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MySQL NDB Cluster 7.4 Release Notes  /  Changes in MySQL NDB Cluster 7.4.31 (5.6.51-ndb-7.4.31) (2021-01-19, General Availability)

Changes in MySQL NDB Cluster 7.4.31 (5.6.51-ndb-7.4.31) (2021-01-19, General Availability)

MySQL NDB Cluster 7.4.31 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

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.

Deprecation and Removal Notes

  • NDB Client Programs: Effective with this release, the MySQL NDB Cluster Auto-Installer ( has been has been removed from the NDB Cluster binary and source distributions, and is no longer supported. (Bug #32084831)

    References: See also: Bug #31888835.

  • ndbmemcache: ndbmemcache, which was deprecated in the previous release of NDB Cluster, has now been removed from NDB Cluster, and is no longer supported. (Bug #32106576)

Bugs Fixed

  • Using the maximum size of an index key supported by index statistics (3056 bytes) caused buffer issues in data nodes. (Bug #32094904)

    References: See also: Bug #25038373.

  • When a table creation schema transaction is prepared, the table is in TS_CREATING state, and is changed to TS_ACTIVE state when the schema transaction commits on the DBDIH block. In the case where the node acting as DBDIH coordinator fails while the schema transaction is committing, another node starts taking over for the coordinator. The following actions are taken when handling this node failure:

    • DBDICT rolls the table creation schema transaction forward and commits, resulting in the table involved changing to TS_ACTIVE state.

    • DBDIH starts removing the failed node from tables by moving active table replicas on the failed node from a list of stored fragment replicas to another list.

    These actions are performed asynchronously many times, and when interleaving may cause a race condition. As a result, the replica list in which the replica of a failed node resides becomes nondeterministic and may differ between the recovering node (that is, the new coordinator) and other DIH participant nodes. This difference violated a requirement for knowing which list the failed node's replicas can be found during the recovery of the failed node recovery on the other participants.

    To fix this, moving active table replicas now covers not only tables in TS_ACTIVE state, but those in TS_CREATING (prepared) state as well, since the prepared schema transaction is always rolled forward.

    In addition, the state of a table creation schema transaction which is being aborted is now changed from TS_CREATING or TS_IDLE to TS_DROPPING, to avoid any race condition there. (Bug #30521812)