Grouping by a subquery in a query with a distinct aggregate
function lead to a wrong result (wrong and unordered
grouping values).
There are two related problems:
1) The query like this:
SELECT (SELECT t1.a) aa, COUNT(DISTINCT b) c
FROM t1 GROUP BY aa
returned wrong result, because the outer reference "t1.a"
in the subquery was substituted with the Item_ref item.
The Item_ref item obtains data from the result_field object
that refreshes once after the end of each group. This data
is not applicable to filesort since filesort() doesn't care
about groups (and doesn't update result_field objects with
copy_fields() and so on). Also that data is not applicable
to group separation algorithm: end_send_group() checks every
record with test_if_group_changed() that evaluates Item_ref
items, but it refreshes those Item_ref-s only after the end
of group, that is a vicious circle and the grouped column
values in the output are shifted.
Fix: if
a) we grouping by a subquery and
b) that subquery has outer references to FROM list
of the grouping query,
then we substitute these outer references with
Item_direct_ref like references under aggregate
functions: Item_direct_ref obtains data directly
from the current record.
2) The query with a non-trivial grouping expression like:
SELECT (SELECT t1.a) aa, COUNT(DISTINCT b) c
FROM t1 GROUP BY aa+0
also returned wrong result, since JOIN::exec() substitutes
references to top-level aliases in SELECT list with Item_copy
caching items. Item_copy items have same refreshing policy
as Item_ref items, so the whole groping expression with
Item_copy inside returns wrong result in filesort() and
end_send_group().
Fix: include aliased items into GROUP BY item tree instead
of Item_ref references to them.
logging is disabled
The server would hit an assertion because of a DBUG violation.
There was a missing DBUG_RETURN and instead a plain return
was used.
This patch replaces the return with DBUG_RETURN.
into slow log
While processing a statement, down the mysql_parse execution
stack, the thd->enable_slow_log can be assigned to
opt_log_slow_admin_statements, depending whether one is executing
administrative statements, such as ALTER TABLE, OPTIMIZE,
ANALYZE, etc, or not. This can have an impact on slow logging for
statements that are executed after an administrative statement
execution is completed.
When executing statements directly from the user this is fine
because, the thd->enable_slow_log is reset right at the beginning
of the dispatch_command function, ie, everytime a new statement
is set is set to execute.
On the other hand, for slave SQL thread (sql_thd) the story is a
bit different. When in SBR the sql_thd applies statements by
calling mysql_parse. Right after, it calls log_slow_statement
function to log them if they take too long. Calling mysql_parse
directly is fine, but also means that dispatch_command function
is bypassed. As a consequence, thd->enable_slow_log does not get
a chance to be reset before the next statement to be executed by
the sql_thd. If the statement just executed by the sql_thd was an
administrative statement and logging of admin statements was
disabled, this means that sql_thd->enable_slow_log will be set to
0 (disabled) from that moment on. End result: sql_thd stops
logging slow statements.
We fix this by resetting the value of sql_thd->enable_slow_log to
the value of opt_log_slow_slave_statements right after
log_slow_stement is called by the sql_thd.
To 5.x Release
Notes
=====
This is a backport of BUG#23300 into 5.1 GA.
Original cset revid (in betony):
luis.soares@sun.com-20090929140901-s4kjtl3iiyy4ls2h
Description
===========
When using replication, the slave will not log any slow query
logs queries replicated from the master, even if the
option "--log-slow-slave-statements" is set and these take more
than "log_query_time" to execute.
In order to log slow queries in replicated thread one needs to
set the --log-slow-slave-statements, so that the SQL thread is
initialized with the correct switch. Although setting this flag
correctly configures the slave thread option to log slow queries,
there is an issue with the condition that is used to check
whether to log the slow query or not. When replaying binlog
events the statement contains the SET TIMESTAMP clause which will
force the slow logging condition check to fail. Consequently, the
slow query logging will not take place.
This patch addresses this issue by removing the second condition
from the log_slow_statements as it prevents slow queries to be
binlogged and seems to be deprecated.
Fixed 2 problems :
1. test_if_order_by_key() was continuing on the primary key
as if it has a primary key suffix (as the secondary keys do).
This leads to crashes in ORDER BY <pk>,<pk>.
Fixed by not treating the primary key as the secondary one
and not depending on it being clustered with a primary key.
2. The cost calculation was trying to read the records
per key when operating on ORDER BYs that order on all of the
secondary key + some of the primary key.
This leads to crashes because of out-of-bounds array access.
Fixed by assuming we'll find 1 record per key in such cases.
The problem was that the dbug facility was being used after the
per-thread dbug state had already been finalized. The was present
in a few functions which invoked decrement_handler_count, which
in turn invokes my_thread_end on Windows. In my_thread_end, the
per-thread dbug state is finalized. Any use after the state is
finalized ends up creating a new state.
The solution is to process the exit of a function before the
decrement_handler_count function is called.
flush_cached_records() was not correctly checking for errors after calling
Item::val_xxx() methods. The expressions may contain subqueries
or stored procedures that cause errors that should stop the statement.
Fixed by correctly checking for errors and propagating them up the call stack.
Bug #49984 Test 'rpl_loaddata_symlink' fails with "Could not find target log"
Sometimes the symbolic link is available on Windows if
you have some Unix (emulation) layer installed like
Cygwin, MKS or other. But symbolic link is not always
available. It depends on versions, file volume and
system environment of Windows. And the symbolic link
is not typically used on Windows, at least not in the
degree and style they are used on Unix. We can not
change the test case to do without symbolic link,
because the test case is used to test that if the
symbolic link works fine.
To fix the problem, skip the test on windows.
Need to make sure the tmp join doesn't point to the structure already
freed by the cleanup() for the "base" join, as this can lead to
double free, because sometimes both tmp_join and join point to the
same tmp_table_params.copy_field array.
path names than 99 characters, using the USTAR format of the
resulting source TAR.
To be able to specify the use of USTAR when creating the source
TAR, we needed both to update the GNU autotools version requirements
slightly, and update the initiation of the tools to use more
modern constructs.
error in the query.
Fixes a leak after materializing a GROUP BY subquery to a
temp table when the subquery has a blob column in the SELECT
list.
Fixed by correctly destructing temporary buffers for re-usable
queries
The test case rpl_binlog_corruption fails on windows because when
adding a line to the binary log index file it gets terminated
with a CR+LF (which btw, is the normal case in windows, but not on
Unixes - LF). This causes mismatch between the relay log names,
causing mysqld to report that it cannot find the log file.
We fix this by creating the instrumented index file through
mysql, ie, using SELECT ... INTO DUMPFILE ..., as opposed on
relying on ultimatly OS commands like: -- echo "..." >
index. These changes go into the file and make the procedure
platform independent:
include/setup_fake_relay_log.inc
Side note: when using SELECT ... INTO DUMPFILE ..., one needs to
check if mysqld is running with secure_file_priv. If it is, we do
it in two steps: 1. create the file on the allowed location;
2. move it to the datadir. If it is not, then we just create the
file directly on the datadir (so previous step 2. is not needed).
REVOKE/GRANT; ALTER EVENT.
The following statements support the CURRENT_USER() where a user is needed.
DROP USER
RENAME USER CURRENT_USER() ...
GRANT ... TO CURRENT_USER()
REVOKE ... FROM CURRENT_USER()
ALTER DEFINER = CURRENT_USER() EVENT
but, When these statements are binlogged, CURRENT_USER() just is binlogged
as 'CURRENT_USER()', it is not expanded to the real user name. When slave
executes the log event, 'CURRENT_USER()' is expand to the user of slave
SQL thread, but SQL thread's user name always NULL. This breaks the replication.
After this patch, All above statements are rewritten when they are binlogged.
The CURRENT_USER() is expanded to the real user's name and host.
column is used for ORDER BY
Problem: filesort isn't meant for null length sort data
(e.g. char(0)), that leads to a server crash.
Fix: disregard sort order if sort data record length is 0 (nothing
to sort).
in multitable delete/subquery
SQL_BUFFER_RESULT should not have an effect on non-SELECT
statements according to our documentation.
Fixed by not passing it through to multi-table DELETE (similarly
to how it's done for multi-table UPDATE).
Rename method as to not hide a base.
Reorder attributes initialization.
Remove unused variable.
Rework code to silence a warning due to assignment used as truth value.
printstack() being present
When Bug#47391 was fixed, no assumption was made that support
for Solaris 8 was needed. Solaris 8 lacks printstack(), and
the build breaks because of this.
This patch adds a test for the presence of printstack() to
configure.in for 5.0, and uses HAVE_PRINTSTACK to make
decisions rather than the __sun define.
The 'rpl_get_master_version_and_clock' test verifies if the slave I/O
thread tries to reconnect to master when it tries to get the values of
the UNIX_TIMESTAMP, SERVER_ID from master under network disconnection.
So the master server is restarted for making the transient network
disconnection, during the period the COM_REGISTER_SLAVE failures are
produced in server log file when the slave I/O thread tries to
register on master.
To fix the problem, suppress COM_REGISTER_SLAVE failures in server log
file by mtr suppression, because they are expected.
MySQL's hash functions MD5 and SHA relied on the somewhat slow
sprintf function to convert the digests to hex representations.
This patch replaces the sprintf with a specific and inline hex
conversion function.
Patch contributed by Jan Steemann.
