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MySQL NDB Cluster 7.3 Release Notes  /  Release Series Changelogs: MySQL NDB Cluster 7.3  /  Changes in MySQL NDB Cluster 7.3.16 (5.6.35-ndb-7.3.16) (2017-01-17, General Availability)

Changes in MySQL NDB Cluster 7.3.16 (5.6.35-ndb-7.3.16) (2017-01-17, General Availability)

Bugs Fixed

  • 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.

  • 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)

  • 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.

  • 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)