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.
Relates to MDEV-17863 DROP TEMPORARY TABLE creates a transaction in
binary log on read only server
Other things:
- Fixed that insert into normal_table select from tmp_table is
replicated as row events if tmp_table doesn't exists on slave.
- Any temporary tables created under read-only mode will never be logged
to binary log. Any usage of these tables to update normal tables, even
after read-only has been disabled, will use row base logging (as the
temporary table will not be on the slave).
- Analyze, check and repair table will not be logged in read-only mode.
Other things:
- Removed not used varaibles in
MYSQL_BIN_LOG::flush_and_set_pending_rows_event.
- Set table_share->table_creation_was_logged for all normal tables.
- THD::binlog_query() now returns -1 if statement was not logged., This
is used to update table_share->table_creation_was_logged.
- Don't log admin statements in opt_readonly is set.
- Table's that doesn't have table_creation_was_logged will set binlog format to row
logging.
- Removed not needed/wrong setting of table->s->table_creation_was_logged
in create_table_from_items()
For release builds, do not declare unused variables.
unpack_row(): Omit a debug-only variable from WSREP diagnostic message.
create_wsrep_THD(): Fix -Wmaybe-uninitialized for the PSI_thread_key.
* do not allow versioned table to be without versioned (non-system) fields
* prohibit changing field versioning, when removing table versioning
* handle CREATE...SELECT as well
* remove one level of virtual functions
* remove redundant checks
* remove an if() as the value is always known at compilation time
don't pretend that "DEFAULT expr" and "ON UPDATE DEFAULT NOW"
are "basically the same thing"
1. Revert incorrect treatment of m_needs_reopen;
2. Close single instance of TABLE instead of all instances since
reopened only those that are marked for reopen.
Problem:
=======
DROP TABLE IF EXISTS was killed. The table still exists on
the master but the DDL was still logged.
Analysis:
=========
During the execution of DROP TABLE command "ha_delete_table" call is invoked
to delete the table. If the query is killed at this point, the kill command
is not handled within the code. This results in two issues.
1) The table which is not dropped also gets written into the binary log.
2) The code continues further upon receiving 'KILL QUERY'.
Fix:
===
Upon receiving the KILL command the query should stop its current execution.
Tables which were successfully dropped prior to KILL command should be
included in the binary log.
Use DEBUG_SYNC to hang the execution at the interesting point,
and then kill and restart the server externally. This will work
also with Valgrind. DBUG_SUICIDE() causes Valgrind to hang,
and it could also cause uninteresting reports about memory leaks.
While we are at it, let us clean up innodb.innodb_bulk_create_index_debug
so that it will actually test the desired functionality also in future
versions (with instant ADD COLUMN and DROP COLUMN) and avoid
some unnecessary restarts.
We are adding two DEBUG_SYNC points for ALTER TABLE, because there were
none that would be executed right before ha_commit_trans().
1. Fix DBUG_ASSERT(!table->pos_in_locked_tables) in tc_release_table();
2. Fix access of prematurely freed MDL_ticket: don't close ticket if table was not closed;
3. Fix deadlock after erroneous ALTER.
mysql_alter_table() leaves dirty table->m_needs_reopen in case of
error exit which then incorrectly treated by mysql_lock_tables().
Problem:
=======
Failed CREATE OR REPLACE TEMPORARY TABLE statement which dropped the table but
failed at a later stage of creation of temporary table is not written to
binarylog in row based replication. This causes the slave to diverge.
Analysis:
========
CREATE OR REPLACE statements work as shown below.
CREATE OR REPLACE TABLE table_name (a int);
is basically the same as:
DROP TABLE IF EXISTS table_name;
CREATE TABLE table_name (a int);
Hence every CREATE OR REPLACE TABLE command which dropped the table should be
written to binary log, even when following CREATE TABLE part fails. In order
to achieve this, during the execution of CREATE OR REPLACE command, when a
table is dropped 'thd->log_current_statement' flag is set. When table creation
results in an error within 'mysql_create_table' code, the error handling part
looks for this flag. If it is set the failed CREATE OR REPLACE statement is
written into the binary log inspite of error. This ensure that slave doesn't
diverge from the master. In case of row based replication the error handling
code returns very early, if the table is of type temporary. This is done based
on the assumption that temporary tables are not replicated in row based
replication.
It fails to handle the cases where a temporary table was created as part of
statement based replication at an earlier stage and the binary log format was
changed to row because of an unsafe statement. In this case when a CREATE OR
REPLACE statement is executed on this temporary table it will dropped but the
query will not be written to binary log. Hence slave diverges.
Fix:
===
In error handling code check the return status of create table operation. If
it is successful and replication mode is row based and table is of type
temporary then return. Other wise proceed further to the code which checks for
thd->log_current_statement flag and does appropriate logging.
MDEV-5589 commit set up a policy to skip DROP TEMPORARY TABLE binary logging
in case the target table has not been "CREATEed" in binlog (no CREATE
Query-log-event was logged into the binary log).
It turns out that
1. the rule did not cover non-existing table DROPped with IF-EXISTS clause.
The logged-create knowledge for the non-existing one does not even need
MDEV-5589 patch, and
2. connection close disobeys it to trigger automatic DROP-IF-EXISTS
binlogging.
Either 1 or 2 or even both is/are also responsible for unexpected binlog
records observed in MDEV-17863, actually rendering a referred
@@global.read_only irrelevant as far as the described stored procedure
definition *and* the ROW binlog-format are concerned.
Analysis
========
Point in time recovery using mysqlbinlog containing queries
operating on temporary tables results in an error.
While writing the query log event in the binary log, the
thread id used for execution of DROP TABLE and DELETE commands
were incorrect. The thread variable 'thread_specific_used'
is used to determine whether a specific thread id is to used
while executing the statements i.e using 'SET
@@session.pseudo_thread_id'. This variable was not set
correctly for DROP TABLE query and was never set for DELETE
query. The thread id is important for temporary tables
since the tables are session specific. DROP TABLE and DELETE
queries executed using a wrong thread id resulted in errors
while applying the queries generated by mysqlbinlog utility.
Fix
===
Set the 'thread_specific_used' THD variable for DROP TABLE and
DELETE queries.
ReviewBoard: 21833
Problem:
========
There is a possibility that there can be more concurrent DMLs While the
alter table thread is waiting for upgrading to MDL_EXCLUSIVE before commit phase.
In commit phase, InnoDB acquires dict_operation_lock and it already holds MDL_EXCLUSIVE
on the table. After that, InnoDB applies the concurrent DML logs in commit phase.
This could lead to blocking of the following things:
1) DML on the particular table (due to MDL_EXCLUSIVE on the table)
2) InnoDB DDLs (due to dict_operation_lock)
3) Purge thread, stats thread, the master thread (due to dict_operation_lock)
Fix:
====
Apply the concurrent DML logs in commit phase but before acquiring
dict_operation_lock in commit phase. It makes sure that (2), (3) can't be
blocked for longer time.
There was two separate problems:
- Aria pagecache didn't properly handle re-reading of blocks
that have given errors before (this triggered an assert)
- temporary tables that where opened several times where
not properly closed in ALTER, REPAIR or OPTIMIZE table
Other things
- Added a couple of asserts that will make it easier to
find problems like this in the future.
