MySQL Cluster NDB 7.2.15 is a new release of MySQL Cluster,
incorporating new features in the
NDBCLUSTER storage engine, and
fixing recently discovered bugs in previous MySQL Cluster NDB
7.2 development releases.
Obtaining MySQL Cluster NDB 7.2. MySQL Cluster NDB 7.2 source code and binaries can be obtained from http://dev.mysql.com/downloads/cluster/.
This release also incorporates all bugfixes and changes made in previous MySQL Cluster releases, as well as all bugfixes and feature changes which were added in mainline MySQL 5.5 through MySQL 5.5.35 (see Changes in MySQL 5.5.35 (2013-12-03)).
When attempting to start memcached with a
cache_size larger than that of the available
memory and with
preallocate=true failed, the
error message provided only a numeric code, and did not indicate
what the actual source of the error was.
(Bug #17509293, Bug #70403)
ndbmemcache: A memcached server running the NDB engine could crash after being disconnected from a cluster. (Bug #14055851)
Compilation of ndbmtd failed on Solaris 10
and 11 for 32-bit
x86, and the binary was not
included in the binary distributions for these platforms.
Disk Data: When using Disk Data tables and ndbmtd data nodes, it was possible for the undo buffer to become overloaded, leading to a crash of the data nodes. This issue was more likely to be encountered when using Disk Data columns whose size was approximately 8K or larger. (Bug #16766493)
UINT_MAX64 was treated as a signed value by
Visual Studio 2010. To prevent this from happening, the value is
now explicitly defined as unsigned.
References: See also Bug #17647637.
Monotonic timers on several platforms can experience issues which might result in the monotonic clock doing small jumps back in time. This is due to imperfect synchronization of clocks between multiple CPU cores and does not normally have an adverse effect on the scheduler and watchdog mechanisms; so we handle some of these cases by making backtick protection less strict, although we continue to ensure that the backtick is less than 10 milliseconds. This fix also removes several checks for backticks which are thereby made redundant. (Bug #17971449)
Under certain specific circumstances, in a cluster having two SQL nodes, one of these could hang, and could not be accessed again even after killing the mysqld process and restarting it. (Bug #17875885)
References: See also Bug #17934985.
Poor support or lack of support on some platforms for monotonic timers caused issues with delayed signal handling by the job scheduler for the multithreaded data node. Variances (timer leaps) on such platforms are now handled in the same way the multithreaded data node process that they are by the singlethreaded version. (Bug #17857442)
References: See also Bug #17475425, Bug #17647637.
In some cases, with
ndb_join_pushdown enabled, it
was possible to obtain from a valid query the error
Got error 290 'Corrupt key in TC, unable to xfrm'
from NDBCLUSTER even though the data was not
It was determined that a
NULL in a
VARCHAR column could be used to
construct a lookup key, but since
never equal to any other value, such a lookup could simple have
been eliminated instead. This
NULL lookup in
turn led to the spurious error message.
This fix takes advantage of the fact that a key lookup with
NULL never finds any matching rows, and so
NDB does not try to perform the
lookup that would have led to the error.
When using single-threaded (ndbd) data nodes
enabled, the CPU did not, as intended, temporarily lower its
scheduling priority to normal every 10 milliseconds to give
other, non-realtime threads a chance to run.
It was theoretically possible in certain cases for a number of
output functions internal to the
NDB code to supply an uninitialized
buffer as output. Now in such cases, a newline character is
(Bug #17775602, Bug #17775772)
Use of the
localtime() function in
NDB multithreading code led to
otherwise nondeterministic failures in
ndbmtd. This fix replaces this function,
which on many platforms uses a buffer shared among multiple
localtime_r(), which can have
allocated to it a buffer of its own.
During arbitrator selection,
QMGR Block) runs through
a series of states, the first few of which are (in order)
START. A check
for an arbitration selection timeout occurred in the
FIND state, even though the corresponding
timer was not set until
QMGR reached the
Attempting to read the resulting uninitialized timestamp value
could lead to false Could not find an arbitrator,
cluster is not partition-safe warnings.
This fix moves the setting of the timer for arbitration timeout
INIT state, so that the value later
FIND is always initialized.
The global checkpoint lag watchdog tracking the number of times a check for GCP lag was performed using the system scheduler and used this count to check for a timeout condition, but this caused a number of issues. To overcome these limitations, the GCP watchdog has been refactored to keep track of its own start times, and to calculate elapsed time by reading the (real) clock every time it is called.
In addition, any backticks (rare in any case) are now handled by taking the backwards time as the new current time and calculating the elapsed time for this round as 0. Finally, any ill effects of a forward leap, which possibly could expire the watchdog timer immediately, are reduced by never calculating an elapsed time longer than the requested delay time for the watchdog timer. (Bug #17647469)
References: See also Bug #17842035.
Timers used in timing scheduler events in the
NDB kernel have been refactored, in
part to insure that they are monotonic on all platforms. In
particular, on Windows, event intervals were previously
calculated using values obtained from
GetSystemTimeAsFileTime(), which reads
directly from the system time (“wall clock”), and
which may arbitrarily be reset backward or forward, leading to
false watchdog or heartbeat alarms, or even node shutdown. Lack
of timer monotonicity could also cause slow disk writes during
backups and global checkpoints. To fix this issue, the Windows
implementation now uses
QueryPerformanceCounters() instead of
GetSystemTimeAsFileTime(). In the event that
a monotonic timer is not found on startup of the data nodes, a
warning is logged.
In addition, on all platforms, a check is now performed at
compile time for available system monotonic timers, and the
build fails if one cannot be found; note that
CLOCK_HIGHRES is now supported as an
CLOCK_MONOTONIC if the latter
is not available.
The length of the interval (intended to be 10 seconds) between
GCP_COMMIT when the GCP progress
watchdog did not detect progress in a global checkpoint was not
always calculated correctly.
In certain rare cases on commit of a transaction, an
Ndb object was released before
the transaction coordinator (
block) sent the expected
NDB failed to send a
COMMIT_ACK signal in response, which caused a
memory leak in the
NDB kernel could later
lead to node failure.
Ndb object is not released until the
COMMIT_CONF signal has actually been
After restoring the database metadata (but not any data) by
-m), SQL nodes would hang while trying to
SELECT from a table in the
database to which the metadata was restored. In such cases the
attempt to query the table now fails as expected, since the
table does not actually exist until
ndb_restore is executed with
Losing its connections to the management node or data nodes
while a query against the
ndbinfo.memoryusage table was
in progress caused the SQL node where the query was issued to
(Bug #14483440, Bug #16810415)
The ndbd_redo_log_reader utility now supports
Using this options causes the program to print basic usage
information, and then to exit.
(Bug #11749591, Bug #36805)
Cluster API: Compilation of example NDB API program files failed due to missing include directives. (Bug #17672846, Bug #70759)
It was possible for an
object to receive signals for handling before it was
initialized, leading to thread interleaving and possible data
node failure when executing a call to
Ndb::init(). To guard against
this happening, a check is now made when it is starting to
receive signals that the
Ndb object is
properly initialized before any signals are actually handled.