special code to handle tricky cases:
- contraction head followed by a wild character
- full contraction
- contraction part followed by another contraction part,
but they are not a contraction together.
Thanks to Martin Friebe for finding and submitting a fix for this bug!
A table with maximum number of key segments and maximum length key name
would have a corrupted .frm file, due to an incorrect calculation of the
complete key length. Now the key length is computed correctly (I hope) :-)
MyISAM would reject a table with the maximum number of keys and the maximum
number of key segments in all keys. It would allow one less than this total
maximum. Now MyISAM accepts a table defined with the maximum. (This is a
very minor issue.)
Sometimes special 0 ENUM values was ALTERed to normal
empty string ENUM values.
Special 0 ENUM value has the same string representation
as normal ENUM value defined as '' (empty string).
The do_field_string function was used to convert
ENUM data at an ALTER TABLE request, but this
function doesn't care about numerical "indices" of
ENUM values, i.e. do_field_string doesn't distinguish
a special 0 value from an empty string value.
A new copy function called do_field_enum has been added to
copy special 0 ENUM values without conversion to an empty
string.
a lookup into a BINARY index by a key ended with spaces. It caused
an assertion abort for a debug version and wrong results for non-debug
versions.
The problem occurred because the function _mi_pack_key stripped off
the trailing spaces from binary search keys while the function _mi_make_key
did not do it when keys were inserted into the index.
Now the function _mi_pack_key does not remove the trailing spaces from
search keys if they are of the binary type.
If one sets MYSQL_READ_DEFAULTS_FILE and MYSQL_READ_DEFAULT_GROUP options
after mysql_real_connect() called with that MYSQL instance,
these options will affect next mysql_reconnect then.
As we use a copy of the original MYSQL object inside mysql_reconnect,
and mysql_real_connect frees options.my_cnf_file and _group strings,
we will free these twice when we execute mysql_reconnect with the
same MYSQL for the second time.
I don't think we should ever read defaults files handling mysql_reconnect.
So i just set them to 0 for the temporary MYSQL object there/
LOCK TABLES takes a list of tables to lock. It may lock several
tables successfully and then encounter a tables that it can't lock,
e.g. because it's locked. In such case it needs to undo the locks on
the already locked tables. And it does that. But it has also notified
the relevant table storage engine handlers that they should lock.
The only reliable way to ensure that the table handlers will give up
their locks is to end the transaction. This is what UNLOCK TABLE
does : it ends the transaction if there were locked tables by LOCK
tables.
It is possible to end the transaction when the lock fails in
LOCK TABLES because LOCK TABLES ends the transaction at its start
already.
Fixed by ending (again) the transaction when LOCK TABLES fails to
lock a table.
the loose scan optimization for grouping queries was applied returned
a wrong result set when the query was used with the SQL_BIG_RESULT
option.
The SQL_BIG_RESULT option forces to use sorting algorithm for grouping
queries instead of employing a suitable index. The current loose scan
optimization is applied only for one table queries when the suitable
index is covering. It does not make sense to use sort algorithm in this
case. However the create_sort_index function does not take into account
the possible choice of the loose scan to implement the DISTINCT operator
which makes sorting unnecessary. Moreover the current implementation of
the loose scan for queries with distinct assumes that sorting will
never happen. Thus in this case create_sort_index should not call
the function filesort.
