NDB Cluster APIs: Executing a transaction with an NdbIndexOperation based on an obsolete unique index caused the data node process to fail. Now the index is checked in such cases, and if it cannot be used the transaction fails with an appropriate error. (Bug #79494, Bug #22299443)

During node failure handling, the request structure used to drive the cleanup operation was not maintained correctly when the request was executed. This led to inconsistencies that were harmless during normal operation, but these could lead to assertion failures during node failure handling, with subsequent failure of additional nodes. (Bug #22643129)

The previous fix for a lack of mutex protection for the internal TransporterFacade::deliver_signal() function was found to be incomplete in some cases. (Bug #22615274)

References: This issue is a regression of: Bug #77225, Bug #21185585.

When setup of the binary log as an atomic operation on one SQL node failed, this could trigger a state in other SQL nodes in which they appeared to detect the SQL node participating in schema change distribution, whereas it had not yet completed binary log setup. This could in turn cause a deadlock on the global metadata lock when the SQL node still retrying binary log setup needed this lock, while another mysqld had taken the lock for itself as part of a schema change operation. In such cases, the second SQL node waited for the first one to act on its schema distribution changes, which it was not yet able to do. (Bug #22494024)

Duplicate key errors could occur when ndb_restore was run on a backup containing a unique index. This was due to the fact that, during restoration of data, the database can pass through one or more inconsistent states prior to completion, such an inconsistent state possibly having duplicate values for a column which has a unique index. (If the restoration of data is preceded by a run with --disable-indexes and followed by one with --rebuild-indexes, these errors are avoided.)

Added a check for unique indexes in the backup which is performed only when restoring data, and which does not process tables that have explicitly been excluded. For each unique index found, a warning is now printed. (Bug #22329365)

Restoration of metadata with ndb_restore -m occasionally failed with the error message Failed to create index... when creating a unique index. While disgnosing this problem, it was found that the internal error PREPARE_SEIZE_ERROR (a temporary error) was reported as an unknown error. Now in such cases, ndb_restore retries the creation of the unique index, and PREPARE_SEIZE_ERROR is reported as NDB Error 748 Busy during read of event table. (Bug #21178339)

References: See also: Bug #22989944.

Optimization of signal sending by buffering and sending them periodically, or when the buffer became full, could cause SUB_GCP_COMPLETE_ACK signals to be excessively delayed. Such signals are sent for each node and epoch, with a minimum interval of TimeBetweenEpochs; if they are not received in time, the SUMA buffers can overflow as a result. The overflow caused API nodes to be disconnected, leading to current transactions being aborted due to node failure. This condition made it difficult for long transactions (such as altering a very large table), to be completed. Now in such cases, the ACK signal is sent without being delayed. (Bug #18753341)