Changes in MySQL NDB Cluster 7.5.5 (5.7.17-ndb-7.5.5) (2017-01-17, General Availability)

Bugs Fixed

• Packaging: NDB Cluster Auto-Installer RPM packages for SLES 12 failed due to a dependency on python2-crypto instead of python-pycrypto. (Bug #25399608)

• Packaging: The RPM installer for the MySQL NDB Cluster auto-installer package had a dependency on python2-crypt instead of python-crypt. (Bug #24924607)

• Microsoft Windows: Installation failed when the Auto-Installer (ndb_setup.py) was run on a Windows host that used Swedish as the system language. This was due to system messages being issued using the cp1252 character set; when these messages contained characters that did not map directly to 7-bit ASCII (such as the ä character in Tjänsten ... startar), conversion to UTF-8—as expected by the Auto-Installer web client—failed.

  This fix has been tested only with Swedish as the system language, but should work for Windows systems set to other European languages that use the cp1252 character set. (Bug #83870, Bug #25111830)

• ndbinfo Information Database: A number of inconsistencies and other issues had arisen regarding ndbinfo tables due to manual copying of the table and view definitions in the sources. Now the SQL statements for these are generated, for consistency. (Bug #23305078)

  References: See also: Bug #25047951.

• ndb_restore did not restore tables having more than 341 columns correctly. This was due to the fact that the buffer used to hold table metadata read from .ctl files was of insufficient size, so that only part of the table descriptor could be read from it in such cases. This issue is fixed by increasing the size of the buffer used by ndb_restore for file reads. (Bug #25182956)

  References: See also: Bug #25302901.

• No traces were written when ndbmtd received a signal in any thread other than the main thread, due to the fact that all signals were blocked for other threads. This issue is fixed by the removal of SIGBUS, SIGFPE, SIGILL, and SIGSEGV signals from the list of signals being blocked. (Bug #25103068)

• The rand() function was used to produce a unique table ID and table version needed to identify a schema operation distributed between multiple SQL nodes, relying on the assumption that rand() would never produce the same numbers on two different instances of mysqld. It was later determined that this is not the case, and that in fact it is very likely for the same random numbers to be produced on all SQL nodes.

  This fix removes the usage of rand() for producing a unique table ID or version, and instead uses a sequence in combination with the node ID of the coordinator. This guarantees uniqueness until the counter for the sequence wraps, which should be sufficient for this purpose.

  The effects of this duplication could be observed as timeouts in the log (for example NDB create db: waiting max 119 sec for distributing) when restarting multiple mysqld processes simultaneously or nearly so, or when issuing the same CREATE DATABASE or DROP DATABASE statement on multiple SQL nodes. (Bug #24926009)

• The ndb_show_tables utility did not display type information for hash maps or fully replicated triggers. (Bug #24383742)

• Long message buffer exhaustion when firing immediate triggers could result in row ID leaks; this could later result in persistent RowId already allocated errors (NDB Error 899). (Bug #23723110)

  References: See also: Bug #19506859, Bug #13927679.

• The NDB Cluster Auto-Installer did not show the user how to force an exit from the application (CTRL+C). (Bug #84235, Bug #25268310)

• The NDB Cluster Auto-Installer failed to exit when it was unable to start the associated service. (Bug #84234, Bug #25268278)

• The NDB Cluster Auto-Installer failed when the port specified by the --port option (or the default port 8081) was already in use. Now in such cases, when the required port is not available, the next 20 ports are tested in sequence, with the first one available being used; only if all of these are in use does the Auto-Installer fail. (Bug #84233, Bug #25268221)

• Multiples instances of the NDB Cluster Auto-Installer were not detected. This could lead to inadvertent multiple deployments on the same hosts, stray processes, and similar issues. This issue is fixed by having the Auto-Installer create a PID file (mcc.pid), which is removed upon a successful exit. (Bug #84232, Bug #25268121)

• when a parent NDB table in a foreign key relationship was updated, the update cascaded to a child table as expected, but the change was not cascaded to a child table of this child table (that is, to a grandchild of the original parent). This can be illustrated using the tables generated by the following CREATE TABLE statements:

  CREATE TABLE parent(
    id INT PRIMARY KEY AUTO_INCREMENT,
    col1 INT UNIQUE,
    col2 INT
  ) ENGINE NDB;
  
  CREATE TABLE child(
    ref1 INT UNIQUE,
    FOREIGN KEY fk1(ref1)
      REFERENCES parent(col1) ON UPDATE CASCADE
  ) ENGINE NDB;
  
  CREATE TABLE grandchild(
    ref2 INT,
    FOREIGN KEY fk2(ref2)
      REFERENCES child(ref1) ON UPDATE CASCADE
  ) ENGINE NDB;

  Table child is a child of table parent; table grandchild is a child of table child, and a grandchild of parent. In this scenario, a change to column col1 of parent cascaded to ref1 in table child, but it was not always propagated in turn to ref2 in table grandchild. (Bug #83743, Bug #25063506)

• The NDB binlog injector thread used an injector mutex to perform two important tasks:

  1. Protect against client threads creating or dropping events whenever the injector thread waited for pollEvents().

  2. Maintain access to data shared by the injector thread with client threads.

  The first of these could hold the mutex for long periods of time (on the order of 10ms), while locking it again extremely quickly. This could keep it from obtaining the lock for data access (“starved”) for unnecessarily great lengths of time.

  To address these problems, the injector mutex has been refactored into two—one to handle each of the two tasks just listed.

  It was also found that initialization of the binlog injector thread held the injector mutex in several places unnecessarily, when only local thread data was being initialized and sent signals with condition information when nothing being waited for was updated. These unneeded actions have been removed, along with numerous previous temporary fixes for related injector mutex starvation issues. (Bug #83676, Bug #83127, Bug #25042101, Bug #24715897)

  References: See also: Bug #82680, Bug #20957068, Bug #24496910.

• When a data node running with StopOnError set to 0 underwent an unplanned shutdown, the automatic restart performed the same type of start as the previous one. In the case where the data node had previously been started with the --initial option, this meant that an initial start was performed, which in cases of multiple data node failures could lead to loss of data. This issue also occurred whenever a data node shutdown led to generation of a core dump. A check is now performed to catch all such cases, and to perform a normal restart instead.

  In addition, in cases where a failed data node was unable prior to shutting down to send start phase information to the angel process, the shutdown was always treated as a startup failure, also leading to an initial restart. This issue is fixed by adding a check to execute startup failure handling only if a valid start phase was received from the client. (Bug #83510, Bug #24945638)

• When ndbmtd was built on Solaris/SPARC with version 5.3 of the GNU tools, data nodes using the resulting binary failed during startup. (Bug #83500, Bug #24941880)

  References: See also: Bug #83517, Bug #24947597.

• MySQL NDB Cluster failed to compile using GCC 6. (Bug #83308, Bug #24822203)

• When a data node was restarted, the node was first stopped, and then, after a fixed wait, the management server assumed that the node had entered the NOT_STARTED state, at which point, the node was sent a start signal. If the node was not ready because it had not yet completed stopping (and was therefore not actually in NOT_STARTED), the signal was silently ignored.

  To fix this issue, the management server now checks to see whether the data node has in fact reached the NOT_STARTED state before sending the start signal. The wait for the node to reach this state is split into two separate checks:

  • Wait for data nodes to start shutting down (maximum 12 seconds)

  • Wait for data nodes to complete shutting down and reach NOT_STARTED state (maximum 120 seconds)

  If either of these cases times out, the restart is considered failed, and an appropriate error is returned. (Bug #49464, Bug #11757421)

  References: See also: Bug #28728485.