Important Change: The YEAR(2) data type is now deprecated because it is problematic. Support for YEAR(2) will be removed in a future release of MySQL. For more information, see Section 11.3.4, “YEAR(2) Limitations and Migrating to YEAR(4)”.
* The --safe-mode server option now is deprecated and will be removed in MySQL
5.6.
* Performance: InnoDB: Improved the algorithm related to adaptive flushing.
This fix increases the rate of flushing in cases where compression is used
and the data set is larger than the buffer pool, leading to eviction.
* InnoDB: In a transaction using the REPEATABLE READ isolation level, an UPDATE
or DELETE statement for an InnoDB table could sometimes overlook rows
recently committed by other transactions. As explained in Section 14.3.9.2,
“Consistent Nonlocking Reads”, DML statements within a REPEATABLE READ
transaction apply to rows committed by other transactions, even if a query
could not see those rows.
* InnoDB: The Innodb_buffer_pool_pages_flushed status variable was incorrectly
set to twice the value it should be. Its value should never exceed the value
of Innodb_pages_written.
* InnoDB: The error handling and message was improved for attempting to create
a foreign key with a column referencing itself. The message suggested
a potential problem with the data dictionary, when no such problem existed.
* InnoDB: The CHECK TABLE statement could fail for a large InnoDB table due to
a timeout value of 2 hours. For typical storage devices, the issue could
occur for tables that exceeded approximately 200 or 350 GB, depending on I/O
speed. The fix relaxes the locking performed on the table being checked,
which makes the timeout less likely. It also makes InnoDB recognize the
syntax CHECK TABLE QUICK, which avoids the possibility of the timeout
entirely.
* Replication: It was theoretically possible for concurrent execution of more
than one instance of SHOW BINLOG EVENTS to crash the MySQL Server.
* Replication: Statements using AUTO_INCREMENT, LAST_INSERT_ID(), RAND(), or
user variables could be applied in the wrong context on the slave when using
statement-based replication and replication filtering server options (see
Section 16.2.3, “How Servers Evaluate Replication Filtering Rules”).
* Replication: An INSERT into a table that has a composite primary key that
includes an AUTO_INCREMENT column that is not the first column of this
composite key is not safe for statement-based binary logging or replication.
Such statements are now marked as unsafe and fail with an error when using
the STATEMENT binary logging format. For more information, see Section
16.1.2.3, “Determination of Safe and Unsafe Statements in Binary Logging”, as
well as Section 16.4.1.1, “Replication and AUTO_INCREMENT”.
Changes (http://dev.mysql.com/doc/refman/5.5/en/news-5-5-24.html):
Functionality Added or Changed
* Important Change: Replication: INSERT ON DUPLICATE KEY UPDATE is now
marked as unsafe for statement-based replication if the target table has
more than one primary or unique key. For more information, see Section
16.1.2.3, "Determination of Safe and Unsafe Statements in Binary
Logging".
Bugs Fixed
* Security Fix: Bug #64884 was fixed.
* InnoDB: Replication: When binary log statements were replayed on the
slave, the Com_insert, Com_update, and Com_delete counters were
incremented by BEGIN statements initiating transactions affecting InnoDB
tables but not by COMMIT statements ending such transactions. This
affected these statements whether they were replicated or they were run
using mysqlbinlog. (Bug #12662190)
* If the --bind-address option was given a host name value and the host
name resolved to more than one IP address, the server failed to
start. For example, with --bind-address=localhost, if localhost resolved
to both 127.0.0.1 and ::1, startup failed. Now the server prefers the
IPv4 address in such cases. (Bug #61713, Bug #12762885)
* mysql_store_result() and mysql_use_result() are not for use with
prepared statements and are not intended to be called following
mysql_stmt_execute(), but failed to return an error when invoked that
way in libmysqld. (Bug #62136, Bug #13738989)
References: See also Bug #47485.
* On Windows, mysqlslap crashed for attempts to connect using shared
memory. (Bug #31173, Bug #11747181, Bug #59107, Bug #11766072)
Bugs Fixed
* Security Fix: Bug 59533 was fixed.
* Performance: Partitioning: InnoDB Storage Engine: The statistics used by the
optimizer for queries against partitioned InnoDB tables were based only on the
first partition of each such table, leading to use of the wrong execution
plan.
* References: This bug was introduced by Bug 11756867.
* Performance: InnoDB Storage Engine: Improved the performance of the DROP TABLE
statement for InnoDB tables, especially on systems with a large buffer pool.
The fix speeds up the processing for freeing entries in the adaptive hash
index.
* InnoDB Storage Engine: Deleting a huge amount of data from InnoDB tables
within a short time could cause the purge operation that flushes data from the
buffer pool to stall. If this issue occurs, restart the server to work around
it. This issue is only likely to occur on 32-bit platforms.
* InnoDB Storage Engine: If the server crashed during a TRUNCATE TABLE or CREATE
INDEX statement for an InnoDB table, or a DROP DATABASE statement for
a database containing InnoDB tables, an index could be corrupted, causing an
error message when accessing the table after restart:
InnoDB: Error: trying to load index index_name for table table_name
InnoDB: but the index tree has been freed!
In MySQL 5.1, this fix applies to the InnoDB Plugin, but not the built-in
InnoDB storage engine.
* InnoDB Storage Engine: When data was removed from an InnoDB table, newly
inserted data might not reuse the freed disk blocks, leading to an unexpected
size increase for the system tablespace or .ibd file (depending on the
setting of innodb_file_per_table. The OPTIMIZE TABLE could compact a .ibd file
in some cases but not others. The freed disk blocks would eventually be
reused as additional data was inserted.
More...
* InnoDB Storage Engine: A deprecation warning is now issued when
--ignore-builtin-innodb is used.
* yaSSL was upgraded from version 1.7.2 to 2.2.0.
* Security Fix: Bug 13510739 and Bug 63775 were fixed.
* Important Change: InnoDB Storage Engine: When a row grew in size due to an
UPDATE operation, other (non-updated) columns could be moved to off-page
storage so that information about the row still fit within the constraints of
the InnoDB page size. The pointer to the new allocated off-page data was not
set up until the pages were allocated and written, potentially leading to
lost data if the system crashed while the column was being moved out of the
page. The problem was more common with tables using ROW_FORMAT=DYNAMIC or
ROW_FORMAT=COMPRESSED along with the Barracuda file format, particularly with
the innodb_file_per_table setting enabled, because page allocation operations
are more common as the .ibd tablespace files are extended. Still, the problem
could occur with any combination of InnoDB version, file format, and row
format.
* InnoDB Storage Engine: An erroneous assertion could occur, in debug builds
only, when creating an index on a column containing zero-length values (that
is, '').
* InnoDB Storage Engine: A DDL operation such as ALTER TABLE ... ADD COLUMN
could stall, eventually timing out with an Error 1005: Can't create table
message referring to fil_rename_tablespace.
* InnoDB Storage Engine: A DDL operation for an InnoDB table could cause a busy
MySQL server to halt with an assertion error:
More...
* A new CMake option, MYSQL_PROJECT_NAME, can be set on Windows or Mac OS X to
be used in the project name.
Bugs Fixed
* Performance: InnoDB Storage Engine: Memory allocation for InnoDB tables was
reorganized to reduce the memory overhead for large numbers of tables or
partitions, avoiding situations where the “resident set size” could grow
regardless of FLUSH TABLES statements. The problem was most evident for tables
with large row size.
* Incompatible Change: An earlier change (in MySQL 5.1.62 and 5.5.21) was found
to modify date-handling behavior in General Availability-status series (MySQL
5.1 and 5.5). This change has been reverted.
* The change was that several functions became more strict when passed a DATE()
function value as their argument, thus they rejected incomplete dates with
a day part of zero. These functions were affected: CONVERT_TZ(), DATE_ADD(),
DATE_SUB(), DAYOFYEAR(), LAST_DAY(), TIMESTAMPDIFF(), TO_DAYS(), TO_SECONDS(),
WEEK(), WEEKDAY(), WEEKOFYEAR(), YEARWEEK(). The previous behavior has been
restored.
* InnoDB Storage Engine: A Valgrind error was fixed in the function
os_aio_init().
* InnoDB Storage Engine: The server could crash when creating an InnoDB
temporary table under Linux, if the $TMPDIR setting points to a tmpfs
filesystem and innodb_use_native_aio is enabled, as it is by default in MySQL
5.5.4 and higher.
* InnoDB Storage Engine: References to C preprocessor symbols and macros
HAVE_purify, UNIV_INIT_MEM_TO_ZERO, and UNIV_SET_MEM_TO_ZERO were removed
from the InnoDB source code. They were only used in debug builds instrumented
for Valgrind. They are replaced by calls to the UNIV_MEM_INVALID() macro.
* A new server option, --slow-start-timeout, controls the Windows service
control manager's service start timeout. The value is the maximum number of
milliseconds that the service control manager waits before trying to kill the
MySQL service during startup. The default value is 15000 (15 seconds). If the
MySQL service takes too long to start, you may need to increase this value.
A value of 0 means there is no timeout.
Bugs Fixed:
* Important Change: Replication: Setting an empty user in a CHANGE MASTER TO
statement caused an invalid internal result and is no longer permitted. Trying to use MASTER_USER='' or setting MASTER_PASSWORD while leaving MASTER_USER
unset causes the statement to fail with an error.
* Important Change: Replication: Moving the binary log file, relay log file, or
both files to a new location, then restarting the server with a new value for
--log-bin, --relay-log, or both, caused the server to abort on start. This
was because the entries in the index file overrode the new location. In
addition, paths were calculated relative to datadir (rather than to the
--log-bin or --relay-log values).
* InnoDB Storage Engine: When doing a live downgrade from MySQL 5.6.4 or later, with innodb_page_size set to a value other than 16384, now the earlier MySQL
version reports that the page size is incompatible with the older version,
rather than crashing or displaying a “corruption” error.
* InnoDB Storage Engine: Issuing INSERT...ON DUPLICATE KEY statements for
InnoDB tables from concurrent threads could cause a deadlock, particularly
with the INSERT...ON DUPLICATE KEY UPDATE form. The fix avoids deadlocks
caused by the same row being accessed by more than one transaction. Deadlocks
could still occur when multiple rows are inserted and updated simultaneously
by different transactions in inconsistent order; those types of deadlocks
require the standard error handling on the application side, of re-trying the
transaction.
* An incorrect InnoDB assertion could cause the server to halt. This issue only
affected debug builds. The assertion referenced the source file btr0pcur.ic
and the variable cursor->pos_state.
* Locale information for FORMAT() function instances was lost in view
definitions.
* The handle_segfault() signal-handler code in mysqld could itself crash due to
calling unsafe functions.
* Enabling myisam_use_mmap could cause the server to crash.
* Concurrent access to ARCHIVE tables could cause corruption.
* Performance of metadata locking operations on Windows XP systems was improved
by instituting a cache for metadata lock objects. This permits the server to
avoid expensive operations for creation and destruction of synchronization
objects on XP. A new system variable, metadata_locks_cache_size, permits
control over the size of the cache. The default size is 1024.
* Replication: Previously, replication slaves could connect to the master
server through master accounts that use nonnative authentication, except
Windows native authentication. This is now also true for Windows native
authentication.
Bugs Fixed:
* InnoDB Storage Engine: An internal deadlock could occur within InnoDB, on
a server doing a substantial amount of change buffering for DML operations,
particularly DELETE statements.
* Rounding DBL_MAX returned DBL_MAX, not 'inf'.
* mysql_upgrade did not upgrade the system tables or create the
mysql_upgrade_info file when run with the --write-binlog or
--skip-write-binlog option.
* If a plugin was uninstalled, thread local variables for plugin variables of
string type with wth PLUGIN_VAR_MEMALLOC flag were not freed.
* Deadlock could occur when these four things happened at the same time: 1) An
old dump thread was waiting for the binary log to grow. 2) The slave server
that replicates from the old dump thread tried to reconnect. During
reconnection, the new dump thread tried to kill the old dump thread.
3) A KILL statement tried to kill the old dump thread. 4) An INSERT statement
caused a binary log rotation.
Functionality Added or Changed
* Upgrading from an Advanced GPL RPM package to an Advanced RPM package did not
work. Now on Linux it is possible to use rpm -U to replace any installed
MySQL product by any other of the same release family. It is not necessary to
remove the old produce with rpm -e first.
Bugs Fixed
* Incompatible Change: Replication.
* During the table-opening process, memory was allocated and later freed that
was needed view loading, even for statements that did not use views. These
unnecessary allocation and free operations are no longer done.
* mysql_plugin mishandled the --plugin-ini, --mysqld, and --my-print-defaults
options under some circumstances.
* mysql_plugin returned the wrong error code from failed server bootstrap
execution.
* Several improvements were made to the libedit library bundled with MySQL
distributions, and that is available for all platforms that MySQL supports
except Windows.
* ARCHIVE tables with NULL columns could cause server crashes or become corrupt
under concurrent load.
* OPTIMIZE TABLE could corrupt MyISAM tables if myisam_use_mmap was enabled.
* A query that selected a GROUP_CONCAT() function result could return different
values depending on whether an ORDER BY of the function result was present.
* For FEDERATED tables, loss of connection to the remote table during some
insert operations could cause a server crash.
* Replication: Previously, replication slaves could connect to the master
server only through master accounts that use native authentication. Now
replication slaves can also connect through master accounts that use
nonnative authentication (except Windows native authentication) if the
required client-side plugin is installed on the slave side in the directory
named by the slave plugin_dir system variable.
* MEMORY table creation time is now available in the CREATE_TIME column of the
INFORMATION_SCHEMA.TABLES table and the Create_time column of SHOW TABLE
STATUS output.
* InnoDB Storage Engine: This fix improves the performance of instrumentation
code for InnoDB buffer pool operations.
* InnoDB Storage Engine: Data from BLOB columns could be lost if the server
crashed at a precise moment when other columns were being updated in an
InnoDB table.
* InnoDB Storage Engine: Lookups using secondary indexes could give incorrect
matches under a specific set of conditions. The conditions involve an index
defined on a column prefix, for a BLOB or other long column stored outside
the index page, with a table using the Barracuda file format.
* InnoDB Storage Engine: This fix corrects cases where the MySQL server could
hang or abort with a long semaphore wait message. (This is a different issue
than when these symptoms occurred during a CHECK TABLE statement.)
* Internal conversion of zero to binary and back could yield a result with
incorrect precision.
* Valgrind warnings generated by filesort operations were fixed.
* mysqld_safe did not properly check for an already running instance of mysqld.
* The help message for mysql_install_db did not indicate that it supports the
--defaults-file, --defaults-extra-file and --no-defaults options.
* An assertion designed to detect zero-length sort keys also was raised when
the entire key set fit in memory.
* myisampack could create corrupt FULLTEXT indexes when compressing tables.
* A linking problem prevented the FEDERATED storage engine plugin from loading.
* The default thread-handling model in MySQL Server executes statements using
one thread per client connection.
* Commercial distributions of MySQL now include two plugins that enable MySQL
Server to use external authentication methods to authenticate MySQL users
* Important Change: Replication: The RESET SLAVE statement has been extended
with an ALL keyword.
* A new utility, mysql_plugin, enables MySQL administrators to manage which
plugins a MySQL server loads.
* Bugs fixed.
* The undocumented --all option for perror is deprecated and will be removed in
MySQL 5.6.
Bugs Fixed:
* InnoDB Storage Engine: A failed CREATE INDEX operation for an InnoDB table
could result in some memory being allocated and not freed. This memory leak
could affect tables created with the ROW_FORMAT=DYNAMIC and
ROW_FORMAT=COMPRESSED settings.
* Partitioning: Auto-increment columns of partitioned tables were checked even
when they were not being written to. In debug builds, this could lead to a
crash of the server.
* Partitioning: The UNIX_TIMESTAMP() function was not treated as a monotonic
function for purposes of partition pruning.
* Replication: If a LOAD DATA INFILE statement—replicated using statement-based
replication—featured a SET clause, the name-value pairs were regenerated
using a method (Item::print()) intended primarily for generating output for
statements such as EXPLAIN EXTENDED, and which cannot be relied on to return
valid SQL. This could in certain cases lead to a crash on the slave.
* To fix this problem, we now name each value in its original, user-supplied
form, and use that to create LOAD DATA INFILE statements for statement-based
replication.
* Previously, an inappropriate error message was produced if a multiple-table
update for an InnoDB table with a clustered primary key would update a table
through multiple aliases, and perform an update that may physically move the
row in at least one of these aliases. Now the error message is: Primary
key/partition key update is not allowed since the table is updated both as
'tbl_name1' and 'tbl_name2'
* ALTER TABLE {MODIFY|CHANGE} ... FIRST did nothing except rename columns if
the old and new versions of the table had exactly the same structure with
respect to column data types. As a result, the mapping of column name to
column data was incorrect. The same thing happened for ALTER TABLE DROP
COLUMN, ADD COLUMN statements intended to produce a new version of table with
exactly the same structure as the old version.
* Incorrect handling of metadata locking for FLUSH TABLES WITH READ LOCK for
statements requiring prelocking caused two problems:
* Execution of any data-changing statement that required prelocking (that is,
involved a stored function or trigger) as part of transaction slowed down
somewhat all subsequent statements in the transaction. Performance in a
transaction that periodically involved such statements gradually degraded
over time.
* CMake configuration support on Linux now provides a boolean ENABLE_GCOV
option to control whether to include support for gcov.
* InnoDB now permits concurrent reads while creating a secondary index.
* Client programs now display more information for SSL errors to aid in
diagnosis and debugging of connection problems.
* In the audit plugin interface, the event_class member was removed from the
mysql_event_general structure and the calling sequence for the notification
function changed. Originally, the second argument was a pointer to the event
structure. The function now receives this information as two arguments: an
event class number and a pointer to the event. Corresponding to these
changes, MYSQL_AUDIT_INTERFACE_VERSION was increased to 0x0300.
* The plugin_audit.h header file, and the NULL_AUDIT example plugin in the
plugin/audit_null directory have been modified per these changes. See
Section 21.2.4.7, “Writing Audit Plugins”.
* Bug fixes.
* InnoDB Storage Engine: If the server crashed while an XA transaction was
prepared but not yet committed, the transaction could remain in the system
after restart, and cause a subsequent shutdown to hang.
* InnoDB Storage Engine: Similar problem to the foreign key error in bug
11831040 / 60196 / 60909, but with a different root cause and occurring on
Mac OS X. With the setting lower_case_table_names=2, inserts into InnoDB
tables covered by foreign key constraints could fail after a server restart.
* Partitioning: The internal get_partition_set() function did not take into
account the possibility that a key specification could be NULL in some cases.
* Partitioning: When executing a row-ordered retrieval index merge, the
partitioning handler used memory from from that allocated for the table,
rather than that allocated to the query, causing table object memory not to
be freed until the table was closed.
* Replication: A spurious error malformed binlog: it does not contain any
Format_description_log_event... was generated when mysqlbinlog was invoked
using --base64-output=decode-row and --start-position=pos, where pos is a
point in the binary log past the format description log event. However, there
is nothing unsafe about not printing the format description log event, so the
error has been removed for this case.
* Replication: Typographical errors appeared in the text of several replication error messages. (The word “position” was misspelled as “postion”.)
* Assignments to NEW.var_name within triggers, where var_name had a BLOB or
TEXT type, were not properly handled and produced incorrect results.
* XA COMMIT could fail to clean up the error state if it discovered that the
current XA transaction had to be rolled back. Consequently, the next XA
transaction could raise an assertion when it checked for proper cleanup of
the previous transaction.
* An internal client macro reference was removed from the client_plugin.h
header file. This reference made the file unusable.
* The server consumed memory for repeated invocation of some stored procedures,
which was not released until the connection terminated.
* The server did not check for certain invalid out of order sequences of XA
statements, and these sequences raised an assertion.
* With the conversion from GNU autotools to CMake for configuring MySQL, the
USE_SYMDIR preprocessor symbol was omitted. This caused failure of symbolic
links (described at Section 7.11.3.1, “Using Symbolic Links”).
* Fixed bugs: Illegal mix of collations
* Problem: comparison of a DATETIME sp variable and NOW() led to Illegal mix of
collations error when character_set_connection=utf8.
* Error happened in Arg_comparator::set_compare_func(), because the first
argument was errouneously converted to utf8, while the second argument was
not.
* Fix: separate agg_arg_charsets_for_comparison() into two functions:
- agg_arg_charsets_for_comparison() - for pure comparison, when we don't need
to return any string result and therefore don't need to convert arguments
to @@character_set_connection:
SELECT a = b;
- agg_arg_charsets_for_string_results_with_comparison() - when we need to
return a string result, but we also need to do comparison internally:
SELECT REPLACE(a,b,c)
If all arguments are numbers:
SELECT REPLACE(123,2,3) -> 133
we convert arguments to @@character_set_connection.
popular database language in the world. MySQL is a client-server implementation
that consists of a server daemon `mysqld' and many different client
programs/libraries.
The main goals of MySQL are speed and robustness.
The base upon which MySQL is built is a set of routines that have been used in
a highly demanding production environment for many years. While MySQL is still
in development it already offers a rich and highly useful function set.
The official way to pronounce 'MySQL' is 'My Ess Que Ell' (Not MY-SEQUEL).
This package contains the MySQL client programs and libraries.
