Dear MySQL Users,

MySQL Cluster is the distributed, shared-nothing variant of MySQL.
This storage engine provides:

  - In-Memory storage - Real-time performance (with optional
    checkpointing to disk)
  - Transparent Auto-Sharding - Read & write scalability
  - Active-Active/Multi-Master geographic replication

  - 99.999% High Availability with no single point of failure
    and on-line maintenance
  - NoSQL and SQL APIs (including C++, Java, http, Memcached
    and JavaScript/Node.js)

MySQL Cluster 7.5.9, has been released and can be downloaded from

  http://www.mysql.com/downloads/cluster/

where you will also find Quick Start guides to help you get your
first MySQL Cluster database up and running.

MySQL Cluster 7.5 is also available from our repository for Linux
platforms, go here for details:

  http://dev.mysql.com/downloads/repo/

The release notes are available from

  http://dev.mysql.com/doc/relnotes/mysql-cluster/7.5/en/index.html

MySQL Cluster enables users to meet the database challenges of next
generation web, cloud, and communications services with uncompromising
scalability, uptime and agility.

More details can be found at

  http://www.mysql.com/products/cluster/

Enjoy !

Changes in MySQL NDB Cluster 7.5.9 (5.7.21-ndb-7.5.9) (2018-01-17,
General Availability)

   MySQL NDB Cluster 7.5.9 is a new release of MySQL NDB Cluster
   7.5, based on MySQL Server 5.7 and including features in
   version 7.5 of the NDB
   (http://dev.mysql.com/doc/refman/5.7/en/mysql-cluster.html)
   storage engine, as well as fixing recently discovered bugs in
   previous NDB Cluster releases.

   Obtaining MySQL NDB Cluster 7.5.  MySQL NDB Cluster 7.5
   source code and binaries can be obtained from
   http://dev.mysql.com/downloads/cluster/.

   For an overview of changes made in MySQL NDB Cluster 7.5, see
   What is New in NDB Cluster 7.5
(http://dev.mysql.com/doc/refman/5.7/en/mysql-cluster-what-is-new-7-5.html).

   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 5.7
   through MySQL 5.7.21 (see Changes in MySQL 5.7.21 (Not yet
   released, General Availability)
(http://dev.mysql.com/doc/relnotes/mysql/5.7/en/news-5-7-21.html)).

   Bugs Fixed

     * NDB Replication: On an SQL node not being used for a
       replication channel with sql_log_bin=0
(http://dev.mysql.com/doc/refman/5.7/en/server-system-variables.html#sysvar_sql_log_bin)
       it was possible after
       creating and populating an NDB table for a table map
       event to be written to the binary log for the created
       table with no corresponding row events. This led to
       problems when this log was later used by a slave cluster
       replicating from the mysqld where this table was created.
       Fixed this by adding support for maintaining a cumulative
       any_value bitmap for global checkpoint event operations
       that represents bits set consistently for all rows of a
       specific table in a given epoch, and by adding a check to
       determine whether all operations (rows) for a specific
       table are all marked as NOLOGGING, to prevent the
       addition of this table to the Table_map held by the
       binlog injector.
       As part of this fix, the NDB API adds a new
       getNextEventOpInEpoch3()
(http://dev.mysql.com/doc/ndbapi/en/ndb-ndb-getnexteventopinepoch3.html)
       method which provides information about
       any AnyValue received by making it possible to retrieve
       the cumulative any_value bitmap. (Bug #26333981)

     * A query against the INFORMATION_SCHEMA.FILES
       (http://dev.mysql.com/doc/refman/5.7/en/files-table.html)
       table returned no results when it included an ORDER BY
       clause. (Bug #26877788)

     * During a restart, DBLQH loads redo log part metadata for
       each redo log part it manages, from one or more redo log
       files. Since each file has a limited capacity for
       metadata, the number of files which must be consulted
       depends on the size of the redo log part. These files are
       opened, read, and closed sequentially, but the closing of
       one file occurs concurrently with the opening of the
       next.
       In cases where closing of the file was slow, it was
       possible for more than 4 files per redo log part to be
       open concurrently; since these files were opened using
       the OM_WRITE_BUFFER option, more than 4 chunks of write
       buffer were allocated per part in such cases. The write
       buffer pool is not unlimited; if all redo log parts were
       in a similar state, the pool was exhausted, causing the
       data node to shut down.
       This issue is resolved by avoiding the use of
       OM_WRITE_BUFFER during metadata reload, so that any
       transient opening of more than 4 redo log files per log
       file part no longer leads to failure of the data node.
       (Bug #25965370)

     * In certain circumstances where multiple Ndb objects were
       being used in parallel from an API node, the block number
       extracted from a block reference in DBLQH was the same as
       that of a SUMA block even though the request was coming
       from an API node. Due to this ambiguity, DBLQH mistook
       the request from the API node for a request from a SUMA
       block and failed. This is fixed by checking node IDs
       before checking block numbers. (Bug #88441, Bug
       #27130570)

     * When the duplicate weedout algorithm was used for
       evaluating a semi-join, the result had missing rows. (Bug
       #88117, Bug #26984919)
       References: See also: Bug #87992, Bug #26926666.

     * A table used in a loose scan could be used as a child in
       a pushed join query, leading to possibly incorrect
       results. (Bug #87992, Bug #26926666)

     * When representing a materialized semi-join in the query
       plan, the MySQL Optimizer inserted extra QEP_TAB and
       JOIN_TAB objects to represent access to the materialized
       subquery result. The join pushdown analyzer did not
       properly set up its internal data structures for these,
       leaving them uninitialized instead. This meant that later
       usage of any item objects referencing the materialized
       semi-join accessed an initialized tableno column when
       accessing a 64-bit tableno bitmask, possibly referring to
       a point beyond its end, leading to an unplanned shutdown
       of the SQL node. (Bug #87971, Bug #26919289)

     * When a data node was configured for locking threads to
       CPUs, it failed during startup with Failed to lock tid.
       This was is a side effect of a fix for a previous issue,
       which disabled CPU locking based on the version of the
       available glibc. The specific glibc issue being guarded
       against is encountered only in response to an internal
       NDB API call (Ndb_UnlockCPU()) not used by data nodes
       (and which can be accessed only through internal API
       calls). The current fix enables CPU locking for data
       nodes and disables it only for the relevant API calls
       when an affected glibc version is used. (Bug #87683, Bug
       #26758939)
       References: This issue is a regression of: Bug #86892,
       Bug #26378589.

     * The NDBFS block's OM_SYNC flag is intended to make sure
       that all FSWRITEREQ signals used for a given file are
       synchronized, but was ignored by platforms that do not
       support O_SYNC, meaning that this feature did not behave
       properly on those platforms. Now the synchronization flag
       is used on those platforms that do not support O_SYNC.
       (Bug #76975, Bug #21049554)


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