MySQL Community Server 8.0.23 has been released [ part 2/2 ]
Posted by: Bjørn Munch
Date: January 18, 2021 08:01AM
Date: January 18, 2021 08:01AM
[ This is part 2 of the announcement ]
Bugs Fixed
* InnoDB: A CREATE TABLE operation that specified the
COMPRESSION option was permitted with a warning on a
system that does not support hole punching. The operation
now fails with an error instead. (Bug #32174200)
* InnoDB: A MySQL DB system restart following an upgrade
that was initiated while a data load operation was in
progress raised an assertion failure. (Bug #32173596)
* InnoDB: An error message regarding the number of truncate
operations on the same undo tablespace between
checkpoints incorrectly indicated a limit of 64. The
limit was raised from 64 to 50,000 in MySQL 8.0.22. (Bug
#32151601, Bug #101601)
* InnoDB: rw_lock_t and buf_block_t source code structures
were reduced in size. (Bug #32084500)
* InnoDB: An InnoDB transaction became inconsistent after
creating a table using a storage engine other than InnoDB
from a query expression that operated on InnoDB tables.
(Bug #32079103)
* InnoDB: In some circumstances, such as when an existing
gap lock inherits a lock from a deleted record, the
number of locks that appear in the
INFORMATION_SCHEMA.INNODB_TRX table could diverge from
the actual number of record locks.
Thanks to Fungo Wang from Alibaba for the patch. (Bug
#32068538, Bug #101305)
* InnoDB: An off-by-one error in Fil_system sharding code
was corrected, and the maximum number of shards
(MAX_SHARDS) was changed to 69. (Bug #32052821, Bug
#101260)
* InnoDB: The TempTable storage engine memory allocator
allocated extra blocks of memory unnecessarily. (Bug
#32018553)
* InnoDB: A SELECT COUNT(*) operation on a table containing
uncommitted data performed poorly due to unnecessary I/O.
Thanks to Brian Yue for the contribution. (Bug #31997733,
Bug #100966)
* InnoDB: A race condition when shutting down the log
writer raised an assertion failure. (Bug #31997362)
* InnoDB: Page cleaner threads were not utilized optimally
in sync-flush mode, which could cause page flush
operations to slow down or stall in some cases.
Sync-flush mode occurs when InnoDB is close to running
out of free space in the redo log, causing the page
cleaner coordinator to initiate aggressive page flushing.
(Bug #31994031)
* InnoDB: A high frequency of updates while undo log
truncation was enabled caused purge to lag. The lag was
due to the innodb_purge_rseg_truncate_frequency setting
being changed temporarily from 128 to 1 when an undo
tablespace was selected for truncation. The code that
modified the setting has been removed. (Bug #31991688)
* InnoDB: Automated truncation of undo tablespaces caused a
performance regression. To address this issue, undo
tablespace files are now initialized at 16MB and extended
by a minimum of 16MB. To handle aggressive growth, the
file extension size is doubled if the previous file
extension happened less than 0.1 seconds earlier.
Doubling of the extension size can occur multiple times
to a maximum of 256MB. If the previous file extension
occurred more than 0.1 seconds earlier, the extension
size is reduced by half, which can also occur multiple
times, to a minimum of 16MB. Previously, the initial size
of an undo tablespace depended on the InnoDB page size,
and undo tablespaces were extended four extents at a
time.
If the AUTOEXTEND_SIZE option is defined for an undo
tablespace, the undo tablespace is extended by the
greater of the AUTOEXTEND_SIZE setting and the extension
size determined by the logic described above.
When an undo tablespace is truncated, it is normally
recreated at 16MB in size, but if the current file
extension size is larger than 16MB, and the previous file
extension happened within the last second, the new undo
tablespace is created at a quarter of the size defined by
the innodb_max_undo_log_size variable.
Stale undo tablespace pages are no longer removed at the
next checkpoint. Instead, the pages are removed in the
background by the InnoDB master thread. (Bug #31965404,
Bug #32020900, Bug #101194)
* InnoDB: A posix_fallocate() failure while preallocating
space for a temporary tablespace raised an error and
caused an initialization failure. A warning is now issued
instead, and InnoDB falls back to the
non-posix_fallocate() method for preallocating space.
(Bug #31965379)
* InnoDB: An invalid pointer caused a shutdown failure on a
MySQL Server compiled with the DISABLE_PSI_MEMORY source
configuration option enabled. (Bug #31963333)
* InnoDB: A long SX lock held by an internal function that
calculates new statistics for a given index caused a
failure. (Bug #31889883)
* InnoDB: The INFORMATION_SCHEMA.INNODB_TABLESPACES table
reported a FILE_SIZE of 0 for some tables and schemas.
When the associated tablespace was not in the memory
cache, the tablespace name was used to determine the
tablespace file name, which was not always a reliable
method. The tablespace ID is now used instead. Using the
tablespace name remains as a fallback method. (Bug
#31841617)
* InnoDB: After dropping a FULLTEXT index and renaming the
table to move it to a new schema, the FULLTEXT auxiliary
tables were not renamed accordingly and remained in the
old schema directory. (Bug #31773368, Bug #100570)
* InnoDB: After upgrading to MySQL 8.0, a failure occurred
when attempting to perform a DML operation on a table
that was previously defined with a full-text search
index. (Bug #31749490)
* InnoDB: Importing a tablespace with a page-compressed
table did not report a schema mismatch error for source
and destination tables defined with a different
COMPRESSION setting. The COMPRESSION setting of the
exported table is now saved to the .cfg metadata file
during the FLUSH TABLES ... FOR EXPORT operation, and
that information is checked on import to ensure that both
tables are defined with the same COMPRESSION setting.
(Bug #31744694)
* InnoDB: Dummy keys used to check if the MySQL Keyring
plugin is functioning were left behind in an inactive
state, and the number of inactive dummy keys increased
over time. The actual master key is now used instead, if
present. If no master key is available, a dummy master
key is generated. (Bug #31737924)
* InnoDB: Querying the INFORMATION_SCHEMA.FILES table after
moving the InnoDB system tablespace outside of the data
directory raised a warning indicating that the
innodb_system filename is unknown. (Bug #31603047)
* InnoDB: In a replication scenario involving a replica
with binary logging or log_slave_updates disabled, the
server failed to start due to an excessive number of gaps
in the mysql.gtid_executed table. The gaps occurred for
workloads that included both InnoDB and non-InnoDB
transactions. GTIDs for InnoDB transactions are flushed
to the mysql.gtid_executed table by the GTID persister
thread, which runs periodically, while GTIDs for
non-InnoDB transactions are written to the to the
mysql.gtid_executed table directly by replica server
threads. The GTID persister thread fell behind as it
cycled through merging entries and compressing the
mysql.gtid_executed table. As a result, the size of the
GTID flush list for InnoDB transactions grew over time
along with the number of gaps in the mysql.gtid_executed
table, eventually causing a server failure and subsequent
startup failures. To address this issue, the GTID
persister thread now writes GTIDs for both InnoDB and
non-InnoDB transactions, and foreground commits are
forced to wait if the GTID persister thread falls behind.
Also, the gtid_executed_compression_period default
setting was changed from 1000 to 0 to disabled explicit
compression of the mysql.gtid_executed table by default.
Thanks to Venkatesh Prasad for the contribution. (Bug
#31599938, Bug #100118)
* InnoDB: Persisting GTID values for XA transactions
affected XA transaction performance. Two GTID values are
generated for XA transactions, one for the prepare stage
and another for the commit stage. The first GTID value is
written to the undo log and later overwritten by the
second GTID value. Writing of the second GTID value could
only occur after flushing the first GTID value to the
gtid_executed table. Space is now reserved in the undo
log for both XA transaction GTID values. (Bug #31467953,
Bug #99638)
* InnoDB: InnoDB source files were updated to address
warnings produced when building Doxygen source code
documentation. (Bug #31354760)
* InnoDB: The full-text search synchronization thread
attempted to read a previously-freed word from the index
cache. (Bug #31310404)
* InnoDB: A 20µs sleep in the buf_wait_for_read() function
introduced with parallel read functionality in MySQL
8.0.17 took 1ms on Windows, causing an unexpected timeout
when running certain tests. Also, AIO threads were found
to have uneven amounts of waiting operating system IO
requests. (Bug #31095274)
References: This issue is a regression of: Bug #31123564.
* InnoDB: Cleanup in certain replicated XA transactions
failed to reattach transaction object (trx_t), which
raised an assertion failure. (Bug #31006095)
* InnoDB: An interrupted tablespace encryption operation
did not update the encrypt_type table option information
in the data dictionary when the operation resume
processing after the server was restarted. (Bug
#30883833, Bug #98537, Bug #30883833, Bug #98537, Bug
#30888919, Bug #98564)
* InnoDB: The tablespace encryption type setting was not
properly updated due to a failure during the resumption
of an ALTER TABLESPACE ENCRYPTION operation following a
server failure. (Bug #30883833, Bug #98537)
* InnoDB: Internal counter variables associated with thread
sleep delay and threads entering an leaving InnoDB were
revised to use C++ std::atomic. Built-in atomic
operations were removed. Thanks to Yibo Cai from ARM for
the contribution. (Bug #30567060, Bug #97704)
* InnoDB: A relaxed memory order was implemented for
dictionary memory variable fetch-add
(dict_temp_file_num.fetch_add) and store
(dict_temp_file_num.store) operations.
Thanks to Yibo Cai for the contribution. (Bug #30567054,
Bug #97703)
* InnoDB: A background thread that resumed a tablespace
encryption operation after the server started failed to
take an metadata lock on the tablespace, which permitted
concurrent DDL operations and led to a race condition
with the startup thread. The startup thread now waits
until the tablespace metadata lock is taken. (Bug
#28531637)
* InnoDB: Calls to numa_all_nodes_ptr were replaced by the
numa_get_mems_allowed() function. Thanks to Daniel Black
for the contribution. (Bug #24693086, Bug #83044)
* Partitioning: ALTER TABLE t1 EXCHANGE PARTITION ... WITH
TABLE t2 led to an assert when t1 was not a partitioned
table. (Bug #100971, Bug #31941543)
References: This issue is a regression of: Bug #29706669.
* Replication: The network_namespace parameter for the
asynchronous_connection_failover_add_source() and
asynchronous_connection_failover_delete_source() UDFs is
no longer used from MySQL 8.0.23. These UDFs add and
remove replication source servers from the source list
for a replication channel for the asynchronous connection
failover mechanism. The network namespace for a
replication channel is managed using the CHANGE
REPLICATION SOURCE statement, and has special
requirements for Group Replication source servers, so it
should no longer be specified in the UDFs. (Bug
#32078189)
* Replication: When the system variable
transaction_write_set_extraction=XXHASH64 is set, which
is the default in MySQL 8.0 and a requirement for Group
Replication, the collection of writes for a transaction
previously had no upper size limit. Now, for standard
source to replica replication, the numeric limit on write
sets specified by
binlog_transaction_dependency_history_size is applied,
after which the write set information is discarded but
the transaction continues to execute. Because the write
set information is then unavailable for the dependency
calculation, the transaction is marked as non-concurrent,
and is processed sequentially on the replica. For Group
Replication, the process of extracting the writes from a
transaction is required for conflict detection and
certification on all group members, so the write set
information cannot be discarded if the transaction is to
complete. The byte limit set by
group_replication_transaction_size_limit is applied
instead of the numeric limit, and if the limit is
exceeded, the transaction fails to execute. (Bug
#32019842)
* Replication: When mysqlbinlog's --print-table-metadata
option was used, mysqlbinlog used a different method for
assessing numeric fields to the method used by the server
when writing to the binary log, resulting in incorrect
metadata output relating to these fields. mysqlbinlog now
uses the same method as the server. (Bug #31956206)
* Replication: When using network namespaces in a
replication channel and the initial connection from the
replica to the master was interrupted, subsequent
connection attempts failed to use the correct namespace
information. (Bug #31954087)
* Replication: If the Group Replication applier channel
(group_replication_applier) was holding a lock on a
table, for example because of a backup in progress, and
the member was expelled from the group and tried to
rejoin automatically, the auto-rejoin attempt was
unsuccessful and did not retry. Now, Group Replication
checks during startup and rejoin attempts whether the
group_replication_applier channel is already running. If
that is the case at startup, an error message is
returned. If that is the case during an auto-rejoin
attempt, that attempt fails, but further attempts are
made as specified by the
group_replication_autorejoin_tries system variable. (Bug
#31648211)
* Replication: If a group member was expelled and made an
auto-rejoin attempt at a point when some tables on the
instance were locked (for example while a backup was
running), the attempt failed and no further attempts were
made. This scenario is now handled correctly. (Bug
#31460690)
* Replication: As the number of replicas replicating from a
semisynchronous source server increased, locking
contention could result in a performance degradation. The
locking mechanisms used by the plugins have been changed
to use shared locks where possible, avoid unnecessary
lock acquisitions, and limit callbacks. The new behaviors
can be implemented by enabling the following system
variables:
+ replication_sender_observe_commit_only=1 limits
callbacks.
+ replication_optimize_for_static_plugin_config=1 adds
shared locks and avoids unnecessary lock
acquisitions. This system variable must be disabled
if you want to uninstall the plugin.
Both system variables can be enabled before or after
installing the semisynchronous replication plugin, and
can be enabled while replication is running.
Semisynchronous replication source servers can also get
performance benefits from enabling these system
variables, because they use the same locking mechanisms
as the replicas. (Bug #30519928)
* Replication: On a multi-threaded replica where the commit
order is preserved, worker threads must wait for all
transactions that occur earlier in the relay log to
commit before committing their own transactions. If a
deadlock occurs because a thread waiting to commit a
transaction later in the commit order has locked rows
needed by a transaction earlier in the commit order, a
deadlock detection algorithm signals the waiting thread
to roll back its transaction. Previously, if transaction
retries were not available, the worker thread that rolled
back its transaction would exit immediately without
signalling other worker threads in the commit order,
which could stall replication. A worker thread in this
situation now waits for its turn to call the rollback
function, which means it signals the other threads
correctly. (Bug #26883680, Bug #87796)
* Replication: GTIDs are only available on a server
instance up to the number of non-negative values for a
signed 64-bit integer (2 to the power of 63 minus 1). If
you set the value of gtid_purged to a number that
approaches this limit, subsequent commits can cause the
server to run out of GTIDs and take the action specified
by binlog_error_action. From MySQL 8.0.23, a warning
message is issued when the server instance is approaching
the limit. (Bug #26035544)
* Microsoft Windows: On Windows, running the MySQL server
as a service caused shared-memory connections to fail.
(Bug #32009251)
* JSON: JSON_ARRAYAGG() did not always perform proper error
handling. (Bug #31856260, Bug #32012559, Bug #32181438)
* JSON: When updating a JSON value using JSON_SET(),
JSON_REPLACE(), or JSON_REMOVE(), the target column can
sometimes be updated in-place. This happened only when
the target table of the update operation was a base
table, but when the target table was an updatable view,
the update was always performed by writing the full JSON
value.
Now in such cases, an in-place update (that is, a partial
update) is also performed when the target table is an
updatable view. (Bug #25840784)
* JSON: Work done in MySQL 8.0.22 to cause prepared
statements to be prepared only once introduced a
regression in the handling of dynamic parameters to JSON
functions. All JSON arguments were classified as data
type MYSQL_TYPE_JSON, which overlooked the fact that JSON
functions take two kinds of JSON parameters---JSON values
and JSON documents---and this distinction cannot be made
with the data type only. For Bug #31667405, this problem
was solved for comparison operators and the IN() operator
by making it possible to tag a JSON argument as being a
scalar value, while letting arguments to other JSON
functions be treated as JSON documents.
The present fix restores for a number of JSON functions
their treatment of certain arguments as JSON values, as
listed here:
The first argument to MEMBER OF()
The third, fifth, seventh, and subsequent odd-numbered
arguments to the functions JSON_INSERT(), JSON_REPLACE(),
JSON_SET(), JSON_ARRAY_APPEND(), and JSON_ARRAY_INSERT().
(Bug #101284, Bug #32063203)
References: See also: Bug #31667405.
* JSON: When mysqld was run with --debug, attempting to
execute a query that made use of a multi-valued index
raised an error. (Bug #99833, Bug #31474182)
* Use of the thread_pool plugin could result in Address
Sanitizer warnings. (Bug #32213294)
* While pushing a condition down to a materialized derived
table, and a condition is partially pushed down, the
optimizer may, in some cases in which a query
transformation has added new conditions to the WHERE
condition, call the internal fix_fields() function for
the condition that remains in the outer query block. A
successful return from this function call was
misinterpreted as an error, leading to the silent failure
of the original statement. (Bug #32150145)
* Multiple calls to a stored procedure containing an ALTER
TABLE statement that included an ORDER BY clause could
cause a server exit. (Bug #32147402)
* Prepared statements involving stored programs could cause
heap-use-after-free memory problems. (Bug #32131022, Bug
#32045681, Bug #32051928)
* Queries on INFORMATION_SCHEMA tables that involved
materialized derived tables could fail. (Bug #32127562,
Bug #101504)
* A potential buffer overflow was fixed. Thanks to Sifang
Zhao for pointing out the issue, and for suggesting a fix
(although it was not used). (Bug #32113015, Bug #101448)
* Conversion of FLOAT values to values of type INT could
generate Undefined Behavior Sanitizer warnings. (Bug
#32099994, Bug #32100033)
* In multiple-row queries, the LOAD_FILE() function
evaluated to the same value for every row. (Bug
#32096341, Bug #101401)
* Generic Linux tar file distributions had too-restrictive
file permissions after unpacking, requiring a manual
chmod to correct. (Bug #32080900)
* For debug builds, prepared SET statements containing
subqueries in stored procedures could raise an assertion.
(Bug #32078387)
References: See also: Bug #32100210.
* For prepared statements, illegal mix of collations errors
could occur for legal collation mixes. (Bug #32077842,
Bug #101346, Bug #32145078, Bug #101575)
* The functions REGEXP_LIKE(), REGEXP_INSTR(), and
REGEXP_REPLACE() raise errors for malformed regular
expression patterns, but could also return NULL for such
cases, causing subsequent debug asserts. Now we ensure
that these functions do not return NULL except in certain
specified cases.
The function REGEXP_SUBSTR() can always return NULL, so
no such check is needed, and for this function we make
sure that one is not performed. (Bug #32053093)
* Testing an aggregate function for IS NULL or IS NOT NULL
in a HAVING condition using WITH ROLLUP led to wrong
results. (Bug #32049313)
* When a new aggregate function was added to the current
query block because an inner query block had an aggregate
function requiring evaluation in the current one, the
server did not add rollup wrappers to it as needed. (Bug
#32034914)
* For debug builds, certain CREATE TABLE statements with
CHECK constraints could raise an assertion. (Bug
#32018406, Bug #101180)
* Incorrect BLOB field values were passed from InnoDB
during a secondary engine load operation. (Bug #32014483)
* The LOCK_ORDER tool did not correctly represent InnoDB
share exclusive locks. (Bug #31994052)
* The server did not handle properly an error raised when
trying to use an aggregation function with an invalid
column type as part of a hash join. (Bug #31989333)
* The length of the WORD column of the
INFORMATION_SCHEMA.KEYWORDS table could change depending
on table contents. (Bug #31982157)
* The Performance Schema host_cache table was empty and did
not expose the contents of the host cache if the
Performance Schema was disabled. The table now shows
cache contents regardless of whether the Performance
Schema is enabled. (Bug #31978763)
* A HANDLER READ statement sometimes hit an assert when a
previous statement did not restore the original value of
THD::mark_used_columns after use. (Bug #31977414)
* Importing a compressed table could cause an unexpected
server exit if the table contained values that were very
large when uncompressed. (Bug #31943021)
* Removed a memory leak that could occur when a subquery
using a hash join and LIMIT was executed repeatedly. (Bug
#31940549)
* A compilation failure on Ubuntu was corrected. (Bug
#31930934, Bug #100938)
* Memory used for storing partial-revokes information could
grow excessively for sessions that executed a large
number of statements. (Bug #31919448)
* The server did not handle all cases of the
WHERE_CONDITION optimization correctly. (Bug #31905199)
* FLUSH TABLES WITH READ LOCK could block other sessions
from executing SHOW TABLE STATUS. (Bug #31894662)
* In some cases, MIN() and MAX() incorrectly returned NULL
when used as window functions with temporal or JSON
values as arguments. (Bug #31882291)
* GRANT ... GRANT OPTION ... TO and GRANT ... TO .. WITH
GRANT OPTION sometimes were not correctly written to the
server logs. (Bug #31869146, Bug #100793)
* For debug builds, CREATE TABLE using a partition list of
more than 256 entries raised an assertion. (Bug
#31867653)
* It was possible for queries in the file named by the
init_file system variable to cause server startup
failure. (Bug #31835782)
* When performing a hash join, the optimizer could register
a false match between a negative integer value and a very
large unsigned integer value. (Bug #31832001, Bug
#31940639, Bug #100967)
* SHOW VARIABLES could report an incorrect value for the
partial_revokes system variable. (Bug #31819558, Bug
#100677)
* In the Performance Schema user_defined_functions table,
the value of the UDF_LIBRARY column is supposed to be
NULL for UDFs registered via the service API. The value
was incorrectly set to the empty string. (Bug #31791754)
* The server automatic upgrade procedure failed to upgrade
older help tables that used the latin1 character set.
(Bug #31789964)
* Duplicate warnings could occur when executing an SQL
statement that read the grant tables in serializable or
repeatable-read transaction isolation level. (Bug
#31769242)
* In certain queries with DISTINCT aggregates (which in
general are solved by sorting before aggregation), the
server used a temporary table instead of streaming due to
the mistaken assumption that the logic for handling the
temporary table performed deduplication. Now the server
checks for the implied unique index instead, which is
more robust and allows for the removal of unnecessary
logic. (Bug #31762806)
* Certain combinations of lower_case_table_names values and
schema names in Event Scheduler event definitions could
cause the server to stall. (Bug #31733090)
* Calling one stored function from within another could
produce a conflict in field resolution, resulting in a
server exit. (Bug #31731334)
* User-defined functions defined without a udf_init()
method could cause an unexpected server exit. (Bug
#31701219)
* Setting the secure_file_priv system variable to NULL
should disable its action, but instead caused the server
to create a directory named NULL. (Bug #31700734, Bug
#100384)
* mysqlpump could exit unexpectedly due to improper
simultaneous accesses to shared structures. (Bug
#31696241)
* Uninstalling a component and deregistering user-defined
functions (UDFs) installed by the component was not
properly synchronized with whether the UDFs were
currently in use. (Bug #31646698)
* Cleanup following execution of a prepared statement that
performed a multi-table UPDATE or DELETE was not always
done correctly, which meant that, following the first
execution of such a prepared statement, the server
reported a nonzero number of rows updated, even though no
rows were actually changed. (Bug #31640267)
References: See also: Bug #32100210.
* For the engines which support primary key extension, when
the total key length exceeded MAX_KEY_LENGTH or the
number of key parts exceeded MAX_REF_PARTS, key parts of
primary keys which did not fit within these limits were
not added to the secondary key, but key parts of primary
keys were unconditionally marked as part of secondary
keys.
This led to a situation in which the secondary key was
treated as a covering index, which meant sometimes the
wrong access method was chosen.
This is fixed by modifying the way in which key parts of
primary keys are added to secondary keys so that those
which do not fit within which do not fit within the
limits mentioned previously mentioned are cleared. (Bug
#31617858)
* When MySQL is configured with -DWITH_ICU=system, CMake
now checks that the ICU library version is sufficiently
recent. (Bug #31600044)
* Enabling DISABLE_PSI_xxx Performance Schema-related CMake
options caused build failures. (Bug #31549724)
* When invoked with the --binary-as-hex option, mysql
displayed NULL values as empty binary strings (0x).
Selecting an undefined variable returned the empty binary
string (0x) rather than NULL. (Bug #31549724, Bug
#31638968, Bug #100251)
* Some queries returned different results depending on the
value of internal_tmp_mem_storage_engine.
The root cause of this issue related to the fact that,
when buffering rows for window functions, if the size of
the in-memory temporary table holding these buffered rows
exceeds the limit specified, a new temporary table is
created on disk; the frame buffer partition offset is set
at the beginning of a new partition to the total number
of rows that have been read so far, and is updated
specifically for use when the temporary table is moved to
disk (this being used to calculate the hints required to
process window functions). The problem arose because the
frame buffer partition offset was not updated for the
specific case when a new partition started while creating
the temporary table on disk, which caused the wrong rows
to be read.
This issue is fixed by making sure to update the frame
buffer partition offset correctly whenever a new
partition starts while a temporary table is moved to
disk. (Bug #31546816)
* While buffering rows for window functions, if the size of
the in-memory temporary table holding these buffered rows
exceeds the limit specified by temptable_max_ram, a new
temporary table is created on disk. After the creation of
the temporary table, hints used to process window
functions need to be reset, since the temporary table is
now moved to disk, making the existing hints unusable.
When the creation of the temporary table on disk occurred
when the first row in the frame buffer was being
processed, the hints had not been initialized and trying
to reset these uninitialized hints resulted in an
unplanned server exit.
This issue is fixed by adding a check to verify whether
frame buffer hints have been initialized, prior to
resetting them. (Bug #31544404)
* The Performance Schema could produce incorrect results
for joins on a CHANNEL_NAME column when the index for
CHANNEL_NAME was disabled with USE INDEX (). (Bug
#31544023, Bug #99989)
* When removing unused window definitions, a subquery that
was part of an ORDER BY was not removed. (Bug #31518806)
* In certain cases, the server did not handle
multiply-nested subqueries correctly. (Bug #31472704)
* The recognized syntax for a VALUES statement includes an
ORDER BY clause, but this clause was not resolved, so the
execution engine could encounter invalid data. (Bug
#31387510)
* The server attempted to access a non-existent temporary
directory at startup, causing a failure. Checks were
added to ensure that temporary directories exist, and
that files are successfully created in the tmpdir
directory. (Bug #31377118)
* While removing redundant sorting, a window's ordering was
removed due to the fact that rows were expected to come
in order because of the ordering of another window. When
the other window was subsequently removed because it was
unused, this resulted in unordered rows, which was not
expected during evaluation.
Now in such cases, removal of redundant sorts is not
performed until after any unused windows have been
removed. In addition, resolution of any rollups has been
moved to the preparation phase. (Bug #31361393)
* Semisynchronous replication errors were incorrectly
written to the error log with a subsystem tag of Server.
They are now written with a tag of Repl, the same as for
other replication errors. (Bug #31327337)
* A user could grant itself as a role to itself. (Bug
#31222230)
* The server did not always correctly handle cases in which
multiple WHERE conditions, one of which was always FALSE,
referred to the same subquery. (Bug #31216115)
* With a lower_case_table_names=2 setting, InnoDB
background threads sometimes acquired table metadata
locks using the wrong character case for the schema name
part of a lock key, resulting in unprotected metadata and
race conditions. The correct character case is now
applied. Changes were also implemented to prevent
metadata locks from being released before corresponding
data dictionary objects, and to improve assertion code
that checks lock protection when acquiring data
dictionary objects. (Bug #31165802)
* If a CR_UNKNOWN_ERROR was to be sent to a client, an
exception occurred. (Bug #31123643)
* Conversion of DOUBLE values to values of type BIT, ENUM,
or SET could generate Undefined Behavior Sanitizer
warnings. (Bug #31019130)
* Certain accounts could cause server startup failure if
the --skip-name-resolve option was enabled. (Bug
#31018510)
* Client programs could unexpectedly exit if communication
packets contained bad data. (Bug #30890850)
* A buffer overflow in the client library was fixed. (Bug
#30885987)
* When creating a multi-valued or other functional index, a
performance drop was seen when executing a query against
the table on which the index was defined, even though the
index itself was not actually used. This occurred because
the hidden virtual column that backs such indexes was
evaluated unnecessarily for each row in the query. (Bug
#30838749)
References: This issue is a regression of: Bug #28069731.
* CMake checks for libcurl dependencies were improved. (Bug
#30268245)
* mysql_config_editor incorrectly treated # in password
values as a comment character. (Bug #29861961, Bug
#95597)
* In some cases, the optimizer attempted to compute the
hash value for an empty string. Now a fixed value is
always used instead. (Bug #22588319)
* The INSERT() and RPAD() functions did not correctly set
the character set of the result. (Bug #22523946, Bug
#79909, Bug #31887870, Bug #100841)
* Some corner cases for val1 BETWEEEN val2 AND val3 were
fixed, such as that -1 BETWEEN 9223372036854775808 AND 1
returned true. (Bug #22515857, Bug #79878)
* For the Performance Schema
memory_summary_global_by_event_name table, the low
watermark columns could have negative values, and the
high watermark columns had ever-increasing values even
when the server memory usage did not increase. (Bug
#22246001, Bug #79285)
* Several issues converting strings to numbers were fixed.
(Bug #19186271, Bug #73248)
* Certain group by queries that performed correctly did not
return the expected result when WITH ROLLUP was added.
This was due to the fact that decimal information was not
always correctly piped through rollup group items,
causing functions returning decimal values such as
TRUNCATE() to receive data of the wrong type. (Bug
#101684, Bug #32179240)
* When creating fields for materializing temporary tables
(that is, when needing to sort a join), the optimizer
checks whether the item needs to be copied or is only a
constant. This was not done correctly in one specific
case; when performing an outer join against a view or
derived table containing a constant, the item was not
properly materialized into the table, which could yield
spurious occurrences of NULL in the result. (Bug #101622,
Bug #32162862)
References: See also: Bug #31790217.
* When REGEXP_REPLACE() was used in an SQL statement, the
internal function Regexp_engine::Replace() did not reset
the error code value after handling a record, which could
affect processing of the next record, which lead to
issues.
Our thanks to Hope Lee for the contribution. (Bug
#101256, Bug #32050219)
* For a query having the following form, the column list
sometimes assumed an inconsistent state after temporary
tables were created, causing out-of-bounds indexing
later:
SELECT * FROM (
SELECT PI()
FROM t1 AS table1, t1 AS table2
ORDER BY PI(), table1.a
) AS d1;
(Bug #101012, Bug #31955761, Bug #31978439)
References: This issue is a regression of: Bug #31790217.
* When aggregating data that was already sorted (known as
performing streaming aggregation, due to no temporary
tables being used), it was not possible to determine when
a group ended until processing the first row in the next
group, by which time the group expressions to be output
were often already overwritten.
This is fixed by replacing the complex logic previously
used with the much simpler method of saving a
representative row for the group when encountering it the
first time, so that its columns can easily be retrieved
for the output row when needed. (Bug #100791, Bug
#27272052, Bug #31073167, Bug #31790217, Bug #31868610)
* Subqueries making use of fulltext matching might not
perform properly when subquery_to_derived was enabled,
and could lead to an assert in debug builds. (Bug
#100749, Bug #31851600)
* When an ALTER TABLE ... CONVERT TO CHARACTER SET
statement is executed, the character set of every CHAR,
VARCHAR, and TEXT column in the table is updated to the
new CHARACTER SET value. This change was also applied to
the hidden CHAR column used by an ARRAY column for a
multi-valued index; since the character set of the hidden
column must be one of my_charset_utf8mb4_0900_bin or
binary, this led to an assert in debug builds of the
server.
This issue is resolved by no longer setting the character
set of the hidden column to that of the table when
executing the ALTER TABLE statement referenced
previously; this is similar to what is done for BLOB
columns in similar circumstances. (Bug #99403, Bug
#31301101)
* In some cases, the server's internal string-conversion
routines had problems handling floating-point values
which used length specifiers and triggered use of
scientific notation. (Bug #92537, Bug #101570, Bug
#28691605, Bug #32144265)
References: See also: Bug #88256, Bug #27041543.
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