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MySQL Cluster 8.0.19 has been released
Posted by: Jocelyn Ramilison
Date: January 13, 2020 12:06PM

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 8.0.19 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 8.0 is also available from our repository for Linux
platforms, go here for details:

  https://dev.mysql.com/downloads/

The release notes are available from

  http://dev.mysql.com/doc/relnotes/mysql-cluster/8.0/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 8.0.19 (2020-01-13, General Availability)

   MySQL NDB Cluster 8.0.19 is a new release of NDB
   8.0, based on MySQL Server 8.0 and including features in
   version 8.0 of the NDB storage engine, as well as fixing
   recently discovered bugs in previous NDB Cluster releases.

   Obtaining NDB Cluster 8.0.  NDB Cluster 8.0 source code and
   binaries can be obtained from
   https://dev.mysql.com/downloads/cluster/.

   For an overview of changes made in NDB Cluster 8.0, see What
   is New in NDB Cluster
   (https://dev.mysql.com/doc/refman/8.0/en/mysql-cluster-what-is-new.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 8.0
   through MySQL 8.0.19 (see Changes in MySQL 8.0.19
   (2020-01-13, General Availability)
   (https://dev.mysql.com/doc/relnotes/mysql/8.0/en/news-8-0-19.html)).

Functionality Added or Changed


     * Important Change: The default value for the
       ndb_autoincrement_prefetch_sz server system variable has
       been increased to 512. (Bug #30316314)

     * Important Change: NDB now supports more than 2 replicas
       (up to a maximum of 4). Setting NoOfReplicas=3 or
       NoOfReplicas=4 is now fully covered in our internal
       testing and thus supported for use in production. (Bug
       #97479, Bug #97579, Bug #25261716, Bug #30501414, Bug
       #30528105)

     * Important Change: Added the TransactionMemory data node
       configuration parameter which simplifies configuration of
       data node memory allocation for transaction operations.
       This part of ongoing work on pooling of transactional and
       Local Data Manager (LDM) memory.
       This new parameter is intended to supersede several older
       transactional memory parameters which have been
       deprecated (and which are thus subject to removal in a
       future release of NDB Cluster). In particular, the
       following parameters are incompatible with
       TransactionMemory and cannot be set in the config.ini
       configuration file if this parameter has been set:

          + MaxNoOfConcurrentIndexOperations

          + MaxNoOfFiredTriggers

          + MaxNoOfLocalOperations

          + MaxNoOfLocalScans
       If you attempt to set any of these incompatible
       parameters concurrently with TransactionMemory, the
       cluster management server cannot start.
       For more information, see the description of the
       TransactionMemory parameter and Parameters incompatible
       with TransactionMemory
       (https://dev.mysql.com/doc/refman/8.0/en/mysql-cluster-ndbd-definition.html#mysql-cluster-transactionmemory-incompatible).
       See also Data Node Memory Management
       (https://dev.mysql.com/doc/refman/8.0/en/mysql-cluster-data-node-memory-management.html),
       for information about how memory resources are allocated
       by NDB Cluster data nodes. (Bug #96995, Bug #30344471)

     * Important Change: The maximum or default values for
       several NDB Cluster data node configuration parameters
       have been changed in this release. These changes are
       listed here:

          + The maximum value for DataMemory is increased from 1
            terabyte to 16 TB.

          + The maximum value for DiskPageBufferMemory is also
            increased from 1 TB to 16 TB.

          + The default value for StringMemory is decreased to 5
            percent. Previously, this was 25 percent.

          + The default value for LcpScanProgressTimeout is
            increased from 60 seconds to 180 seconds.

     * Performance: Read from any replica, which greatly
       improves the performance of table reads at a very low
       cost to table write performance, is now enabled by
       default for all NDB tables. This means both that the
       default value for the ndb_read_backup system variable is
       now ON, and that the value of the NDB_TABLE comment
       option READ_BACKUP is 1 when creating a new NDB table.
       (Previously, the default values were OFF and 0,
       respectively.)
       For more information, see Setting NDB_TABLE Options
       (https://dev.mysql.com/doc/refman/8.0/en/create-table-ndb-table-comment-options.html),
       as well as the description
       of the ndb_read_backup system variable.

     * NDB Disk Data: The latency of checkpoints for Disk Data
       files has been reduced when using non-volatile memory
       devices such as solid-state drives (especially those
       using NVMe for data transfer), separate physical drives
       for Disk Data files, or both. As part of this work, two
       new data node configuration parameters, listed here, have
       been introduced:

          + MaxDiskDataLatency sets a maximum on allowed latency
            for disk access, aborting transactions exceeding
            this amount of time to complete

          + DiskDataUsingSameDisk makes it possible to take
            advantage of keeping Disk Data files on separate
            disks by increasing the rate at which Disk Data
            checkpoints can be made
       This release also adds three new tables to the ndbinfo
       database. These tables, listed here, can assist with
       performance monitoring of Disk Data checkpointing:

          + diskstat provides information about Disk Data
            tablespace reads, writes, and page requests during
            the previous 1 second

          + diskstats_1sec provides information similar to that
            given by the diskstat table, but does so for each of
            the last 20 seconds

          + pgman_time_track_stats table reports on the latency
            of disk operations affecting Disk Data tablespaces
       For additional information, see Disk Data latency
       parameters
       (https://dev.mysql.com/doc/refman/8.0/en/mysql-cluster-ndbd-definition.html#mysql-cluster-ndbd-definition-disk-data-latency-parameters).

     * Added the ndb_metadata_sync server system variable, which
       simplifies knowing when metadata synchronization has
       completed successfully. Setting this variable to true
       triggers immediate synchronization of all changes between
       the NDB dictionary and the MySQL data dictionary without
       regard to any values set for ndb_metadata_check or
       ndb_metadata_check_interval. When synchronization has
       completed, its value is automatically reset to false.
       (Bug #30406657)

     * A stack trace is now written to the data node log on
       abnormal termination of a data node.

     * Automatic synchronization of metadata from the MySQL data
       dictionary to NDB now includes databases containing NDB
       tables. With this enhancement, if a table exists in NDB,
       and the table and the database it belongs to do not exist
       on a given SQL node, it is no longer necessary to create
       the database manually. Instead, the database, along with
       all NDB tables belonging to this database, should be
       created on the SQL node automatically.

Bugs Fixed


     * Incompatible Change: ndb_restore no longer restores
       shared users and grants to the mysql.ndb_sql_metadata
       table by default. A new command-line option
       --include-stored-grants is added to override this
       behavior and enable restoring of shared user and grant
       data and metadata.
       As part of this fix, ndb_restore can now also correctly
       handle an ordered index on a system table. (Bug
       #30237657)
       References: See also: Bug #29534239, Bug #30459246.

     * Incompatible Change: The minimum value for the
       RedoOverCommitCounter data node configuration parameter
       has been increased from 0 to 1. The minimum value for the
       RedoOverCommitLimit data node configuration parameter has
       also been increased from 0 to 1.
       You should check the cluster global configuration file
       and make any necessary adjustments to values set for
       these parameters before upgrading. (Bug #29752703)

     * macOS: On MacOS, SQL nodes sometimes shut down
       unexpectedly during the binary log setup phase when
       starting the cluster. This occurred when there existed
       schemas whose names used uppercase letters and
       lower_case_table_names was set to 2. This caused
       acquisition of metadata locks to be attempted using keys
       having the incorrect lettercase, and, subsequently, these
       locks to fail. (Bug #30192373)

     * Microsoft Windows; NDB Disk Data: On Windows, restarting
       a data node other than the master when using Disk Data
       tables led to a failure in TSMAN. (Bug #97436, Bug
       #30484272)

     * Solaris: When debugging, ndbmtd consumed all available
       swap space on Solaris 11.4 SRU 12 and later. (Bug
       #30446577)

     * Solaris: The byte order used for numeric values stored in
       the mysql.ndb_sql_metadata table was incorrect on
       Solaris/Sparc. This could be seen when using
       ndb_select_all or ndb_restore --print. (Bug #30265016)

     * NDB Disk Data: After dropping a disk data table on one
       SQL node, trying to execute a query against
       INFORMATION_SCHEMA.FILES on a different SQL node stalled
       at Waiting for tablespace metadata lock. (Bug #30152258)
       References: See also: Bug #29871406.

     * NDB Disk Data: ALTER TABLESPACE ... ADD DATAFILE could
       sometimes hang while trying to acquire a metadata lock.
       (Bug #29871406)

     * The fix made in NDB 8.0.18 for an issue in which a
       transaction was committed prematurely aborted the
       transaction if the table definition had changed midway,
       but failed in testing to free memory allocated by
       getExtraMetadata(). Now this memory is properly freed
       before aborting the transaction. (Bug #30576983)
       References: This issue is a regression of: Bug #29911440.

     * Excessive allocation of attribute buffer when
       initializing data in DBTC led to preallocation of api
       connection records failing due to unexpectedly running
       out of memory. (Bug #30570264)

     * Improved error handling in the case where NDB attempted
       to update a local user having the NDB_STORED_USER
       privilege but which could not be found in the
       ndb_sql_metadata table. (Bug #30556487)

     * Failure of a transaction during execution of an ALTER
       TABLE ... ALGORITHM=COPY statement following the rename
       of the new table to the name of the original table but
       before dropping the original table caused mysqld to exit
       prematurely. (Bug #30548209)

     * Non-MSI builds on Windows using -DWITH_NDBCLUSTER did not
       succeed unless the WiX toolkit was installed. (Bug
       #30536837)

     * The allowed_values output from ndb_config --xml
       --configinfo for the Arbitration data node configuration
       parameter in NDB 8.0.18 was not consistent with that
       obtained in previous releases. (Bug #30529220)
       References: See also: Bug #30505003.

     * A faulty ndbrequire() introduced when implementing
       partial local checkpoints assumed that m_participatingLQH
       must be clear when receiving START_LCP_REQ, which is not
       necessarily true when a failure happens for the master
       after sending START_LCP_REQ and before handling any
       START_LCP_CONF signals. (Bug #30523457)

     * A local checkpoint sometimes hung when the master node
       failed while sending an LCP_COMPLETE_REP signal and it
       was sent to some nodes, but not all of them. (Bug
       #30520818)

     * Added the DUMP 9988 and DUMP 9989 commands. (Bug
       #30520103)

     * The management server did not handle all cases of
       NODE_FAILREP correctly. (Bug #30520066)

     * With SharedGlobalMemory set to 0, some resources did not
       meet required minimums. (Bug #30411835)

     * Execution of ndb_restore --rebuild-indexes together with
       the --rewrite-database and --exclude-missing-tables
       options did not create indexes for any tables in the
       target database. (Bug #30411122)

     * When writing the schema operation into the ndb_schema
       table failed, the states in the NDB_SCHEMA object were
       not cleared, which led to the SQL node shutting down when
       it tried to free the object. (Bug #30402362)
       References: See also: Bug #30371590.

     * If a transaction was aborted while getting a page from
       the disk page buffer and the disk system was overloaded,
       the transaction hung indefinitely. This could also cause
       restarts to hang and node failure handling to fail. (Bug
       #30397083, Bug #30360681)
       References: See also: Bug #30152258.

     * When synchronizing extent pages it was possible for the
       current local checkpoint (LCP) to stall indefinitely if a
       CONTINUEB signal for handling the LCP was still
       outstanding when receiving the FSWRITECONF signal for the
       last page written in the extent synchronization page. The
       LCP could also be restarted if another page was written
       from the data pages. It was also possible that this issue
       caused PREP_LCP pages to be written at times when they
       should not have been. (Bug #30397083)

     * Data node failures with the error Another node failed
       during system restart... occurred during a partial
       restart. (Bug #30368622)

     * Automatic synchronization could potentially trigger an
       increase in the number of locks being taken on a
       particular metadata object at a given time, such as when
       a synchronization attempt coincided with a DDL or DML
       statement involving the same metadata object; competing
       locks could lead to the NDB deadlock detection logic
       penalizing the user action rather than the background
       synchronization. We fix this by changing all exclusive
       metadata lock acquisition attempts during
       auto-synchronization so that they use a timeout of 0
       (rather than the 10 seconds previously allowed), which
       avoids deadlock detection and gives priority to the user
       action. (Bug #30358470)

     * If a SYNC_EXTENT_PAGES_REQ signal was received by PGMAN
       while dropping a log file group as part of a partial
       local checkpoint, and thus dropping the page locked by
       this block for processing next, the LCP terminated due to
       trying to access the page after it had already been
       dropped. (Bug #30305315)

     * The wrong number of bytes was reported in the cluster log
       for a completed local checkpoint. (Bug #30274618)
       References: See also: Bug #29942998.

     * Added the new ndb_mgm client debugging commands DUMP 2356
       and DUMP 2357. (Bug #30265415)

     * Executing ndb_drop_table using the --help option caused
       this program to terminate prematurely, and without
       producing any help output. (Bug #30259264)

     * A mysqld trying to connect to the cluster, and thus
       trying to acquire the global schema lock (GSL) during
       setup, ignored the setting for ndb_wait_setup and hung
       indefinitely when the GSL had already been acquired by
       another mysqld, such as when it was executing an ALTER
       TABLE statement. (Bug #30242141)

     * When a table containing self-referential foreign key (in
       other words, a foreign key referencing another column of
       the same table) was altered using the COPY algorithm, the
       foreign key definition was removed. (Bug #30233405)

     * In MySQL 8.0, names of foreign keys explicitly provided
       by user are generated automatically in the SQL layer and
       stored in the data dictionary. Such names are of the form
       [table_name]_ibfk_[#] which align with the names
       generated by the InnoDB storage engine in MySQL 5.7. NDB
       8.0.18 introduced a change in behavior by NDB such that
       it also uses the generated names, but in some cases, such
       as when tables were renamed, NDB still generated and used
       its own format for such names internally rather than
       those generated by the SQL layer and stored in the data
       dictionary, which led to the following issues:

          + Discrepancies in SHOW CREATE TABLE output and the
            contents of I_S.REFENTIAL_CONSTRAINTS

          + Improper metadata locking for foreign keys

          + Confusing names for foreign keys in error messages
       Now NDB also renames the foreign keys in such cases,
       using the names provided by the MySQL server, to align
       fully with those used by InnoDB. (Bug #30210839)
       References: See also: Bug #96508, Bug #30171959.

     * When a table referenced by a foreign key was renamed,
       participating SQL nodes did not properly update the
       foreign key definitions for the referencing table in
       their data dictionaries during schema distribution. (Bug
       #30191068)

     * Data node handling of failures of other data nodes could
       sometimes not be synchronized properly, such that two or
       more data nodes could see different nodes as the master
       node. (Bug #30188414)

     * Some scan operations failed due to the presence of an old
       assert in DbtupBuffer.cpp that checked whether API nodes
       were using a version of the software previous to NDB 6.4.
       This was no longer necessary or correct, and has been
       removed. (Bug #30188411)

     * When executing a global schema lock (GSL), NDB used a
       single Ndb_table_guard object for successive retires when
       attempting to obtain a table object reference; it was not
       possible for this to succeed after failing on the first
       attempt, since Ndb_table_guard assumes that the
       underlying object pointer is determined once only---at
       initialisation---with the previously retrieved pointer
       being returned from a cached reference thereafter.
       This resulted in infinite waits to obtain the GSL,
       causing the binlog injector thread to hang so that mysqld
       considered all NDB tables to be read-only. To avoid this
       problem, NDB now uses a fresh instance of Ndb_table_guard
       for each such retry. (Bug #30120858)
       References: This issue is a regression of: Bug #30086352.

     * When upgrading an SQL node to NDB 8.0 from a previous
       release series, the .frm file whose contents are read and
       then installed in the data dictionary does not contain
       any information about foreign keys. This meant that
       foreign key information was not installed in the SQL
       node's data dictionary. This is fixed by using the
       foreign key information available in the NDB data
       dictionary to update the local MySQL data dictionary
       during table metadata upgrade. (Bug #30071043)

     * Restoring tables with the --disable-indexes option
       resulted in the wrong table definition being installed in
       the MySQL data dictionary. This is because the serialized
       dictionary information (SDI) packed into the NDB
       dictionary's table definition is used to create the table
       object; the SDI definition is updated only when the DDL
       change is done through the MySQL server. Installation of
       the wrong table definition meant that the table could not
       be opened until the indexes were re-created in the NDB
       dictionary again using --rebuild-indexes.
       This is fixed by extending auto-synchronization such that
       it compares the SDI to the NDB dictionary table
       information and fails in cases in which the column
       definitions do not match. Mismatches involving indexes
       only are treated as temporary errors, with the table in
       question being detected again during the next round of
       change detection. (Bug #30000202, Bug #30414514)

     * Restoring tables for which MAX_ROWS was used to alter
       partitioning from a backup made from NDB 7.4 to a cluster
       running NDB 7.6 did not work correctly. This is fixed by
       ensuring that the upgrade code handling PartitionBalance
       supplies a valid table specification to the NDB
       dictionary. (Bug #29955656)

     * The number of data bytes for the summary event written in
       the cluster log when a backup completed was truncated to
       32 bits, so that there was a significant mismatch between
       the number of log records and the number of data records
       printed in the log for this event. (Bug #29942998)

     * mysqld sometimes aborted during a long ALTER TABLE
       operation that timed out. (Bug #29894768)
       References: See also: Bug #29192097.

     * When an SQL node connected to NDB, it did not know
       whether it had previously connected to that cluster, and
       thus could not determine whether its data dictionary
       information was merely out of date, or completely
       invalid. This issue is solved by implementing a unique
       schema version identifier (schema UUID) to the ndb_schema
       table in NDB as well as to the ndb_schema table object in
       the data dictionary. Now, whenever a mysqld connects to a
       cluster as an SQL node, it can compare the schema UUID
       stored in its data dictionary against that which is
       stored in the ndb_schema table, and so know whether it is
       connecting for the first time. If so, the SQL node
       removes any entries that may be in its data dictionary.
       (Bug #29894166)
       References: See also: Bug #27543602.

     * Improved log messages generated by table discovery and
       table metadata upgrades. (Bug #29894127)

     * Using 2 LDM threads on a 2-node cluster with 10 threads
       per node could result in a partition imbalance, such that
       one of the LDM threads on each node was the primary for
       zero fragments. Trying to restore a multi-threaded backup
       from this cluster failed because the datafile for one LDM
       contained only the 12-byte data file header, which
       ndb_restore was unable to read. The same problem could
       occur in other cases, such as when taking a backup
       immediately after adding an empty node online.
       It was found that this occurred when ODirect was enabled
       for an EOF backup data file write whose size was less
       than 512 bytes and the backup was in the STOPPING state.
       This normally occurs only for an aborted backup, but
       could also happen for a successful backup for which an
       LDM had no fragments. We fix the issue by introducing an
       additional check to ensure that writes are skipped only
       if the backup actually contains an error which should
       cause it to abort. (Bug #29892660)
       References: See also: Bug #30371389.

     * For NDB tables, ALTER TABLE ... ALTER INDEX did not work
       with ALGORITHM=INPLACE. (Bug #29700197)

     * ndb_restore failed in testing on 32-bit platforms. This
       issue is fixed by increasing the size of the thread stack
       used by this tool from 64 KB to 128 KB. (Bug #29699887)
       References: See also: Bug #30406046.

     * An unplanned shutdown of the cluster occurred due to an
       error in DBTUP while deleting rows from a table following
       an online upgrade. (Bug #29616383)

     * In some cases the SignalSender class, used as part of the
       implementation of ndb_mgmd and ndbinfo, buffered
       excessive numbers of unneeded SUB_GCP_COMPLETE_REP and
       API_REGCONF signals, leading to unnecessary consumption
       of memory. (Bug #29520353)
       References: See also: Bug #20075747, Bug #29474136.

     * The setting for the BackupLogBufferSize configuration
       parameter was not honored. (Bug #29415012)

     * When mysqld was run with the --upgrade=FORCE option, it
       reported the following issues:
      [Warning]  Table 'mysql.ndb_apply_status' requires repair.
      [ERROR]    Table 'mysql.ndb_apply_status' repair failed.
       This was because --upgrade=FORCE causes a bootstrap
       system thread to run CHECK TABLE FOR UPGRADE, but
       ha_ndbcluster::open() refused to open the table before
       schema synchronization had completed, which eventually
       led to the reported conditions. (Bug #29305977)
       References: See also: Bug #29205142.

     * When using explicit SHM connections, with ShmSize set to
       a value larger than the system's available shared memory,
       mysqld hung indefinitely on startup and produced no
       useful error messages. (Bug #28875553)

     * The maximum global checkpoint (GCP) commit lag and GCP
       save timeout are recalculated whenever a node shuts down,
       to take into account the change in number of data nodes.
       This could lead to the unintentional shutdown of a viable
       node when the threshold decreased below the previous
       value. (Bug #27664092)
       References: See also: Bug #26364729.

     * A transaction which inserts a child row may run
       concurrently with a transaction which deletes the parent
       row for that child. One of the transactions should be
       aborted in this case, lest an orphaned child row result.
       Before committing an insert on a child row, a read of the
       parent row is triggered to confirm that the parent
       exists. Similarly, before committing a delete on a parent
       row, a read or scan is performed to confirm that no child
       rows exist. When insert and delete transactions were run
       concurrently, their prepare and commit operations could
       interact in such a way that both transactions committed.
       This occurred because the triggered reads were performed
       using LM_CommittedRead locks (see
       NdbOperation::LockMode), which are not strong enough to
       prevent such error scenarios.
       This problem is fixed by using the stronger LM_SimpleRead
       lock mode for both triggered reads. The use of
       LM_SimpleRead rather than LM_CommittedRead locks ensures
       that at least one transaction aborts in every possible
       scenario involving transactions which concurrently insert
       into child rows and delete from parent rows. (Bug
       #22180583)

     * Concurrent SELECT and ALTER TABLE statements on the same
       SQL node could sometimes block one another while waiting
       for locks to be released. (Bug #17812505, Bug #30383887)

     * Failure handling in schema synchronization involves
       pushing warnings and errors to the binary logging thread.
       Schema synchronization is also retried in case of certain
       failures which could lead to an accumulation of warnings
       in the thread. Now such warnings and errors are cleared
       following each attempt at schema synchronization. (Bug
       #2991036)

     * An INCL_NODECONF signal from any local blocks should be
       ignored when a node has failed, except in order to reset
       c_nodeStartSlave.nodeId. (Bug #96550, Bug #30187779)

     * When returning Error 1022, NDB did not print the name of
       the affected table. (Bug #74218, Bug #19763093)
       References: See also: Bug #29700174.

On Behalf of Oracle/MySQL Release Engineering Team,
Hery Ramilison

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