- Removed duplicate words, like "the the" and "to to"
- Removed duplicate lines (one double sort line found in mysql.cc)
- Fixed some typos found while searching for duplicate words.
Command used to find duplicate words:
egrep -rI "\s([a-zA-Z]+)\s+\1\s" | grep -v param
Thanks to Artjoms Rimdjonoks for the command and pointing out the
spelling errors.
See also MDEV-30046.
Idempotent write_row works same as REPLACE: if there is a duplicating
record in the table, then it will be deleted and re-inserted, with the
same update optimization.
The code in Rows:log_event::write_row was basically copy-pasted from
write_record.
What's done:
REPLACE operation was unified across replication and sql. It is now
representred as a Write_record class, that holds the whole state, and allows
re-using some resources in between the row writes.
Replace, IODKU and single insert implementations are split across different
methods, reluting in a much cleaner code.
The entry point is preserved as a single Write_record::write_record() call.
The implementation to call is chosen on the constructor stage.
This allowed several optimizations to be done:
1. The table key list is not iterated for every row. We find last unique key in
the order of checking once and preserve it across the rows. See last_uniq_key().
2. ib_handler::referenced_by_foreign_key acquires a global lock. This call was
done per row as well. Not all the table config that allows optimized replace is
folded into a single boolean field can_optimize. All the fields to check are
even stored in a single register on a 64-bit platform.
3. DUP_REPLACE and DUP_UPDATE cases now have one less level of indirection
4. modified_non_trans_tables is checked and set only when it's really needed.
5. Obsolete bitmap manipulations are removed.
Also:
* Unify replace initialization step across implementations:
add prepare_for_replace and finalize_replace
* alloca is removed in favor of mem_root allocation. This memory is reused
across the rows.
* An rpl-related callback is added to the replace branch, meaning that an extra
check is made per row replace even for the common case. It can be avoided with
templates if considered a problem.
Server-level UNIQUE constraints (namely, WITHOUT OVERLAPS and USING HASH)
only worked with InnoDB in REPEATABLE READ isolation mode, when the
constraint was checked first and then the row was inserted or updated.
Gap locks prevented race conditions when a concurrent connection
could've also checked the constraint and inserted/updated a row
at the same time.
In READ COMMITTED there are no gap locks. To avoid race conditions,
we now check the constraint *after* the row operation. This is
enabled by the HA_CHECK_UNIQUE_AFTER_WRITE table flag that InnoDB
sets in the READ COMMITTED transactions.
Checking the constraint after the row operation is more complex.
First, the constraint will see the current (inserted/updated) row,
and needs to skip it. Second, IGNORE operations become tricky,
as we need to revert the insert/update and continue statement execution.
write_row() (INSERT IGNORE) is reverted with delete_row(). Conveniently
it deletes the current row, that is, the last inserted row.
update_row(a,b) (UPDATE IGNORE) is reverted with a reversed update,
update_row(b,a). Conveniently, it updates the current row too.
Except in InnoDB when the PK is updated - in this case InnoDB internally
performs delete+insert, but does not move the cursor, so the "current"
row is the deleted one and the reverse update doesn't work.
This combination now throws an "unsupported" error and will
be fixed in MDEV-37233
Log tables cannot work with transactional InnoDB or Aria, that is
checked by ALTER TABLE for ER_UNSUPORTED_LOG_ENGINE. But it was
possible to circumvent this check with CREATE TABLE. The patch makes
the check of supported engine common for ALTER TABLE and CREATE TABLE.
This commit fixes a bug where Aria tables are used in
(master->slave1->slave2) and a backup is taken on slave2. In this case
it is possible that the replication position in the backup, stored in
mysql.gtid_slave_pos, will be wrong. This will lead to replication
errors if one is trying to use the backup as a new slave.
Analyze:
Replicated row events are committed with trans_commit_stmt() and
thd->transaction->all.ha_list != 0.
This means that backup_commit_lock is not taken for Aria tables,
which means the rows are committed and binary logged on the slave
under BLOCK_COMMIT which should not happen.
This issue does not occur on the master as thd->transaction->all.ha_list
is == 0 under AUTO_COMMIT, which sets 'is_real_trans' and 'rw_trans'
which in turn causes backup_commit_lock to be taken.
Fixed by checking in ha_check_and_coalesce_trx_read_only() if all handlers
supports rollback and if not, then wait for BLOCK_COMMIT also for
statement commit.
7544fd4cae had to make use of a static array to avoid memory
use-after-free or leak.
Instead, let us make a function returning String, this is the only way
to automatically manage the memory after the function returned.
To make it all correct, move constructor is added. Normally, it is
expected, that the constructor will be elided upon return of an object
by value, but if something goes different, or -fno-elide-constructors is
used, we can have a problem. So this was a move constructor avoids
copy elision-related UB.
dbug_print_row returning char* is still there for convenient use in a
debugger.
Partial commit of the greater MDEV-34348 scope.
MDEV-34348: MariaDB is violating clang-16 -Wcast-function-type-strict
Reviewed By:
============
Marko Mäkelä <marko.makela@mariadb.com>
When a derived table which has distinct values and BLOB fields is
materialized, an index is created over all columns to ensure only
unique values are placed to the result.
This index is created in a special mode HA_UNIQUE_HASH to support BLOBs.
Later the optimizer may incorrectly choose this index to retrieve values
from the derived table, although such type of index cannot be used
for data retrieval.
This commit excludes HA_UNIQUE_HASH indexes from adding to
`JOIN::keyuse` array thus preventing their subsequent usage for
data retrieval
work consistently on replication
Row-based replication does not execute CREATE .. SELECT but instead
CREATE TABLE. CREATE .. SELECT creates implict system fields on
unusual place: in-between declared fields and select fields. That was
done because select_field_pos logic requires select fields go last in
create_list.
So, CREATE .. SELECT on master and CREATE TABLE on slave create system
fields on different positions and replication gets field mismatch.
To fix this we've changed CREATE .. SELECT to create implicit system
fields on usual place in the end and updated select_field_pos for
handling this case.
Fixed by checking handler_stats if it's active instead of
thd->variables.log_slow_verbosity & LOG_SLOW_VERBOSITY_ENGINE.
Reviewed-by: Sergei Petrunia <sergey@mariadb.com>
The method was declared to return an unsigned integer, but it is
really a boolean (and used as such by all callers).
A secondary change is the addition of "const" and "noexcept" to this
method.
In ha_mroonga.cpp, I also added "inline" to the two helper methods of
referenced_by_foreign_key(). This allows the compiler to flatten the
method.
