Changes in MySQL 5.6.46
Configuration Notes
It is now possible to compile MySQL 5.6 using OpenSSL 1.1.1, enabling compilation support for MySQL 5.6 against OpenSSL even when OpenSSL 1.0.2 reaches End of Life status at the end of 2019.
In addition, MySQL 5.6 now supports TLSv1.1 and TLSv1.2 protocols for encrypted connections. This applies to MySQL Server, MySQL clients such as mysql and mysqldump, and master/slave replication. Previously, MySQL 5.6 supported only TLSv1, so TLSv1.1/TLSv1.2 support enables use of more secure TLS protocols. It also enables connecting from MySQL 5.6 clients and replication slaves to MySQL 5.7 and higher servers that have TLSv1 disabled, which previously was not possible. It also means that MySQL 5.7 and higher clients that do not want to use TLSv1 can connect to MySQL 5.6 servers.
All MySQL 5.6 builds now use OpenSSL. MySQL no longer supports using yaSSL as the SSL library, and source distributions no longer include yaSSL.
The WITH_SSL CMake option no longer permits bundled (use yaSSL) as a valid value, and the default option value has changed from bundled to system (use the version of OpenSSL installed on the host system).
Bugs Fixed
Improper locking during storage engine initialization could cause a server exit.
A query with a WHERE clause whose predicate contained a numeric value in scientific notation was not handled correctly.
VS2019 produced compilation errors with debug compilation selected due to use of the /ZI flag. Now /Z7 is used instead.
Password masking was incomplete for SHOW PROCESSLIST and some INFORMATION_SCHEMA and Performance Schema tables.
The -DWITH_EXAMPLE_STORAGE_ENGINE=1 CMake option was ignored but should not have been. If -DWITH_EXAMPLE_STORAGE_ENGINE=0 is given, the EXAMPLE storage engine is built as a plugin.
Changes in MySQL 5.6.45:
Functionality Added or Changed
Microsoft Windows: A new warning message now reminds DBAs that connections made using the MySQL named pipe on Windows has limited the permissions a connector can request on the named pipe.
Previously, the named_pipe_full_access_group system variable was set to a value that maps to the built-in Windows Everyone group (SID S-1-1-0) by default. However, this group is not ideal and should be replaced with a group that restricts its membership for connectors that are unable to request fewer permissions on the MySQL named pipe.
The new warning is written to the error log at startup if the string value assigned to named_pipe_full_access_group is '*everyone*' (or the Windows System Language equivalent) and named pipes are enabled. In addition, the warning is written to the error log and raised to the client if the system variable is reset to the Everyone group at runtime.
Bugs Fixed
InnoDB: A query that scanned the primary key of a table did not return the expected result.
InnoDB: A full-text cache lock taken when data is synchronized was not released if the full-text cache size exceeded the full-text cache size limit.
InnoDB: Client sessions using different auto_increment_increment values while performing concurrent insert operations could cause a duplicate key error.
Replication: In query log events in the binary log, the thread ID used for the execution of DROP TABLE and DELETE statements was identified incorrectly or not at all. On a multi-threaded replication slave, where temporary tables were involved (which require the correct thread ID as they are session specific), this omission resulted in errors when using mysqlbinlog to replay the binary log for point-in-time recovery. The thread ID is now set correctly.
Installing from RPM packages could result in an error log with incorrect permissions.
Enabling audit log encryption could cause a server exit.
MySQL Installer did not install OpenSSL DLL dependencies if the Development component was not selected.
The parser could leak memory for certain multiple-statement queries.
MySQL does not support OpenSSL session tickets, but did not set the SSL_OP_NO_TICKET flag to inform OpenSSL of that. The flag is now set.
UpdateXML() did not always free memory properly in certain cases.
Empty values in the name column of the mysql.plugin system table caused the server to exit during startup.
Some PROXY grants were not replicated to slaves, causing incorrect replication.
If an INSTALL PLUGIN statement contained invalid UTF-8 characters in the shared library name, it caused the server to hang (or to raise an assertion in debug builds).
* Windows builds now use the default runtime libraries (builds use the /MD flag).
* CMake support was added for compiling with Developer Studio 12.6.
MySQL failed to compile if -DENABLE_DEBUG_SYNC=OFF AND -DWITH_DEBUG=ON were both given. The ENABLE_DEBUG_SYNC option has been removed and enabling WITH_DEBUG enables Debug Sync.
* Changes in RPM package structure require a larger set of packages to be removed to install MySQL Server cleanly.
* To avoid potential race conditions, Debian packages now use the GNU install utility rather than a combination of mkdir, touch, and chown.
* CMake-generated packaging for Debian/Ubuntu packages was refactored for improved maintainability. The change includes updated logic for correctly replacing native distribution packaging in Debian and Ubuntu.
* Reminder: MySQL 5.6 requires the Microsoft Visual C++ 2010 Redistributable Package to run on Windows platforms. Users should make sure the package has been installed on the system before starting the server. The package is available at the Microsoft Download Center.
* The linked OpenSSL library for the MySQL Commercial Server has been updated to version 1.0.2k. For a description of issues fixed in this version, see http://www.openssl.org/news/vulnerabilities.html.
* The mysql_options() C API function now supports a MYSQL_OPT_SSL_MODE option.
Bugs Fixed
InnoDB: Full-text search auxiliary tables could be dropped by one session while being access by another.
InnoDB: Selecting full-text index information schema tables for a deleted table caused a segmentation fault.
InnoDB: Rollback of a full-text index synchronization operation raised an assertion. The rollback operation attempted to acquire a mutex still held by the background synchronization thread.
InnoDB: Setting innodb_monitor_enable to all did not enable all counters.
Replication: After issuing a PURGE BINARY LOGS statement, if the binary log index file was not available, for example because it had been opened by another application such as MEB, the server could stop unexpectedly. Although this situation was rare, the handling has been made more robust to avoid unexpected halts and more informative errors are provided.
Replication: When using row-based replication and InnoDB, replication slaves reverted to using an older locking scheme when a transaction had already acquired an AUTOINC lock related to a LOAD FILE or INSERT ... SELECT type of statement, reducing replication slave performance. The fix ensures that sql_command is set correctly for any of the DML events such as WRITE_ROWS_EVENT, UPDATE_EVENT, and DELETE_EVENT.
Replication: A MySQL version 5.5 slave does not have a server_uuid and replication identified servers by their server_id. Starting from MySQL version 5.6, replication masters detected a zombie dump thread based only on a slave's server_uuid value, under the assumption that each slave has a unique UUID. Connecting a MySQL 5.5 slave to a MySQL 5.6 and later master meant that the master was unable to detect zombie dump threads that were created to serve slaves running versions older than MySQL 5.6. The fix ensures that a master now first checks if a slave has a server_uuid set. If it is set, zombie dump thread detection happens based on the slave's UUID. If a slave's server_uuid is not set, zombie dump thread detection happens based on server_id.
Replication: With slave_skip_errors enabled there were still special cases when slave errors were not being correctly ignored. For example:
When opening and locking a table failed.
When field conversions failed on a server running row-based replication.
In these cases the error was considered critical and it was not respecting the state of slave_skip_errors. The fix ensures that with slave_skip_errors enabled, all errors reported during applying a transaction are correctly handled. This means that in such a set up, upon receiving an error with the log_warnings option set to greater than 1, if the error can be ignored then the warning is printed into the error log and the server continues as it does in the case of other ignored errors.
Replication: When using statement-based or mixed binary logging format with --read-only=ON, it was not possible to modify temporary tables.
MySQL Server upgrades performed using RPM packages failed when upgrading from MySQL 5.5 Community to MySQL 5.6 Community or MySQL 5.5 Commercial to MySQL 5.6 Commercial.
The code for reading character set information from Performance Schema statement events tables (for example, events_statements_current) did not prevent simultaneous writing to that information. As a result, the SQL query text character set could be invalid, which could result in a server exit. Now an invalid character set causes SQL_TEXT column truncation.
A buffer overflow in the regex library was fixed.
Certain arguments to NAME_CONST() could cause a server exit.
For unit-testing with the MySQL test suite, the make unit-test command is no longer available. The ctest program should be used instead. See Unit Tests Added to Main Test Runs.
ST_Distance() could raise an assertion for NULL return values.
With the query cache enabled, executing a prepared statement with CURSOR_TYPE_READ_ONLY and then again with CURSOR_TYPE_NO_CURSOR caused the server to return an error.
mysql_real_connect() was not thread-safe when invoked with the MYSQL_READ_DEFAULT_FILE or MYSQL_READ_DEFAULT_GROUP option enabled.
Installing MySQL from a yum or zypper repository resulted in /var/log/mysqld.log being created with incorrect user and group permissions.
If a stored function updated a view for which the view table had a trigger defined that updated another table, it could fail and report an error that an existing table did not exist.
If an INSTALL PLUGIN statement contained invalid UTF-8 characters in the shared library name, it caused the server to hang (or to raise an assertion in debug builds).
For multibyte character sets, LOAD DATA could fail to allocate space correctly and ignore input rows as a result.
under $PKG_SYSCONFDIR, and prevents mysql_install_db from creating
$PREFIX/my.cnf. Brings mysql56-client and mysql56-server in sync
WRT my.cnf location. Bump respective PKGREVISIONs.
Noticed by peterkelm@ on Github.
* Security Fix: Due to the LogJam issue (https://weakdh.org/), OpenSSL has changed the Diffie-Hellman key length parameters for openssl-1.0.1n and up.
* Replication: When using a multi-threaded slave, each worker thread has its own queue of transactions to process. In previous MySQL versions, STOP SLAVE waited for all workers to process their entire queue. This logic has been changed so that STOP SLAVE first finds the newest transaction that was committed by any worker thread. Then, it waits for all workers to complete transactions older than that. Newer transactions are not processed. The new logic allows STOP SLAVE to complete faster in case some worker queues contain multiple transactions.
* Previously, the max_digest_length system variable controlled the maximum digest length for all server functions that computed statement digests. However, whereas the Performance Schema may need to maintain many digest values, other server functions such as MySQL Enterprise Firewall need only one digest per session. Increasing the max_digest_length value has little impact on total memory requirements for those functions, but can increase Performance Schema memory requirements significantly. To enable configuring digest length separately for the Performance Schema, its digest length is now controlled by the new performance_schema_max_digest_length system variable.
* Previously, changes to the validate_password plugin dictionary file (named by the validate_password_dictionary_file system variable) while the server was running required a restart for the server to recognize the changes. Now validate_password_dictionary_file can be set at runtime and assigning a value causes the named file to be read without a restart.
In addition, two new status variables are available. validate_password_dictionary_file_last_parsed indicates when the dictionary file was last read, and validate_password_dictionary_file_words_count indicates how many words it contains.
* Bugs fixed
With OpenSSL 1.0.1p upgrade, DH parameters below 1024 bits are now
refused. MySQL hardcodes 512 bits DH parameters and will therefore
fail to run SSL connexions with OpenSSL 1.0.1p
Apply fix from upstream:
866b988a76
Functionality Added or Changed
* MySQL Enterprise Firewall operates on parser states and does not work well together with the query cache, which circumvents the parser. MySQL Enterprise Firewall now checks whether the query cache is enabled. If so, it displays a message that the query cache must be disabled and does not load.
* my_print_defaults now masks passwords. To display passwords in cleartext, use the new --show option.
* MySQL distributions now include an innodb_stress suite of test cases. Thanks to Mark Callaghan for the contribution.
Bugs Fixed
* InnoDB; Partitioning: The CREATE_TIME column of the INFORMATION_SCHEMA.TABLES table now shows the correct table creation time for partitioned InnoDB tables. The CREATE_TIME column of the INFORMATION_SCHEMA.PARTITIONS table now shows the correct partition creation time for a partition of partitioned InnoDB tables.
The UPDATE_TIME column of the INFORMATION_SCHEMA.TABLES table now shows when a partitioned InnoDB table was last updated by an INSERT, DELETE, or UPDATE. The UPDATE_TIME column of the INFORMATION_SCHEMA.PARTITIONS table now shows when a partition of a partitioned InnoDB table was last updated.
* InnoDB: An assertion was raised on shutdown due to XA PREPARE transactions holding explicit locks.
* InnoDB: The strict_* forms of innodb_checksum_algorithm settings (strict_none, strict_innodb, and strict_crc32) caused the server to halt when a non-matching checksum was encountered, even though the non-matching checksum was valid. For example, with innodb_checksum_algorithm=strict_crc32, encountering a valid innodb checksum caused the server to halt. Instead of halting the server, a message is now printed to the error log and the page is accepted as valid if it matches an innodb, crc32 or none checksum.
* InnoDB: The memcached set command permitted a negative expire time value. Expire time is stored internally as an unsigned integer. A negative value would be converted to a large number and accepted. The maximum expire time value is now restricted to INT_MAX32 to prevent negative expire time values.
* InnoDB: Removal of a foreign key object from the data dictionary cache during error handling caused the server to exit.
* InnoDB: SHOW ENGINE INNODB STATUS output showed negative reservation and signal count values due to a counter overflow error.
* InnoDB: Failure to check the status of a cursor transaction read-only option before reusing the cursor transaction for a write operation resulted in a server exit during a memcached workload.
* InnoDB: MDL locks taken by memcached clients caused a MySQL Enterprise Backup FLUSH TABLES WITH READ LOCK operation to hang.
* InnoDB: Estimates that were too low for the size of merge chunks in the result sorting algorithm caused a server exit.
* InnoDB: For full-text searches, the optimizer could choose an index that does not produce correct relevancy rankings.
* Partitioning: When creating a partitioned table, partition-level DATA DIRECTORY or INDEX DIRECTORY option values that contained an excessive number of characters were handled incorrectly.
* Partitioning: Executing an ALTER TABLE on a partitioned table on which a write lock was in effect could cause subsequent SQL statements on this table to fail.
* Replication: When binary logging was enabled, using stored functions and triggers resulting in a long running procedure that inserted many records caused the memory use to increase rapidly. This was due to memory being allocated per variable. The fix ensures that in such a situation, memory is allocated once and the same memory is reused.
* Replication: If an error was encountered while adding a GTID to the received GTID set, the log lock was not being correctly released. This could cause a deadlock.
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Security Fix: The linked OpenSSL library for the MySQL 5.6 Commercial Server has been updated from version 1.0.1g to version 1.0.1h. Versions of OpenSSL prior to and including 1.0.1g are reported to be vulnerable to CVE-2014-0224.
This change does not affect the Oracle-produced MySQL Community build of MySQL Server 5.6, which uses the yaSSL library instead.
DTrace Support
MySQL now includes DTrace support on Oracle Linux 6 or higher with UEK kernel. If DTrace is present, server builds will detect it with no special CMake options required. For information about using DTrace on MySQL, see Tracing mysqld Using DTrace.
InnoDB Notes
Important Change: Redo log writes for large, externally stored BLOB fields could overwrite the most recent checkpoint. The 5.6.20 patch limits the size of redo log BLOB writes to 10% of the redo log file size. The 5.7.5 patch addresses the bug without imposing a limitation. For MySQL 5.5, the bug remains a known limitation.
As a result of the redo log BLOB write limit introduced for MySQL 5.6, innodb_log_file_size should be set to a value greater than 10 times the largest BLOB data size found in the rows of your tables plus the length of other variable length fields (VARCHAR, VARBINARY, and TEXT type fields). Failing to do so could result in “Row size too large” errors. No action is required if your innodb_log_file_size setting is already sufficiently large or your tables contain no BLOB data.
Functionality Added or Changed
Replication: The new system variable binlog_impossible_mode controls what happens if the server cannot write to the binary log, for example, due to a file error. For backward compatibility, the default for binlog_impossible_mode is IGNORE_ERROR, meaning the server logs the error, halts logging, and continues updates to the database. Setting this variable to ABORT_SERVER makes the server halt logging and shut down if it cannot write to the binary log.
CMake support was updated to handle CMake version 3.
New Debian7, Ubuntu12.04, and Ubuntu14.04 distribution support that was introduced with 5.6.17 now comes with the platform-specific packaging source placed under the packaging directory, in the deb-precise, deb-wheezy, and deb-trusty directories.
Support for LinuxThreads has been removed from the source code. LinuxThreads was superseded by NPTL in Linux 2.6.
By default, mysql_install_db creates a my.cnf file in the installation base directory using a template. This may be undesireable for some deployments. To enable this behavior to be suppressed, mysql_install_db now supports a --keep-my-cnf option to preserve any existing my.cnf file and not create a new my.cnf file.
The mysqlhotcopy utility is now deprecated and will be removed in a future version of MySQL. Among the reasons for this: It works only for the MyISAM and ARCHIVE storage engines; it works on Unix but not Windows. Alternatives include mysqldump and MySQL Enterprise Backup.
The timed_mutexes system variable has no effect and is deprecated.
Bugs Fixed
* Previously, MySQL Server distributions included the MySQL Reference Manual in Info format (the Docs/mysql.info file). Because the license for the manual restricts redistribution, its inclusion in Community packages caused problems for downstream redistributors, such as those who create Linux distributions. Community distributions of MySQL Server no longer include the mysql.info file, to make the repackaging and redistribution process easier (for example, the source tarball and its checksum can be used directly). This change applies to all source and binary Community packaging formats. Commercial (Enterprise) distributions are unchanged.
* Incompatible Change: Several statement instruments in the setup_instruments table are used by the Performance Schema during the early stages of statement classification before the exact statement type is known.
* The Performance Schema now instruments the read/write lock Delegate::lock
* A new CMake option, WITH_ASAN, permits enabling address sanitization for compilers that support it.
* The hash function used for metadata locking was modified to reduce overhead.
* Bugs Fixed
* MySQL 5.7 changed audit log file output to a new format that has better compatibility with Oracle Audit Vault. This format has been backported to MySQL 5.6 and it is possible to select either the old or new format using the new audit_log_format system variable, which has permitted values of OLD and NEW (default OLD). For details about each format, see The Audit Log File.
* Important Change; Replication: START SLAVE UNTIL SQL_AFTER_GTIDS did not cause the slave to stop until the next GTID event was received following execution of the transaction having the indicated GTID, which could cause issues in the case when the next GTID event is delayed, or does not exist. Now the slave stops after completing the transaction with that GTID.
* InnoDB; Partitioning: Following any query on the INFORMATION_SCHEMA.PARTITIONS table, InnoDB index statistics as shown in the output of statements such as SELECT * FROM INFORMATION_SCHEMA.STATISTICS were read from the last partition, instead of from the partition containing the greatest number of rows.
* InnoDB: When logging the delete-marking of a record during online ALTER TABLE...ADD PRIMARY KEY, InnoDB writes the transaction ID to the log as it was before the deletion or delete-marking of the record. When doing this, InnoDB would overwrite the DB_TRX_ID field in the original table, which could result in locking issues.
* InnoDB: The row_sel_sec_rec_is_for_clust_rec function would incorrectly prepare to compare a NULL column prefix in a secondary index with a non-NULL column in a clustered index.
* InnoDB: An incorrect purge would occur when rolling back an update to a delete-marked record.
* InnoDB: An assertion would be raised in fil_node_open_file due to a missing .ibd file. Instead of asserting, InnoDB should return false and the caller of fil_node_open_file should handle the return message.
* InnoDB: The assertion ut_ad(oldest_lsn <= cur_lsn) in file buf0flu.cc would fail because the current max LSN would be retrieved from the buffer pool before the oldest LSN.
* InnoDB: InnoDB memcached add and set operations would perform more slowly than SQL INSERT operations.
* InnoDB: The InnoDB memcached plugin could be initialized to insert into an InnoDB table with an INTEGER primary key.
More...
* Important Change; Replication: By default, when promoting integers from a smaller type on the master to a larger type on the slave (for example, from a SMALLINT column on the master to a BIGINT column on the slave), the promoted values are treated as though they are signed. Now in such cases it is possible to modify or override this behavior using one or both of ALL_SIGNED, ALL_UNSIGNED in the set of values specified for the slave_type_conversions server system variable. For more information, see Row-based replication: attribute promotion and demotion, as well as the description of the variable.
* Previously, program options could be specified in full or as any unambiguous prefix. For example, the --compress option could be given to mysqldump as --compr, but not as --comp because the latter is ambiguous. Option prefixes now are deprecated. They can cause problems when new options are implemented for programs. A prefix that is currently unambiguous might become ambiguous in the future. If an unambiguous prefix is given, a warning now occurs to provide feedback. For example:
Warning: Using unique option prefix compr instead of compress is
deprecated and will be removed in a future release. Please use the
full name instead.
Option prefixes are no longer supported in MySQL 5.7; only full options are accepted.
* The C API libmysqlclient shared-library .so files now have version 18.1.0 (up from version 18.0.0 used in MySQL 5.5).
* In batch mode, mysql formatted result status messages such as “"Query OK, 1 row affected"” but did not print them. Now these messages are not formatted.
* Bugs Fixed
Replication: The functions GTID_SUBTRACT() and GTID_SUBSET() were formerly available in libmysqld only when it was built with replication support. Now these functions are always available when using this library, regardless of how it was built.
MySQL no longer uses the default OpenSSL compression.
There is now a distinct error code (ER_MUST_CHANGE_PASSWORD_LOGIN) for the error sent by the server to a client authenticating with an expired password.
mysql_config_editor now supports --port and --socket options for specifying TCP/IP port number and Unix socket file name.
mysqlcheck has a new --skip-database option. The option value is the name of a database (case sensitive) for which checks should be skipped.
mysql_upgrade uses this option to upgrade the system tables in the mysql database before tables in other databases: It upgrade the mysql database, then all databases except the mysql database. This avoids problems that can occur if user tables are upgraded before the system tables.
The only supported value for the innodb_mirrored_log_groups system variable is 1, so this variable is now deprecated. Setting it to 1 at startup results in a warning. Setting it to a value other than 1 at startup results in an error and the server exits. This variable will be removed in a future release.
