When one session SELECT ... FOR UPDATE and holds the lock, subsequent
sessions that SELECT ... FOR UPDATE will wait to get the lock.
Currently, that event is labeled as `wait/io/table/sql/handler`, which
is incorrect. Instead, it should have been
`wait/lock/table/sql/handler`.
Two factors contribute to this bug:
1. Instrumentation interface and the heavy usage of `TABLE_IO_WAIT` in
`sql/handler.cc` file. See interface [^1] for better understanding;
2. The balancing act [^2] of doing instrumentation aggregration _AND_
having good performance. For example, EVENTS_WAITS_SUMMARY... is
aggregated using EVENTS_WAITS_CURRENT. Aggregration needs to be based
on the same wait class, and the code was overly aggressive in label a
LOCK operation as an IO operation in this case.
The proposed fix is pretty simple, but understanding the bug took a
while. Hence the footnotes below. For future improvement and
refactoring, we may want to consider renaming `TABLE_IO_WAIT` and making
it less coarse and more targeted.
Note that newly added test case, events_waits_current_MDEV-29091,
initially didn't pass Buildbot CI for embedded build tests. Further
research showed that other impacted tests all included not_embedded.inc.
This oversight was fixed later.
All new code of the whole pull request, including one or several files
that are either new files or modified ones, are contributed under the
BSD-new license. I am contributing on behalf of my employer Amazon Web
Services, Inc.
[^1]: To understand `performance_schema` instrumentation interface, I
found this URL is the most helpful:
https://dev.mysql.com/doc/dev/mysql-server/latest/PAGE_PFS_PSI.html
[^2]: The best place to understand instrumentation projection,
composition, and aggregration is through the source file. Although I
prefer reading Doxygen produced html file, but for whatever reason, the
rendering is not ideal. Here is link to 10.6's pfs.cc:
https://github.com/MariaDB/server/blob/10.6/storage/perfschema/pfs.cc
- Added missing information about database of corresponding table for various types of commands
- Update some typos
- Reviewed by: <vicentiu@mariadb.org>
* FreeBSD returns errno 31 (EMLINK, Too many links),
not 40 (ELOOP, Too many levels of symbolic links)
* (`mysqlbinlog|mysql`) was just crazy, why did it ever work?
* socket_ipv6.inc check (that checked whether ipv6 is supported)
only worked correctly when ipv6 was supported
* perfschema.socket_summary_by_instance was changing global variables
and then skip-ing the test (because on missing ipv6)
Improve documentation of performance_schema tables by appending COLUMN
comments to tables. Additionally improve test coverage and update corresponding
tests.
report correct error codes in ed25519.
Invalid value stored in the user table or an OpenSSL error is CR_ERROR.
When a user provided incorrect password when logging in -
it's CR_AUTH_USER_CREDENTIALS.
Also fixes:
MDEV-21487: Implement option for mysql_upgrade that allows root@localhost to be replaced
MDEV-21486: Implement option for mysql_install_db that allows root@localhost to be replaced
Add user mariadb.sys to be definer of user view
(and has right on underlying table global_priv for
required operation over global_priv
(SELECT,UPDATE,DELETE))
Also changed definer of gis functions in case of creation,
but they work with any definer so upgrade script do not try
to push this change.
Unfortunate DROP TEMPORARY..IF EXISTS on a regular table may allow
subsequent CREATE TABLE statements to steal away the PFS_table_share
instance from the dropped table.
This allows one to run the test suite even if any of the following
options are changed:
- character-set-server
- collation-server
- join-cache-level
- log-basename
- max-allowed-packet
- optimizer-switch
- query-cache-size and query-cache-type
- skip-name-resolve
- table-definition-cache
- table-open-cache
- Some innodb options
etc
Changes:
- Don't print out the value of system variables as one can't depend on
them to being constants.
- Don't set global variables to 'default' as the default may not
be the same as the test was started with if there was an additional
option file. Instead save original value and reset it at end of test.
- Test that depends on the latin1 character set should include
default_charset.inc or set the character set to latin1
- Test that depends on the original optimizer switch, should include
default_optimizer_switch.inc
- Test that depends on the value of a specific system variable should
set it in the test (like optimizer_use_condition_selectivity)
- Split subselect3.test into subselect3.test and subselect3.inc to
make it easier to set and reset system variables.
- Added .opt files for test that required specfic options that could
be changed by external configuration files.
- Fixed result files in rockdsb & tokudb that had not been updated for
a while.
