MySQL 8.0 Release Notes
<COMMAND_CLASS>
was not populated for
<NAME>Execute</NAME>
.
For more information, see Logging Specific Event Classes. (Bug #36686351)
Group Replication: The OpenSSL Engine interface is deprecated, and is no longer being included in OpenSSL v3 main packages by some Linux distributions, including Fedora.
To avoid build issues, the usage of the OpenSSL Engine interface by the Group Communication System (GCS) is now restricted to OpenSSL versions previous to 1.1. (Bug #37475769)
Linux: Use /usr/bin/gcc (GCC 14.2.1) when building the server on Oracle Linux 10. (Bug #37616148)
Upgraded the bundled Curl library to version 8.12.1. (Bug #37633587)
Abseil could not be built on FreeBSD. (Bug #37611924)
In order to use xxhash
functions
independently from the lz4
library (bundled
or source), we compiled xxhash.c
into our
own binaries, which required using a great many CMake
directives. Instead, we now build an interface library for
xxhash
, and link with that wherever such
functions are used.
(Bug #37417386)
Use xxHash-0.8.2 from GitHub rather than the version bundled with lz4. (Bug #37387318)
Important Change:
When an SQL function is improved from one release to the next,
it may throw SQL errors in situations in which it previously did
not. If this happens in a table's constraints, default
expressions, partitioning expressions, or virtual columns, the
table could not be opened. This prevented both analyzing the
problem (using, for example, SHOW CREATE
TABLE
) and addressing it (such as with an
ALTER TABLE ...
DROP ...
statement).
Now, on server upgrade, we scan the data dictionary for tables
that use any of the features just mentioned. We then try to open
such tables, and if we fail to do so, we alert the user. This
patch addresses this. The
--check-table-functions
server
option introduced in this release helps to address this problem
by making it possible to specify the server's behavior when
encountering an error with such a function. Set this option to
WARN
in order to log a warning for each table
which the server could not open; setting it to
ABORT
also logs these warnings as
WARN
, but aborts the server upgrade if any
issues were found.
ABORT
is the default; this enables the user
to fix the issue using the older version of the server before
upgrading to the new one. WARN
flags the
issues, but allows the user to continue in interactive mode
while addressing the problem.
(Bug #36890891)
References: See also: Bug #37009318. This issue is a regression of: Bug #98950, Bug #98951, Bug #31031886, Bug #31031888.
Fixed a performance issue in the
PROCESSLIST
table.
(Bug #36778475)
Important Change: For platforms on which OpenSSL libraries are bundled, the linked OpenSSL library for MySQL Server has been updated to version 3.0.16. For more information, see OpenSSL 3.0 Series Release Notes and OpenSSL Security Advisory (11th February 2025). (Bug #36033684)
Performance; Replication:
The data structure used in tracking binary log transaction
dependencies has been changed from Tree
to
ankerl::unordered_dense::map
, which uses
approximately 60% less space, and which should thus contribute
to better dependency tracking performance.
(Bug #37008442, Bug #37529256)
InnoDB:
To improve debugging, the buf_page_t
and
buf_block_t
structure's metadata is now
printed to the error log.
(Bug #35115629)
References: See also: Bug #35115601.
Increased the historical 1024-byte limit when printing the current query during signal handling to 1073741824 (1024 * 1024 * 1024). (Bug #37603354)
InnoDB: Fixed a potential memory leak in several places in the innobase code. (Bug #37403052)
InnoDB: Under certain circumstances, MySQL could crash during shutdown due to pages which were still fixed or dirty. Errors similar to the following were logged:
[ERROR] [MY-011908] [InnoDB] [FATAL] Page [page id: space=46, page number=75] still fixed or dirty [ERROR] [MY-013183] [InnoDB] Assertion failure: buf0buf.cc:5889:ib::fatal triggered thread 139963705668608
(Bug #37391519)
References: See also: Bug #35115601.
InnoDB:
CHECK TABLE
for spatial indexes
did not verify the MBR against the geometry MBR stored in the
clustered index record. This could result in incorrect behaviour
of spatial indexes.
As of this release, CHECK TABLE EXTENDED
verifies the MBR matches the MBR stored in the clustered index
record.
(Bug #37359538)
InnoDB: Fixed an issue relating to pessimistic row update.
Our thanks to Mengchu Shi and the team at Alibaba for the contribution. (Bug #37292404)
InnoDB:
The CHECK TABLE
operation could
incorrectly report corruption in spatial indexes.
(Bug #37286473)
InnoDB: Fixed an issue relating to InnoDB redo log recovery. (Bug #37061960)
InnoDB:
Fixed an issue relating to reading index_id
values.
(Bug #36993445, Bug #37709706)
InnoDB:
Fixed an issue relating to
lower_case_table_names
.
(Bug #32288105)
InnoDB: Partition table indexes were not checked when retrieving a record count while that table's definition was being altered by another client session. The record count was executed without error.
As of this release, the index is checked to ensure it is usable when retrieving a record count. (Bug #117459, Bug #37617773)
InnoDB: Refactored code related to BPR_PCUR_* positioning for restore operations. (Bug #117259, Bug #37505746)
References: This issue is a regression of: Bug #37318367.
InnoDB:
Changes made to
innodb_spin_wait_delay
in MySQL
8.0.30 negatively impacted performance.
(Bug #116463, Bug #37212019)
InnoDB:
Under certain circumstances, using ALTER
TABLE
with INPLACE
to modify the
size of a column could result in an index which exceeds the
valid size limit (767 bytes). This occurred for tables with a
row format of Redundant
or
Compact
and the row format was not explicitly
defined in the table creation.
As of this release, a validation is performed and an error returned by any ALTER TABLE, INPLACE operation which will result in an invalid index size. (Bug #116353, Bug #37168132)
InnoDB:
Fixed a memory leak in the Clone_persist_gtid
thread.
Our thanks to Baolin Huang and the team at Alibaba for the contribution. (Bug #107991, Bug #34454572)
Partitioning:
When inserting NOW()
into a
column not part of the partition key of a partitioned table, all
partitions were retrived, and no pruning occurred.
(Bug #37397306)
Replication:
In a source-replica setup, the replica encountered irregular
failures of UPDATE
and
DELETE
statements with
ER_KEY_NOT_FOUND
errors on the
same table. (The replica's binary log and GTID records
showed that the row required was committed, and had not been
deleted or updated.) This occurred on the replica when the
row-matching algorithm used was HASH_SCAN
and
two rows in the same table had the same CRC32 value.
In the event of such a CRC32 collision, finding a matching CRC32 in the hash table does not guarantee that the correct row is being updated, so the algorithm iterates over any multiple entries having the same CRC32, and compares the full record for each of them in a loop; the problem occurred due to the fact that the logic to exit this loop was incorrect. This logic has now been corrected. (Bug #37462058)
Replication:
The
asynchronous_connection_failover_delete_source()
function did not always perform as expected in all cases.
(Bug #36479088)
Replication:
In some cases, the
asynchronous_connection_failover_add_source()
function did not perform as expected.
(Bug #36479083)
Replication:
In some cases, MASTER_POS_WAIT()
did not perform as expected.
(Bug #36421684, Bug #37709187)
Replication:
The
asynchronous_connection_failover_add_managed()
function in some cases did not produce the expected result.
(Bug #34648589)
Replication:
When the server was under a heavy write load, the binary log
position for gtid_executed
as
shown in the Performance Schema
log_status
table did not match that
of the gtid shown in the binary log file.
We fix this by increasing the scope of the lock on the
log_status
table when querying it to ensure
that transactions in the commit pipeline are completed. This
ensures that a query against the log_status
table waits until gtid_executed
has been
fully updated, thereby guaranteeing consistency with its
position in the binary log.
(Bug #102175, Bug #32442772)
Group Replication:
When a secondary joined the group, it might happen that all
group members started to grow the value of the column
COUNT_TRANSACTIONS_ROWS_VALIDATING
column of
the Performance Schema
replication_group_member_stats
table indefinitely. This impacted memory consumption in all
group members, eventually leading to thrashing if not mitigated
by restarting the secondary group member that triggered the
behavior, or in some cases, by restarting the whole group.
Analysis pointed to issues with the Group Replication start
operation, which checks whether there are partial transactions
on the group_replication_applier
channel from
previous group participation; if any are found, this channel is
stopped after applying all complete transactions and its relay
logs purged, and then the channel is restarted. After this,
distributed recovery is performed, applying any missing data
from group members.
The issues arose when the Group Replication pipeline operation
for stopping the group_replication_applier
channel incorrectly stopped a periodic task from the certifier
module, which caused some periodic internal operations not to
take place. One of these tasks was the periodic sending of the
committed transactions; this omission prevented garbage
collection for certification, which in turn caused a continuous
increase in
COUNT_TRANSACTIONS_ROWS_VALIDATING
in the
Performance Schema
replication_group_member_stats
table.
To solve this problem, we have taken steps to ensure that the
pipeline operation for stopping the
group_replication_applier
channel no longer
interferes with the certifier module, which also stops spurious
values from being added for
COUNT_TRANSACTIONS_ROWS_VALIDATING
.
(Bug #37613510)
Group Replication: When running Group Replication, some transactions may not have write sets, as with empty transactions with GTID_NEXT specified, or DDL statements. For such transactions, Group Replication cannot check conflicts; thus, it is not known whether they can be applied in parallel, and for this reason, Group Replication follows a pessimistic approach, and runs them sequentially, potentially leading to an impact on performance.
While DDL must be applied sequentially, there is no actual reason to force such behavior for empty transactions, so this fix makes it possible for empty transactions to be applied concurrently with other nondependent transactions. (Bug #37597512, Bug #37569333)
Group Replication:
A group running group replication with a primary
i1
and two secondaries i2
and i3
started to have intermittent issues
because of high memory usage on the primary. The secondaries
began reporting the primary as unreachable then reachable again,
and the primary began reporting the secondaries as
intermittently reachable then reachable as well. Following a
period of such instability, the secondaries expelled the
original primary (i1
) and elected a new one
(i2
).
Under these conditions, queries against the
performance_schema.replication_group_members
table on the former primary (i1
) reported
i1
as ONLINE
and
PRIMARY
, i2
as
ONLINE
and SECONDARY
, and
i3
as ONLINE
and
SECONDARY
for an extended period of time (12
hours or more) until the mysqld process was
restarted on i1
.
The problems observed were found to have begun on the original
primary (i1
) when one of the secondaries was
overloaded and began intermittently leaving and joining the
group, its connections being dropped and recreated repeatedly on
the primary server. During the reconnection process, the primary
hung when trying to create the connection, thus blocking the
single XCom thread. This was traced to the invocation of
SSL_connect()
on the XCom communication
stack, which changed in MySQL 8.0.27 from asynchronous to
synchronous form. When a node was overloaded, it might not
respond to the SSL_connect()
call, leaving
the connecting end blocked indefinitely.
To fix this, we now connect in a way that is non-blocking, and that returns in case of a timeout, leaving the retry attempts to the caller—in this specific case, the XCom thread when trying to reconnect to another node. (Bug #34348094, Bug #36047891)
References: See also: Bug #37587252.
The fprintf_string()
function in
mysqldump did not use the actual quote
character for string escaping.
(Bug #37607195)
EXPLAIN
did not always handle
subqueries correctly.
(Bug #37560280)
If a demangled function name exceeded 512 bytes in a stack trace, the function name was truncated and a newline was not printed.
As of this release, long strings, such as filenames and demangled functions, are written directly to the output. (Bug #37543598)
mysqldump did not escape certain special characters properly in its output. With this fix, mysqldump now follows the rules as described in String Literals. (Bug #37540722, Bug #37709163)
Some operations on tables having functional indexes were not handled properly. (Bug #37523857)
Attempting to install an unknown component using
INSTALL COMPONENT
was not always
handled correctly.
(Bug #37437317)
The Audit Log plugin did not handle errors correctly when writing JSON output.
See MySQL Enterprise Audit, for more information. (Bug #37370439)
An UPDATE
subsequent to an
INSERT
affecting a table which
had a BEFORE INSERT
trigger was sometimes
rejected with a null value error when the
INSERT
had set a NOT NULL
column to NULL
, even though this should have
been allowed by the server
sql_mode
in effect.
(Bug #37337527)
In some cases, components could not reuse the same connection for running multiple queries. (Bug #37286895)
Improved error handling for stored routines. (Bug #37193011)
Stored routines were not always invoked correctly in prepared statements. (Bug #37077424, Bug #37292797)
Increased the size of SEL_ROOT::elements
from
uint16
to size_t
.
(Bug #36610878)
Removed an issue with multibyte UTF8 handling. (Bug #36593253)
An ORDER BY
containing an aggregation was not
always handled correctly.
(Bug #36593253)
An optimizer hint was ignored, unexpectedly requiring the use of
FORCE INDEX
, when querying a view that
included a UNION
. For more
information, see Optimizer Hints.
(Bug #36536936)
Some subselects were not handled correctly. (Bug #36421690)
An invalid DDL statement in certain cases was not always rejected as expected. (Bug #35721121)
Improved the internal function
append_identifier()
.
(Bug #35633084)
Normally, a view with an unused window definition should be updatable, but when it contained a subquery, it was marked as not updatable. At update time, the window was eliminated, but this was too late to allow an update to be performed.
We fix this by testing mergeability, by checking the presence of
window functions, rather than that of window definitions; this
allows the view to be updateable, and the problematic
UPDATE
to succeed.
(Bug #35507777)
In some cases, SET
did not
perform correctly in prepared statements.
(Bug #35308309)
This fix addresses the following issues:
Query_expression::is_set_operation()
was
not always executed properly.
Some sequences of DML statements could lead to an unplanned exit.
Some nested subselects were not always handled correctly.
(Bug #34361287, Bug #35889583, Bug #35996409, Bug #36404149, Bug #37611264)
On Debian, dh_strip_nondeterminism is no longer executed on zip and gzip files within the packages. (Bug #33791880)
Removed an issue relating to invalid UTF8 values. (Bug #27618273, Bug #37709687)
Addressed an issue relating to an invalid identifier. (Bug #22958632, Bug #37709664)
A negative impact in performance was observed when using a
multivalued index with ORDER BY DESC
and
LIMIT
in a query, where the value specified
by LIMIT
was greater than the number of rows
actually in the result.
(Bug #117085, Bug #37436310)
References: This issue is a regression of: Bug #104897, Bug #33334911.
When pushing a condition down to a derived table, we clone the
condition, and, if the underlying field is a view reference
(that is, a field from a merged derived table), we strip off the
view reference and clone the expression that it references. When
the underlying expression is a constant expression from a table
that is on the inner side of an outer join, it cannot be treated
as a normal constant because of the need to generate
NULL
values. When we stripped off the view
reference, this information was lost, leading to wrong results.
We fix this by avoiding condition pushdown for such cases. (Bug #111355, Bug #35634714)