Changes in MySQL NDB Cluster 7.5.22 (5.7.34-ndb-7.5.22) (2021-04-21, General Availability)

Bugs Fixed

• A node was permitted during a restart to participate in a backup before it had completed recovery, instead of being made to wait until its recovery was finished. (Bug #32381165)

• Running out of disk space while performing an NDB backup could lead to an unplanned shutdown of the cluster. (Bug #32367250)

• The default number of partitions per node (shown in ndb_desc output as PartitionCount) is calculated using the lowest number of LDM threads employed by any single live node, and was done only once, even after data nodes left or joined the cluster, possibly with a new configuration changing the LDM thread count and thus the default partition count. Now in such cases, we make sure the default number of partitions per node is recalculated whenever data nodes join or leave the cluster. (Bug #32183985)

• Event buffer congestion could lead to unplanned shutdown of SQL nodes which were performing binary logging. We fix this by updating the binary logging handler to use Ndb::pollEvents2() (rather than the deprecated pollEvents() method) to catch and handle such errors properly, instead. (Bug #31926584)

• Generation of internal statistics relating to NDB object counts was found to lead to an increase in transaction latency at very high rates of transactions per second, brought about by returning an excessive number of freed NDB objects. (Bug #31790329)