MySQL Cluster enables users to meet the database challenges of next generation web, cloud, and communications services with uncompromising scalability, uptime and agility.
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Changes in MySQL Cluster NDB 7.5.2 (5.7.12-ndb-7.5.2) (2016-06-01, Developer Milestone 3)
MySQL Cluster NDB 7.5.2 is a new release of MySQL 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 MySQL Cluster releases.
Obtaining MySQL Cluster NDB 7.5. MySQL Cluster NDB 7.5 source code and binaries can be obtained from http://dev.mysql.com/downloads/cluster/.
For an overview of changes made in MySQL Cluster NDB 7.5, see What is New in MySQL Cluster NDB 7.5 (http://dev.mysql.com/doc/refman/5.7/en/mysql-cluster-what-is -new.html <http://dev.mysql.com/doc/refman/5.7/en/mysql-cluster-what-is-new.html>).
This release also incorporates all bugfixes and changes made in previous MySQL Cluster releases, as well as all bugfixes and feature changes which were added in mainline MySQL 5.7 through MySQL 5.7.12 (see Changes in MySQL 5.7.12 (2016-04-11) (http://dev.mysql.com/doc/relnotes/mysql/5.7/en/news-5-7-12.h tml <http://dev.mysql.com/doc/relnotes/mysql/5.7/en/news-5-7-12.html>)).
* Performance: A performance problem was found in an internal polling method do_poll() where the polling client did not check whether it had itself been woken up before completing the poll. Subsequent analysis showed that it is sufficient that only some clients in the polling queue receive data. do_poll() can then signal these clients and give up its polling rights, even if the maximum specified wait time (10 ms) has not expired. This change allows do_poll() to continue polling until either the maximum specified wait time has expired, or the polling client itself has been woken up (by receiving what it was waiting for). This avoids unnecessary thread switches between client threads and thus reduces the associated overhead by as much as 10% in the API client, resulting in a significant performance improvement when client threads perform their own polling. (Bug #81229, Bug #23202735)
* Incompatible Change: When the data nodes are only partially connected to the API nodes, a node used for a pushdown join may get its request from a transaction coordinator on a different node, without (yet) being connected to the API node itself. In such cases, the NodeInfo object for the requesting API node contained no valid info about the software version of the API node, which caused the DBSPJ block to assume (incorrectly) when aborting to assume that the API node used NDB version 7.2.4 or earlier, requiring the use of a backward compatability mode to be used during query abort which sent a node failure error instead of the real error causing the abort. Now, whenever this situation occurs, it is assumed that, if the NDB software version is not yet available, the API node version is greater than 7.2.4. (Bug #23049170)
* Important Change: When started with the --initialize (http://dev.mysql.com/doc/refman/5.7/en/server-options.ht ml#option_mysqld_initialize <http://dev.mysql.com/doc/refman/5.7/en/server-options.html#option_mysqld_initialize>) option, mysqld no longer enables the NDBCLUSTER (http://dev.mysql.com/doc/refman/5.7/en/mysql-cluster.htm l <http://dev.mysql.com/doc/refman/5.7/en/mysql-cluster.html>) storage engine plugin. This change was needed to prevent attempted initialization of system databases as distributed (rather than as specific to individual SQL nodes), which could result in a metadata lock deadlock. This fix also brings the behavior of --initialize in this regard into line with that of the discontinued --bootstrap (http://dev.mysql.com/doc/refman/5.7/en/server-options.ht ml#option_mysqld_bootstrap <http://dev.mysql.com/doc/refman/5.7/en/server-options.html#option_mysqld_bootstrap>) option, which started a minimal mysqld instance without enabling NDB. (Bug #22758238)
* Microsoft Windows: ndb_mgmd failed to start on 32-bit Windows platforms, due to an issue with calling dynamically loaded functions; such issues were also likely to occur with other NDB programs using ndb_init(). It was found that all of the functions used are already supported in targeted versions of Windows, so this problem is fixed by removing the dynamic loading of these functions and using the versions provided by the Windows header files instead. (Bug #80876, Bug #23014820)
* Microsoft Windows: When building MySQL Cluster on Windows using more than one parallel build job it was sometimes possible for the build to fail because host_info.exe could not be be installed. To fix this problem, the install_mcc target is now always built prior to the host_info target. (Bug #80051, Bug #22566368)
* Microsoft Windows: Performing ANALYZE TABLE (http://dev.mysql.com/doc/refman/5.7/en/analyze-table.htm l <http://dev.mysql.com/doc/refman/5.7/en/analyze-table.html>) on a table having one or more indexes caused ndbmtd to fail with an InvalidAttrInfo error due to signal corruption. This issue occurred consistently on Windows, but could also be encountered on other platforms. (Bug #77716, Bug #21441297)
* Reserved send buffer for the loopback transporter, introduced in MySQL Cluster NDB 7.4.8 and used by API and management nodes for administrative signals, was calculated incorrectly. (Bug #23093656) References: This issue is a regression of: Bug #21664515.
* During a node restart, re-creation of internal triggers used for verifying the referential integrity of foreign keys was not reliable, because it was possible that not all distributed TC and LDM instances agreed on all trigger identities. To fix this problem, an extra step is added to the node restart sequence, during which the trigger identities are determined by querying the current master node. (Bug #23068914) References: See also: Bug #23221573.
* Following the forced shutdown of one of the 2 data nodes in a cluster where NoOfReplicas=2 (http://dev.mysql.com/doc/refman/5.7/en/mysql-cluster-ndb d-definition.html#ndbparam-ndbd-noofreplicas <http://dev.mysql.com/doc/refman/5.7/en/mysql-cluster-ndbd-definition.html#ndbparam-ndbd-noofreplicas>), the other data node shut down as well, due to arbitration failure. (Bug #23006431)
* Aborting a CREATE LOGFILE GROUP (http://dev.mysql.com/doc/refman/5.7/en/create-logfile-gr oup.html <http://dev.mysql.com/doc/refman/5.7/en/create-logfile-group.html>) statement which had failed due to lack of shared global memory was not performed correctly, causing node failure. In addition, the transaction in which this occurred was not rolled back correctly, also causing any subsequent CREATE LOGFILE GROUP to fail. (Bug #22982618)
* The ndbinfo.tc_time_track_stats (http://dev.mysql.com/doc/refman/5.7/en/mysql-cluster-ndb info-tc-time-track-stats.html <http://dev.mysql.com/doc/refman/5.7/en/mysql-cluster-ndbinfo-tc-time-track-stats.html>) table uses histogram buckets to give a sense of the distribution of latencies. The sizes of these bucket were also reported as HISTOGRAM BOUNDARY INFO messages during data node startup; this printout was redundant and so has been removed. (Bug #22819868)
* Online upgrades from previous versions of MySQL Cluster to MySQL Cluster NDB 7.5 were not possible due to missing entries in the matrix used to test upgrade compatibility between versions. (Bug #22024947)
* A failure occurred in DBTUP in debug builds when variable-sized pages for a fragment totalled more than 4 GB. (Bug #21313546)
* Restoration of metadata with ndb_restore -m (http://dev.mysql.com/doc/refman/5.7/en/mysql-cluster-pro grams-ndb-restore.html#option_ndb_restore_restore_meta <http://dev.mysql.com/doc/refman/5.7/en/mysql-cluster-programs-ndb-restore.html#option_ndb_restore_restore_meta>) 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.
* mysqld did not shut down cleanly when executing ndb_index_stat. (Bug #21098142)
* The following improvements were made to the data node error logging mechanism:
+ Increased the message slot size 499 bytes to 999 bytes to prevent log messages from overwriting one another or from being truncated.
+ Added a Trace file name field to the output. This field contains the trace file name (without any path) and trace file number for the thread causing the trace.
+ ndbmtd trace files are also now shown in the error log. (Bug #21082710)
* DBDICT and GETTABINFOREQ queue debugging were enhanced as follows:
+ Monitoring by a data node of the progress of GETTABINFOREQ signals can be enabled by setting DictTrace (http://dev.mysql.com/doc/refman/5.7/en/mysql-cluste r-ndbd-definition.html#ndbparam-ndbd-dicttrace <http://dev.mysql.com/doc/refman/5.7/en/mysql-cluster-ndbd-definition.html#ndbparam-ndbd-dicttrace>) > 2.
+ Added the ApiVerbose (http://dev.mysql.com/doc/refman/5.7/en/mysql-cluste r-api-definition.html#ndbparam-api-apiverbose <http://dev.mysql.com/doc/refman/5.7/en/mysql-cluster-api-definition.html#ndbparam-api-apiverbose>) configuration parameter, which enables NDB API debug logging for an API node where it is set greater than or equal to 2.
+ Added DUMP code 1229 which shows the current state of the GETTABINFOREQ queue. (See DUMP 1229 (http://dev.mysql.com/doc/ndbapi/en/ndb-internals-du mp-command-1229.html <http://dev.mysql.com/doc/ndbapi/en/ndb-internals-dump-command-1229.html>).) See also The DBDICT Block (http://dev.mysql.com/doc/ndbapi/en/ndb-internals-kernel- blocks-dbdict.html <http://dev.mysql.com/doc/ndbapi/en/ndb-internals-kernel-blocks-dbdict.html>). (Bug #20368450) References: See also: Bug #20368354.
* When a write to the ndb_binlog_index table failed during a MySQL Server shutdown, mysqld killed the NDB binary logging thread. (Bug #81166, Bug #23142945)
* Memory associated with table descriptions was not freed by the internal table information method NdbDictInterface::parseTableInfo(). (Bug #81141, Bug #23130084)
* Fixed a memory leak that occurred when an error was raised in ha_ndbcluster::get_metadata() or one of the functions which this method calls. (Bug #81045, Bug #23089566)
* An internal function used to validate connections failed to update the connection count when creating a new Ndb (http://dev.mysql.com/doc/ndbapi/en/ndb-ndb.html) object. This had the potential to create a new Ndb object for every operation validating the connection, which could have an impact on performance, particularly when performing schema operations. (Bug #80750, Bug #22932982)
* A table scan on an NDB (http://dev.mysql.com/doc/refman/5.7/en/mysql-cluster.htm l <http://dev.mysql.com/doc/refman/5.7/en/mysql-cluster.html>) table using neither an ordered index nor any Disk Data columns normally uses an ACC scan. If this happened while scanning an unique but unordered index which shrank (due to rows being deleted) after the scan started and then grew again (rows inserted), a single row that had been neither deleted nor inserted could be scanned twice. (Bug #80733, Bug #22926938)
* Starting a backup in the ndb_mgm client after creating a large number of tables caused a forced shutdown of the cluster. (Bug #80640, Bug #228849958)
* When an SQL node was started, and joined the schema distribution protocol, another SQL node, already waiting for a schema change to be distributed, timed out during that wait. This was because the code incorrectly assumed that the new SQL node would also acknowledge the schema distribution even though the new node joined too late to be a participant in it. As part of this fix, printouts of schema distribution progress now always print the more significant part of a bitmask before the less significant; formatting of bitmasks in such printouts has also been improved. (Bug #80554, Bug #22842538)
* The ndb_print_file utility failed consistently on Solaris 9 for SPARC. (Bug #80096, Bug #22579581)
* The MySQL Cluster Auto-Installer failed to work in various ways on different platforms. (Bug #79853, Bug #22502247)
* The internal function ndbrequire(), which, like assert(), evaluates a given expression and terminates the process if the expression does not evaluate as true, now includes the failed expression in its output to the error logs. (Bug #77021, Bug #21128318)
* Trying to drop a table during an ongoing backup failed with the error message Unknown table; now, it fails with Unable to alter table as backup is in progress. (Bug #47301, Bug #11755512) References: See also: Bug #44695, Bug #11753280.
* Disk Data: The following improvements were made to logging during restarts by data nodes using MySQL Cluster Disk Data:
+ The total amount of undo log to be applied by the data node is now provided as the total number of pages present in the log. This is a worst case estimate.
+ Progress information is now provided at regular intervals (once for each 30000 records) as the undo log is applied. This information is supplied as the number of records and number of undo log pages applied so far during the current restart. (Bug #22513381)
* Cluster API: Deletion of Ndb objects used a dispoportionately high amount of CPU. (Bug #22986823)
* Cluster API: Executing a transaction with an NdbIndexOperation (http://dev.mysql.com/doc/ndbapi/en/ndb-ndbindexoperation ..html <http://dev.mysql.com/doc/ndbapi/en/ndb-ndbindexoperation.html>) 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)
* mysql_upgrade failed to upgrade the sys schema if a sys database directory existed but was empty. (Bug #81352, Bug #23249846, Bug #22875519)
On behalf of the MySQL RE Team, Lars Tangvald
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