Changes in MySQL NDB Cluster 7.4.29 (5.6.49-ndb-7.4.29) (2020-07-14, General Availability)

MySQL NDB Cluster 7.4.29 is a new release of MySQL NDB Cluster 7.4, based on MySQL Server 5.6 and including features in version 7.4 of the NDB storage engine, as well as fixing recently discovered bugs in previous NDB Cluster releases.

Obtaining MySQL NDB Cluster 7.4.  MySQL NDB Cluster 7.4 source code and binaries can be obtained from https://dev.mysql.com/downloads/cluster/.

For an overview of changes made in MySQL NDB Cluster 7.4, see What is New in NDB Cluster 7.4.

This release also incorporates all bug fixes and changes made in previous NDB Cluster releases, as well as all bug fixes and feature changes which were added in mainline MySQL 5.6 through MySQL 5.6.49 (see Changes in MySQL 5.6.49 (2020-07-13, General Availability)).

Bugs Fixed

• During a node restart, the SUMA block of the node that is starting must get a copy of the subscriptions (events with subscribers) and subscribers (NdbEventOperation instances which are executing) from a node already running. Before the copy is complete, nodes which are still starting ignore any user-level SUB_START or SUB_STOP requests; after the copy is done, they can participate in such requests. While the copy operation is in progress, user-level SUB_START and SUB_STOP requests are blocked using a DICT lock.

  An issue was found whereby a starting node could participate in SUB_START and SUB_STOP requests after the lock was requested, but before it is granted, which resulted in unsuccessful SUB_START and SUB_STOP requests. This fix ensures that the nodes cannot participate in these requests until after the DICT lock has actually been granted. (Bug #31302657)

• The Dojo toolkit included with NDB Cluster and used by the Auto-Installer was upgraded to version 1.15.3. (Bug #31029110)

• A packed version 1 configuration file returned by ndb_mgmd could contain duplicate entries following an upgrade to NDB 8.0, which made the file incompatible with clients using version 1. This occurs due to the fact that the code for handling backwards compatibility assumed that the entries in each section were already sorted when merging it with the default section. To fix this, we now make sure that this sort is performed prior to merging. (Bug #31020183)

• When executing any of the SHUTDOWN, ALL STOP, or ALL RESTART management commands, it is possible for different nodes to attempt to stop on different global checkpoint index (CGI) boundaries. If they succeed in doing so, then a subsequent system restart is slower than normal because any nodes having an earlier stop GCI must undergo takeover as part of the process. When nodes failing on the first GCI boundary cause surviving nodes to be nonviable, surviving nodes suffer an arbitration failure; this has the positive effect of causing such nodes to halt at the correct GCI, but can give rise to spurious errors or similar.

  To avoid such issues, extra synchronization is now performed during a planned shutdown to reduce the likelihood that different data nodes attempt to shut down at different GCIs as well as the use of unnecessary node takeovers during system restarts. (Bug #31008713)