mariadb/mysql-test
Monty 232533978f MDEV-36290: ALTER TABLE with multi-master can cause data loss
One can have data loss in multi-master setups when 1) both masters
update the same table, 2) ALTER TABLE is run on one master which
re-arranges the column ordering, and 3) transactions are binlogged
in ROW binlog_format.

This is because the slave assumes that all columns are in the same
order on the master and slave and all columns on the master also
exists on the slave. This happens even if binlog_row_metadata=FULL is
used.  If this is not the case, this will lead to silent data loss.

A new option for slave_type_conversions bit field,
ERROR_IF_MISSING_FIELD, has been added. This allows the user to define if
the slave should abort replication if it is missing some field that
existed on the master. This option is off by default to keep things
compatible with earlier versions.
If a field is missing on the slave and log_warnings >= 1, a warning
will be logged to the error log.

This patch fixes this, when binlog_row_metadata=FULL is used on the
master, by mapping fields with identical names on the master and slave.
If slave has fields that does not exist in the row event, these will
be set to their default value.

The main idea is that we added two conversion tables:
m_tabledef.master_to_slave_map[master_column_index] -> slave_column_index
and m_tabledef.master_to_slave_error[master_column_index] which contains
an error number if the master_column does not exists on the slave or
it is not possible to convert the master data to the slave column.
master_to_slave_error[#] contains 0 if the column exists and is compatible.

General code changes:
- Instead of looping over row fields in the order of slave table
  we are instead looping over fields in the order of the binary log.
- We are using table->write_set to know which fields should be updated
  on the slave. This is reflected in unpack_row
- We are calling TABLE::mark_columns_per_binlog_row_image() to ensure
  that rpl_write_set is properly set. This is needed if the slave also
  is doing binary logging.
- Before replication aborted if the master and slave tables where too
  different.  Now replication is only aborted if the row actually uses
  columns that does not exists on the slave (and ALLOW_MISSING_FIELDS
  is not used) or uses columns that cannot be converted.
  - Instead of giving errors in compatible_with(), used when table is
    accessed by first the row event, we are instead giving errors
    when we examine a row event and notice that it is accessing
    a not existing or not compatible field.

Other code changes:
- Removed conv_table argument from compatible_with() and store it
  directly in RPL_TABLE_LIST->m_conv_table
- table_def::compatible_with() returns now 1 on error (not 0).
- Remove m_width and skip arguments from prepare_record() as we are
  now using table->write_set() to check which elements need a default
  value.
- Moved DBUG_ENTER() to it's proper place (after variable
  declarations) in a few functions.
- Some changes in unpack_row():
  - Replaced null_mask and null_ptr with an indexed bit check for
    simplicity.
  - Removed check of rgi == null and table_found which never worked.
  - Updated comments to reflect current code.
  - Indentation changes as the code now uses 'continue' instead of
    'if-else' in the main loop.
  - The code to throw away 'extra master fields' is not needed as we
    are now looping over fields in binary log, not over fields in
    slave table.
- fill_extra_persistent_columns() is now using table->cond_set to know
  which columns where not updated from binlog.
- Simplified get_table_data(TABLE *table_arg) by returning found
  table_list.
- Errors for row events are now initialized in compatible_with(),
  checked in check_wrong_column_usage() and reported in
  give_compatibility_error().

Test cases and some code patchs provide by Brandon Nesterenko
<brandon.nesterenko@mariadb.com>
2025-05-19 19:57:47 +03:00
..
collections
include Merge 10.5 into 10.6 2025-03-26 17:09:57 +02:00
lib Merge branch '10.5' into 10.6 2025-01-29 11:17:38 +01:00
main MDEV-36290: ALTER TABLE with multi-master can cause data loss 2025-05-19 19:57:47 +03:00
std_data Merge branch '10.5' into '10.6' 2025-02-27 04:02:33 +01:00
suite MDEV-36290: ALTER TABLE with multi-master can cause data loss 2025-05-19 19:57:47 +03:00
asan.supp
CMakeLists.txt Merge branch '10.5' into 10.6 2025-03-31 12:12:50 +02:00
dgcov.pl
lsan.supp
mariadb-stress-test.pl
mariadb-test-run.pl MDEV-36226 Stall and crash when page cleaner fails to generate free pages during Async flush 2025-03-31 19:09:23 +05:30
mtr.out-of-source
purify.supp
README
README-gcov
README.stress
suite.pm Merge 10.5 into 10.6 2024-10-03 09:31:39 +03:00
valgrind.supp

This directory contains test suites for the MariaDB server. To run
currently existing test cases, execute ./mysql-test-run in this directory.

Some tests are known to fail on some platforms or be otherwise unreliable.
In the file collections/smoke_test there is a list of tests that are
expected to be stable.

In general you do not have to have to do "make install", and you can have
a co-existing MariaDB installation, the tests will not conflict with it.
To run the tests in a source directory, you must do "make" first.

In Red Hat distributions, you should run the script as user "mysql".
The user is created with nologin shell, so the best bet is something like
  # su -
  # cd /usr/share/mysql-test
  # su -s /bin/bash mysql -c ./mysql-test-run

This will use the installed MariaDB executables, but will run a private
copy of the server process (using data files within /usr/share/mysql-test),
so you need not start the mysqld service beforehand.

You can omit --skip-test-list option if you want to check whether
the listed failures occur for you.

To clean up afterwards, remove the created "var" subdirectory, e.g.
  # su -s /bin/bash - mysql -c "rm -rf /usr/share/mysql-test/var"

If tests fail on your system, please read the following manual section
for instructions on how to report the problem:

https://mariadb.com/kb/en/reporting-bugs

If you want to use an already running MySQL server for specific tests,
use the --extern option to mysql-test-run. Please note that in this mode,
you are expected to provide names of the tests to run.

For example, here is the command to run the "alias" and "analyze" tests
with an external server:

  # mysql-test-run --extern socket=/tmp/mysql.sock alias analyze

To match your setup, you might need to provide other relevant options.

With no test names on the command line, mysql-test-run will attempt
to execute the default set of tests, which will certainly fail, because
many tests cannot run with an external server (they need to control the
options with which the server is started, restart the server during
execution, etc.)

You can create your own test cases. To create a test case, create a new
file in the main subdirectory using a text editor. The file should have a .test
extension. For example:

  # xemacs t/test_case_name.test

In the file, put a set of SQL statements that create some tables,
load test data, and run some queries to manipulate it.

Your test should begin by dropping the tables you are going to create and
end by dropping them again. This ensures that you can run the test over
and over again.

If you are using mysqltest commands in your test case, you should create
the result file as follows:

  # mysql-test-run --record test_case_name

  or

  # mysqltest --record < t/test_case_name.test

If you only have a simple test case consisting of SQL statements and
comments, you can create the result file in one of the following ways:

  # mysql-test-run --record test_case_name

  # mysql test < t/test_case_name.test > r/test_case_name.result

  # mysqltest --record --database test --result-file=r/test_case_name.result < t/test_case_name.test

When this is done, take a look at r/test_case_name.result.
If the result is incorrect, you have found a bug. In this case, you should
edit the test result to the correct results so that we can verify that
the bug is corrected in future releases.

If you want to submit your test case you can send it
to developers@lists.mariadb.org or attach it to a bug report on
http://mariadb.org/jira/.

If the test case is really big or if it contains 'not public' data,
then put your .test file and .result file(s) into a tar.gz archive,
add a README that explains the problem, ftp the archive to
ftp://ftp.mariadb.org/private and submit a report to
https://mariadb.org/jira about it.

The latest information about mysql-test-run can be found at:
https://mariadb.com/kb/en/mariadb/mysqltest/

If you want to create .rdiff files, check
https://mariadb.com/kb/en/mariadb/mysql-test-auxiliary-files/