The code in choose_best_splitting() assumed that the join prefix is
in join->positions[].
This is not necessarily the case. This function might be called when
the join prefix is in join->best_positions[], too.
Follow the approach from best_access_path(), which calls this function:
pass the current join prefix as an argument,
"const POSITION *join_positions" and use that.
This bug could affect queries containing a subquery over splittable derived
tables and having an outer references in its WHERE clause. If such subquery
contained an equality condition whose left part was a reference to a column
of the derived table and the right part referred only to outer columns
then the server crashed in the function st_join_table::choose_best_splitting()
The crashing code was added in the commit ce7ffe61d8
that made the code of the function sensitive to presence of the flag
OUTER_REF_TABLE_BIT in the KEYUSE_EXT::needed_in_prefix fields.
The field needed_in_prefix of the KEYUSE_EXT structure should not contain
table maps with OUTER_REF_TABLE_BIT or RAND_TABLE_BIT.
Note that this fix is quite conservative: for affected queries it just
returns the query plans that were used before the above mentioned commit.
In fact the equalities causing crashes should be pushed into derived tables
without any usage of split optimization.
Approved by Sergei Petrunia <sergey@mariadb.com>
EXPLAIN EXTENDED should always print the field item used in the left part
of an equality expression from the SET clause of an update statement as a
reference to table column.
Approved by Oleksandr Byelkin <sanja@mariadb.com>
The problem, introduced in patch for MDEV-26301:
When check_join_cache_usage() decides not to use join buffer, it must
adjust the access method accordingly. For BNL-H joins this means switching
from pseudo-"ref access"(with index=MAX_KEY) to some other access method.
Failing to do this will cause assertions down the line when code that is
not aware of BNL-H will try to initialize index use for ref access with
index=MAX_KEY.
The fix is to follow the regular code path to disable the join buffer for
the join_tab ("goto no_join_cache") instead of just returning from
check_join_cache_usage().
RocksDB (in a submodule) has to include <cstdint> to use uint64_t
but it doesn't. Until the submodule is upgraded, let's replace
problematic types with something that's available
select_insert::store_values() must reset
has_value_set bitmap before every row, just like mysql_insert() does.
because ON DUPLICATE KEY UPDATE and triggers modify it
This patch optimizes the number of refills for the lateral derived table
to which a materialized derived table subject to split optimization is
is converted. This optimized number of refills is now considered as the
expected number of refills of the materialized derived table when searching
for the best possible splitting of the table.
- Update wsrep-lib which contains fix for the assertion
- Fix error handling for appending fragment to streaming log,
make sure tables are closed after rollback.
Signed-off-by: Julius Goryavsky <julius.goryavsky@mariadb.com>
Adding virtual methods to class Schema:
make_item_func_replace()
make_item_func_substr()
make_item_func_trim()
This is a non-functional preparatory change for MDEV-27744.
Variant #2.
When Histogram::point_selectivity() sees that the point value of interest
falls into one bucket, it tries to guess whether the bucket has many
different (unpopular) values or a few popular values. (The number of
rows is fixed, as it's a Height-balanced histogram).
The basis for this guess is the "width" of the value range the bucket
covers. Buckets covering wider value ranges are assumed to contain
values with proportionally lower frequencies.
This is just a [brave] guesswork. For a very narrow bucket, it may
produce an estimate that's larger than total #rows in the bucket
or even in the whole table.
Remove the guesswork and replace it with basic logic: return
either the per-table average selectivity of col=const, or selectivity
of one bucket, whichever is lower.
Fix-up for commit 476b24d084
Author: Monty
Date: Thu Feb 16 14:19:33 2023 +0200
MDEV-20057 Distinct SUM on CROSS JOIN and grouped returns wrong result
which misses initializing of sorder->suffix_length.
In this commit the initialization is implemented by passing
MY_ZEROFILL flag to the allocation of SORT_FIELD elements
When using binlog_row_image=FULL with sequence table inserts, a
replica can deadlock because it treats full inserts in a sequence as DDL
statements by getting an exclusive lock on the sequence table. It
has been observed that with parallel replication, this exclusive
lock on the sequence table can lead to a deadlock where one
transaction has the exclusive lock and is waiting on a prior
transaction to commit, whereas this prior transaction is waiting on
the MDL lock.
This fix for this is on the master side, to raise FL_DDL
flag on the GTID of a full binlog_row_image write of a sequence table.
This forces the slave to execute the statement serially so a deadlock
cannot happen.
A test verifies the deadlock also to prove it happen on the OLD (pre-fixes)
slave.
OLD (buggy master) -replication-> NEW (fixed slave) is provided.
As the pre-fixes master's full row-image may represent both
SELECT NEXT VALUE and INSERT, the parallel slave pessimistically
waits for the prior transaction to have committed before to take on the
critical part of the second (like INSERT in the test) event execution.
The waiting exploits a parallel slave's retry mechanism which is
controlled by `@@global.slave_transaction_retries`.
Note that in order to avoid any persistent 'Deadlock found' 2013 error
in OLD -> NEW, `slave_transaction_retries` may need to be set to a
higher than the default value.
START-SLAVE is an effective work-around if this still happens.
The error was seen by a number of mtr tests being caused
by overdue initialization of rpl_parallel::LOCK_parallel_entry.
Specifically, SHOW-SLAVE-STATUS might find in
rpl_parallel::workers_idle() a gtid domain hash entry
already inserted whose mutex had not done
mysql_mutex_init().
Fixed with swapping the mutex init and the its entry's stack insertion.
Tested with a generous number of `mtr --repeat` of a few of the reported
to fail tests, incl rpl.parallel_backup.
When replicating MDL events for a table that uses system versioning
without primary keys, ensure that for data sets with duplicate
records, the updates to these records with duplicates are enacted on
the correct row. That is, there was a bug (reported in MDEV-30430)
such that the function to find the row to update would stop after
finding the first matching record. However, in the absence of
primary keys, the version of the record is needed to compare the row
to ensure we are updating the correct one.
The fix, therefore, updates the record comparison functionality to
use system version columns when there are no primary keys on the
table.
Reviewed By:
============
Andrei Elkin <andrei.elkin@mariadb.com>
Problem:
========
A master can segfault if it can't set up decryption for its binary
log during a binlog dump with Using_Gtid=Slave_Pos. If slave
connects using GTID mode, the master will call into
log.cc::get_gtid_list_event(), which iterate through binlog events
looking for a Gtid_list_log_event. On an encrypted binlog that the
master cannot decrypt, the first event will be a
START_ENCRYPTION_EVENT which will call into the following decryption branch
if (fdle->start_decryption((Start_encryption_log_event*) ev))
errormsg= ‘Could not set up decryption for binlog.’;
The event iteration however, does not stop in spite of this error.
The master will try to read the next event, but segfault while
trying to decrypt it because decryption failed to initialize.
Solution:
========
Break the event iteration if decryption cannot be set up.
Reviewed By:
============
Andrei Elkin <andrei.elkin@mariadb.com>
This bug could manifest itself at the first execution of prepared statement
created for queries using a materialized view defined as union. A crash
could happen for sure if the query contained a condition pushable into
the view and this condition was over the column defined via a complex string
expression requiring implicit conversion from one charset to another for
some of its sub-expressions. The bug could cause crashes when executing
PS for some other queries whose optimization needed building clones for
such expressions.
This bug was introduced in the patch for MDEV-29988 where the class
Item_direct_ref_to_item was added. The implementations of the virtual
methods get_copy() and build_clone() were invalid for the class and this
could cause crashes after the method build_clone() was called for
expressions containing objects of the Item_direct_ref_to_item type.
Approved by Sergei Golubchik <serg@mariadb.com>
Fixing buildbot failures on mariabackup.aria_log_dir_path_rel.
The problem was that directory_exists() was called with the
relative aria_log_dir_path value, while the current directory
in mariadb-backup is not necessarily equal to datadir when MTR is running.
Fix:
- Moving building the absolute path un level upper:
from the function copy_back_aria_logs() to the function copy_back().
- Passing the built absolute path to both directory_exists() and
copy_back_aria_logs() as a parameter.
This bug caused server crash when processing a multi-update statement that
used views if optimizer tracing was enabled.
The bug was introduced in the patch for MDEV-30539 that could incorrectly
detect the most top level selects of queries if views were used in them.
Approved by Oleksandr Byelkin <sanja@mariadb.com>
- `mariadb-backup --backup` was fixed to fetch the value of the
@@aria_log_dir_path server variable and copy aria_log* files
from @@aria_log_dir_path directory to the backup directory.
Absolute and relative (to --datadir) paths are supported.
Before this change aria_log* files were copied to the backup
only if they were in the default location in @@datadir.
- `mariadb-backup --copy-back` now understands a new my.cnf and command line
parameter --aria-log-dir-path.
`mariadb-backup --copy-back` in the main loop in copy_back()
(when copying back from the backup directory to --datadir)
was fixed to ignore all aria_log* files.
A new function copy_back_aria_logs() was added.
It consists of a separate loop copying back aria_log* files from
the backup directory to the directory specified in --aria-log-dir-path.
Absolute and relative (to --datadir) paths are supported.
If --aria-log-dir-path is not specified,
aria_log* files are copied to --datadir by default.
- The function is_absolute_path() was fixed to understand MTR style
paths on Windows with forward slashes, e.g.
--aria-log-dir-path=D:/Buildbot/amd64-windows/build/mysql-test/var/...
fp->field_length was unsigned and therefore the negative
condition around it.
Backport of cc182aca93 fixes it, however to correct the
consistent use of types pcf->Length needs to be unsigned
too.
At one point pcf->Precision is assigned from pcf->Length so
that's also unsigned.
GetTypeSize is assigned to length and has a length argument.
A -1 default value seemed dangerious to case, so at least 0
should assert if every hit.
