"SHOW PROCESSLIST"
Analysis:
----------
The problem here is, if one connection changes its
default db and at the same time another connection executes
"SHOW PROCESSLIST", when it wants to read db of the another
connection then there is a chance of accessing the invalid
memory.
The db name stored in THD is not guarded while changing user
DB and while reading the user DB in "SHOW PROCESSLIST".
So, if THD.db is freed by thd "owner" thread and if another
thread executing "SHOW PROCESSLIST" statement tries to read
and copy THD.db at the same time then we may endup in the issue
reported here.
Fix:
----------
Used mutex "LOCK_thd_data" to guard THD.db while freeing it
and while copying it to processlist.
* use sql_mode_for_dates() where appropriate.
* always specify an argument for sql_mode_for_dates()
(future-proof. easier to notice and fix if the caller
will start using thd from a local variable or an argument)
Description:
Original fix Bug#11765744 changed mutex to read write lock
to avoid multiple recursive lock acquire operation on
LOCK_status mutex.
On Windows, locking read-write lock recursively is not safe.
Slim read-write locks, which MySQL uses if they are supported by
Windows version, do not support recursion according to their
documentation. For our own implementation of read-write lock,
which is used in cases when Windows version doesn't support SRW,
recursive locking of read-write lock can easily lead to deadlock
if there are concurrent lock requests.
Fix:
This patch reverts the previous fix for bug#11765744 that used
read-write locks. Instead problem of recursive locking for
LOCK_status mutex is solved by tracking recursion level using
counter in THD object and acquiring lock only once when we enter
fill_status() function first time.
Description:
Original fix Bug#11765744 changed mutex to read write lock
to avoid multiple recursive lock acquire operation on
LOCK_status mutex.
On Windows, locking read-write lock recursively is not safe.
Slim read-write locks, which MySQL uses if they are supported by
Windows version, do not support recursion according to their
documentation. For our own implementation of read-write lock,
which is used in cases when Windows version doesn't support SRW,
recursive locking of read-write lock can easily lead to deadlock
if there are concurrent lock requests.
Fix:
This patch reverts the previous fix for bug#11765744 that used
read-write locks. Instead problem of recursive locking for
LOCK_status mutex is solved by tracking recursion level using
counter in THD object and acquiring lock only once when we enter
fill_status() function first time.
includes:
* remove some remnants of "Bug#14521864: MYSQL 5.1 TO 5.5 BUGS PARTITIONING"
* introduce LOCK_share, now LOCK_ha_data is strictly for engines
* rea_create_table() always creates .par file (even in "frm-only" mode)
* fix a 5.6 bug, temp file leak on dummy ALTER TABLE
revno: 4559
committer: Marc Alff <marc.alff@oracle.com>
branch nick: mysql-5.6-bug14741537-v4
timestamp: Thu 2012-11-08 22:40:31 +0100
message:
Bug#14741537 - MYSQL 5.6, GTID AND PERFORMANCE_SCHEMA
Before this fix, statements using performance_schema tables:
- were marked as unsafe for replication,
- did cause warnings during execution,
- were written to the binlog, either in STATEMENT or ROW format.
When using replication with the new GTID feature,
unsafe warnings are elevated to errors,
which prevents to use both the performance_schema and GTID together.
The root cause of the problem is not related to raising warnings/errors
in some special cases, but deeper: statements involving the performance
schema should not even be written to the binary log in the first place,
because the content of the performance schema tables is 'local' to a server
instance, and may differ greatly between nodes in a replication
topology.
In particular, the DBA should be able to configure (INSERT, UPDATE, DELETE)
or flush (TRUNCATE) performance schema tables on one node,
without affecting other nodes.
This fix introduces the concept of a 'non-replicated' or 'local' table,
and adjusts the replication logic to ignore tables that are not replicated
when deciding if or how to log a statement to the binlog.
Note that while this issue was detected using the performance_schema,
other tables are also affected by the same problem.
This fix define as 'local' the following tables, which are then never
replicated:
- performance_schema.*
- mysql.general_log
- mysql.slow_log
- mysql.slave_relay_log_info
- mysql.slave_master_info
- mysql.slave_worker_info
Existing behavior for information_schema.* is unchanged by this fix,
to limit the scope of changes.
Coding wise, this fix implements the following changes:
1)
Performance schema tables are not using any replication flags,
since performance schema tables are not replicated.
2)
In open_table_from_share(),
tables with no replication capabilities (performance_schema.*),
tables with TABLE_CATEGORY_LOG (logs)
and tables with TABLE_CATEGORY_RPL_INFO (replication)
are marked as non replicated, with TABLE::no_replicate
3)
A new THD member, THD::m_binlog_filter_state,
indicate if the current statement is written to the binlog
(normal cases for most statements), or is to be discarded
(because the statements affects non replicated tables).
4)
In THD::decide_logging_format(), the replication logic
is changed to take into account non replicated tables.
Statements that affect only non replicated tables are
executed normally (no warning or errors), but not written
to the binlog.
Statements that affect (i.e., write to) a replicated table
while also using (i.e., reading from or writing to) a non replicated table
are executed normally in MIXED and ROW binlog format,
and cause a new error in STATEMENT binlog format.
THD::decide_logging_format() uses THD::m_binlog_filter_state
to indicate if a statement is to be ignored, when writing to
the binlog.
5)
In THD::binlog_query(), statements marked as ignored
are not written to the binary log.
6)
For row based replication, the existing test for 'table->no_replicate',
has been moved from binlog_log_row() to check_table_binlog_row_based().
Hook in the wait-for-prior-commit logic (not really tested yet).
Clean up some resource maintenance around rpl_group_info (may still be some
smaller issues there though).
Add a ToDo list at the top of rpl_parallel.cc
Implement facility for the commit in one thread to wait for the commit of
another to complete first. The wait is done in a way that does not hinder
that a waiter and a waitee can group commit together with a single fsync()
in both binlog and InnoDB. The wait is done efficiently with respect to
locking.
The patch was originally made to support TaoBao parallel replication with
in-order commit; now it will be adapted to also be used for parallel
replication of group-committed transactions.
A waiter THD registers itself with a prior waitee THD. The waiter will then
complete its commit at the earliest in the same group commit of the waitee
(when using binlog). The wait can also be done explicitly by the waitee.
Users can set different repplication filter rules for each replication connection, in my.cnf or command line.
But the rules set online will not record in master.info, it means if users restart MySQL, these rules will lose.
So if users wantn't their replication filter rules lose, they should write the rules in my.cnf.
Users can set rules by 2 ways:
1. Online SET command, "SET connection_name.replication_filter_settings = rules;".
2. In my.cnf, "connection_name.replication_filter_settings = rules".
If no connection_name in my.cnf, this rule will apply for ALL replication connection.
If no connetion_name in SET statement, this rull will apply for default_connection_name.
Merge of 10.0-mdev26 feature tree into 10.0-base.
Global transaction ID is prepended to each event group in the binlog.
Slave connect can request to start from GTID position instead of specifying
file name/offset of master binlog. This facilitates easy switch to a new
master.
Slave GTID state is stored in a table mysql.rpl_slave_state, which can be
InnoDB to get crash-safe slave state.
GTID includes a replication domain ID, allowing to keep track of distinct
positions for each of multiple masters.
Syntax modified to allow statements:
ALTER TABLE ADD/DROP COLUMN
ALTER TABLE ADD/DROP INDEX
ALTER TABLE ADD/DROP FOREIGN KEY
ALTER TABLE ADD/DROP PARTITION
ALTER TABLE CHANGE COLUMN
ALTER TABLE MODIFY COLUMN
DROP INDEX
to have IF (NOT) EXISTS options.
Appropriate implementations added to mysql_alter_table().
per-file comments:
mysql-test/r/alter_table.result
MDEV-318 IF (NOT) EXIST clauses for ALTER TABLE (MWL #252).
test result updated.
mysql-test/r/fulltext.result
MDEV-318 IF (NOT) EXIST clauses for ALTER TABLE (MWL #252).
mysql-test/r/partition.result
test result updated.
MDEV-318 IF (NOT) EXIST clauses for ALTER TABLE (MWL #252).
mysql-test/t/alter_table.test
tests added.
MDEV-318 IF (NOT) EXIST clauses for ALTER TABLE (MWL #252).
mysql-test/t/fulltext.test
MDEV-318 IF (NOT) EXIST clauses for ALTER TABLE (MWL #252).
tests added.
mysql-test/t/partition.test
MDEV-318 IF (NOT) EXIST clauses for ALTER TABLE (MWL #252).
tests added.
sql/field.cc
MDEV-318 IF (NOT) EXIST clauses for ALTER TABLE (MWL #252).
create_if_not_exists field added.
sql/field.h
MDEV-318 IF (NOT) EXIST clauses for ALTER TABLE (MWL #252).
create_if_not_exists field added.
sql/partition_info.h
MDEV-318 IF (NOT) EXIST clauses for ALTER TABLE (MWL #252).
has_unique_name made public.
sql/sp_head.cc
MDEV-318 IF (NOT) EXIST clauses for ALTER TABLE (MWL #252).
sql/sql_class.cc
MDEV-318 IF (NOT) EXIST clauses for ALTER TABLE (MWL #252).
create_if_not_exists inited.
sql/sql_class.h
MDEV-318 IF (NOT) EXIST clauses for ALTER TABLE (MWL #252).
create_if_not_exists inited.
sql/sql_lex.cc
MDEV-318 IF (NOT) EXIST clauses for ALTER TABLE (MWL #252).
check_exists inited.
sql/sql_lex.h
MDEV-318 IF (NOT) EXIST clauses for ALTER TABLE (MWL #252).
check_exists inited.
sql/sql_parse.cc
MDEV-318 IF (NOT) EXIST clauses for ALTER TABLE (MWL #252).
check_exists inited.
sql/sql_table.cc
MDEV-318 IF (NOT) EXIST clauses for ALTER TABLE (MWL #252).
handle_if_exists_options() added.
it's called in mysql_alter_table().
sql/sql_trigger.cc
MDEV-318 IF (NOT) EXIST clauses for ALTER TABLE (MWL #252).
check_exists instead of drop_if_exists.
sql/sql_view.cc
MDEV-318 IF (NOT) EXIST clauses for ALTER TABLE (MWL #252).
check_exists instead of drop_if_exists.
sql/sql_yacc.yy
MDEV-318 IF (NOT) EXIST clauses for ALTER TABLE (MWL #252).
sintax modified.
The patch contributed by Konstantin Osipov applied.
Native comments:
Implement multiple user-level locks per connection.
GET_LOCK() function in MySQL allows a connection to hold at most
one user level lock. Taking a new lock automatically releases the
old lock, if any.
The limit of one lock per session existed since early versions
of MySQL didn't have a deadlock detector for SQL locks.
MDL patches in MySQL 5.5 added a deadlock detector,
so starting from 5.5 it became possible to take multiple locks
in any order -- a deadlock, should it occur, would be detected
and an error returned to the client which closed the wait chain.
This is exactly what is done in this patch: ULLs are moved
to use MDL subsystem.
The function was adjusted to be able to aggregate
the counters of the merged elements.
Before this change it was not possible to guarantee the correctness
of the counters passed to the the call-back parameter walk_action.
As a result, when some elements of a Unique object were flushed into
disk the function passed to merge_walk() as the call-back parameter
could return wrong counters of elements. This could lead to building
wrong histograms.
-Change my_rnd() slightly to make it safer if two threads use it at the same time.
-Avoid some sprintf and strmov in vio.
-Changed thread_count to be automaticly incremented (instead of under LOCK_thread_count).
-Thread cache now uses LOCK_thread_cache instead of LOCK_thread_count.
-Moved delete thd out from LOCK_thread_count.
-Save some mysql_cond_broadcast(&COND_thread_count) calls.
-Removed call to getsockname() during connect.
-Initialize random generator without locks.
Other things:
-Fixed test cases that depends on changes for LOCK_grant
-Added thread_safe_decrement32() and thread_safe_increment32()
-Removed sql_rnd_with_mutex() and get_thread_running()
-In check_table_access() don't lock LOCK_grant if we can resolve the grant with user or db level grants (the normal case).
-Don't use a lock for setting THD->query_id.
-Fixed bug where thd->set_query_id() could be set to same value by multiple threads.
Thanks to Yoshinori Matsunobu for the benchmark of connection speed and to
Domas Mituzas for the inspiration for many of the fixes.
include/violite.h:
Change desc to a string pointer
mysql-test/suite/perfschema/r/all_instances.result:
Added new mutex
mysql-test/suite/perfschema/t/func_mutex.test:
Test for LOCK_system_variables_hash instead of LOCK_grant, as LOCK_grant is not anymore always taken for SELECT's.
mysys/my_gethwaddr.c:
More DBUG
mysys/my_rnd.c:
Change my_rnd() slightly to make it safer if two threads use it at the same time.
sql/event_scheduler.cc:
Changed thread_count to be automically incremented
Moved some safe things out from LOCK_thread_count.
Simplify deleting of THD for running thread.
sql/mysqld.cc:
Changed thread_count to be automically incremented
Thread cache now uses LOCK_thread_cache instead of LOCK_thread_count
Added delete_running_thd()
Moved delete thd out from LOCK_thread_count
More DBUG
Only call mysql_cond_broadcast(&COND_thread_count) if thread_count is 0
Removed call to getsockname() (old not anymore needed check)
sql/mysqld.h:
Removed sql_rnd_with_mutex() (not needed anymore)
Removed not used function get_thread_running()
Added thread_safe_decrement32() and thread_safe_increment32()
Simplified dec_thread_running() and inc_thread_running()
next_query_id() should return the original value for global_query_id, not the next one.
(Bug introduced with MySQL 5.5 merge).
sql/sql_acl.cc:
In check_table_access() don't lock LOCK_grant if we can resolve the grant with user or db level grants (the normal case).
sql/sql_class.cc:
Removed thd_lock_thread_count() and thd_unlock_thread_count()
Initialize random generator without locks
Don't use a lock for setting THD->query_id.
(This is only accessed by thread owning the THD)
sql/sql_class.h:
Don't use a lock for setting THD->query_id.
sql/sql_insert.cc:
Changed thread_count to be automically incremented
sql/sql_parse.cc:
Changed thread_count to be automically incremented
Fixed bug where thd->set_query_id() could be set to same value by multiple threads.
vio/vio.c:
Don't generate 'desc' with sprintf/strmov. Assign a pointer instead.
(Good enough as this is just for debugging)
revid:georgi.kodinov@oracle.com-20120309130449-82e3bs5v3et1x0ef
committer: Georgi Kodinov <Georgi.Kodinov@Oracle.com>
timestamp: Fri 2012-03-09 15:04:49 +0200
message:
Bug #12408412: GROUP_CONCAT + ORDER BY + INPUT/OUTPUT SAME
USER VARIABLE = CRASH
Moved the preparation of the variables that receive the output from
SELECT INTO from execution time (JOIN:execute) to compile time
(JOIN::prepare). This ensures that if the same variable is used in the
SELECT part of SELECT INTO it will be properly marked as non-const
for this query.
Test case added.
Used proper fast iterator.
a better fix (much smaller and without regressions) is coming from 5.1
