Dear MySQL users,

MySQL Server 5.6.42, a new version of the popular Open Source Database
Management System, has been released. MySQL 5.6.42 is recommended for
use on production systems.

   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 5.5 through MySQL 5.5.62
   (see Changes in MySQL 5.5.62 (Not yet released, General availability)
   For an overview of what's new in MySQL 5.6, please see

     Starting with 5.6.11, Microsoft Windows packages for MySQL 5.6 are
     available both as a "full" installer and as a "web" installer.  The
     full installer is significantly larger and comes bundled with the
     latest software releases available. This bundle makes it easy to
     download and configure a full server and development suite.

     The web installer doesn't come bundled with any actual products and
     instead relies on download-on-demand to fetch only the products you
     choose to install. This makes the initial download much smaller but
     increases install time as the individual products will need to be

For information on installing MySQL 5.6.42 on new servers or upgrading
to MySQL 5.6.42 from previous MySQL releases, please see

MySQL Server is available in source and binary form for a number of
platforms from our download pages at

Not all mirror sites may be up to date at this point in time, so if you
can't find this version on some mirror, please try again later or choose
another download site.

We welcome and appreciate your feedback, bug reports, bug fixes,
patches, etc:

The following link lists the changes in the MySQL 5.6 since the release
of MySQL 5.6.41. It may also be viewed online at


Changes in MySQL 5.6.42 (2018-10-22, General Availability)

     * Functionality Added or Changed

     * Bugs Fixed

Functionality Added or Changed

     * Previously, file I/O performed in the I/O cache in the
       mysys library was not instrumented, affecting in particular file
       I/O statistics reported by the Performance Schema about the
       binary log index file. Now, this I/O is instrumented and
       Performance Schema statistics are accurate. Thanks to Yura
       Sorokin for the contribution. (Bug #27788907, Bug #90264)

     * The zlib library version bundled with MySQL was raised
       from version 1.2.3 to version 1.2.11. MySQL implements
       compression with the help of the zlib library.  The zlib
       compressBound() function in zlib 1.2.11 returns a slightly higher
       estimate of the buffer size required to compress a given length
       of bytes than it did in zlib version 1.2.3. The compressBound()
       function is called by InnoDB functions that determine the maximum
       row size permitted when creating compressed InnoDB tables or
       inserting rows into compressed InnoDB tables. As a result, CREATE
       TABLE ... ROW_FORMAT=COMPRESSED or INSERT operations with row
       sizes very close to the maximum row size that were successful in
       earlier releases could now fail.  If you have compressed InnoDB
       tables with large rows, it is recommended that you test
       compressed table CREATE TABLE statements on a MySQL 8.0.3 test
       instance prior to upgrading.

Bugs Fixed

     * InnoDB: An ALTER TABLE operation that added a primary key
       produced a segmentation fault. (Bug #28395278) References: This
       issue is a regression of: Bug #27753193.

     * InnoDB: An assertion was raised during an OPTIMIZE TABLE
       operation. (Bug #27753193)

     * InnoDB: A foreign key constraint name was duplicated
       during a rename table operation, causing a failure during later
       query execution. (Bug #27545888)

     * InnoDB: The location of the Innodb Merge Temp File that
       reported by the wait/io/file/innodb/innodb_temp_file Performance
       Schema instrument was incorrect. (Bug #21339079, Bug #77519)

     * Replication: When FLUSH statements for specific log types
       (such as FLUSH SLOW LOGS) resulted in an error, the statements
       were still written to the binary log. This stopped replication
       because the error had occurred on the master, but did not occur
       on the slave. MySQL Server now checks on the outcome of these
       FLUSH statements, and if an error occurred, the statement is not
       written to the binary log. (Bug #24786290, Bug #83232)

     * Microsoft Windows: On Windows, uninstallation of the
       MySQL Server MSI package through MySQL Installer produced a
       spurious popup window. (Bug #27463864)

     * Concurrent INSERT and SELECT statements on a MERGE table
       could result in a server exit. (Bug #28379285)

     * MySQL Server and test RPM packages were missing
       perl-Data-Dumper as a dependency. (Bug #28144933, Bug #72926)

     * For the mysql client, the -b short option was associated
       with two long options, --no-beep and --binary-as-hex. The -b
       option now is associated only with --no-beep. (Bug #28093271)

     * Very long table keys were handled incorrectly on
       replication slaves. (Bug #27930505)

     * During server startup/shutdown, PID files could be
       mishandled. (Bug #27919254)

     * For MEMORY tables, memory overflow errors could occur.
       (Bug #27799513)

     * When converting from a BLOB (or TEXT) type to a smaller
       BLOB (or TEXT) type, no warning or error was reported informing
       about the truncation or data loss. Now an appropriate error is
       issued in strict SQL mode and a warning in nonstrict SQL mode.
       (Bug #27788685, Bug #90266)

     * Failure to create a temporary table during a MyISAM query
       could cause a server exit. Thanks to Facebook for the patch. (Bug
       #27724519, Bug #90145)

     * An attempted read of an uncommitted transaction raised an
       assertion. (Bug #26876608)

     * ALTER TABLE ... REORGANIZE PARTITION ... could result in
       incorrect behavior if any partition other than the last was
       missing the VALUES LESS THAN part of the syntax. (Bug #26791931)

     * yum update did not properly update from RHEL5 RPM
       packages to current packages. (Bug #20560761)

     * It was possible for a subquery that used a unique key on
       a column allowing NULL to return multiple rows. (Bug #88670, Bug

On Behalf of MySQL Release Engineering Team,
Surabhi Bhat

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